Robust Architecture. Low Tech Design 9783955536022, 9783955536015

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EDELTRAUD HASELSTEINER

ROBUST ARCHITECTURE LOW-TECH DESIGN Edition ∂

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Editor  Edeltraud Haselsteiner Authors  Thomas Auer, Gaetano Bertino, ­Edeltraud Haselsteiner, ­Anna Heringer, ­Johannes Kisser, Andrea Klinge, Steffi Lenzen, ­Bernhard Lipp, Ute Muñoz-Czerny, Eike RoswagKlinge, Ursula Schneider, Helmut Schöberl, ­Bertram von Negelein, Robert ­Wimmer, Maria Wirth, Thomas ­Zelger Project editing  Steffi Lenzen, Anne SchäferHörr (project management), Cosima Frohnmaier (project examples), Jana Rackwitz (copy editing German edition and layout), Charlotte Petereit and Selma Popp (editorial team), Sandra Leitte (proofreading German ­edition) Translation into English  Susanne Hauger, New York (US) Copy editing (English edition)  Stefan Widdess, Berlin (DE) Proofreading (English edition)  Meriel Clemett, Bromborough (GB) Cover design  Wiegand von Hartmann, ­Munich Drawings  Ralph Donhauser Production and DTP  Simone Soesters Reproduction  ludwig:media, Zell am See Printing and binding  Gutenberg Beuys ­Feindruckerei, Langenhagen Paper:  Remake Smoke 120 g/m² (cover), Magno Volume 135g/m2 (content) © 2023, first edition DETAIL Business Information GmbH, Munich (DE) detail.de

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This product was manufactured from materials originating from reputably managed, FSC®certified forests and other monitored sources. ISBN 978-3-95553-601-5 (Print) ISBN 978-3-95553-602-2 (E-book) This work is subject to copyright. All rights reserved. These rights specifically include the rights of translation, reprinting and presentation, the reuse of illustrations and diagrams, the reproduction on microfilm or on any other media and storage in data processing systems. Furthermore, these rights pertain to any and all parts of the material. Any reproduction of this work, whether whole or in part, even in individual cases, is only permitted within the scope specified by the applicable copyright law. Any reproduction is subject to remuneration. Any infringement will be subject to the penalty clauses of copyright law. Bibliographic information from the German National Library: The German National Library lists this publication in the Deutsche Nationalbibliografie (German National Bibliography); detailed bibliographic data is available on the Internet at http://dnb.d-nb.de. The contents of this textbook were researched and developed with great diligence and a conscientious effort to reflect the best available knowledge. We assume no liability for any errors or omissions. No legal claims may be derived from the contents of this book. The editor and publishers are grateful for the support for this publication provided by the Austrian research programme “Stadt der Zukunft” (City of the Future).

Contents

PREFACE Robust Architecture

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INTRODUCTION Low Tech — Utopia or Realistic Option? The Sustainable Low-tech Building Building Using Natural Materials and Local Resources

6 8 22 32

ANALYSIS Low-tech Focus: Design, Concept, System   Design Strategies   Nature-based Solutions   Climate-sensitive Construction Low-tech Focus: Building Technology    Energy Potential of the Environment   Sufficient Energy Design   Robust Building Design Low-tech Focus: Materials   Sustainable Choice of Building Materials   Recyclable Construction and Renovation Low-tech Focus: Renovation   Utilising Existing Buildings   Renovation Strategies and Concepts for Existing Buildings

36 38 40 48 52 56 58 68 72 78 78 86 92 92 98

ASSESSMENTS Low Tech in the Context of International Building Evaluation Systems and Standards Building Evaluations and Life Cycle Assessments

106 108 118

BEST PRACTICE Ten Realised Example Projects

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STRATEGIES Planning and Design Strategies APPENDIX Picture Credits, Bibliography, Authors

180 192

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Robust Architecture

“A low-energy policy allows for a wide choice of lifestyles and cultures. [...] If, on the other hand, a society opts for high energy consumption, its social relations must be dictated by technocracy, and will be equally distasteful whether labelled capitalist or socialist.” [1]    Ivan Illich

What are responsibility and equity in construction? And does the issue not go beyond this, requiring a limitation to more modest means, a reversion to local building traditions and the potentials of simplicity?

appropriate ventilation flaps can be used to heat other living spaces next to or above it. Long-lasting wood protection is provided by appropriate constructive means, such as large roof overhangs. This is obviously simple, yet functional, aesthetic, intrinsically valuable and extremely efficient in multiple respects. But the farmhouse is not the only building that works like this. Observations of old stone houses in Wales and Tuscany as well as clay buildings in East Asia and Africa yield similar insights. Built with craftsmanlike precision, using whatever was locally available, these houses are geared toward actual requirements and optimised for relevant weather conditions. For this reason, a lot of these houses are still around, and have stood the test of time remarkably well in many respects.

Take a centuries-old farmhouse in the Alps, built according to the artisanal tradition of solid timber from the surrounding forest. It is situated so that the location allows for an orientation optimised against weather influences and capable of withstanding other adverse conditions (e.g. the danger of winter avalanches) as much as possible. The ground plan concept varies with size, but as a rule boils down to what is necessary to accommodate a residence and livestock under one roof, so that in winter the living spaces adjacent to the livestock pens can benefit from the animals’ body heat. The kitchen and its hearth are positioned so that

Nowadays, placing even a single opening into a building envelope in accordance with standards has become a science. Aside from a knowledge of diverse rules and regulations, it generally requires specialised technical literature offering pages-long guidance. Last but not least, the users need voluminous handbooks to operate the buildings in compliance with the rules. This seems absurd, but is in many regards a feature of contemporary practice – all around the world, in fact. Thanks to globalisation, industrialisation and rationalisation of building production, traditional building culture and its associated knowledge and crafts-

The energy transition today can only succeed with some measure of technology. The dependencies that Ivan Illich presented are therefore unavoidable. Central to his thoughts on Energy and Equity [1], however, is the reduction of the per-capita energy allotment to a level that does not exceed the amount critical to societal wellbeing. Low-tech design and robust architecture, as elucidated by this publication, take up this question. The hope that technology represents the sole solution for the climate crisis, on the other hand, relegates the responsibility to future generations.

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The basic reflections and the idea for this publication were created during a study sponsored by the research programme “Stadt der Zukunft” (City of the Future) by the Austrian Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK). The editor thanks the sponsor for its support and the publisher for the chance to realise this project as well as for the excellent collabo­ration during its creation.

Notes [1]  Illich 1978 [2]  Rosa 2016

manship have gradually been lost. The ­separation of ground plan and facade and the detachment from locally anchored and ­traditional building methods have led to a building method that is supposedly egalitarian. The use of “smart technology” in the building sector has removed the effort to produce heat and fresh air from human activity. At the same time, demand for comfort and expectations of year-round uniform comfort levels have risen, while the willingness to work with n ­ atural seasonal or weather-related tem­perature fluctuations and cycles has fallen. Conversely, increasing sensory overload and the accelerating pace of living have led to a growing desire for sensory experiences and resonance [2]. We want experiences such as a fire in a log burner that slowly warms a room. As glass high-rises in desert regions, specialised high-tech facades in salt-laden sea air and oversized villas in the sprawling developments outside metropolitan centres arise, gobbling fossil fuels for air conditioning, paving over large tracts of land and leading to exploding maintenance costs, the question to ask is whether this building approach is really sensible in the long term. How is it possible that all the energy-saving measures implemented over the last few decades have led to the consumption of ever more energy? And in these days of ­climate and energy crises, is it not high time to return to locally adapted and needoriented building methods in order to arrive, if possible, at a new, robust architecture? An architecture that meets today’s requirements and demands for comfort, but that once again guarantees long-lived, intrin­ sically valuable buildings – or better yet: restores the value of existing buildings – by taking into account simple low-tech parameters. Resilient buildings of natural materials

that do not end up in hazardous waste landfills at the end of their service life, but whose components are rather reused or allocated to biological material loops. That would be wonderful! Low-tech design is intended to pull the value of natural building materials and buildings, a high regard for craftsmanship and a conscious appreciation of nature and our ecosystem more solidly into focus. With this in mind, we have gone in search of reliable criteria, scrutinised design processes and found exemplary projects that show that this method of building is not only possible, but actually even relatively simple. Low-tech construction can be much more than – as is commonly assumed – just foregoing automatic ventilation. However, the examples also illustrate that, in view of existing norms, standards and funding guidelines, low-tech buildings are possible only after a careful assessment by the clients of the costs and risks involved. The only way to exit from the spiral of energy dependence is via a sweeping paradigm shift. We need robust architecture that lasts a long time, consumes few resources and is needoriented and resilient. We need it so that the building sector will soon no longer be responsible for immense energy consumption and waste removal costs. We need it so that, from an architectural perspective, we can look forward to a positive future. Edeltraud Haselsteiner & Steffi Lenzen July 2022

Robust Architecture

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Introduction

Low Tech — Utopia or Realistic Option?   Is energy-efficient technology a solution for climate change?   Eco tech, low tech, high tech   Sufficient building concepts and rebound effects   Designs for users, scrutiny of needs and basic requirements in building   Building within the context of nature, health and tradition

8 8 10 13 17 18

The Sustainable Low-tech Building   System limits and the role of technology in the life cycle   Low-tech design strategies as a holistic approach to solutions   Low-tech matrix

22 22 25 27

Building With Natural Materials and Local Resources

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About 4,000 used ­timber window frames from all EU countries form the approx. 3,000 m2 area of the glass facades on the administrative headquarters of the Council of the European Union in Brussels (BE) 2015, Philippe Samyn & ­Partners with Studio Valle and BuroHappold

Low Tech — Utopia or Realistic Option?

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Low Tech — Utopia or ­Realistic Option? Edeltraud Haselsteiner

“A system is efficient if it functions well in the sense that its output is high in relation to its input.” [1] Increasingly, buildings resemble complex systems, in which the required “output” is reduced to energy efficiency parameters and contrasted with investment costs. The potentials of the location and the architecture itself, as well as a conscious look at the needs of the users, are often given short shrift in these purely economic considerations. Robust architecture and low-tech design attempt to reveal alternative paths to sustainable construction that are oriented towards the long term. The need to phase out fossil fuel energy entirely is incontrovertible in the face of the challenges posed by climate change. Beyond this, robust architecture has pushed the potential of simplicity, the consideration of regional economic cycles and local resources as well as the interaction between architecture and its users back into more intense focus. In principle, low-tech design does not oppose technology, but rather tries to integrate it more efficiently. The critical issues of equitable distribution, social responsibility and behaviour patterns in daily life are solved through new forms of socio-economic networks and ecological cycles. Is energy-efficient technology a solution for climate change? In our efforts to succeed in making the necessary transition into a post-fossil-fuel age, great faith is placed in technical solutions and innovations that have yielded con­

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siderable progress in energy-efficient technology and energy conversion in recent decades. Based on these technological advances, building concepts in the construction sector are now possible in which more energy is produced on balance per year than is consumed. Climate-neutral or rather climate-positive design and building are increasingly becoming the required standard. Because of a lack of balance among energy savings, costs and user comfort, however, these primarily technology-driven developments have also generated numerous points of criticism. • Cost escalation and high investment expenditure for building technology: In terms of growing construction costs, building technology is seen as a substantial cost driver. In the past 20 years, cost increases of 45 % have occurred in technical building equipment (TBE) alone [2]. Savings in energy costs for heating and hot water therefore come up against high investment costs that are amortised only over the (very) long term. • Complexity, a lack of quality assurance in design and execution, cost and component savings without regard for the overall concept: Often, missing quality control during construction or cost-saving mea­ sures lead to construction flaws or reduced functionality relative to the efficiency cri­ teria projected in the design. Because of the technological complexity, coordi­ nation and collaboration among the various

building trades take on a key role. Comprehensive specialised knowledge is necessary in order for this multilayered task to be properly accomplished. Such expert­ ise is available only from highly specialised companies; it is not generally found in conventionally trained construction site management. Furthermore, in the course of construction, cost-saving measures ­frequently become necessary, so that designed and intended components are installed not at all or only on a reduced scale. The results of completed monitoring studies show that these savings come at the cost of a functioning overall concept, and in the worst case make the originally fixed design goals unachievable. • Long adjustment periods: Experience shows that it often takes an adjustment period of one to two years for the building technology to be adapted to the ­operational needs of the users. If insufficient time is allotted to this adjustment process, efficiency potential will often remain untapped, or users may be dissatisfied because the controls for heating, ventilation and shade are not optimally adapted to company operations. • Specialised staff, high maintenance costs and uncertainty about the procurement of replacement parts: Maintaining complex building technology or replacing individual components in case of damage often requires specialist professionals. The costs for this kind of expert service and

repair work not only underlie significant price increases due to growing staff and procurement costs, but are also difficult to calculate in advance. Moreover, most technical building components are manufactured outside of the European sphere. This generates uncertainties associated with delivery costs, delivery times and supply chain bottlenecks. • Reduced lifetime of electronic building components: An additional concern is the shorter service life of technical components, control and feedback control systems (sensors, electronics, etc.) when compared to the building itself. For example, while components of heat ­generators and burners have a reported nominal lifetime of ten years, the lifetime of the actual building structure should be a multiple of that. • “Uncertain constraints”: Savings due to more efficient technology are com­ pensated for by rebound effects in user behaviour. The user behaviour in the ­category of “uncertain constraints” contributes the greatest proportion of this. In the long term, it is advisable to factor in 50 % for rebound effects [3]. • Health considerations: Health issues connected with airtight building envelopes and the use of ventilation systems are drawing increasing attention. Because of their reliance on air impermeability, energy-efficient building methods necessarily go hand-in-hand with an antimicrobial interior climate, which among other

Low Tech — Utopia or Realistic Option?

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Abbildung 29 (links): Grundrisse NullheizenergieHaus Trin. Abbildung 30 (unten): Schnitt.

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Abbildung 31 (ganz unten): Ansicht von Südost.

1 Direct solar-gain zeroenergy houses, Trin (CH) 1994, Andrea Rüedi. The solar buildings in Trin are considered pioneering structures in solar architecture. They cover all heating requirements through incident solar radiation and passive

thermal storage. Largescale glazing of the south facade, a directly sun-exposed floor of polished and dark-­ coloured concrete as well as indirectly heated solid walls and ceilings of limestone make houses without conventional heating possible.

things is seen as responsible for the rise in allergies [4]. Increasingly, planners and architects are tending toward a stronger reduction of “technology”, instead favouring low-tech design over highly complex, automationand technology-dependent building concepts. Eco tech, low tech, high tech In the 1970s, as a reaction to the oil crisis of that era, the first reform movements toward an environmentally oriented low-tech architecture were created. Their goal was to present an ecologically sound alternative to the expansive and increasingly industrially oriented building industry. The countertrend was expressed primarily in the form of do-it-yourself initiatives in residential construction, based on environmental building methods using natural materials. This first “energy crisis” also brought the issue of ­forward-looking concepts for energy supply into the consciousness of broad swaths of the population. The first attempts to experiment with thermal collectors in self-build groups eventually resulted in a broad and extremely successful DIY initiative for solar collectors. While the potential of passive solar-energy utilisation was recognised quite early in architectural circles, the first step toward solar technology was taken with the implementation of solar collectors. Since then, the development of “eco or green technology” has progressed by leaps

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and bounds. In pursuit of maximum energy efficiency, passive-house building concepts were developed in which heat loss is sig­ nificantly reduced thanks to a completely airtight building envelope. The building functions using automated ventilation but no conventional heating. The energy response of a building due to climatic conditions, its structural form or its usage can now be determined very precisely through building simulations. Meanwhile, owing to advances in energy efficiency technologies, even positive-balance plus-energy buildings are now possible. Energy-saving construction In the early 1990s, climate engineering and new computer simulation options were linked with a revolutionary change in building design: “With the aid of computer simulations, we are in a position to adapt buildings to natural energy flows. New concepts of passive modulation can be developed. The implementation of novel technologies during the design can make technology in the finished building largely unnecessary. Intelligent design makes the building itself into a climate device: Rooms become v­ entilation channels, windows and doors become valves, ceilings turn into light reflectors and facades into heaters.” [5] Developments of recent years, however, have pointed in a different direction. Today, technology largely makes up for caprice in design. A comfortable interior

READ = Renewable Energies in Architecture and Design. The text was developed by Thomas Herzog in 1994/95 within the framework of a READ Project of the European Commission DG XII, and the wording was discussed and agreed upon in collaboration with leading European architects.

a 2 a— b  Autonomous energy residence, Maladers (CH) 2011, Matthias Stöckli Architektur. Building upon the first experimental solar houses by Andrea Rüedi in Trin, numerous successor structures were created that furthered the development of autonomous energy construction and solar architecture. The building concept relies on direct solar gain with thermal storage in floors, walls and ceilings and natural thermal lift. A photovoltaic array on the south side delivers electricity; cooking is done with wood only in winter, otherwise with solar electricity.

­ limate, lighting and heated spaces can c be produced anywhere, regardless of the surrounding conditions and outdoor climate. The prevailing question is not one of feasibility, but rather of cost and the affordability of comfort. But the initial approaches to energy-efficient building in the early 1990s were based strongly on building concepts optimised for the passive use of solar energy or environmental cycles without the implementation of technology. The preamble of the “European Charter for Solar Energy in Architecture and Urban Planning”, adopted by the READ (Renewable Energies in Architecture and Design) Group in 1996, reads: “Roughly half of the energy consumed in Europe is used to run buildings. A further 25 % is accounted for by traffic. Large quantities of non-renewable fossil fuel are used to generate this energy, fuel that will not be available to future generations. The processes involved in the conversion of fuel into energy also have a lasting negative effect on the environment through the emissions they cause. In addition to this, unscrupulous, intensive cultivation, a destructive exploi­ tation of raw materials, and a worldwide reduction in the areas of land devoted to agriculture are leading to a progressive diminution of ­natural habitats. This situation calls for a rapid and fundamental reorientation in our thinking, particularly on the part of planners and institutions involved in the process of construction. The form of our future built environment must be based on

b

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a responsible approach to nature and the use of the inexhaustible energy potential of the sun. The role of architecture as a responsible profession is of far-reaching significance in this respect. Architects must exert a far more decisive influence on the conception and layout of urban structures and buildings, on the use of materials and construction components, and thus on the use of energy, than they have in the past. The aim of our work in the future must, therefore, be to design buildings and urban spaces in such a way that natural resources will be conserved and renewable forms of energy – especially solar energy – will be used as extensively as possible, thus avoiding many of these undesirable developments.” [6] Energy-saving building concepts of the 1990s were characterised by their ambition to make optimal use of the sun as an energy source and to establish a “solar architecture”. In this context, the direct solar-gain houses in Trin and subsequent buildings are considered pioneers of solar architecture (Figs. 1 and 2). By now, the implementation of components for the utilisation of solar energy is an inherent partt of every design. However, the focus has noticeably shifted from an architecture and design oriented toward solar gains to the solar technology itself. That is to say that building concepts are usually reduced to “making room” for technical components for the use of solar energy, solar collectors and PV panels.

Low Tech — Utopia or Realistic Option?

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Summer

Spring, autumn, sunny winter days

Winter

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Robust low-tech architecture After a phase during which building technology was conceptualised primarily as a barrier against external influences, there are now also countercurrents towards simpler, more robust building concepts that are more strongly integrated with local environmental conditions. The main motivator for this trend in the direction of low-tech architecture, i.e. the design of lower-complexity buildings that depend less on the use of technology, is a supposedly high susceptibility to failure in high-tech buildings, with maintenance costs that are hard to calculate ahead of time and higher consumption than projected. The borders between low and high tech, however, are fluid. In general, a building is considered low-tech when it is conceptualised, designed and constructed in harmony with local environmental conditions. In addition, its operation and the creation of a comfortable interior should require as little technology as possible and should draw on locally available environmentally friendly resources. This in turn presupposes detailed knowledge of local climatic and weather conditions such as wind, humidity, sun and temperature, but also of the physical properties of materials and their interactions. Low-tech architecture represents sophisticated design taking into account local conditions. High-tech building concepts, on the other hand, function on the basis of smart building technology,

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using a high degree of automation with the goal of maximising efficiency. A study entitled “Nachhaltiges Low Tech Gebäude (Sustainable Low-Tech Building)” [7] undertaken by the University of Liechtenstein analysed texts and summarised the various ideas they associated with the terms “high tech” and “low tech”: Hightech buildings are more frequently linked to an intricate, complex and cost-intensive construction method and building technology. These make an above-average building standard and comprehensive functionality possible. However, maintenance and repairs require sophisticated processes and specialist expertise. It is also considered probable that the building technology will have a shorter life expectancy. Low-tech buildings, on the other hand, represent simple, robust and therefore also longer-lasting building types and technologies. In connection with this, lower costs and modest specialised expenditures in the manufacture, operation and maintenance, but also simple and limited functionality as well as reduced quality in terms of the standard of “precision” can be assumed. The planning and investment costs for both types of building are classified as “higher than average”, though high tech’s fall into the “much higher than average” category. In order for low-tech building concepts to be implemented successfully, it is presumed that these must be in agreement with present-day standards. The critical issue is thus not so much the degree of

3 a —b Housing complex in Greve (DK) 1992, Bente Aude and Boje Lundgaard. This housing complex in Greve was designed with the premise of combining inexpensive living space with energy-saving construction. An upstream conservatory oriented toward solar gains, a middle section heated by passive heat gains and a northern-facing core separate each residential unit into three climate zones. The design provided for the full use of the entire building cross section only during the summer months, while the north zone would be fully included and lived in only in winter and the middle zone only on sunny days or in the transitional spring and fall seasons. In practice, since the middle section was provided with auxiliary underfloor heating, it is lived in year-round, which has a significant negative impact on the energy balance [11].

technology but, rather, which building concepts guarantee success in reaching longterm sustainability goals – with or w ­ ithout the use of technology. Conversely, with regard to reaching climate goals, even today’s standards must be continually reexamined, and targets must be set for a ­lifestyle that more consciously confronts the use of fossil fuels and resources. Sufficient building concepts and rebound effects Low-tech design contributes substantially to energy efficiency, in that it places sufficiency – that is, a measured handling of resources and a critical eye toward consumer behaviours – at the centre of the design. Built examples provide eye-opening evidence for how a consistent approach can result in a reduction of more than 85 % in primary energy use (see “Sufficient Energy Design”, p. 68ff.). While energy ­efficiency technology makes increasingly frugal building concepts possible, the p ­ henomenon of rebound effects, in which the responses to efficiency measures counteract the original goals, remain underestimated (see “Growth in energy demand due to rebound effects”, p. 16f. and Fig. 3). Energy efficiency strategies and climate goals in Europe Climate-related extreme weather events are on the rise and already cause more than €12 billion per year in economic losses in the European Union (EU) alone. If the Earth

warms by 3 °C relative to pre-industrial ­levels, annual losses of at least €170 billion are projected, not to mention the health repercussions for humans and the irrepar­ able damage done to the ecosystem [8]. The Climate Agreement reached in 2015 at the UN Climate Conference in Paris, which sought to limit the warming of the planet to a maximum of 2 °C above preindustrial levels and to target a temperature rise of no more than 1.5 °C, was celebrated as a milestone in international climate politics. The subsequent unambitious measures and suggestions of individual nations, on top of the economic setbacks since 2019 from managing the fallout of the Covid-19 pandemic, have moved this goal ever further away. In December of 2019, the European Commission announced the European Green Deal, which outlines the steps that could make Europe climate-neutral by the year 2050. Ursula von der Leyen, the President of the Commission, explained: “The European Green Deal is our new growth strategy for growth that delivers more than it costs us. It shows how we must change the way we live and work, produce and consume, in order to live healthier lives and make our businesses capable of innovation. We can all participate in this transition, and we can all seize this opportunity. In doing so, we will help our economy to become a global trailblazer by having it act ahead of all ­others and by having it act quickly. We are determined to succeed in the interests of

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our planet and the life it supports – for Europe’s natural heritage, for biodiversity, for our forests and our oceans. If we serve as models of sustainability and competition, we will convince other countries to keep pace with us as well.” [9] Critics of the European Green Deal fault it for being primarily economically motivated, for depending on technological systems to meet the challenges of the climate crisis, and for the fact that, unlike the “Green New Deal” in the US, it fails to consider the associated sociological issues and the transition of the entire economy to more sustainable systems. Similarly, social economist Andreas Novy points out the missing congruence with the original idea, the New Deal of the 1930s under Franklin D. Roosevelt, a social security programme that put significant equity considerations and the strengthening of public institutions front and centre [10]. A European climate law that was agreed upon in June of 2021 is meant to legally bind the EU to its goal of becoming climateneutral by 2050. At the same time, all Member States are invited to pass legally binding measures on a national level. The first intermediate goal is to lower greenhouse gas emissions by 55 % relative to 1990 levels by the year 2030. This in turn sets clear targets for the energy efficiency of buildings. The building sector (construction, use, renovation and demolition) plays a critical role in energy politics. In the EU, for example, it is responsible for 40 % of energy consumption and 36 % of greenhouse gas emissions.

A significant proportion of the energy is “wasted” in existing buildings as well. Seventy-five per cent of existing ­buildings are not energy-efficient, and a low average renovation rate of less than 1 % per year shows up one of the ­problems that must be addressed most urgently. The EU has an ambitious planning framework for achieving climate neutrality in Europe by 2050 and for adopting a ­pioneering role with respect to other nations. The EU directive for the “Energy Performance of Buildings” (EPBD), known as the EU Building Directive, specifies the minimum requirements for the evalu­ ation of overall energy efficiency within a common framework for all EU Member States. According the EU Building Dir­ ective, all new buildings built from 2021 onwards must be nearly zero-energy buildings (that is, conform to a minimum or nearzero energy standard). In order to move the ecological transition forward, another new EU initiative begun in January of 2021, the “New European Bauhaus”, will connect to the power of reform and design through the integration of art, economics and science. However, a c ­ entral theme of the ­Bauhaus, founded in Weimar in 1919 by Walter G ­ ropius, was also to reposition ­artisanal craftsmanship in the face of increasing industrialisation. To that end, ­artists and a ­ rtisans were to return to a closer working relationship with one another to usher in a renaissance of craftsmanship with contemporary stylistic ele­

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4 a—c  In 1941, Scottish-­ Swedish architect Ralph Erskine built a simple timber house that met all of his and his family’s everyday requirements on just 20 m2. Simple ­functional means were used to implement numerous practical solutions: For example, the north wall is ­additionally insulated inside by a closet, and outside by stored firewood. Indirect ­lighting in the kitchen is achieved by means of a perforated upper panel [15].

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5 a—b  PopUp Dorms, student residences, Vienna (AT) 2015, F2 Architekten. The mobile dormitory was built with the aim of providing econom­ ical living accommodations for students in Vienna, using a vacant property for the temporary structures. Each of the 75 m2-area boxes houses a group of students and features four rooms, two bathroom units and a kitchenette. Over the course of two construction stages, a total of 22 living modules including furnishings were prefabricated at a nearby plant and installed on site within one week. In distinct contrast to conventional container-based construction, these passive-house units are built to high energetic standards. Each of the modules is designed to be transported on the bed of a truck. The PopUp Dorms were relocated to a new open site in 2021 [16].

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ments. While the EU directive on the zeroenergy standard will presumably be achieved only over a long life cycle through the implementation of robust architecture and low-tech design, the basic concept of the “New E ­ uropean Bauhaus” will possibly prove to be trend-setting for low-tech design and loop-oriented construction. Need-oriented design In the conversation about sustainability, the term “sufficiency” takes its place next to “efficiency” and “consistency” as the third of the urgent strategies toward achieving the climate goals. Earth Overshoot Day, the day on which the resource budget for the current year has been used up, has been moving up continually for years. In 2021, it fell on the 29th of July, which means that it took only a little over half a year for people to consume more resources than can be regenerated. By this point in time, the world would require 1.7 Earths on average to maintain our style of living. When viewed in detail, this wasteful consumption of resources ­differs considerably from country to country. It occurs mainly at the hands of Western industrialised nations. In this calculation, if the whole world consumed like the USA, it would now need 5 Earths, Austria’s ­consumption would require 3.8 Earths and Germany’s 2.9; meanwhile, India’s ­consumption at 0.7 Earths still lags behind the world average of 1.7 Earths by quite a large margin.

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Sufficiency therefore means limiting activ­ ities that lead to excessive consumption of resources, without significantly restricting well-being or quality of life. The concept relies on a high quality-of-life valuation based on indicators such as social relationships and recreation and leisure time that are not necessarily linked to consumption. Restricting consumption and comfort requirements to a measured and moderate level does not stand in opposition to consumer-oriented living practices. The timber house built by architect Ralph Erskine illustrates that it is possible to accommodate all essential everyday needs on a footprint of only 20 m2 without sacri­ ficing comfort (Fig. 4). Recently, tiny-house concepts have again taken up this idea. However, they can only be considered truly sustainable if they reduce living space and are not built merely as an additional holiday home. In Austria alone, from 2017 to 2020, an average of 11.5 ha per day of new land area was claimed, thereby proportionately reducing biologically productive ground [12]. Temporary housing on vacant properties is one of the options for a more efficient use of ground resources (Fig. 5). In reference to building concepts, “sufficiency” means that the need for resources, materials and comfort requirements must be critically examined. It also involves avoiding frequently occurring redundancies in technical systems and in the dimensioning of materials. Furthermore, low-tech design

Low Tech — Utopia or Realistic Option?

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strategies take the approach of prioritising the individual responsibility of users over automated control and regulation, and of once again assigning greater importance to craftsmanship and manual labour. The growth of energy demand due to rebound effects Experts generally speak of both direct and indirect rebound effects. The direct rebound effect describes the immediate changes in user behaviour in response to measures or products that have been put into effect. In heating, for example, this could be reflected in a significantly higher temperature setting in indoor spaces due to energy-efficient construction. Studies show that often, after building renovations involving efficient ­insulation and building technology were completed, the comfort parameters for room temperatures rose by several degrees ­Celsius [13]. However, indirect rebound effects are becoming just as powerful. These are energy cost savings that are reinvested in other consumer goods or services. In the building sector, this most often manifests itself in more living area per resident or, for example, greater expenditure for ­transportation. Despite increasingly more energy-efficient devices and buildings, energy consumption and its associated CO2 emissions keep climbing. Studies show that only 50 % or less of the expected efficiency gains through technology actually take effect [14]. Rebound effects therefore represent a ­powerful argument in favour of low-tech design solutions. Tilman Santarius, Professor of Socio-Ecological Transformation at the Technische Universität Berlin, defines rebound effects as “efficiency-triggered growth in demand”. He differentiates between financial, economic, industrial, motiva­ tional and temporal rebound effects [17]. A financial rebound effect is one in which money that was made available through an increase in technological energy efficiency is spent instead on greater comfort requirements, increased usage rates or intensified consumption of other goods and services. Opinions diverge sharply on how great an

16

impact can be expected from direct and indirect rebound effects. However, in ­industrialised nations, values between 10 and 30 % for direct rebounds and a ­further 5 –10 % for indirect rebounds are considered responsible estimates. ­Economic rebound effects are “energy-­ production-related growth effects”, that is, they are responses to the economic growth that is attributable to increases in energy efficiency [18]. Thus far, no reliable data exists for the quantification of the active effects, which Santarius dubs the “terms of trade between capital and energy”. The industrial rebound effect describes ­secondary effects based on production increases and embodied energy. The production of energy-efficient technology itself imposes additional energy demand, which is reflected in the budget as embodied energy. Other factors that result in industrial rebound effects are the expansion of production due to efficiency-enhancing mea­ sures and investment in new products and services due to greater profits or because of a redesign of existing products “in the expectation of income effects on the part of the consumer” [19]. The phenomenon in which resource consumption rises as a result of a change in technological assessments is called a m ­ otivational rebound effect. An example of this occurs when energy-efficient products experience greater demand because of their improved social image. The last of the culprits responsible for growing resource consumption despite increasingly efficient technologies is the temporal rebound effect. On an individual as well as a societal level, purported efficiency technology allows for the redistribution of temporal resources. However, this rarely leads to a savings in resources. On an individual level, it often manifests as a densification of time, a greater number of activities packed into the same time interval; on a societal level, it is reflected in the accelerating pace of all facets of life, which brings with it an increased demand for energy. In general, energy demand also rises due to the increased mechanisation impacting every sphere of life: buildings, households, computers and mobile phones.

6 Long-term trends in winter residential ­temperatures in the United Kingdom, the USA, Japan and China. Owing to the development of district heating systems, starting in the 1950s the indoor ­temperatures in northern China began to approach those of the USA, while the temperatures in southern China, which could not profit from the development, remain at very low levels.

Indoor air temperature [°C]

Low-tech design as an effective climate strategy The growing capabilities of technology bring with them increasing expectations and greater requirements for comfort and functionality. Climate experts agree that a broad societal transition is needed in order for us to be able to reach our climate goals. They also stress that this problem cannot be solved through technology alone. The consequences of climate change can be seen as the result of an approach that is based exclusively on economic growth, proclaims the maximisation of consumption and gain as a priority and reduces the quality of life to a question of consumption. In the effort towards achieving a profound transition, lowtech design can open up a framework for new ways of thinking. Low-tech design does not mean that technology must be forgone entirely. It is more a question of integrating technology in a deliberate way, and priori­ tising not so much its feasibility but rather its use, its actual effects, its frugal approach to resources and its far-reaching repercussions with an eye to the entire life cycle and necessary climate change consequences. Annual climate reports show that western industrial nations in particular live beyond their means and consume more resources than are available (see “Need-oriented design”, p. 15f.). However, a shift in political and societal thinking and the transformation of consciousness that is necessary to deal with the climate crisis are slow in coming.

22 20 18

US living room US bedroom northern China

GB living room

16 14 12 10

GB bedroom Japan northern USA 1800 1970

southern China 1980

1990

2000 2010 year 6

Low-tech design and robust architecture, which pursue quality over quantity, offer to take things in a new direction. One of the approaches must be to reevaluate the importance of manual labour as opposed to the maximisation of consumption and gain. Another, in light of the enormous inventory of existing buildings, is to assign a much greater priority to their reuse and renovation over the construction of new buildings. Designs for users, scrutiny of needs and basic requirements in building What is a good life? What do we need to live well, without living at the expense of others? Among other factors, the restrictions put in place in the course of the Covid-19 pandemic moved the importance of social relationships back into focus. Trend researchers saw this as an acceleration of a previously existing tendency. Likewise, changes such as expressing greater appreciation for one’s own home are traced back to the pandemic [20]. Comfort and spatial needs are now geared toward the new necessity of finding an optimal combination of work and home life. This also brings with it a novel tendency toward more mindfulness. Investment is geared less toward quantity and more toward qualitative considerations; high-value natural materials are in demand. Similarly, a connection to nature is gaining importance. The age-old need for wellbeing and security is becoming more ­pronounced. Residential concepts that ­contribute actively to health and wellness are expected. A look at the past shows not only that comfort requirements and parameters have historically changed, but also that they were interpreted differently depending on their cultural and societal context. The perception of comfort has developed continually over the course of history and is based on several technological, economic, social and cultural influences [21]. In the 19th century, the term was first used for room comfort in connection with warmth, ventilation and light. Nowadays, comfort is associated with bodily and thermal well-being. Satisfaction with the room climate and temperaturerelated cosiness are the result of an adjust-

Low Tech — Utopia or Realistic Option?

17

ment process between the physical environment and subjective comfort expectations. Individual requirements and well-being are thus based on our experiences and are strongly socio-culturally influenced [22]. A study on long-term interior temperature trends in the United Kingdom, the USA, Japan and China illustrates how different the ­characteristic expectations of temperature levels have been over the past 50 years or so (Fig. 6). Though the results show that the various country-specific heat expectations are trending toward a neutral indoor winter temperature of about 21 °C, ­differences of a few degrees can still be discerned [23]. The use of technology in the building sector has made possible not only energy-efficient buildings, but also a marked increase in room comfort. This development is accompanied by growing expectations of reliable and uniform interior climate values. By now, a few empirical research studies have ­substantiated the relationship between the level of technical equipment and individual expectations [24]; a comparison between air conditioning and natural ventilation, for example, revealed differences in user attitudes. An analysis of data from an inter­ national building database makes clear that the type of interior comfort regulation (air conditioning, mixed-mode air conditioning, natural ventilation) influences the expectations of users with regard to their workplace satisfaction. In naturally ventilated buildings, good temperature conditions correlated with significantly elevated overall workplace satisfaction, and even poorly rated heating performance did not negatively impact overall satisfaction. In fully air-conditioned working environments, on the other hand, thermal conditions corresponded more directly with a negative overall workplace satisfaction rating; that is, a poorly rated interior climate had an additional negative impact on such a rating [25]. Advances in building and interior climate control technologies (heating, cooling and ventilation) have made it possible to construct buildings and to guarantee any desired comfort standards for them without regard for exterior climatic conditions and regional

18

situational factors. However, this development brings with it growing energy consumption, for which efficiency technologies alone cannot compensate. Even though positive developments can be seen, albeit slow and highly variable from country to country, 2021 was projected to have the second-highest increase in CO2 emissions since 1990 [26]. So far little is known about the degree to which reductions in comfort parameters and higher tolerances with regard to ­temperature variations in line with exterior temperatures, for example, would be accepted. Comprehensive results on user satisfaction in energy-efficient buildings are already available. However, studies investigating pared-down building concepts would be of interest, in order to obtain user statements about their minimum basic requirements of the building on the one hand, and data concerning the adaptability of users as a function of the prevailing inter­ ior climate on the other. Also missing to date are studies that specifically address the topic of “personal responsibility” for control and regulation as opposed to automated systems. Just as in all aspects of living, our ideas of comfort are derived from habits formed in the course of everyday routine. To rethink these and consequently to redefine basic requirements and demands, would be the subject of further important research. Building within the context of nature, health and tradition Today, buildings can be conceptualised and developed to fulfil functional criteria largely independently of location (apart from infrastructural connectivity considerations and spatial restrictions). This ensures that quality remains uniform regardless of climate and situational factors. However, it also results in an often-criticised compartmentalisation from natural surroundings and exterior spaces that can have negative effects on health. Regenerative design In the discourse on sustainability, this has rightly led to increasing calls to once again

7 a — b  Achleitner organic farm, E ­ ferding (AT) 2005, Preisack / Holzer / Rodleitner; Vegetation: Jürgen Frantz. The basic principles of the Achleitner organic farm – a conservationist approach to nature, a variety of employment positions in liveable surroundings and providing customers with healthy foods and valuable organic products – are reflected in the overall concept of this new building. Aside from the use of regionally sourced building materials for the structure (straw, clay and timber), large portions of the interior were ­air-conditioned using ­vegetation. The affordable straw was harvested directly from fields belonging to the organic farm or other regional operations. A plant-based air-conditioning system with hundreds of plants, running the gamut from orchids and bromeliads via diverse ferns to philodendrons, provides a comfortable indoor ­climate both in the workplace and in the sales and recreational spaces frequented by customers.

regard building within the context of an entire ecosystem. The term “regenerative design” has been attracting growing attention as an important concept for a transformative process. Regenerative sustain­ ability aims to steer away from narrow considerations of specific aspects such as energy efficiency, renewable resources and sustainable technologies and towards a holistic systemic view, as well as towards the creation of a self-regenerating social and ecological system [27]. The first use of the phrase “regenerative design” is attributed to the landscape architect John Tillmann Lyle, who introduced a “regenerative cycle” model in 1994. Essential needs of daily life, such as housing, food, water and waste management, were to be kept in a regenerative energy and material loop, so that self-generating ecological cycles can form that are capable of re-establishing themselves in the built environment [28]. Concentrating exclusively on the energy consumption or CO2 emissions of buildings merely shifts the environmental impact of the buildings from one sector to another. For this reason, regenerative principles take into account the built environment as a whole. The design process is based on continual learning and feedback, allowing man-made and natural systems to ­contribute jointly to positive changes within the ecosystem. In this context, buildings are catalysts for effecting such positive changes. The fundamental concepts of regenerative design therefore mesh with the goals of low-tech design.

a

b

7

Building with nature: Biophilic design The beneficial effect of nature and its ­positive impacts on the human psyche are undisputed. Even in built environments, people desire a connection with nature. Evolutionary biologists contend that the emotional link to nature is an innate trait. In 1984, in his book Biophilia, American biologist Edward O. Wilson explained the essential meaning of our natural affinity for life – biophilia (from the Greek “bios” (life) and “philia” (love)), the love for all living things that binds us to all other species and hence the love of nature:

“We are human in good part because of the particular way we affiliate with other organisms. They are the matrix in which the human mind originated and is permanently rooted, and they offer the challenge and freedom innately sought. To the extent that each person can feel like a naturalist, the old excitement of the untrammelled world will be regained.“ [29] Before Wilson put forward his hypothesis, Erich Fromm had already coined the term “biophilia”. In reference to Sigmund Freud’s “life drive and death drive”, Fromm presents biophilia in opposition to “necrophilia”, the love for all dead things. “Biophilia is the passionate love of life and all that is alive; it is the wish to further growth, whether in a person, a plant, an idea or a social group.” [30] While biophilia is portrayed as a normal ­biological impulse, necrophilia is contrasted with it as a psychopathological phenom­enon, which, according to Fromm “stems from stunted growth, a crippling of the spirit.” Biophilia has by now established itself as an independent design concept. The in­­ corporation of natural elements into buildings, facades or interior spaces makes greater allowance for the urgent desire for a connection to nature. The positive psycho­ logical effects of nature, such as stress reduction and a healthier room environment, are brought to the fore. Beyond this, however, nature can also make significant contributions to low-tech design. The possibilities range, for example, from the incorporation of surrounding vegetation for shading and cooling to green facades for thermal insulation to the use of plants indoors to moderate air dryness (Fig. 7) to the use of microclimatic properties of vegetation and trees in more densely built-up areas. Air impermeability and microbial diversity Microbes are invisible microorganisms that occur in inconceivable numbers in nature and in our buildings. Physician ­Walter Hugentobler calls attention to the fact that they represent an absolutely ­essential resource for our health. According

Low Tech — Utopia or Realistic Option?

19

to him, microbes are unfairly cast as purely pathogenic “bogeymen”. Without a connection to nature and without the development of a competent immune and allergy system, that is, without the interaction with the multitudinous microbes of the environment that support this development, a healthy life would be impossible [31]. Increasingly airtight buildings and vehicles will have grave consequences for health: “For 350,000 years of evolutionary history, the learning process our immune system undergoes took place in direct connection with nature, with the microbes present in the air, water, soil, fauna and flora. The rooms in the naturally ventilated houses were likewise well-networked with the microbial variety of nature. Constructions made of natural materials were not airtight, windows were used for airing out, animals were kept close by, and household dirt was pre­ sent, all of which ensured that permanent contact with microbes of the environment was maintained. [...] In less than 200 years, advances in building technology have replaced simple houses with energy-efficient, hermetically sealed HIGH-TECH buildings. Today, mechanical ventilation that filters the outdoor air, heightened cleanliness and a lifestyle removed from nature hinder the ­exchange with the natural microbiome. In our ‘building habitat’ we live in a permanent comfort climate, breathe filtered air and are surrounded by an impoverished microbial mix.” [32] Airtight building concepts, the desire for a comfortable year-round climate and an average 3 – 5 °C rise in heating temperatures thanks to increasingly energy-efficient ­building techniques result in an excessively dry indoor climate. An intended consequence of this is the prevention of negative occurrences such as mould formation and bacterial growth. At the same time, however, microbes important for the development of the immune system are eliminated, while infectious diseases, auto-immune ­diseases and allergies are on the rise [33]. The optimum humidity level for interior air lies between 40 and 60 %. Humidity values below 40 % have a negative impact on health. However, to date this issue has

20

received little attention. Hugentobler also attributes negative health effects to the increased use of “industrial products”: “While practically all natural materials are permeable and porous, industrial products are characterised by their compactness and smooth, non-porous surfaces. Natural materials absorb moisture according to their sorption isotherms and release it again in a delayed manner as the humidity drops. [...] Industrial materials are inert with respect to moisture exchange and are either dry or wet. [...] Compact, nonporous, hydrophobic and extremely smooth plastic surfaces are free of water and dirt. No harmless commensal biota can survive on such surfaces. Multi-­ resistant bacteria, however, temporarily shut off their metabolism on these surfaces, become ‘persisters’ and are therefore ­undetectable even with culturing methods. After they are transmitted through the air or by direct contact, they resume their metabolism in the moist environment of the respiratory tract or the gut of the infected individual and can trigger an ­infection.” [34] For these reasons, Hubentobler urges that buildings be “viewed, planned and operated as habitats and living ecosystems”. The correct method would make use of what is known as BioInformed Design, in which harmless, useful microbes are consciously cultivated and only the dangerous ones are suppressed. Research into ways to design interior spaces so as to encourage the growth of beneficial microorganisms while inhibiting that of microorganisms

Summer

Winter

Hay supply/vehicles Bedrooms workshop/wood Living area/kitchen livestock Cellar

8

8  Schematic longitu­ dinal section of a Black ­Forest house. Agricultural buildings of early modern times made use not only of a climate-adapted building form, but also the opportunities represented by passive ­temperature control and seasonal zoning of the floor plan. In winter months, only a few rooms adjoining the heated kitchen and the tiled stove in the “parlour” were occupied. The bedrooms above were collaterally heated by the “warm parlour”, while the full hay loft and the stable provided additional heat buffers during the winter [37].

harmful to humans is admittedly still in its early stages.

Notes  [1] Thurner 2020  [2] Endres 2020  [3] Santarius 2020  [4] Hugentobler 2020  [5] Oswalt 1994   [6]  Herzog et al. 1996  [7] Ritter 2014  [8]  European ­Commission 24 Feb 2021  [9]  European Commission 11 Dec 2019 [10]  Novy 2021 [11]  Detail 5/1986 [12] umweltbundesamt.at [13] Biermayr et al. 2005 [14]  see Note 3 [15] Naboni 2018, p. 561– 567 [16] nachhaltigwirtschaften.at [17]  see Note 3 [18]  see Note 3 [19]  see Note 3, p. 16 [20] Horx-Strathern, Zukunftsinstitut 2020 [21] Brager, de Dear 2008 [22] Haselsteiner 2021; Haselsteiner et al. 2021 [23]  Luo et al. 2016 [24] Frontczak, ­Wargocki 2011 [25] Kim, de Dear 2012 [26] IEA.org [27] Brown 2016; Haselsteiner et al. 2021 [28]  Lyle 1996 [29]  Wilson 1984 [30]  Fromm 1974 [31]  see Note 4 [32]  see Note 4 [33]  see Note 4 [34]  see Note 4 [35]  Kuhnert 1987 [36] Hanus, Radinger, 2019, p. 6–10 [37]  Hönger 2013

Tradition and building culture “The present day is dominated by two fundamentally different ideas of building, that of the Modern age and that of reawakened tradition. They differ in their form (unbounded versus bounded space), in their building technology (high or low tech) and in their building ecology (autonomy from nature or incorporation into nature).” [35] With the Modern age, the waning years of the 19th century and advancing developments of the Industrial Revolution, society has become more and more removed from the knowledge handed down through earlier generations. Advances in technology have decreased the degree to which ­location-specific experiential knowledge based on the complex interrelationships among the natural environmental, geo­ logical and climatic conditions is necessary. Craftsmanship has likewise been increasingly relegated to the background in favour of industrial and serial production. Only with rising concerns related to local climate adaptation strategies have microclimatic or regional peculiarities begun to reinfiltrate the discussion. In the alpine regions of Europe and around the world, timber construction has a welldeserved centuries-long tradition. Wood in those places is available as a local resource in the immediate surroundings, and has proven its worth in countries with an alpine climate – that is, relatively cool summers and long, snowy winters – thanks to its excellent insulating properties. In these regions, stone and solid constructions have persevered mainly because of timber scarcity or as a response to frequent fires. In warmer and drier climatic zones, on the other hand, stone and solid constructions have established themselves as suitable building types. Characteristics such as the thermal inertia of thick exterior walls serve to seal off rooms against outdoor heat, while their thermal retention properties provide natural heating overnight. Through their proven robustness and longevity, often over several centuries, histor­

ical structures fulfil important features of ­sustainability. Beyond this, they are the bearers of historical building culture and convey knowledge about dealing with the challenges of climate and the natural environment. Tradition, craftsmanship and locally available materials formed the foundations of a building culture that was consciously attuned to the environmental and location-specific conditions. Just as import­ ant is its frugal approach to resources and space, rooted in the basic habits and requirements of people. Life cycle analyses show that the preservation of traditional historical structures also represents an important facet of sustain­ ability. Even if experience indicates that their maintenance requires more effort and expense than that of similar new buildings, because of their longevity old buildings come out ahead both ecologically and economically on the overall balance sheet [36]. This statement is vividly illustrated by the example of historical box sash windows. Expertly manufactured and carefully maintained, these can last centuries without sacrificing their functionality. Low-tech design attempts to re-establish a closer connection to the building traditions and culture of our ancestors. Knowledge of the craftsmanship of separable and structural connections between building com­ ponents can promote loop-compatible construction and building recycling. Skills in handling and incorporating locally available materials will contribute to technology savings in both the manufacturing process and in transportation, especially with regard to embodied energy. Last but not least, knowledge about climate-adapted building, passed on by word of mouth and stored in the building fabric itself, represents a valuable resource in the development of climate adaptation strategies (Fig. 8).

Low Tech — Utopia or Realistic Option?

21

The Sustainable Low-tech Building Edeltraud Haselsteiner

The goal of sustainable construction is to implement a mutually balanced combin­ ation of ecological, economic and social ­sustainability and insure its continuation over the entire life cycle of the building. To this end, sustainable low-tech building concepts question the use particularly of information and communications technology (ICT) and building automation systems as a long-term best approach to sustainable construction. System limits and the role of technology in the life cycle Though ICT systems offer options for build­ ing optimisation, their “intelligence” lies in carefully thought-out design. In his book Low-Tech Light-Tech High-Tech. Bauen in der Informationsgesellschaft (Building in the Information Society), Klaus Daniels provides the first comprehensive look at the entry of information technology into the building sector in the German-speaking sphere, an important milestone in the devel­ opment of so-called “smart” building tech­ nology: “Intelligently designed and operated build­ ings, often falsely referred to as “smart buildings”, are characterised not only by their highly interconnected information, communications and building automa­ tion systems, but primarily by the fact that they are capable of serving user needs directly from the environment, bypassing the utilisation of technical installations.” [1] In order to be able to not only maintain,

22

but properly use buildings throughout their entire lifetime requires a well thoughtout and forward-looking design concept. Energy efficiency during operations should be valued just as highly as the consumption of embodied energy or the recyclability of materials. The same is true for sustainable low-tech buildings. The overarching ques­ tion is, of course, what temporal or spatial dimensions define the limits of “low tech”. In concrete terms, it must be clarified whether the technology input should only be included when it can be directly con­ nected to the construction, operation or deconstruction of the building, or whether the technological component of the manu­ facture of the building materials and parts should also be considered. One can also differentiate between assessments in the temporal dimension, along life cycle phases, or in the spatial, according to ­distance from the building. The life cycle is roughly subdivided into four phases: Design and manufacture (raw materials) – assembly, construction and renovation – use, operation and main­ tenance – deconstruction and disposal. ­Different life cycle phases require different forms of technological input (Fig. 2). In the operations phase, a look at the tech­ nological contributions can be further sim­ plified by considering the spatial distance to the building [2]: • Technology directly in or on the building or plot (heating, ventilation system, col­ lectors, etc.)

a

b

1 a—b  Klan Kosova Television Studio, Pristina (RKS) 2017, ANARCH, Astrit Nixha. A former indus­ trial building in Pristina was renovated for the private television station TV Klan using primarily natural local materials, recycled demolition materials from the original indus­ trial building and mate­ rials from buildings destroyed in the war. An additional goal of the renovation was to create a renewed awareness of recycling and reuse.

• Amount of neighbourhood technol­ ogy required for the building (energy ­distributor, water and sewer connec­ tions, etc.) • Amount of municipal /urban technol­ ogy required for the building (energy ­supply, waste disposal and recycling, etc.) • Amount of supra-regional technology required for the building (extraction of energy source material, etc.)

2  Life cycle phases and technology used (examples)

1

With regard to the comparability and eco­ logical balance assessment, and also as a starting point for design decisions, how­ ever, this spatial categorisation provides ­little relevant information. For the following investigation of low-tech concepts, there­ fore, a material-related approach has been chosen. Significant technological contribu­ tions are those that can be proportionately attributed to a building and are either gen­ erated in the building itself or in its immedi­ ate surroundings in connection with its con­ struction, use or deconstruction throughout its entire life cycle.

Technological contributions during the design and in material/commodity production According to the estimates of international experts, the share of global emissions due to information and communications tech­ nologies (ICT) now lies in the 2.1– 3.9 % range [3]. The upper limit of this estimate for the carbon footprint of computers, ­servers and the Internet thereby exceeds the 3 % contribution (as of 2018) to global greenhouse gas emissions of planetwide air traffic. In addition, the energy ­consumption of ICT grows by 9 % annu­ ally [4]. In the absence of targeted regu­ latory measures, ICT emissions will rise. Nevertheless, the direct and indirect envir­ onmental impact of the increasing use of digital media is being constantly under­ estimated. For the past few decades, digital technolo­ gies have played an important role through­ out building planning. All design processes are now carried out with the help of CAD programs, various design software tools and electronic aids. In the past years, the use of building simulations to estimate the thermal-energetic behaviour of a build­ ing and the utilisation of Building Informa­ tion Modelling (BIM) has also increasingly become the norm. A considerable technological contribu­ tion is therefore already generated in the conceptual and design phases. The extrac­ tion of raw materials, material manufacture and transport account for further sizeable inputs due to technology. The criteria of

Design and Manufacture

Assembly, construction, renovation

Use, operation and ­maintenance

Deconstruction and ­disposal

Design: IT

Machines for excavation and site preparation

Technology linked to build­ ing use

Deconstruction planning / organisation

Technology used in extraction of raw materials

Technology used in construction, assembly and installations

Equipment and components Technology used in used in building operations, ­deconstruction and ­control and regulation (heating, ­disposal cooling, ventilation, lighting, etc.)

Technology used to produce building materials and com­ ponents

Technology used to renovate the ­building structure

Equipment and components used for upkeep and mainte­ nance

Technology employed in reutilisation, recycling, reuse, etc.

Transport of commodities and materials

Transport of people, building materials and components

Transport of people and goods for operations, upkeep and maintenance

Transport of waste, ­materials and components 2

The Sustainable Low-tech Building

23

sustainable low-tech building should there­ fore always scrutinise and factor in the ­technological share. One way to broadly reduce this share in the production of pri­ mary products and materials is to utilise materials or building elements from existing buildings (Fig. p. 6; fig. 1, p. 23). Consider­ ations such as the regional availability of building materials, as well as a carefully considered utilisation of digital technolo­ gies, should be part of the overall concept. Technological contributions from assembly, construction and renovation Because of the temporally and spatially defined framework of the construction phase, data on the technological contribu­ tion of this phase is comparatively unam­ biguous. From excavation to completion, all technologies, construction vehicles and equipment necessary to prepare the building for assembly, build it, join parts together or install components are rele­ vant. In addition, depending on the build­ ing method and the degree of prefabrica­ tion of the building components, consider­ able technological contributions can be attributed to processes at some remove from the object itself. A significant share of the construction phase technology, however, for new build­ ings as well as renovations, falls to the entire transport sector for people and goods. The removal of excavation mate­ rials, demolition materials and construc­ tion debris, as well as all the primary prod­ ucts and materials transported by truck to the construction site, generate enor­ mous CO2 emissions. Long and poorly ­coordinated transport routes cause high traffic volume with its associated signifi­ cant levels of environmental pollution. Pilot and research projects [5], such as pilot ­project RUMBA [6], demonstrate that a logistically more efficient organ­isation of the construction site on the one hand, and the use of sustainable transport options (e.g. shifting transport to railways) on the other, make significant reductions in transportation demand and a more eco­ logically compatible building site pos­sible. In reno­vations, moreover, the more mate­ rials can be reused or recycled directly

24

at the construction site, the fewer tech­ nologies or additional transport are required. Technological contributions from use, operation and maintenance In the use and operations phase, all build­ ing technology is of consequence that ­supplies fresh air, water, light and heat (or cold), removes return air, sewage and waste, and also, where applicable, pro­ vides transport within the building via lifts [7]. In addition, technology employed for the maintenance, servicing and repair of the building technology systems is also ­relevant. Increasingly, safety technology is an issue not only for offices and work­ places, but in the private sphere as well. Depending on the way the building is used, there may also be specific functions that are initiated and regulated via technical building equipment. Under the umbrella term “Smart Home” – the development of digital technologies for the automation and networked con­ trol and regulation of individual buildingtechnological processes and devices – the technological component particularly of the routine functioning and operation of devices in the home is sharply on the rise. The simple mechanical doorbell of yore is now a highly technical door security apparatus with audio and video functions to provide controlled access. Instead of the conventional opening of windows for ­airing out, sensor-driven window-opening mechanisms provide an alternative or ­supplement to ventilation systems. Tech­ nological systems are becoming “smarter” and are taking over tasks that were for­

Mining / extraction of raw materials

Production of building materials

3  Life cycle phases

Fabrication

External recycling Disposal Usage phase Processing /  reutilisation

Deconstruction / demolition

3

merly done by people. In this way, among other things, digital technologies increas­ ingly facilitate age-appropriate living in the same residence. Ambient Assisted Living (AAL) offers technical assistance through numerous functions, such as built-in sen­ sors to detect falls and changes, or digi­ tally controlled access capabilities that allow emergency personnel entry in cases of need. The tech component of the use phase, ­however, once again raises the question of which system boundaries should be ­considered a reference point for low-tech buildings. That is to say, does the assess­ ment of technology only include that which is located directly in or on the building or on the associated property, or encompass that at a farther distance as well? Integra­ tion into local and supra-regional supply and waste removal networks (electricity, local or district heating grids, facilities ­communally managed by neighbourhood associations, etc.) show that a generally applicable sharp delineation is difficult to define. In principle, an adherence to sus­ tainability criteria should be of primary importance even beyond narrowly defined system boundaries. However, when it comes to assessing the tech component, a clear spatial boundary encompassing all technol­ ogy within the immediate surroundings of the building and clearly belonging to the property is very useful.

as the case may be, the introduction into re- or upcycling processes would already be determined and fixed in the design and construction phases. The study “Recycling­ fähig konstruieren” (Recyclable construc­ tion) [8], provides a compilation of design recommendations and a catalogue of superstructural components with which a recycling share of up to 95 % can be achieved. The results of this study and of a broad analysis on the state of technol­ ogy of existing structures and during demo­ lition and disassembly show that signifi­ cant weak spots and flaws still remain in the drive towards recyclable construc­ tion and recycling capability. It is a pre­ requisite of the successful recycling or reuse of individual building components or waste materials that construction methods and structures are chosen which allow for material separation and disassembly right at the building site during deconstruction. Comprehensive documentation of all build­ ing elements during the assembly phase would support this goal. To determine the technological compo­ nent of the deconstruction phase, the ­system boundaries can be placed so that they encompass the portion of the mate­ rials stemming directly from the deconstruc­ tion of the building at the site itself and are connected with their disposal, reuse or input into re- or upcycling processes (Fig. 3).

Technological contributions from deconstruction and disposal The fact that the demolition, disassembly and disposal of buildings and building parts generate a considerable amount of harmful greenhouse gases is often neglected in ­calculations of investment and construction costs. The goal should be – as is already being done in life cycle assessments – not to focus merely on the manufacture and integration of building components, but to incorporate the entire cycle, from the pro­ duction of the individual materials and parts through disposal or recycling, into a com­ prehensive sustainability concept. In such a concept, the eventual need for techno­ logically costly disposal or reprocessing, or,

Low-tech design strategies as a holistic approach to solutions A radical shift in thinking is needed to ­manage the threat of climate collapse. Effi­ cient building technologies alone will not be enough to promote the changes neces­ sary in the building sector to reach the cli­ mate objectives. Seen from this perspec­ tive, low tech can be considered as a social critique as well as a criticism of the prevail­ ing growth and efficiency paradigms. This critical stance toward technology is the ex­­ pression of a conscious intent to uncouple growth from the consumption of further resources, replace quantity with quality and to reconnect building more strongly with tradition and nature.

The Sustainable Low-tech Building

25

The term “low tech” in architecture is cur­ rently not precisely defined. Rather, it sig­ nals a reassessment of the assumption that technology represents a cure-all for society, and expresses an experimentation with other options through greater utilisation of nature-based solutions, the use of natural materials and a preference for analogue processes. However, this is less a complete rejection of technology per se or of its evalu­ ation in and of itself, and more about a holistic consideration of complete systems with regard to the goals of regenerative sus­ tainability. Regenerative sustainability aspires to the creation of auto-regenerating social and ecological systems. In this sense, natureand biology-based solutions, local environ­ mental resources as well as social and ­cultural potential represent the weight-­ bearing pillars of an integrated low-tech overall concept. The three aspects of sus­ tainability – ecology, economy and social concerns – form the framework. However, since regional building traditions require more personal responsibility and activity on the one hand, and represent multiple funda­ mental building blocks of low-tech building concepts on the other, an expansion of the framework to include what scientific-political discourse dubs the fourth pillar (the “cul­ tural” or “political-procedural” component of “institutions”, that is to say, “participation”) is essential [9]. Figure 4 gives an overview of examples of low-tech options that could make contributions toward the achievement of sustainability goals.

Low-tech architecture aims to maximise the use of local resources, natural elements and active principles in order to avoid the excessive consumption of energy and resources. The critical stance towards imple­ mented technology is intended to scrutinise its effective contributions to the overall sys­ tem and, with a view to the entire life cycle, demand more efficiency, social acceptance and health and well-being. Therefore, based on the four sustainability aspects, sustain­ able low-tech design can be characterised by the following basic design strategies: • Ecology = a climate and resource-­ onserving building method that broadly employs available environmental condi­ tions (climate, location and origin) for its operations and makes significant contribu­ tions to the regeneration of the ecosystem • Economy = a sufficient, robust and costeffective building method that targets a reduced technological footprint through­ out the whole life cycle (production – operation – deconstruction) • Social concerns = a needs-based and socially equitable building method that provides for an agreeable level of com­ fort, provisioning and waste removal while simultaneously eliminating potential for harm and competition with others for food for this and future generations • Participation / culture = a simple, under­ standable, locally proven building method based on personal responsibility, which promotes self-build construction, DIY maintenance and upkeep and the regional building culture

Level of impact

Aspect of sustainability Ecology

Economy

Social concerns Culture / participation

Ecosystem

Microclimate, geology, vegetation, natural resources

Location / topography

Circular ­economy

Nature / biology-based solutions

Environment / resources

Life cycle, ­renewable ­resources

Local ­resources, ­robustness

(Distribution) equity

Sharing, multiple use, mixed use

Humans

Personal responsibility

Simplicity

Sufficiency, reduction

Building culture, ­tradition 4

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4  Aspects of sustainabil­ ity and possible impact levels of low tech (examples)

A  Ecological quality ECOSYSTEM — climate, regeneration, resilience RESOURCES — form, energy, recycling systems B  Economic quality ROBUSTNESS — life cycle costs, homogeneity, quality SIMPLICITY — functionality, maintenance, servicing C  Social quality SUFFICIENCY — minimisation of requirements, area consumption, intensity of use HEALTH — natural commodities, material, relationship between humans and nature 5  Low-tech matrix (abbreviated version)

D  Participation / process quality RECYCLABILITY — flexibility of use, deconstruction, documentation RESPONSIBILITY — adaptation to climate change, (building) culture, equity

Low-tech matrix In the following sections, these individual facets will be examined in greater detail and explained by way of a comprehensive low-tech matrix (Fig. 5 and Fig. 8, p. 30f.). Location, climate and ecosystem Low-tech design strategies take a site-­ specific approach. In this approach, local environmental resources are chosen as the means or catalysts of an energy-efficient and ecological initial design. For example, depending on the site, wind, sun, soil or water could represent the resources driving a holistic approach to a supply and waste removal solution, or locally available build­ ing materials could form the foundation for the basic design of the building. In con­ trast to technology-driven concepts, which tend towards a broad compartmentalisation against environmental influences that are unstable or hard to calculate in order to ensure that comfort standards remain con­ stant, low-tech concepts rely on sufficiency and resilience. The goal is to make use of the dynamic ecological unity formed by people, building, location, nature and eco­ system and to develop optimised concepts based on it. Robustness and resource conservation High-quality building standards and con­ struction details based on structures of proven craftsmanship are guarantors of robustness and a long (service) life. Beyond this, carefully thought-out and scrupulously executed structural details can reduce the use of technologically costly building equip­

5

ment. Among the central goals are a ­sufficient and resource-conserving use of primary materials and the avoidance of emissions in all life cycle phases. This includes avoiding transport routes as well as doing without large-scale earth-moving and excavation. Additional characteristics of a low-tech design concept are material homogeneity, measures taken to reduce complexity in building details and the ­conscious decision to allow for “ageing” such as the greying of facades, as long as there are no associated impairments to the structure. Energy and supply Low-tech design relies on harnessing ­simple active principles and employing nat­ ural renewable environmental resources to supply buildings efficiently and based on a sufficient use of technology. An (energy-) efficient building method and an energet­ ically optimised form create the starting point for as low a demand as possible for additional energy in the operations phase. Site-specific factors such as microclimate and topography join regionally available energy and environmental potentials (sun, earth, groundwater, wind, internal heat sources, seasonal and daily rhythms, etc.) as well as the efficient use of natural mate­ rial and primary resource characteristics to form the supporting pillars of an energy concept based on low tech. In addition, it is important to harmonise eventual supply and removal cycles in the building with those of the surrounding buildings and the location (exhaust heat – heating / cooling, combined

The Sustainable Low-tech Building

27

6  Passive clay office building, Tattendorf (AT) 2005, Architektur­ büro Reinberg with Roland Meingast. Clay materials are known for their posi­ tive impact on the indoor climate. Highperform­ance clay plas­ ters ­regulate humidity and tangibly raise liv­ ing comfort. However, the addition of chemi­

cal substances can turn even this natural prod­ uct into non-recyclable waste after a single use. Here, clay build­ ing materials of the highest quality and free of chemical stabil­ isers were used in con­ junction with a passive house to create a pro­ totype for industrial prefabricated construc­ tion in Tattendorf near Vienna [10].

heat and power (CHP), rain / wastewater – service water, etc.) in a meaningful way. Building concepts that bring in sufficient daylight not only save on operational elec­ tricity costs, but also minimise the use of lighting technology. Operation, upkeep and maintenance Simple and easily maintained building tech­ nology is one of the central principles of low-tech architecture. Control and regula­ tion of the equipment should be manage­ able by users lacking specialist training and employing modest maintenance efforts. Interdisciplinary and integrally coordinated planning helps not only to remove redun­ dancies, but usually also raises the quality of the workmanship. The goal is to replace unnecessary complexity in building tech­ nology with a user-friendly overall con­ cept. Tech concepts for low-tech buildings should be based on proven and easilyoperated standard components. Trans­ parency in the communication of decision ­pathways and simple, straightforward instructions contribute to greater accept­ ance and cooperation by users. Sufficiency and intensity of use In order to minimise the use of technology and embodied energy during construction, sustainable low-tech building should avoid consuming additional land and sealing the ground, and should generally utilise avail­ able building substance. With regard to pro­ moting economical and resource-conserving

28

6

construction, it is important to respond to the increase in vacant buildings with lowtech design. Aside from utilising available ­building materials, reducing the usable floor area to conform to usage require­ ments is among the central points. Multipurpose rooms and shared infrastructure and resources contribute significantly to minimising area consumption and building ­technology. The use of recycled or secondhand building materials drawn from avail­ able building substance is an additional facet of sustainability. Zoning the floor plan and temperatures into temporarily and per­ manently supplied areas supports sufficient energy provision. Health and well-being Embodied energy and CO2 emissions gen­ erated through transport can be markedly reduced if locally available and traditional renewable resources and materials are used. The building technology employed for indoor airconditioning can be minim­ ised by taking advantage of the proper­ ties of building materials. In addition, by now the effects of a few select materials on a healthy indoor climate have been acknowledged (Fig. 6). Improving the ­relationship between people and nature has also been shown to promote health and contribute to improved quality of life. Vegetation and plantings enhance natural humidity both indoors and outdoors and thus minimise the supplemental use of devices and technology.

7 a—b  Building capable of being disassembled, Delft (NL) 2019, cepezed. Except for the ground slab, this building — a demon­ stration project for recyclable construction — can be completely disassembled; it can be rebuilt anywhere in its entirety, or else its parts can remain in the material cycle [11].

Notes  [1] Daniels 2000   [2]  Ritter 2014, p. 17   [3]  Freitag et al. 2021   [4]  The Shift Project  [5]  Obernosterer 2021  [6]  MD-Stadtbaudi­ rektion (Municipal Urban Develop­ ment Directorate) of the City of Vienna 2004   [7]  see note 2  [8]  Schneider, Böck, Mötzl 2011  [9] nachhaltigkeit.info [10] nachhaltig­ wirtschaften.at [11]  Detail 6/2021

a

b

Changes in usage and deconstruction A high utilisation of technology and the associated greenhouse gases during ­construction can be put into perspective by the longevity and service life of the ­building. Decisions that determine the ­feasibility of a change in usage or a recy­ clable deconstruction are taken as early as the design phase (Fig. 7). These include open-use concepts, building components and materials that can be removed and separated, in addition to exact documenta­ tion regarding the resources and materials used. The concepts that are considered the most sustain­able, however, are those that strive for the longest possible usage phase for the building. Options for retrofit­ ting, expanding or converting a building to enable a partial or complete change in usage should be factored in and given significantly more weight in a sustainability assessment.

that are adapted to site-specific condi­ tions. Social responsibility carries with it cultural responsibility with regard to build­ ing tradition, building culture and preserved experiential knowledge. Beyond this, it is important to bring our social responsibility towards economically disadvantaged regions and coming generations back into focus. Every construction measure is simul­ taneously an encroachment on the biodiver­ sity of the building site; with regard to an improved ecosystem, it should invoke posi­ tive not negative effects. Nature-based building materials that may be ecologically desirable but are socially questionable because they endanger the nourishment of human beings, must be critically reexam­ ined. Low-tech design could serve to firmly anchor fundamental aspects of construc­ tion, a return to basic needs and a reflec­ tion on one’s own actions in the social con­ sciousness again. Beyond this, however, low-tech design can also become an exper­ imental space for future-oriented concepts as positive contributions to climate stabilisa­ tion and regenerative sustainability goals.

Climate change adaptation, building ­culture, participation and responsibility It is becoming increasingly urgent in the building sector to respond to regional cli­ mate change phenomena and to take ­suitable measures and precautions. The overheating increasingly experienced by urban areas could be effectively mitigated through green spaces. In rural regions, unpredictable, capricious weather events are more and more often determining threat scenarios, which in turn could be counter­ acted by suitably robust building methods

7

The Sustainable Low-tech Building

29

A

Ecological quality

ECOSYSTEM — climate, regeneration, resilience site-based, regenerative and ecological design approach, utilising the eco-dynamic unity of a location and the interrelationships between people, buildings, nature and the ecosystem to achieve a holistic solution Climate

Holistic, ecological and regenerative design approach based on local resources and conditions, such as (micro)climatic factors (e.g. sun, bodies of water, air currents, vegetation), geology (e.g. ground consistency), topography (e.g. terrain, ground surface), etc.

Regeneration

Measures taken as a positive contribution to the restoration/improvement of a functioning (regenerative) ecosystem; that is, to avoid negative impact on and interference with functioning environmental cycles (e.g. land use, biodiversity, vegetation, water)

Resilience

Sufficiency and resilience based on climate, location, geography and existing infrastructure (e.g. regionalism, building density, connection with and utilisation of existing infrastructure, inclusion in local economic cycles)

RESOURCES — form, energy, recycling systems energy-efficient and ecological construction based on a sufficient use of technology, use of simple active principles and nature-based solutions for supplying renewable, regionally available resources, minimisation of embodied energy and avoidance of CO2 emissions ­throughout the entire life cycle Form

Energetically optimised form and orientation (e.g. micro-climatic adaptation of the form /surface / facades, amount of glazing — storage mass) Use of climatic / site-specific factors for thermal, hygienic and acoustic comfort and for natural lighting

Energy

Supply (heating, cooling, ventilation) based on natural, renewable and regionally available (environmental) energy potentials (sun, earth, groundwater, wind, internal heat sources, heating/cooling through seasonal / diurnal rhythms, etc.), observing a sufficient use of technology and optimised energy characteristics (heating require­ ments [kWh/m2a], heating load of the building [W/m2], primary energy reference value [kWh/m2a])

Recycling systems

Formation and use of possible supply and removal cycles in the building, taking into consideration surrounding buildings and the location (exhaust heat – heating / cooling, combined heat and power (CHP), rain / wastewater – service water, etc.)

B

Economical quality

ROBUSTNESS — life cycle costs, homogeneity, quality Robust overall concept executed with a view to longevity and long service life, high-value ecological and economical building standard with durable building techniques and structures of proven craftsmanship, observing sufficient resource and commodity consumption with low life cycle costs Life cycle costs

Minimisation of embodied energy and avoidance of CO2 emissions during the life cycle through short transport routes, avoidance of emissions or increased technological expenditure during construction (e.g. excavation, ­technical costs for cellar and underground floors), sufficiency in resource and material use, etc.

Homogeneity

Use of simple, durable building techniques and structures of proven craftsmanship, simple building details and superstructural components, do-it-yourself and prefabrication options, etc. Material homogeneity, reduced complexity in material choice and sufficient use of materials

Quality

Quality-ensuring measures for the prolongation of the (service) lifetime of building components by way of passive / structural building details (e.g. moisture and UV radiation protection, etc., planning for the “ageing” and “care” of surfaces, structural shading)

SIMPLICITY — functionality, maintenance, servicing Interdisciplinary and integrally coordinated simple and robust building concept, designed with user-friendly control and regulation as well as easy repair and maintenance Functionality

Low-complexity building technology and electrical cabling (e.g. installation requiring no structural engineering, open cable trays)

Maintenance

Simple upkeep and care, simple replacement and maintenance of individual components (e.g. standard ­components) without dedicated technical tools or the need for specialist assistance, minimisation of operating and maintenance costs, etc.

Operation

Simple, intuitive operation, manipulation, control and regulation by users or the provision of (automated) control and regulation via environmental factors (e.g. wind, temperature fluctuations, light intensity, humidity)

30

C

Social quality

SUFFICIENCY — minimisation of requirements, area consumption, intensity of use Economical and resource-conserving size and equipment (area, room volume, interior finish, home technology, appliances, etc.), ­minimal use of space and avoidance of additional ground sealing (with precedence given to the utilisation of existing buildings), increase in usage intensity Minimisation of needs

Utilisation of existing buildings and materials (revitalisation, conversion, recycling, upcycling, use of construction waste and secondary raw materials, etc.)

Area consumption

Minimal use of area, e.g. through a compact and optimised A / V ratio

Usage intensity

Need-based area, floor plan and equipment concept (e.g. zoning of the floor plan, climate / temperature zones, permanent / temporary supply) Taking advantage of multi-use potential and sharing and raising usage intensity

HEALTH — natural commodities, materials, relationship between humans and nature Selection and economical use of local, ecological, renewable, recyclable and robust materials with long lifetimes that contribute to health and well-being Natural raw materials

(Re-)use of locally available renewable resources and materials with high-value recycling and recyclable proper­ ties and minimal transport costs

Material

Efficient utilisation of the characteristics of existing natural building materials in a sufficient and robust building concept to minimise resource consumption (e.g. thermal storage, cooling, easy recyclability, etc.), a healthy indoor environment (e.g. hygroscopic properties) and a long lifetime (e.g. durability)

Relationship between humans and nature

Measures taken to improve the connection between people and nature as a contribution to quality of life, health and well-being (thermal, hygienic and acoustic comfort, natural lighting, natural humidity, vegetation, indoor, outdoor and recreational green spaces, etc.)

D

Participation / process quality

RECYCLABILITY — flexibility of use, deconstruction, documentation Building concept, structure and material connections that permit easy replacement of individual components and make separation-bytype and reutilisation, deconstruction and re-/upcycling of building materials or a partial or entire conversion possible Flexibility of use

Open usage area concept with maximal flexibility with regard to expansion and changes in usage Planning for retrofitting, expansion or dismantling and including adaptation options through simple (non)structural means and modest technological expenditure

Deconstruction

Building parts and / or materials with detachable connections that can be disassembled and sorted by type, ­enabling them to be utilised further as products or in some other manner

Documentation

Documentation of resources, materials and decision paths employed in the production process

RESPONSIBILITY — adaptation to climate change, (building) culture, equity Responsible overall concept as a regenerative contribution to climate change and to social equity, the promotion and advancement of quality in building culture and participation Adaptation to climate change

Precautionary measures taken against regional climate change phenomena to ensure optimal responses to environmental conditions and their changes Future-oriented, innovative concepts to contribute positively to climate stabilisation and regenerative ­sustainability goals (e.g. carbon sequestration in buildings)

(Building) culture

Inclusion / adoption of experiential knowledge represented in regional / historical building traditions Promotion and advancement of quality in building culture Participation and inclusion of users and affected parties

Equity

Equitable distribution and social responsibility, such as avoiding building materials that have the potential to endanger food availability or biodiversity, etc.

8  Low-tech Matrix

The Sustainable Low-tech Building

31

Building with Natural Materials and Local Resources An interview with Anna Heringer

You prefer to work with clay and local nat­ ural building materials, and involve the people living nearby in the design and construction process. In other words, your work as an architect is based on a close connection between cultural values, mate­ rials and also the local economy. That’s right. As a 19-year-old, I was lucky enough to work with a development organ­ isation in Bangladesh. There I learned that the most effective strategy for resilience is to look for resources right where you are and to make the best of those, without allowing yourself to become dependent on external factors. I always look for locally available materials: Clay is always avail­ able, and then there’s usually timber, bamboo or straw, etc. And what are the local energy resources? For me, manual skills are the most important energy resource. Most of the time, when we talk about energy resources, we think of oil, we think of sun and wind, etc., but we are ourselves an energy source, too, every one of us. We are a creative energy source, and we are a growing energy source – there are almost 8 billion of us. It is an age-old human need to be needed and to have good and useful work to do. Building is ­useful work. It is also beautiful work, especially with these natural materials. If we don’t use this energy source, then we may also have a social problem on our hands, unemployment. In that respect, in all projects, people are the most important energy source for me.

32

On top of that, there’s not only the local know-how, not only the local craftsmanship, knowledge or culture, but also a global creativity, global knowledge. ­Knowledge and information should not be restricted, they should be accessible ­everywhere. Some things make sense, and others can’t be used with the local resources. In the past, journeymen took to the road, so knowledge made the rounds, so to speak. And the experiences they ­gathered could then be adapted at home: “Well, unfortunately we don’t have the super stone they have in Italy near us here in Bavaria, but maybe we can use the knowhow in some other way.” The great thing about clay is that its use can be totally low tech, truly with just manual labour and no electricity at all. But it can also be used in high-tech ways, since of course in Europe you can’t have water buffalo knead the clay. That is to say, you have to develop different methods. The material stays the same, clay is 100 % soil, only the tools change. How much of a promising future do you see for clay construction in Europe? Labour is relatively expensive, so it is a very important cost factor. Yes, that is a challenge, but it has nothing to do with the materials or the labour itself, it is a problem with our economic system. If you look at manual labour as a form of energy, then it is probably the most heavily taxed form of energy. But really, oil should prob­

ably be taxed at a much greater rate, or any energy that emits CO2. Building with local, natural building materials is always workintensive, but usually carbon-neutral, so it contributes to the solution of two of our most pressing problems: Climate change and social inequality. So really, we should be saying: Get rid of the subsidies for materials such as cement, steel, aluminium, polymers, etc. and, instead of those, introduce sub­ sidies for natural materials. Or at the very least we should establish cost transparency: All of the energy used and the CO2 created in the production of materials and also in recycling processes should be in-cluded in the calculations. Concrete can only be recycled with loss of quality. You have to add a lot of cement and energy to it to get

a reasonably usable quality again. That’s why recycling doesn’t equal recyc­ling. When I recycle clay, it has the same quality as before, if not even better. And that’s just by adding water. The same thing also applies to the cost transparency of natural fibres. When an insulating material is made from petroleum – as most of the ones used nowadays are – and it is the cheapest, and natural options such as straw, hemp, sheep’s wool or reed are no longer affordable, then something is wrong. What would you suggest to establish clay construction more firmly in Europe? What would production look like? I would imagine it would work much as it

1  Rammed earth walls at the ayurvedic centre, RoSana guest house, Rosenheim (DE) 2021, Anna Heringer with Martin Rauch

1

Building with Natural Materials and Local Resources

33

2  Rammed earth walls and mud-casein floors at the ayurvedic centre, RoSana guest house, Rosenheim (DE) 2021, Anna Heringer with Martin Rauch

already does in Schlins in Vorarlberg: There’s a local clay workshop there that accepts regionally excavated material and produces large prefabricated rammed-earth components with it. The prefabricated parts are stacked up at the building site and then installed without joints using craftsmanship and manpower. Just like there are many local cement factories, because cement can’t be transported very far without setting, there should also be local clay factories to which the excavated material of each region can be delivered over short transport routes and then processed. There is certainly enough material. Instead of paying for storage, we could use clay, a wonderful, valuable resource available for free in nature, that does not generate CO2 and is not only healthy for the environment but for us humans as well. Europe has a big tradition of building with clay: In Germany, primarily in half-timbered houses, but also in the Burgenland in Austria and in France, where entire palaces are made from rammed earth. The Alhambra in Spain is partly built from rammed earth, there are buildings that are centuries old. So the limitations exist only in our heads, it’s something like a cultural blackout. Even taller buildings with five or six storeys can absolutely be built using clay construction, and that already makes very good density possible. The question is also: Do our buildings really need many more storeys, or don’t we all just lose a good sense of scale that way?

34

2

Where else do you see the need to act in order to more firmly establish con­ struction with natural building materials in Europe? In Europe, action is urgently needed in the building regulations and standards, which are very often influenced by the building industry. There are too many ­liability issues and fears are stoked. To act out of fear is not a good strategy. The central problem – I feel this very strongly – of why we do so little sustain­ able building and use so few natural ma­­ terials in Europe is really fear. When we act more out of a sense of beauty and love towards our fellow humans but also towards nature, local building methods and natural resources, then a building will quite naturally be sustainable. Beauty is a very good sustainability engine. You can use beauty and good design as a lever to convince and inspire people. These days, the EU discusses energy ­efficiency a great deal; what are your views on that? Yes, of course energy efficiency is import­ ant, but one should also look at it from an overall view. We must return to a ­contented frugality. What does that really require? Though in many ways we have achieved greater technological efficiency, we also want more, for example much more floor area in our homes. That is the ­rebound effect. We have better engines than we did 20 years ago, but our cars

The interview was conducted by Edeltraud Haselsteiner on 14 February 2022.

have also become much bigger and ­heavier. It is exactly the same in construction. This is where I see the most impor­ tant lever: Downsizing is only possible if the concept of luxury is defined as working with healthy materials and manually ­finished surfaces. I believe that the intensity of manually shaped surfaces is palp­ able, a small space does not have to feel small. Working with Martin Rauch, for ­example, I designed relatively small rooms of 14 m2, 15 m2, 16 m2 for the guest house in Rosenheim (Figs. 1–3). People who are normally used to living in large rooms live in those for two weeks. But no one feels confined, quite the opposite. The layout

and the ­materials of the rooms are carefully planned, lovingly designed and beautifully handcrafted, everything is internally har­ monised, so nothing is perceived as limiting. And the clay in its many gradations – from the satiny look of the mud plaster to the really archaic grainy rammed earth and the mud-casein floors – contributes greatly to this. Only the bathroom has finished tiles made from fired clay. I think this is the direction in which we must go, not relying so much on high tech to get a handle on the problem. A wonderful conclusion. Thanks for taking the time to speak to us.

3  Local natural materials timber, reed matting and clay at the ayur­ vedic centre, RoSana guest house, Rosenheim (DE) 2021, Anna Heringer with Martin Rauch 3

Building with Natural Materials and Local Resources

35

36

Analysis

Low-tech Focus: Design, Concept, System 38   Design Strategies40   Nature-based Solutions48   Climate-sensitive Construction52 Low-tech Focus: Building Technology 56   Energy Potential of the Environment58   Sufficient Energy Design68   Robust Building Design72 Low-tech Focus: Material 78   Choosing Sustainable Building Materials78   Recyclable Construction and Renovation86 Low-tech Focus: Renovation 92   Utilising with Existing Buildings92   Renovation Strategies and Concepts for Existing Buildings98

History museum, Ningbo (CN) 2008, Amateur Architecture Studio, Wang Shu, Lu Wenyu

37

Low-tech Focus: Design, Concept, System Edeltraud Haselsteiner

If a building is intended to require less technical equipment, the designers are ­under greater pressure to find alternate ­solutions. How the building's form and con­ cept interacts with the climate and the loca­ tion becomes the central challenge of a sus­ tainable building concept. Christian Hönger and Roman Brunner of the Lucerne Uni­ versity of Applied Sciences and Arts speak of three spatial and architectural strate­ gies to meet the requirements of climate, ­resources and energy without the utilis­ ing highly developed building technology: the savings, the gain and the evasive ­approaches [1]. Depending on climatic conditions, these three approaches can be used in different ways. With the savings ­approach, the main goal is to reduce heat losses. In accordance with the prevailing climate, surfaces are made smaller, the ­volumes of building component layers are thickened overall to allow them to act as storage mass, buildings are embedded in the ground and usage areas are re­ duced to the necessary minimum during the colder seasons. The gain approach, on the other hand, aims to make optimal use of solar energy gains. Buildings are ­oriented to maximise solar exposure and, in addition, they are “inflated” to facilitate the use of temporary spaces for seasonal transition periods or “wrapped” in an add­ itional layer to create buffer spaces. With the third approach, the evasive approach, the principles of “enclosure”, “airing out” and “roaming” determine the design. That

38

is, in these three methods, usage spaces are enclosed by a second outer enve­ lope that acts as sun protection, are venti­ lated primarily by wind and are varyingly ­inhabited depending on the time of day or year [2]. In order to clarify the challenges and ­potential of the location and the rele­ vance of the individual climate elements – solar radiation, temperature, humidity and wind – to the design, a comprehensive ­climatic analysis at the very outset pro­ vides the key to a climate-compatible ­architecture [3]. In addition, a look at the traditional building techniques of the region in question provides important ­information about possible architectural responses to encounters with climatic ­conditions at the building site. For a long time, the central European ­climate was characterised by relatively cool summers, long fair-weather periods in the autumn and cold winters. Thus, ­traditionally the buildings there are well insulated. The natural building material commonly used was timber, sometimes supplemented with masonry or clay-based bricks. In alpine regions, plenty of timber was locally available, meaning that no long transport routes were needed. It was also advantageous as an insulating mate­ rial because of its high thermal resistance and low heat capacity. Climate change and its repercussions require increasingly forward-thinking ideas about adaptation strategies. Cli­

Notes [1]  Hönger et al. 2013 [2] ibid. [3] Erber, RoßkopfNachbaur 2021; Hausladen et al. 2012, p. 8

mate change affects all regions of the world. Rising temperatures and days of excessive heat push the problem of over­ heating into the foreground, while extreme weather events with heavy rains, floods and droughts are becoming the norm. These changes affect the future of build­ ing and demand a suitable approach. The innovative solutions and judicious proceed­ ings of low-tech design and robust archi­ tecture can contribute to counteracting cli­ mate change phenomena. Natural solutions support the transition to regenerative construction (see “Naturebased Solutions”, p. 48ff.). Beyond this, however, there must be a paradigm shift

and a return to actual requirements in con­ struction. The following sections introduce concepts that respond sensibly to climate, comfort and user demands. The examples also demonstrate how buildings can “grow” or “shrink” depending on need – so that in the cold season, for example, fewer rooms have to be heated – or in reaction to chan­g­ ing requirements or usage. In order for recyclable construction and buildings to be seen as part of an ecological cycle, a future standard must be anticipated. Ultimately, practical applications can illustrate the chal­ lenges that are linked to climate-sensitive design (see “Climate-sensitive Construc­ tion”, p. 52ff.).

1 Idea workshop, Hittisau (AT) 2020, Georg Bechter Architektur. Creative utilisation of existing structure. The architect Georg Bechter refurbished an old stable using regional and renew­ able raw materials. It now functions as an office and a lab for experimenting with proprietary products.

1

Low-tech Focus: Design, Concept, System

39

Design Strategies Edeltraud Haselsteiner

Climate and location-optimised building form “You cannot implement things after the fact that were not factored in at the beginning. So if the climate is not already part of the early design phase, its influences on factors like form and typology are not taken into account and must be compensated for later with technological measures in or on the building.” [1] If technology is to be used in a meaningful way, therefore, climate is the critical design factor. The morphological configuration of the building is an especially dominant variable.

air chambers and air circulation allow these double-skin stone walls to regulate the indoor climate. The building has neither heating nor air-conditioning. Green flat roofs, rainwater recovery, electricity from the neighbouring wind farm and building materials from the excavated ground combine with additional design solutions to yield this sustainable overall concept.

Bioclimatic building on Tenerife In the south of Tenerife, one of the Canary Islands, a total of 25 bioclimatic houses were built that test the various options to address the climatic conditions of the location (Fig. 1). All the buildings are rented out on a temporary basis as holiday homes. The bioclimatic house is protected from the strong Tenerife winds by high, circular walls of volcanic stone. At the same time,

Cultural and Tourism Centre in Terrasson The creation of the Culture and Tourism Centre in Terrasson in the Dordogne marks the first time in architectural history that gabion walls have been used for their energy-absorbing mass. The unworked stone placed within the wire mesh comes from a nearby rock quarry. The building concept itself is based on the principle of a greenhouse. In winter, direct insolation heats the natural stone wall and a portion of the ground slab; in summer, water from the natural stone wall and from surrounding trees supplies evaporative cooling (Fig. 2). Openings between the walls and the glass

1 a–c  Bioclimatic building, ITER Park holiday house, Granadilla, ­Tenerife (ES) 2000, Ruiz Larrea & Asociados Low tech: Building form and surface opti­ mised to the microcli­ mate of the location, use of regional mate­ rials and excavated ground substance, ­natural regulation of the indoor climate

a

b

c

40

1

2 Cultural and tourism centre, Terrasson (FR) 1994, Ian Ritchie ­Architects Low tech: Large ther­ mal storage mass, ­optimised solar gains, natural ventilation, cooling via water ­evaporation 3 a–b Grüne Erde-Welt com­ mercial building, Pettenbach (AT) 2018, architekturbüro arkade with terrain: integral designs Low tech: Recycling of the previous build­ ing, natural lighting and ventilation via green atria, optimised and site-adapted struc­ ture

roof enable the permanent winds of this region to supply natural ventilation. House on a terraced slope in Hiroshima The concept of Stone Terrace, a single-­ family house, takes up the functional prin­ ciples of rice terraces and confers the advantages of light, water and wind for agricultural production onto architecture. The location has a humid, subtropical climate with hot summers and frequent precipitation even during the “dry” months. In summer, the building is cooled via natural thermal lift: On the north side, air that has been cooled above a pool of water is drawn in, while warm air can escape along the ceiling on the south. The sloped roof shades the inte­ rior in the summer and maximises sunlight in winter (Fig. 4). Commercial building in Upper Austria The architecture of the artisanal workshop Grüne Erde-Welt follows the central theme of the business, which is to live and operate in connection with nature and ­people (Fig. 3). The sales and workshop building stands on the site of a former building so as not to burden additional green spaces. All the concrete from the demolition was recycled and reused in the new building. The structure is optimised in many details in order to keep the ecological footprint as small as possible. Natural materials such as timber and sheep’s wool determine the building concept. The structure is nestled within a 5-ha garden complex of native plants and trees. Indoors, thirteen organ­ ically connected green atria generate an agreeable interior climate and provide natural lighting and ventilation.

4 Single-family house STONE TERRACE, ­Hiroshima (JP) 2008, Kazuhide Doi Architects Low tech: Climateand site-adapted ­architecture, use of available materials (stone masonry) and traditional building technology, natural ventilation, cooling and heating

2

a

b

forest

view onto rice field stone wall as privacy screen street

water basin

water garden

cool breeze living from the water area

3

summer sun

passive air removal

winter sun rice terrace

inner courtyard

4

Design Strategies

41

a

b

Ground plan and temperature zoning The use of energy efficiency technologies has lowered energy consumption costs. However, as a result, the maintenance of uniform temperatures throughout entire building units has become a widespread design approach, so that energy savings have been largely relativised. In order to reduce the use of technology in turn, a worthwhile strategy is to zone spaces according to different climate or tem­ perature levels, or to use spaces in vary­ ing ways adapted to different seasonal ­climatic conditions. Role models for this climate-­adapted ground plan and tem­ perature zoning can be found in autoch­ thonous construction, that is, building ­techniques developed by pre-industrial indigenous populations. For example, ­traditional building concepts in alpine regions showcase the possibilities of sea­ sonal ground plan zoning as well as archi­ tecture adapted to local, geological and ­climatic conditions (Fig. 8, p. 20). While the entire floor plan is available during the summer months, in winter the residents retreat into a few inhabited rooms. The bed­ rooms, located directly above the season­ ally heated parlour, are heated collaterally; in the winter months the stable and hay loft function as additional heat sources and insulating layers. In their very frugal use of materials, reduced reliance on simple arti­ sanal techniques and necessary econom­ ical efficiency, traditional building methods offer a treasure trove of possible solutions to passive room temperature control. Modern concepts of a sustainable architecture are shifting these ideas back into the general consciousness.

Research Centre in Barcelona At the University of Barcelona, the new building of the research centre itself became a laboratory for an innovative ­building concept (Fig. 5). The structure is a durable, cost-reduced and quantita­ tively optimised concrete construction with a high storage capacity. Its facades are clad by an equally inexpensive “bioclimatic skin”. In response to the level of insolation, ­automated controls vary the angles of the diagonally placed glass louvres. Well-­ insulated timber boxes of different sizes and shapes are positioned within the base structure and form the actual work spaces. Four inner courtyards supply the building with natural daylight and sufficient venti­ lation. The temperature management is based on the differing usage intensity of individual functional areas. Offices and ­laboratories with significant internal heat loads are situated so that other functional areas can profit from these heat sources during the winter months. In summer the heat is dissipated. The transitional spaces are exclusively passively cooled or heated.

42

c

Solar Decathlon The LISI house was the Austrian entry in the Solar Decathlon 2013. A living space reduced to a minimum can be expanded to

6

5 a–c  Research centre ICTAICP, UAB campus, ­Barcelona (ES) 2011, Harquitectes + DATAAE Low tech: Different temperature zones in the building according to area function, bio­ climatic facade, optimised structure, natural lighting and ventilation, flexibility of usage 6  LISI house, Solar Decathlon 2013, Team Austria, TU Wien et al. Low tech: Modular (expandable) room, structure and building technology concepts, economical ground plan with built-in furnishings (integrated into walls), renewable raw materials

5

7 a–b Einfach Bauen (simple construction) research project, Bad Aibling (DE), Florian Nagler Architekten; wherever possible, all three test buildings are singleshell constructions – of insulating concrete (left), solid timber ­(centre) and plastered insulating bricks (right). Low tech: Reduced structure, minimal tech equipment, classical ground plan geometries and rooms 3 m high

a

b

twice its size into the adjacent patios on its north and south sides. Different “architec­ tural layers”, ranging from simple curtains to solid timber components, facilitate adapt­ able room constructions and an interplay between privacy and transparency (Fig. 6). This residence combines with innovative energy, ventilation and water supply sys­ tems to yield a qualitatively high-value, ­sustainable and efficient overall concept.

found in complex technological solutions, but that just a reduction to the simple con­ struction and design principles of the past can play a central role.

Simple construction In construction, low tech is linked to expec­ tations such as simplicity and to a con­ scious acknowledgement of austerity. A research group at the Technical Univer­ sity of Munich, headed by Florian Nagler, has spent several years investigating how a building must be constructed so that it requires little energy in winter, does not heat up unnecessarily in summer and functions well regardless of the behaviour of its users [2]. To this end, different variations of the structure were compared to arrive at “the robust optimum”. On the grounds of a for­ mer barracks in Bad Aibling, three research buildings were erected with monolithic walls of solid timber, masonry and lightweight concrete, respectively, in order to come to additional conclusions regarding further simplifications in construction (Fig. 7). In the end, comprehensive measurements and data analyses showed that, independent of materials and orientation, rooms function best when their geometry corresponds to the classic geometry of pre-war flats, e.g. about 3 m high with an area of about 6 ≈ 3 m and commensurate window sizes [3]. These results once again illustrate that strategies for sustainable building are not necessarily

7

The house-within-a-house principle Architects Francesco Buzzi and Britta Buzzi-Huppert used a special kind of reno­ vation to make the old stone stables of the small Ticino town inhabitable again. The roof of the building was removed and, in accordance with the house-within-a-house principle, a timber construction of prefabri­ cated panels was inserted into the existing ring of walls. The old granite walls serve as a storage mass and protection against the elements. Low-income housing with buffer zones Architects Anne Lacaton and Jean Philippe are both known for architectural solutions that use the simplest means and simultane­ ously generate great added value for the residents. To optimise costs and thereby create affordable housing, they prefer to employ industrially fabricated elem­ents. In addition, they like to fall back on unheated buffer zones and simple curtains. In sum­ mer, the conservatories are opened wide, preventing overheating by facilitating natu­ ral ventilation, while in winter they provide a buffer zone. At the same time, the ante­ rior placement of the conservatories allows for an expansion of the living space, espe­ cially in the case of renovations, and cre­ ates a new connection with the outdoors. A council building created by the architects in Mulhouse in 2005 is modelled on the con­ struction of greenhouses (Fig. 8, p. 44). Only part of the building is insulated and heatable,

Design Strategies

43

8

a

b

while a seasonally usable conservatory makes up the remainder.

simple building methods showcase alterna­ tive ways of building. After the first trend towards self-build initiatives in the 1970s, there is a renewed uptick in modular ­projects in the direction of joint building ventures. The prerequisites for keeping the house affordable are individual initia­ tive, a frugal use of materials and technical equipment as well as an easily imple­ mented building method. The uncompli­ cated ­workability of timber predestines the material for self-build projects. However, basic designs for concrete or steel struc­ tures that are suited to individual do-it-­ yourself construction can also be found. Approaches that used to spring from neces­ sity but are now more topical than ever, thanks in part to rising construction costs, include need-optimised designs with min­ imal footprints, the layering of usages to limit built-up areas, or the reduction of the tech­ nological building equipment to the min­ imum amount necessary to meet the require­ ments of the actual usage. Flexibility in the design of the ground plan facilitates its adaptability to changing life circumstances, and in a growing number of jointly planned residential projects, private living area is

Office building in Alpnach The administrative building in Alpnach reflects the business philosophy of a Swiss company for high-quality timber construction (Fig. 9). It is built using a proprietary solid timber system of dowel-connected boards and a multistorey solid wood construction that can be disassembled. The walls are com­ posed of several layers of boards, connect­ ed to one another via beech dowels to cre­ ate an overall thickness of 42 cm. The inner layers of this system are made from spruce of lesser quality. Because of the insulat­ ing effect and storage capacity of the solid timber, additional insulation was not needed. With the exception of the central access core of concrete, all interior finishes are ­fabricated from solid wood. Walls, ceilings and floors are clad in beech, rough-sawn or polished silver fir or silver fir timber slats. User-optimised design, self-build and adaptably sized houses Projects in which a high degree of do-ityourself construction is possible thanks to

a

44

b

c

9

8 a–b Low-income housing complexes Cité ­Manifeste and Jardins ­Neppert, Mulhouse (FR) 2005/2015, Lacaton & Vassal Low tech: Simple, industrially fabricated standard elements, ­living space expansion and bioclimatic system through anterior placement of conservatories

9 a–c  Office building, Alpnach (CH) 2020, Seiler Linhart Archi­ tekten Low tech: Disassemblycapable multistorey solid timber construction with no adhesives, solid timber walls, beech dowels used as fasteners to join individual board layers

10 Self-build residential building Wohnregal, Berlin (DE) 1986, Kjell Nylund, Peter Stürzebecher, Christof Puttfarke Low tech: Self-build system timber frame residential building 10

ceded in favour of communally shared spaces. Last but not least, collaboratively designed and built projects raise accept­ ance and the willingness to espouse even unconventional measures, such as tem­ porary renunciation of comfort or a greater share in individual commitment to main­ tenance and operations.

11 a–c Grundbau und Siedler residential building, Hamburg (DE) 2013, BeL Sozietät für Architektur, Bernhardt und Leeser Low tech: Multi-family self-build residence, inexpensive sufficient construction

Various self-build initiatives: Walter Segal German architect Walter Segal (1907–1985), who emigrated to the United Kingdom in 1936, designed a construction system for houses using lightweight prefabricated building elements. He provided detailed building descriptions, lists of materials and quantities based on conventionally avail­ able materials and dimensions, so that untrained people could inexpensively con­ struct their timber­framed houses them­ selves. He wanted his initiative to give low­ income groups in particular the opportunity to acquire residential property. In the early 1980s, two settlements based on his con­ cept were created in Lewisham (GB). In subsequent years, the “Segal method” was used and updated in the design and con­ struction of several self­build programmes

a

b

in England. Various forms of self­build initiatives spread in other countries, as well. At the 1986 International Building Exhibition in Berlin, the seven­storey Wohnregal was realised as a self­build con­ cept (Fig. 10). A co­operative of residents, contractors and architects organised the collaborative construction of two­storey timber flats within a predetermined re­ inforced concrete framework of precast elements [4]. Multi-family self-build residence Self­build initiatives are concepts practiced today that allow even families with low incomes to become home owners. For the Grundbau und Siedler project, much like in the Wohnregal project (Fig. 10), the basic load­bearing structure, complete with instal­ lation tracks and stairwells, was built during the first construction phase (Fig. 11). The future residents themselves were then able to install flats within this skeleton or “base structure” that conformed to their own pref­ erences. The “settlers” received a complete set of building components and a detailed handbook describing the implementation of the individual do­it­yourself steps.

c

11

Design Strategies

45

Erlenmatt Ost studios in Basel A new residential district is being created on the site of a former Deutsche Bahn goods railway station in Basel. The ambi­ tious sustainability concept of the new build­ ings is based on the Swiss principle of the 2000-Watt Society. In addition to values such as car-free mobility and limitations on residential area, another goal of this is to provide living space also to ­disadvantaged groups. The proposed per-capita energy reference area of 45 m2 lies about one fifth below the typical area of new buildings in Basel [5]. On this property, Delego Archi­ tekten have achieved ­studio housing with­ out heating and for a very affordable rent. The 80-cm-thick outer walls and a moder­ ate number of windows make it possible to heat the rooms purely through the waste heat generated by appliances and people. Every residential unit has a sanitary block and electricity and water hook-ups. All the surfaces remain unfinished; the residents themselves take charge of the interior design (Fig. 12). Self-build concept in London London-based architecture firm Practice Architecture realised a self-build concept based on a simple timber frame structure and hempcrete. Its focus lay mainly on low life cycle costs and as little use of embodied energy as possible. The narrow three-storey building accommodates a ­textile workshop and two flats (Fig. 13). The usage is highly flexible. The robust struc­ ture was conceived such that even unskilled workers would be able to build it. The mate­ rial for the building was chosen for its sig­ nificant carbon-sequestering capacity. In

a

46

a

b

addition, the building functions are largely self-regulating and manually controlled.

12 a—b Artist studio and ­residential building, Erlenmatt Ost, Basel (CH) 2019, Degelo Architekten Low tech: Do-it-­ yourself interior design, inexpensive, flexible and sufficient construction, no heating

Recyclable and versatile construction Low-tech design, which considers the tech­ nological input not only of the assembly and construction phase but of the entire life cycle, must broadly aim to be loop- and conversion-capable, so that the building itself or its component parts can remain ­perpetually in the material loop. In addition to the choice of materials, the design of the material connections is a critical factor. Connections that allow for disassembly, a quality-ensuring execution of the connec­ tion details as well as exact documentation of the installed building materials largely determine the life cycle of a structure [6]. These efforts are supported by standardisa­ tion, prefabrication and material homogen­ eity. In order to optimise the “usage value” of a building, that is, to achieve as long a life cycle as possible, the value and utility of the building must be secured beyond its original design and usage plans. For this reason, it is necessary to provide space and options to accommodate future requirements and to design for flexibility.

b

13

13 a—b Workshop and residences, Timber ­Weaver’s Studio, London (GB) 2017, Practice Architecture Low tech: Robust selfbuild concept, manual control and regulation, hempcrete

12

Panels 1 × 1 m in size were sawn out of these existing structures and incorporated as masonry into the facade of the new building. Further measures, such as the use of recycled timber for floor coverings and the reutilisation of glass windows, l­owered the carbon footprint of this struc­ ture by 12 % compared to conventional new construction [7].

14  Resource Rows ­housing complex, Copen­hagen (DK) 2019, Lendager Group Low tech: Recycling of building materials: brick masonry, waste timber and glass ­windows

14

At present, the permanence of property is determined not only by structural flexibil­ ity, but increasingly and more importantly by the technical and infrastructural poten­ tials for conversion and modification. Con­ vertible and therefore “mobile immobile” property can be reused and adapted over a long lifetime. It is represented by build­ ings whose minimal material expenditure and technology correspond to actual cur­ rent needs and which can be retrofitted easily and at any time to adjust to changing requirements.

Notes [1] Hönger et al. 2013, p. 9 [2]  Nagler et al. 2018 [3]  BauNetz 2021 [4]  Detail 5/1986 [5]  Detail 9/2020 [6] Schneider, Böck, Mötzl 2011 [7]  Detail 6/2021

15 a—b Commercial building De Werkspoorfabriek, Utrecht (NL) 2019, Zecc Architecten Low tech: Conversion and adaptation of an existing building with modifiable and modular units, construction compatible with disassembly

Housing complex in Copenhagen With construction of the housing com­ plex Resource Rows, the architect Anders Lendager has created an important ex­­ ample for recyclable construction (Fig. 14). He hopes that it will draw attention to the degree to which architecture is responsible for ecological solutions. His focus lies espe­ cially on the reuse of building materials from demolished structures. The residen­ tial building in the Copenhagen district of Ørestad was given a facade of brick ­panels sourced from an abandoned brew­ ery, old schools and industrial buildings.

a

Commercial building in Utrecht Next to concepts incorporating the use of materials from demolished buildings, the conversion of existing buildings is also one of the goals of recyclable con­ struction. At their Werkspoor Factory in Utrecht, Zecc Architecten converted a giant industrial warehouse into an office and event space (Fig. 15). The industrial character and the structure were largely preserved and were changed only wher­ ever it was necessary to create new func­ tional units. Within the open levels, flexible elements of timber and glass define the individual spatial divisions, which can be changed and adapted at will. The modu­ lar system is assembled without screws or adhesives and is therefore 100 % recy­ clable.

b

15

Design Strategies

47

Nature-based Solutions Maria Wirth

Definition and importance of nature-based solutions In the context of advancing global warming and adaptation to its consequences, nature-based solutions are gaining more and more importance. Natural processes such as evapotranspi­ration, which is the evaporation of water from canopies, water bodies and soil and the transpiration from plants, allow nature-based solutions to ­contribute to the cooling of indoor and outdoor spaces. The greening of buildings and adjacent areas detains and retains rainwater and absorbs surface runoff, thereby doing its part to protect buildings from high water and flash flood damage and thus increasing their robustness. In addition to its ability to store and evap­ orate water, green infrastructure, that is, the network of existing natural and artificially installed landscaping, can also sig­ nificantly reduce the energy consumption of buildings [1]. In the EU, greening 35 % of the sealed urban surfaces would de­­ crease their local summer temperatures by 2.5 – 6 °C and correspondingly lower airconditioning costs, which would otherwise rise to about €221 billion over the next 40 years thanks to the urban heat island effect [2]. Nature-based solutions thus represent sustain­able concepts for settlement and urban planning. The European Commission defines naturebased solutions as solutions “inspired and supported by nature, which are costeffective, simultaneously provide environ-

48

mental, social and economic benefits and help build resilience [...] through locally adapted, resource-efficient and systemic interventions.” [3] The following paragraphs will explore three categories of naturebased solutions: •  Greening of buildings •  Greening of the building’s location • Bioengineering Building greening systems, that is, systems integrating vegetation into the building envelope, comprise the greening of roofs and facades. The greening of impermeable surfaces such as roofs allows rainwater to be absorbed and plants to grow [4]. Green roofs can be either intensive or extensive. Intensive green roofs have a substrate layer of around 25 cm in depth and a composition similar to the soil found in nature. They are watered and fertilised [5]. Extensive green roofs, on the other hand, have a much thinner substrate of 6 –15 cm and are not watered. Green façades come in different forms, such as ground-bound systems with climbing (self-clinging) plants, or plants supported by trellises, and trough- or wall-bound systems such as so-called "living walls". The latter are mounted on the front of the facade and are rear-ventilated. They are almost always watered and fertilised through automated means, and provide an insulating effect for the building [6]. Greening of the building’s location includes the greening of the open areas surrounding

1  Innovative greening opportunities in the city

roof garden

the building as well as water-sensitive urban planning. These areas are either directly adjacent to the building or can be nearby green zones that serve to improve the urban microclimate, water management, air quality, noise pollution and biodiversity. Sustainable drainage systems next to buildings or streets can protect infrastructure and provide additional previously mentioned advantages of greening (Fig. 1). Bioengineering represents the use of vegetation or “living” materials in combination with “dead” and inorganic natural materials for the construction of green infrastructure.

Bioengineering is used for the consolidation of river beds or of hillsides and embankments threatened by erosion or landslides in order to prevent flooding, the discharge of sediment and erosion [7]. In bioengineering, “living” components (especially ­willow) and “dead” organic materials such as green waste, branches, fascines (bundles of brushwood or twigs), bush layers, tree trunks and geotextiles, as well as inorganic natural substances such as stones, are used to stabilise slopes [8] while simultaneously providing natural habitats and therefore benefitting the ecosystem (Fig. 1, p. 49).

lightweight solar industrial green roof retention green roof roof indoor roof with cultigreening vated areas care and ­maintenance vertical ­farming

rain roof water-permeable pavement

plant curtains for glazed surfaces urban ­farming

grey water treatment

biodiversity roof

roof ­garden

roof for sports and play

enlarged root climbing plants space and targeted on trellises water infiltration facade-bound direct greening greening with self-clinging climbing plants 1

Nature-based Solutions

49

a

b

2

Ecosystem benefits and resource flows Climate change is exposing cities to growing challenges. The increasing intensity and frequency of heavy rainfalls have begun to overburden many existing drainage networks. The greater frequency of tropical nights and days at the temperate latitudes and the urban heat island effect are having measurable adverse impacts on the health and well-being of the population. Greening the built infrastructure can sustainably improve drainage, bio­diversity, the groundwater budget and urban temperatures and microclimates. In Europe, energy consumption in residential and commercial buildings is responsible for over 40 % of the total energy consumed [9]. This number includes the operational energy use, that is, the energy used for heating, air conditioning, ventilation and other building operational requirements. According to an EU-wide study, greening 35 % of the surface area in cities of the EU could reduce the energy consumed in airconditioned buildings in summer by up to 92 TWh per year [10]. In temperate climate zones, overheating during the night and indoors has a particularly negative impact on the health of the population [11]. Greening of roofs and facades of buildings are the most effective nature-based solution for insulating and

50

cooling or conditioning the interior [12], and can also contribute to a significant reduction in the energy consumption of buildings, particularly in light of further ­projected temperature increases. The greening of the open spaces at the building locations is considered one of the most effective countermeasures to the outdoor urban heat island effect [13]. Greening guarantees the usability of urban public spaces even on especially hot days and indirectly prevents the inhabitants from withdrawing into air-conditioned buildings and vehicles. Available greening technologies can be implemented in various ways to provide multiple advantages and services. In the EU, converting 35 % of the sealed urban surface to green space could absorb approx. 10 km3 of rainwater per year, thus preventing combined wastewater overflows and flooding; furthermore, it would protect downstream bodies of water and limit flood damage to buildings and infrastructure [14]. Greening systems also allow street run-off to be collected, cleaned and directed to reservoirs, where it is stored and kept ready for reuse. The use of greening systems such as constructed wetlands enable to treat wastewater from residential, commercial and industrial buildings and to reutilise the water as well as contained nutrients directly or to divert it to the surrounding (urban or peri-urban) agricultural areas. As an example, the household wastewater and the compostable kitchen scraps of 77,250 people could replace the nitrogen and phosphorus fertilisers used

3

2  Examples for the use of the sponge city concept in major ­Chinese cities: a Yichun Eco-City (Yichun was named the first environmental test city in China back in 1986.) b Tianjin, along the Weijin River and the Zijinshan Road

3  Copenhagen’s first ­climate-resilient city district. The ­residents of 12–16 Brygger­ vangen have built their own urban garden, which is watered by rain.

4 4  Bishan-Ang Mo Kio Park, Singapore (SG) 2012, Ramboll Group

Notes   [1]  Kisser et al. 2020  [2]  Quaranta, Dorati, Pistocchi 2021  [3]  European Commission 2021   [4]  see note 2   [5] Pearlmutter et al. 2020  [6]  GRÜNSTATTGRAU 2021  [7] Mickovski 2021  [8]  van Hullebusch et al. 2021   [9] Gynther et al. 2016 [10]  see note 2 [11]  Buchin 2016 [12]  see note 4 [13]  see note 4 [14]  see note 2 [15]  Wirth et al. 2021 [16] The City of Vienna 2020 [17] Zevenbergen, Fu, Pathirana 2018 [18] State of Green 2019 [19]  see note 15

for the entire vegetable production of Vienna [15]. Vienna's vegetable production covers about one-third of the total ­vegetable demand of the city [16]. Nature-based solutions in urban planning concepts New urban planning concepts such as the sponge city, green urbanism, resilient cities and blue-green infrastructure utilise the cooling performance and rainwater retention of greening systems to mitigate the advancing effects of global warming. Successful examples can be found all over the world, among them several large cities in China that use the sponge city concept (Fig. 2) [17], the Bishan-Ang Mo Kio Park in Singapore (Fig. 4) and and Copenhagen’s Cloudburst Management Plan and measures for rainwater retention (Fig. 3) [18]. An expansion of the blue-green infrastructure approach merges it with conventional grey infrastructure to yield the concept of blue-green-grey infrastructure. Here, nature-based solutions or greening solutions (blue-green) are combined with grey infrastructure, that is, technical infrastructural elements such as built pipelines, canals and open spaces, etc. – in a system, for instance, in which rainwater and street run-off are infiltrated into treatment raingardens and cleaned there, stored in tanks and transported by pipes. The integration can accelerate the implementation of building greening, greening of surrounding spaces and bioengineering, as existing

infrastructures can be used as a basis. Technological path dependence (i.e., the inertia inherent to the transition to new, improved technologies because of the high construction costs of physical facilities as well as the outmoded knowledge and mindsets of relevant personnel) can be worked around when innovative bluegreen infrastructure is integrated into existing grey infrastructure. Existing municipal wastewater treatment plants (grey infrastructure) can be expanded by constructed wetlands (blue-green infrastructure) to ­further purify the treated wastewater and make it available for reuse, e.g., in irrigation. The greening of existing facades and roofs (blue-green infrastructure) can contribute to rainwater retention and relieve the burden on the municipal sewer network (grey infrastructure). In these schemes the grey infrastructure is not replaced but supplemented by the blue-green in order to benefit from combined advantages. The great potential of nature-based solutions in the adaptation to climate change is increasingly acknowledged by cities [19] and supported through subsidies and other assistance measures. The City of Vienna, for example, provides subsidies for roof and facade greening, and offers advice on the planning and implementation of such systems. Some greening measures are already legally required in several cities in Europe.

Nature-based Solutions

51

Climate-sensitive Construction Ursula Schneider

In most regions of the Earth, people need energy sources to establish comfortable conditions for themselves in buildings, namely a room temperature of 22 – 26 °C, a relative humidity of 40 – 60 % and sufficient air to breathe. While this requires relatively small amounts of energy in temperate zones such as Central Europe – provided that the buildings in question are climate-sensitive – in other places significantly more energy is needed to achieve the same comfort levels. Taking the climate into account The basic factor at the outset of every design is the prevailing climate at the building location, in which the daily and annual path of the sun is of disproportionate im­­ portance (Fig. 1). It is especially critical to ­recognise that in Central Europe, the sun rises in the east and sets in the west only in March and September; in winter, it rises in the southeast and sets in the southwest, achieving an angular elevation of about 20° over the horizon at noon. In summer, however, it rises in the northeast and sets in the northwest, and reaches 60° elevation at midday. The further north one goes, the more shallow the angle and thus the slower the progress of the setting sun as it sinks below the horizon. This contrasts starkly with conditions in equatorial regions, where the sun generally rises in the east and sets in the west throughout the year, nears or reaches zenith daily and takes the shortest route to drop vertically behind the horizon. The combination of the time period of solar

52

radiation with cloud cover, fog, haze, precipitation and wind, and the resulting ­values for the air temperature and the mean temperatures of soil and groundwater layers near the surface, represent the most important climate influences and thus limiting boundary conditions for the design. In contrast, the indoor limiting conditions are defined by the type of usage and the occupancy as well as the density of heatand cold-emitting electrical appliances. ­Living rooms, (open) offices, classrooms, auditoriums, laboratories, fitness studios: Depending on the number of people and / or appliances per m3 of room volume, heating and cooling needs as well as ventilation and (de)humidification requirements predominate. The goal of climate-sensitive design is always to use the building itself to create the greatest possible basic comfort level given the external and internal limiting ­conditions, and then to employ technology only to supplement whatever the building design cannot handle. Low-tech strategies The Central European climate demands solutions addressing winter and summer – or in any case, distinct – requirements. Adaptable technologies such as, for example, exterior shading in the form of indi­ vidually adjustable Venetian blinds instead of sun protection glazing (since the latter cannot differentiate between winter and summer) offer options in this regard.

4

N,0°

N,0°

0° 0° 10° 10° 20° 20° Sonnen4 21.06. 21.06.Sonnen15.07. 30° 30° höhe höhe 20 20 15.05. 40° 40° 5 19 19 15.08. 15.08. 50° 50° 15.04. 6 60° 60° 18 18 70° 70° 15.09. 15.09. 7 17 17 Uhrzeit 8Uhrzeit W,270° E,90° 16 W,270° 16 (MEZ) (MEZ) 15.03. 9 15 9 15 10 10 14 14 15.10. 15.10. 13 12 11 13 12 11 15.02. 15.11. 21.12.

1  Sun path diagrams a Berlin (DE) b Mombasa (KE)

15.11. 21.12.

S,180° a

15.01.

N,0° 4 5 6 7 8

15.07. 15.05. 15.04.

E,90°

15.03.

N, 0°

0° 10° 20° Sonnen30° höhe 40° Uhrzeit Uhrzeit 18 17 21.06. 18 17 21.06. 8 7 16 15 14 13 50° 12 11 1016 915 14 13 60° 15.08. 15.08. 70° 15.09. 15.09.

W,270°

W,270°

15.10.

15.10.

15.11.

15.02.

21.12.

15.11. 21.12.

0° 10° 20° Sonnen30° höhe 40° 15.07. 50° 12 11 10 15.05. 60° 15.04. 70°

E,90°

15.03. 15.02. 15.01.

15.01.

S,180°

Winter conditions In general, designers try to meet the demands of winter conditions with a building envelope of passive-house quality. If the functional and urban development ­criteria allow it, windows can be implemented specifically to facilitate passive solar energy gains and to supply generous amounts of daylight. Efforts are made to achieve as low a U-value (heat trans­ mission coefficient) and as high a VT value (visible transmittance) as possible, while the g-value (solar factor or total solar energy transmittance) is usually kept midrange at 0.5 in order to cover summer and winter conditions equally well. The goal is to gain solar energy in winter, but to avoid creating excessively high inputs in summer. In spaces in which glare would interfere with usage, internal anti-glare blinds can be used to shade the winter sun. In this way, extreme brightness is mitigated while solar heat can still be utilised. To get a significant yield of daylight through the openings and good distribution of light into the depths of the room, it is most advantageous to maximise the glass-to-frame ratio (e.g. by keeping glass panes unpartitioned and using slender frames), to avoid lintels (or keep them low) and to make the windows room-height; light-coloured room surfaces and jambs are also a plus. In residential buildings, the over-heating of spaces through solar gains in winter can

b

S,180°

S, 180° 1

be intentionally permitted, since the intense sunlight during the light-impoverished ­season has health benefits. A compact building envelope provides another advantage in providing heat during the winter. The architectural reasons for an enlargement of the envelope must always be weighed against the energetic and financial drawbacks. A sufficient storage mass for the ab­­ sorption of passive solar gains or gains from other volatile renewable energies (e.g. from siphoning off excess wind-­ generated electricity and from harvesting ­additional heat energy supplied via heat pump through building component acti­ vation) can round out the system during winter. Though mechanical ventilation does not entirely conform with the idea of low tech, it is practical or even imperative for some types of use (in classrooms and event spaces); in addition, it provides other advantages such as increased temperature comfort, better air quality and improved acoustic protection, which would not be realisable through window ventilation alone. Mechanical systems can also be implemented at lower cost if, for example, the exhaust air network is omitted and air ­volume is reduced, or if overflow ports, ­cascading air utilisation and central storeylevel extraction are used. In cascading air utilisation, air flows from its intake area through other spaces before being removed as exhaust.

Climate-sensitive Construction

53

9

8

7

15.07 15.0

15.0

E,

15. 15. 15.0

a

b

c

Summer conditions Even in the Central European climate, summer conditions are becoming increasingly relevant in the design not only of office buildings and other high-occupancy buildings, but of residential buildings as well. In general, the attention here is focused on actual local temperature trends and on the number of tropical nights (i.e. nights durin which the temperature does not drop below 20 °C). In summer, there is a world of difference between an inner-city location and a suburban greenspace. Climate sensitivity for summer conditions involves a combination of different mea­ sures. Aside from good thermal insulation, high-quality glazing and a moderate number of windows, external sun protection is of primary importance. Though a structural sun shade (e.g. a canopy), if properly utilised, offers many advantages, it is never as effective as an exterior Venetian blind, for example, since it cannot keep diffuse radiation at bay. In practice, perforated Venetian blinds with holes of about 0.7 mm diameter and a hole fraction of about 5 – 8 % have proved to be appropriate to the task. The somewhat reduced effectiveness of the shading is compensated for by the enormous advantage of transparency and a sufficient influx of daylight, so that even fully closed, per­ forated Venetian blinds obviate the need for additional artificial lighting. In addition, such “closed” sun protection is useful not only when the sun is shining directly on the facade, but also – particularly on hot days over 29 °C – during the entire day, regardless of the orientation. It

is important to note, however, that the thermal advantage may be counteracted by the unwillingness of some people to keep the blinds closed, because they feel confined by the heavy shading despite their ability to see out. A large storage mass in buildings is especially important in summer conditions. Re­­ inforced concrete floors and ceilings are a good option for this, as are screeds with stone or tile coverings with a high specific heat storage capacity; suspended ceilings should be avoided. These storage mass components slow indoor temperature rises during the day and “discharge” overnight so that they are able to absorb heat again during daylight hours. It is particularly important in timber construction to raise the heat storage mass through appropriate installations. In order for the low-tech approach without air conditioning to function properly, it is critical that the building cools down during the night. If this is not possible because the night-time outdoor temperature fails to drop below 20 °C, then even the best measures cannot guarantee daytime room temperatures below 26 °C. However, on days in which the nocturnal temperature sinks to the appropriate levels, the building can be effectively cooled through nighttime ventilation. This requires a high air exchange rate, which can usually be generated only via cross ventilation. If the windows are all on one side, they must have a large openable cross section and be as tall as possible. Simply tilting the windows is not enough; two tall windows or glazed doors for each occupied room of about

2 a – c Office building and University of Applied Sciences, ENERGYbase, Vienna (AT) 2008, pos architekten Low tech: Facade ­generating solar power, indoor air humidification using plants, concrete core activation

54

25 m2 must be held fully open. For windless nights, during which even cross ven­ tilation cannot ensure a high air renewal rate, the chimney effect through greater room height or air discharge into stairwells or multistorey interior spaces can be advantageous. With regard to night-time ventilation, it is important to make sure the operation is actually carried out, as “low tech” also implies “manual”. Since nocturnal hotweather thunderstorms are not rare, rain and storm safety measures must be put in place. Anti-burglary protection needs to be considered as well. An “organisational” solution is required to address the draughts and associated scattering of papers and other lightweight objects at night. Last but not least, the increased cleaning costs ­generated by the high air renewal rate with unfiltered, dust-laden exterior air must be taken into account. As a rule, the interior heat loads per m3 of enclosed space must also be considered. With regard to summertime over­ heating, accommodating as few people as possible in rooms that are as big and high as possible is generally preferable. Of course, this conflicts directly with compact building and room volumes and a s­ ufficient and frugal use of area. Integrative design and the responsibilities of building clients and users From the very outset of every design process, the integrative collaboration of all ­specialists involved in the technical planning is very advantageous. The architects, however, must have a well-rooted knowledge of robust low-tech structures in particular. In low-tech buildings, established norms are often not or not completely followed. The necessary decisions in this regard have to be made by the clients, who can, for example, commission a dynamic building simulation as a proof of the equivalence of the result. The building clients must make decisions in advance, for example about break-in prevention measures in a building, but primarily with regard to essential fundamental issues,

such as the allowable degree and frequency with which room temperatures fall outside the stipulated range or arrangements for specific adjustments to the ­summer and winter clothing, which sub­ sequent users will have to espouse. The designers can only suggest appropriate solutions when a budget has been allocated for it. In order for a climate-sensitive building to be called low tech, it has to be of practical use and enjoy the active participation of the users. Ultimately they are responsible for whether glare protection in winter and external sun protection in summer are operated, whether sun protection in summer is generally adopted, whether night-time ventilation concepts are accepted and high nightly air renewal rates are supported (by weighing down loose paper, for instance), whether room temperatures of 22 °C in winter and 26 °C in summer are tolerated. The decisions as to whether they will keep their windows closed on hot days, whether they are willing to dress according to the season, all lie within their purview. Though calls for low-tech buildings are becoming ever louder, they are countered by a marked decrease not only in the willingness but especially in the ability of potential users to operate buildings sensitively and with personal responsibility. More and more frequently, most often due to a lack of understanding, wishes are cropping up for buildings in which one can act counterproductively anywhere and anytime without sacrificing a high level of comfort. These demands could only be met at a ­significantly higher cost for technology designed to withstand any incorrect use, which would result in very poor energetic performance. There exists an extreme and pressing need for informing and educating people about sustainable action. Teaching sustainable building usage and basic phys­ ical principles in school is critically import­ ant. In ten years, the young people of today will be the ones who have to make the socially relevant decisions.

Climate-sensitive Construction

55

Low-tech Focus: Building Technology Edeltraud Haselsteiner

The goal of low-tech design is to reduce building technology in order to make buildings more robust for the long term. This does not reflect a desire to exclude technology per se, but rather to critically evaluate its use, e.g. with respect to life cycle costs and a more holistic ecological and social perspective. Reducing technology succeeds, for example, when buildings are more strongly integrated into regenerative loops in the environment and when individual actions by users are engaged. This also requires designing with the environmental potential in mind and making use of what nature has to offer. Climatic elements such as solar radiation, wind, temperature and humidity on the one hand, and environ­ mental influences such as latitude, local and national wind conditions and the altitude of a building site on the other, interact functionally to generate the dominant structural mitigation factors. Figure 2 presents examples of this environmental potential and their influence on construction. The Socrates House (469 – 397 BCE) – a 2,500-year-old concept by the Greek ­philosopher – shows how the sun can be used passively even without technological expenditure (Fig. 1). A compact, funnelshaped building oriented toward the sun, N with large windows on the southern expo5 sure and closed on the north side, featuring solid walls6and stone 4 floors for heat storage as well as buffer zones, embodies a coherent design for practical solar architecture. 3 Socrates even accounted for the varying S

56

position of the sun throughout the year. The principle of solar architecture, using solar heat directly for warmth on the one hand and storing it in the material of the building envelope on the other, has lost some of its significance thanks to the increasingly affordable technological solutions represented by solar and photovoltaic (PV) panels as well as adequate storage systems. The concepts of natural lighting, ventilation and cooling were similarly replaced with buildingtechnological solutions. The following examples provide an alternate perspective, illustrating how centuries-old knowledge can be revived and converted into new approaches to dealing innovatively with the energy potential of the environment.

1  Socrates’ concept for a sun-tempered house 2  Environmental potential: its use and influence on construction

1 N

1 Solar radiation in summer 2 Solar radiation in winter 3 Terrace, patio

5 4

6

3 S

4 Living room 5 Storage2 area, also buffer zone 6 Solid walls to store heat 7 Stone floor, also heat storage

3

4

5

7 1

2

3

4

5

7

1

Climate element

Environmental influences

Utilisation (examples)

Structural mitigation ­factors in context (examples)

Solar radiation

Duration of sunshine: Total annual ­radiation, daily averages throughout the year, etc. Radiation values for direct and diffuse radiation Radiation amounts (for individual facades)

Active and passive solar heat gains / solar cooling /photovoltaics (efficiency) Provision of daylight

Orientation Shading and sun ­protection Amount of window area in the facade Radiant converters, which absorb the energy from radiation (e.g. heat-absorbing Venetian blinds, roller blinds, ­surfaces, etc.)

Wind

(Average annual) wind speed Distribution of wind directions Proportion of windless periods

Natural ventilation (e.g. via pressure and suction loads on the building envelope) Airflow around a building as a function of wind conditions and ­building form Wind farms (conversion of wind energy into electricity)

Building form, building height / depth

(Relative and absolute) humidity / precipitation / surface water

Humidification and dehumidification of intake air Dew point and condensation Frequency and amount of pre­ cipitation (e.g. average annual rainfall) Degree of cloud cover (groundlevel temperature, reduced solar influx or strong cooling)

Rainwater for secondary uses: Supply and wastewater loops (e.g. treating rainwater for use in sanitation and cleaning), cooling of buildings (e.g. by using the evaporative effect from water surfaces) Seepage (e.g. irrigation)

Structure, building details, vegetation (e.g. outdoor greening, bodies of water)

Temperature of the air

Minimum /maximum temperatures, temperature fluctuations throughout the day /year

Ventilation, heating and cooling ­systems in buildings Effectiveness of storage mass or ­passive cooling (e.g. night-time ventilation, building component activation)

Structure, building details, vegetation

Temperature of the soil, groundwater, subterranean water

Ground heat, ground temperature (temperature levels in upper layers determined by solar radiation and weather, in lower layers by ­geothermal current)

Temperature of the ground as a source for heating and cooling: ­geothermal heating, geothermal heat exchangers, etc.

Building form, ­construction details

Microclimate at the ­building site

Vegetation, plantings, bodies of water, etc. in the vicinity of the building

Climate-regulating effect / temperaturemoderating function of green and open areas as well as surface water Natural shading through nearby ­vegetation

Outdoor greening and landscaping, green facades and roofs Limited sealing / paving

Daylight

Quantity of daylight Light intensity

Natural lighting

Proportion of openings

Energy Potential of the ­Environment

57

Energy Potential of the Environment Edeltraud Haselsteiner

Sun houses Hungarian architect Pierre Robert Sabady is considered one of the pioneers of solar architecture in Europe. In the 1970s, he published an article enumerating the “seven pillars of the bio-solar house” [1]. In the article, he uses his single-family bio-solar house Hälg in Lucerne, which he designed in 1977, to explain how buildings can be energetically optimised. With a trapezoidal ground plan, he references Socrates’ original concept (see p. 56). While the broader south side is generously glazed, the narrower north side, which accommodates secondary rooms, is practically windowless. The ground plan is organised so that the stairwell, cellar and attic form interior buffer zones, while a generous conservatory in front of the south facade represents an outer buffer zone or greenhouse (Fig. 1). This basic principle of solar architecture has remained unchanged through the present and is among the most efficient types of energy-conserving construction. Houses heated by the sun do better in terms of life cycle costs than comparative conventional buildings, and their global warming potential is lower than that of normal low-energy and passive houses [2]. Communal living project near Vienna After the oil crisis of the 1970s and a massive rise in oil prices, energy-saving buildings and alternatives to oil as a heating fuel became a dominant theme, especially in the construction of single-family homes. In

58

1984, Georg W. Reinberg realised a communal living project that married the principles of solar architecture and demands for healthful building materials to a community resolved on codetermination. The form of these buildings, placed in a stacked arrangement along a narrow, long, southfacing slope, was based on the need to achieve large sun-exposed surfaces while minimising mutual shading (Fig. 2). The individual buildings themselves are subdivided into three thermal zones: Conservatories and large glazed surfaces to the south, a middle zone including the sanitary core designed for the highest temperatures, and storage rooms on the north side. Direct solar gain house In the early 1990s, the development of direct solar-gain houses (Fig. 1, p. 10) that had been begun by Andrea Rüedi with his experimental solar buildings in Trin made it possible to establish appropriately constructed and designed houses optimally oriented toward the sun and without the need

a

1 1 1 1

1

3

1

Glass

7

1

4 2

5

6 2 a

1 Section and floor plan, bio-solar house Hälg near Lucerne (CH) 1977, Pierre Robert Sabady

1 North-oriented buffer zone 2 South-oriented buffer zone / conservatory 3 Warm air solar heating roof 4 Central hearths 5 Living room 6 Dining area 7 Kitchen 1

2 a–b Communal living ­project, Purkersdorf near Vienna (AT) 1984, Reinberg ZT GmbH Low tech: Solar architecture, sustainable materials

3 a–b Office and residence building, direct solar-gain house in Zweisimmen (CH) 2014, N11 Architekten Low tech: Solid timber construction with no central heating 4  a­–b Residential building, Paris (FR) 2013, Babled Nouvet Reynaud Architectes Low tech: Passive solar architecture, natural ventilation

a

b

for conventional heating. The five-storey ­single structure in Zweisimmen follows in the tradition of this basic idea (Fig. 3). Its western facade is slightly twisted towards the south in order to gain longer sun ex­­ posure during the winter. The solid timber ­construction is combined with a timber-­ concrete composite ceiling and a rammed earth floor to provide the necessary mass for energy storage, while the stairwell serves as a buffer zone for the interior rooms on the north side. Adhesives and chemical additives were avoided entirely to ensure a healthy indoor environment. The solid tim-

ber walls are joined with dowels, meaning that the building can be disassembled and its materials can be reutilised after deconstruction. Interior heat sources, in conjunction with the sun, suffice to keep the house at a comfortable temperature year-round. The building has neither central heating nor ­ventilation.

a

a

b

3

2

Residential building in Paris The fact that solar architecture with passive components, based on an energetically optimised orientation and ground plan ­concept, can function in a densely built-up

b

Energy Potential of the ­Environment

4

59

a

b

urban environment even as social housing is demonstrated in a building by Babled Nouvet Reynaud Architectes in Paris (Fig. 4, p. 59). The double facade incorporating usable conservatories with living spaces arranged behind them faces south to benefit from solar irradiance. The conservatories function as climatic buffers; a fibre-reinforced concrete slab acting as a storage wall absorbs the radiative heat intensified by the outer pane and releases it later into the living spaces [3].

of definition. If the focus is predominantly on the longevity and robustness of the ­overall system, then the implementation of technological means must be viewed in those terms and in those of energy usage.

Active energy facades Even though solar thermal energy and ­photovoltaics have by now made technic­ally mature and affordable solutions for harvesting solar energy available, there have been repeated initiatives to utilise the vertical facade surfaces for energy generation as well. An active energy facade system developed by Rudolf Schwarzmayr controls the solar influx through moveable louvres on the facade (Fig. 5). These employ the solid walls directly to store energy and are therefore also well-suited for renovations, since they can be mounted onto pre-existing solid walls. During times of energy demand and solar irradiation, the louvres open automat­ ically to allow the heat to penetrate into the wall. Depending on the temperature and weather, the function of the facade components can be expanded beyond energy generation to simultaneously include shading and cooling. A corresponding building prototype is currently being tested and evaluated [4]. As in other active energy systems such as solar thermal energy and photovoltaics, the issue of whether this can be classified as low tech is a question

60

5

Passive solar energy facades Phase change or viscoelastic materials, also called latent heat storage materials due to their properties, are able to store thermal energy during phase transitions, for ex­­ ample when changing from a solid to a ­liquid state, without themselves heating up. This has huge advantages for lightweight construction: Heat can be stored in significantly less mass and volume, since the storage capacity of these materials increases by multiples in the vicinity of their melting point. Architect Dietrich Schwarz developed a passive solar facade component with an integrated heat storage module based on salt hydrate crystals. The crystals absorb heat during the day and re-emit it into the interior as radiant heat when the room temperature drops. Anteriorly placed prismatic glass reflects the light of the high summer sun, but allows the rays through when the incident angle is small,

5 a–b Garden studio research building, Thermo­ collect active energy facade, Rudolf ­Schwarzmayr

6 Senior citizens’ residences, Domat / Ems (CH) 2004/2015, Dietrich Schwarz

6

Wind tower (malqaf) a

Stale air

Windcatcher (badgir) Living quarters

b Fresh air

c 7 7 Natural ventilation schematic a wind-driven ­venti­lation b thermal-lift-driven ventilation c ventilation via wind and thermal lift c­ombined 8 Qaa reception hall in a house with a wind tower (malqaf) and a windcatcher (badgir) 9 Natural ventilation, water evaporation and thermal storage masses that cool termite mounds in hot ­climates

9

8

as in winter. This passive solar architectural concept was employed, among other places, in a senior citizens’ residence in Domat-Ems (Fig. 6) and in the new ­Marché International office building near Winterthur [5]. Natural ventilation The positive effects produced by the nat­ ural ventilation of indoor spaces, or airing out rooms by opening windows, are not merely environment and energy-related. From the perspective of the residents, these actions are seen as a chance to make direct contact with nature or to satisfy their need for fresh air. The natural movement of the air comes from pressure differentials that result from temperature differences. As a consequence, natural ventilation can occur either through wind or through thermal lift (Fig. 7). Using wind forces or natural air currents to ventilate and cool the interior spaces of buildings has a similarly ancient tradition as does solar architecture. In the Persian Gulf and in the regions of the Mediterranean, wind towers are among the hallmarks of classical architecture. Their ability to cool rooms makes them the precursors of air conditioners. Their function relies entirely on thermal lift, specifically on the fact that warm air rises, while the denser cold air sinks toward the ground. Ventilation openings, which can vary in design depending on the location and the wind conditions, “catch” the “cool breeze” skimming along the ground or coming from the sea and channel it through the building. During windless periods, the stack or chimney effect supplies the necessary air exchange:

Heat, which has been stored throughout the day in the solid walls, is emitted into the space and drawn upward. At the same time, fresh and cool air flows in through doors and windows to replace it. This principle of natural cooling is often supported by combining it with water evaporation. In such cases, air from the wind tower is channelled through a damp cellar or over water-filled basins. The water evaporates in the cool but dry air and cools it even further (Fig. 8). In the design of natural ventilation systems, an exact climatic and usage-specific analysis is therefore needed so that the ­prevailing local air current conditions are understood. It is now possible to use computer simulations to analyse airflow and its effects in response to various influencing factors. Natural ventilation requires a driving force which guides air currents through a building by pressure or suction. Pressure differentials produced at the building envelope by thermal lift and wind can provide this. The strength of the suction effect depends on the temperature difference and the effective height. For this reason, tall buildings are especially wellsuited to a ventilation concept that relies on thermal lift. Over the course of evolution, nature has developed numerous methods for pro­ tection against heat and cold that can be useful in architecture, as well. The ­Trinervitermes termite colonies in Africa, for example, build mounds more than 30 m high and tunnel down to the groundwater (Fig. 9). By means of a clever venti­ lation system, the structure is naturally ­conditioned through water evaporation and the resulting evaporative cooling [6].

Energy Potential of the ­Environment

61

a

b

10

Office campus in Solihull Arup Associates, an engineering firm in the United Kingdom renowned for energyefficient building design, has created an office campus for itself in Solihull near ­Birmingham. In its building concept, air circulation and lighting rely largely on natural regulation (Fig. 10). Two building wings, whose floors are connected through pierced floor plates about midway along their longi­ tudinal axis, are supplied naturally with fresh air and daylight via solar chimneys. Small ventilation openings incorporated above the lintels and automated flaps on their faces allow fresh air to circulate. Slanted glazing in the roof structures forms large skylights and facilitates the ­distribution of natural daylight from the ­central area to the surrounding offices. Despite the fact that ventilation and lighting controls are automated, sash windows and shutters can also be operated individually by employees at each work­ station [7].

Technische Universität Innsbruck The institute building at the Technische ­Universität Innsbruck, a reinforced concrete skeleton structure erected in 1971, was modernised as the pilot project for highly energy-efficient renovation under the auspices of the Austrian energy research programme “Haus der Zukunft” (House of the Future) [8]. Thanks to the renovation measures implemented, the heat energy requirements could be lowered from 180 to 20 kWh/m2a (according to PHPP). Apart from other noteworthy features, the chosen method for ventilation deserves special mention. Prototypes of top-hung windows and overflow openings were developed in house. These, in combination with the mechanical ventilation of the building core, motor-driven window ventilation and overflow openings into the passageways, represent a sustainable ventilation concept (Fig. 11). Over the course of 40 years, the Passive House Institute conducted an exemplary comparison between the investment, maintenance and energy costs

11 a–c Technische Universität Innsbruck, Civil Engineering Faculty, Innsbruck (AT) 2014, ATP Architekten Low tech: Innovative ventilation concept based on top-hung windows and overflow openings

a

b

c

62

10 a–b Office buildings on the Arup campus, ­Solihull (GB) 2001, Arup Associates Low tech: Natural ventilation and lighting, individual operation of windows and shading elements

11

12 a–b RWS office building, Terneuzen (NL) 2000, opMAAT Low tech: Ventilative cooling, maximisation of passive design ­strategies, e.g. an atrium that supports the passive building concept with regard to daylight and venti­ lation, green roof, ­reuse of materials (e.g. recycled timber for facade cladding, etc.)

13 a–b Office and administrative building Karmeliter­ hof, Graz (AT) 2011, LOVE architecture and urbanism Low tech: Natural ventilation via box window double facade, prevention of overheating in summer

a

b

12

of the motor-driven windows with those of a conventional air conditioning system. Although the investment cost is five times higher for the window solution and the maintenance costs are expected to be more than ten times as high, the life cycle costs are almost 60 % lower than those of the air conditioning because of the energy savings [9]. These results show that, though lowtech solutions may result not only in higher investment costs but also in more expensive maintenance (because components subject to heavy stresses must be replaced more often), overall, they should still be rated as the more sustainable choice.

­ laster, cellulose insulation made from old p newspapers or natural paints. The building is ventilated and lighted naturally. A heat pump draws heat from the canal water in order to warm the building via floor and wall heating. The PV panels in the atrium also serve as sun protection. The building is equipped with its own used-water treatment in the form of a plant-bearing clarification basin, the cleaned water from which is used to flush the toilets.

Office building in Terneuzen In the year 2000, opMAAT Architekten built one of the most sustainable office buildings in the Netherlands in the city of Terneuzen (Fig. 12). Many of the materials in the building are either reused “waste materials” such as old timber posts used for the facade cladding and stairs, or renewable commodities such as clay bricks, clay

Office and administrative building in Graz For the renovation of the historic Carmelite monastery in Graz, LOVE Architekten developed an innovative new interpretation of historical box windows (Fig. 13). The building envelope comprises a climate facade with room-height window elements. These have a fixed glazed face of solar control glass and a circumferential frame with ventilation openings at the base and sides. Together with the inner sliding doors, which represent the actual room closure, they form a transition zone that is used as

a

b

Energy Potential of the ­Environment

13

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South

North

14

a conservatory and simultaneously protects the building interior from overheating during the summer. When the leaves of the sliding doors are opened at night, a natural air exchange takes place. The required intake air can be regulated individually via the ­sliding doors. Daylight Daylight is important not only for its energyconserving aspect and for indoor comfort, but it also regulates a series of body functions, stimulates the human circulatory system and vitamin D production, and thereby significantly impacts physical and psychological health. The influx of daylight is optimised through horizontal glazed surfaces or openings, which is to say that the lighting comes from above, via the ceiling. However, this form of lighting is rare. It is implemented most readily in single-storey buildings or, as is becoming more prevalent, by way of multistorey open stairwells and atria. Historically, this concept was already in use many years ago in densely built-up urban areas in the form of light shafts. Narrow, 1– 2 m2 large areas were kept free throughout all floors of the building, so that even the rooms in the rear sections would be supplied with at least a modicum of light and ventilation. A research team took up this idea and developed an optimised concept combining light shafts with highly reflective materials for maximising the provision of daylight in multistorey buildings [10]. The supply of daylight

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14  “Light catcher” by ­Wilfried Pohl et al. in the model and in building section. Daylight from openings in the roof is uniformly distributed throughout the building.

from these systems, called light catchers, is delivered via skylights in the roof and ­mirrored vertical shafts into the depths of the building (Fig. 14). Planning for daylight should be seen as an integral factor in the development of the overall building concept. There are ­various options for redirecting light that can be implemented to make more effect­ ive use of daylight: • Prismatic systems are often used in conjunction with sun protection systems and utilise geometric-optical properties for the diversion of daylight. Prismatic panels can be mounted on the facade, in tran­ sition spaces in the facade or between glass panes or in the interior in such a way that, depending on the position of the sun, direct irradiation can be reflected or only partially admitted into the interior. • Lightshelves are usually installed as fixed systems. These are light-reflecting fins that are attached to the upper section of the facade or the window to redirect the rays of the sun or daylight toward the ceiling of the interior spaces. • Optical reflector systems, in contrast, make use of the reflective qualities of curved surfaces and the principle that the angle of incidence equals the angle of reflection. Optical reflector systems include, for example, simple mirror blinds and light-directing louvres, as well as light-deflecting light scoops or heliostats. • Holographic systems involve threedimensional refraction gratings that are

15 Office and administration building, Federal Environmental Agency in Dessau (DE) 2005, Sauerbruch Hutton Low tech: Daylight design, atrium as thermal buffer and for ­natural convection

Akershus University Hospital Sufficient amounts of daylight for general health are especially important in the design of hospitals. Therefore, the Akershus University Hospital in Norway was conceived with a glass-roofed “main street”, which acts as a distribution corridor connecting the various departments and services. The light-flooded thoroughfare evokes a citylike atmosphere and lends structure to the different entrances, departments and public areas (Fig. 16).

15

embedded as thin films in laminated glass. The gratings redirect the incoming daylight in a particular direction. Holographic-optical elements have a broad range of applications. They are used for channelling light and improving daylight illumination as well as for sun protection. Federal Environmental Agency in Dessau The new Federal Environmental Agency building in Dessau combines high energetic performance with innovative approaches to environmental construction. The most important components of the energy concept are a highly insulated building envelope of timber with cellulose insulation and a long, extended atrium, which functions as a thermal buffer as well as a convection stack for natural ventilation (Fig. 15). Fresh air flows into the offices through centrally controlled ventilation flaps and is drawn out via the atrium by natural convection. The atrium simultaneously provides an efficient source of daylight to the inner offices.

16 Akershus University Hospital, Nordbyhagen (NO) 2014, C. F. Møller Architects Low tech: Daylight design

16

Vegetation, greening and cooling In addition to protection from wind, rain and sun, one of the central parameters of a low-tech building concept is the consciously incorporated natural element in the overall ecosystem of a building and its immediate environment. Plants and ­vegetation can often be used in targeted ways to significantly reduce the need for technological building equipment for ventilation, cooling or shading. Carefully designed plantings offer protection from environmental influences such as sun, rain and wind and filter pollutants from the air. In recent years, indoor plants used for conditioning the air have once again become an increasingly frequently employed functional principle. Indoors, they raise the humidity; they mediate solar radiation and evaporative cooling to reduce room tem­ peratures. Similarly, horizontal green spaces are an efficient building block in the water supply and wastewater removal cycles: Green roofs can function as rainwater reservoirs, surface water can be clarified by seepage through vegetation-covered soil layers, and much more. The surfaces of bodies of water, in contrast, contribute to natural cooling. When warm, dry air flows over a water surface, it absorbs moisture, which then evaporates and simultaneously cools the air. In urban areas, green facades provide additional habitats for birds and insects and thus contribute to the preservation of biodiversity. They also act as acoustic buffers, relieve stress on the sewer systems during rainstorms by absorbing water and have a significant cooling effect. Neverthe-

Energy Potential of the ­Environment

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17

less, facade greening still remains in the shadows. Fear of vermin and of the pos­ sibility that the plants could destroy the facade is widespread, though largely baseless. Moreover, green facades or roofs can now be produced very simply, even as prefabricated systems (see “Nature-based Solutions”, p. 48ff.). In general, there are three principles for establishing plants at an elevated level: • using self-clinging creepers or climbing plants, which can attain a height of 10 to 20 m (ground-bound plant systems) • using substrate-filled planter boxes ­distributed at points or throughout the ­surface, into which plants are placed • cultivating plants that are viable without a substrate (wall-bound plant systems) The widespread planting system Mur ­Végétal (vertical garden) by botanist Patrick Blanc is of the latter category. It was conceived and patented by him in the 1980s and functions almost entirely without soil. The roots develop on a thin layer of felt and not in a volume of substrate. The wall is irrigated through integrated perforated plastic pipes [11]. Student housing in Barcelona The new student residence building near Barcelona is designed to conform to the low density of buildings in the neighbourhood and to establish a strong connection to its surroundings and to nature. The residential complex is a construction of insulated precast concrete modules. A total of 62 room modules with a floor area of 5 ≈ 11.20 m each were prefabricated at the plant and joined together at the build-

66

17 Student housing in Sant Cugat del Vallès, Barcelona (ES) 2011, dataAE Low tech: Green facade, sufficient and modular construction

ing site via dismountable steel fasteners. The architects simplified the already ­minimal construction method even further by doing without wall and floor coverings and leaving the surfaces unfinished. In order to encourage social interactions among the students, the living modules were oriented inward toward communal courtyards and arbours which function as informal meeting spaces. The exterior facades are encased in steel cable netting in which climbing plants are entwined (Fig. 17). These establish the transition to nature and simultaneously provide necessary protection from the sun and excessive heat [12]. Vienna City Administration Structural analyses at the office building of Wiener Wasser (Vienna water authority) (MA31) revealed that the existing facade from the 1960s would not support the directly applied load of a green facade. As a solution, a structure with its own f­oundations was placed in front of the building, and planter boxes were attached directly to the load-bearing ­columns. The plant-bearing trellises pro18 Administrative building, Vienna City Administration (MA31), Vienna (AT) 2016, ­Rataplan – Architektur Low tech: Facadebound greening with boxes and creeping plants, automated ­irrigation system via sensors in the planter boxes, five irrigation loops 18

Notes  [1] Sabady 1978   [2]  Sölkner et al. 2014  [3] Detail 7–8/2014  [4] Thermocollect  [5]  Detail Green 1/2009  [6] Oswalt 1994  [7] Detail 6/2002  [8] BIGMODERN 2015  [9]  Detail Green 2/2015 [10]  Pohl et al. 2014 [11]  Haselsteiner 2011 [12]  Detail 4/2015 19

vide lateral sun shading. The boxes themselves alternate with fixed timber sun protection louvres to furnish additional shade (Fig. 18). Institute for Forestry and Nature Research The design of the Institute for Forestry and Nature Research in the town of Wageningen in the Netherlands is based on a passive energy concept and natural ventilation. In support of this, two glazed atria were designed as interior conservatories that absorb solar radiation in winter and store it in the solid building components (Fig. 19). In summer, these “indoor gardens” are cooled by the plants and evaporation from the water basins. As with the greenhouses of vegetable farmers, a system of internally hung roller blinds protects against too much sunlight in summer and provides additional insulation in the winter months to minimise heat losses. Electrically operated flaps facilitate the extraction of warm air and foster intensive natural ventilation. Green roofs on top of the buildings absorb rainwater and allow it to be utilised for flushing the toilets, thus conserving drinking water.

20 Office building ASI ­Reisen Headquarters, ­Natters (AT) 2019, Snøhetta Low tech: Facade greening, indoor ­climate control with plants, natural venti­ lation, natural wood preservation

19 Institute for Forestry and Nature Research, Wageningen (NL) 1998, Behnisch & Partner Low tech: Compact building, passive solar energy use via two glazed atria, use of thermal inertia of solid building elements,

­natural ventilation, ­utilisation of local materials and naturally durable timber species, incorporation of plants and water in the atria, rainwater ­reclamation, revitalisation of a contaminated agrarian area

Company headquarters near Innsbruck For its new office location near Innsbruck, this purveyor of trekking and adventure travel wanted a building concept based on sustainable architecture, with an eco­ logical footprint that would remain low over the long term. The four-storey timber frame structure with stiffening solid timber elements possesses a curtain facade draped in luxuriant green plant growth (Fig. 20). This “green curtain” protects against sun glare and provides shade for the large glazed surfaces. Simultaneously, the microclimate created in this verdant buffer zone reduces the energy required to cool the building. Rainwater from the roof is collected in an underground cistern and supplies the automated irrigation system that waters the plants on the facade and in the garden. The timber facade was preserved according to a traditional Japanese method: Lightly charred and thereby carbonised, the facade is waterproof without further surface coatings and also protected against insects. The technological building concept employs high-tech components for passive ventilation: Sensors measure room temperature, humidity, CO2 and wind and use thermal lift and wind pressure conditions to circulate fresh air throughout the building. The ventilation flaps are opened whenever the room climate requires it. Photovoltaic panels on the roof supply some of the building’s energy needs.

20

Energy Potential of the ­Environment

67

Sufficient Energy Design Helmut Schöberl

The EU has mandated climate neutrality for itself by the year 2050 at the latest, though individual EU countries wish to achieve this goal sooner. One focus of this effort are the measures to environmentalise the construction sector and to avoid fossil fuels for indoor heating, as well as a massive expansion of renewable energy resources and the promotion of energy efficiency. The construction sector is considered one of the greatest energy consumers, but at the same time, it harbours considerable potential for energy efficiency measures and for sustainable energy production. For example, if 1 % of energy consumption is saved, this same percentage of energy does not need to be generated in the first place. Plus-energy buildings represent the current pinnacle of energy efficiency and have the potential to play a major role in the achievement of the established climate goals. The successful design of a plus-energy building begins with an essential understanding of all energy flows, their dependencies and their intersections. The key to reaching energy-related sufficiency therefore lies in the details. Optimising the design and fine-tuning all the com­ ponents is critical because it allows for ­minimal building technology and, as a ­consequence, a reduction in costs. Energy sufficiency should therefore not be viewed just as an indication of quality in terms of economic operations, but more generally as a con­servationist approach to the con-

68

sumption of resources. Preconceived ideas about the high cost of energy-efficient solutions remain stubborn. However, a desire to become more independent from rising energy prices, deal sustainably with resources, contribute to the unburdening of the climate and to do all this while also lowering operational costs make sufficient energy and building-technology design more relevant than ever. In this, low and high tech are not to be viewed as contradictory, but rather as mutually comple­ mentary concepts the interactions of which can generate optimised solutions. Using the example of the refurbishment of a high-rise office building at the Technische Universität Wien (TU Wien), the following passages show how a successful overall concept can be implemented (Fig. 1). Definition of a plus-energy building A plus-energy building is a building in which the total primary energy demand (for building operation + usage) is very low. A building is defined here as plus-

1

1  Refurbishment of a high-rise at the TU Wien into a plus-energy building, Vienna (AT) 2014, working collab­ oration of the architects Hiesmayr — Gallister — Kratochwil; Schöberl & Pöll (building physics, passive house consulting and certification)

Primary energy demand, non-renewable [kWh/(m2 · GFA · yr)]

2  Primary energy budget of the high-rise office building at the TU Wien before and after renovation

800

803

700 600 500

458

400 300 200 100 0

56 Before renovation

Typical new office building

Entire plus-energy building

energy if it meets the following criteria [1]. • Primary energy: The amount of nonrenewable primary energy required (for operations + usage) is lower than the electricity generated at the ­building. • Location: Renewable energy is produced on site (within the confines of the building). •  Period of evaluation: 1 year • Assessment boundaries: The definition given above includes heating, cooling and ventilation as well as all the consumption due to usage (e.g. office machines, servers, kitchen appliances), technical building equipment and lighting. The local provision of electricity and heat primarily covers the building’s own elec­ tricity and heat demands. In the example considered here, the electricity that was not used on site was fed into the high-­ voltage current loop in the vicinity of the office tower and was completely consumed by the neighbouring buildings of the TU Wien. None of it was exported into the municipal grid. Project description The world’s first plus-energy office building was completed at the TU Wien in the summer of 2014. The project was the general renovation of a building section constructed in the 1970s known also as the Chemiehochhaus (Chemistry Tower). The only thing preserved during the renovation

61 Energy generation at the building

Lift energy recovery Server waste heat utilisation Photovoltaics Common rooms, kitchenette Additional machines (e.g. copiers, projectors) EDP workstations Communications (telephone, switches) All other electrical components Servers and UPS Measurement and control technology Lifts Lighting Ventilation Hot water and drinking water Cooling and server cooling Heating 2

was the load-bearing reinforced concrete skeleton. The optimisation of daylight and artificial lighting was a particular design challenge, since the building depth is considerable. By means of daylight design, the facades were fundamentally improved (optimised window area, height of light influx) and the walls of the corridors were extensively glazed. The lighting was optimised according to the state of the art at the time (110 lm/W). The building provides high-value work spaces for about 350 employees and approx. 350 students. The entire structure has a net floor space of 13,500 m2 and eleven floors. The goal of the project was to achieve an on-site plus-energy ­standard in terms of primary energy. This included covering the primary energy requirements of all the technological ­building equipment, all office machines, servers, kitchens, artificial lighting and standby equipment with the photovoltaic system, as well as utilising the waste heat of the servers and the regenerative braking of the lifts. The key aspect for reaching the targeted plus-energy standard for the building was an extreme reduction of the energy consumption in all areas and components, ranging from heating and cooling down to the IT devices at the workstations and small electrical appliances. For the ­project, more than 9,300 components from 280 categories were listed, optimised and cleared by a supervising research team. Figure 2 shows the primary energy require-

Sufficient Energy Design

69

ments of the high-rise office building before and after the renovation, which includes the amount needed for provision of energy at the system boundaries. After the reno­ vation, the energy requirements are lower than the building’s own on-site energy ­generation. The path to a plus-energy office tower The whole project was conceptualised on the basis of maximum energy efficiency, technical feasibility and practicality within marketable conditions. In the pursuit of this ambitious goal, the close interdisciplinary teamwork of all project participants was extremely important. The project collabor­ ators from the design and research teams were assisted in the design and execution by expert planners and specialist advisers, particularly in the holistic interdisciplinary implementation of individual innovations. Design meetings and workshops were held regularly to work on technological options and to reach joint agreements and decisions. The plus-energy office tower was executed as a highly efficient building. This includes the building technology systems such as the component activation in the floors. The efficient floor-tempering method is only ­possible in winter as well as summer if the facade is sufficiently airtight and has very low thermal transmission losses. External sun protection is critical to lower solar loads. The building envelope was built to conform to passive-house quality, since the implementation of passive-house standards represents the foundation for meeting the plusenergy standard. The following measures were implemented: Energy efficiency measures: • improved passive-house envelope as baseline • core ventilation converted to automated night-time ventilation (to save cooling energy) •  highly efficient building technology •  LED ceiling lights with 110 lm/W • 24-V grid to raise energy efficiency and centralise the power supply • energy-efficient office equipment, kitchenette appliances and server solutions

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Energy generation: •  Photovoltaics on the roof and facades • Utilisation of waste heat from the server room and building component activation (to cover the bulk of the heating energy requirements) • Lifts which exceed best energy requirement classification A, with energy recovery and counterweight reduction The photovoltaics on the roof and facades of the tower have a total module area of 2,199 m2, making it the largest building-­ integrated system in Austria to date, and ­generate a peak power of 328.4 kWp. The 618-m2 photovoltaic system on the roof achieves 97.8 kWp, while the 1,581-m2 facade system has a peak power of 230.6 kWp. The total simulated annual gain is 248,804 kWh/yr. The energy recovery of the lifts is effected through a regenerative motor. When the lift cabin brakes, the motor is employed as a generator, with the help of which the kinetic energy of the cabin is converted into electricity and fed into the building grid. The waste heat from the servers is channelled into the floor-integrated heating system of the high-rise. The primary energy requirements of the entire building, including office usage, are 56 kWh/(m2 ≈ GFA ≈ yr). The large energy consumers in the building are all the electrical systems, lighting, cooling and ventilation. The electricity requirements of the EDP workstations, servers, uninterrupted power supply, kitchenettes, etc. ­contribute 29.53 kWh/(m2 ≈ GFA ≈ yr). This represents 44 % of the total primary energy needs. The final energy produced by the three energy generators breaks down as follows: •  Facade photovoltaics: 146,360 kWh/yr •  Roof photovoltaics: 102,444 kWh/yr •  Server waste heat: 36,664 kWh/yr •  Lift energy recovery: 15,971 kWh/yr The most innovative aspect of the highrise’s plus-energy renovation, however, is the extreme optimisation of the com­ ponents. While it is well-known that the energy efficiency of a building can be increased through an improved building

a 3  Energy generation through photovoltaic arrays on the building a Terrace with ­photovoltaics b Stairwell with facade-integrated photovoltaics c Photovoltaic arrays on the roof

Notes [1] Rosenberger et al. 2013 [2] Passive house database of the Passive House Institute: passivehouse-database.org/#d_3995

b

envelope, and that energy-generating installations contribute to sustainability, the all-encompassing component optimi­ sation – including usage – represented a completely novel sufficiency approach. More than 9,300 individual components were optimised in this project, resulting in a reduction of the primary energy requirement by 88 %. A concrete example illustrating why even the smallest of energy consumers must be optimised is given by motion detect­ ors. 550 newly developed, highly efficient motion detectors with light sensors were installed. The standby consumption of ­conventional motion detectors lies between 0.8 and 2 W. The analysis compared a standard motion detector with a standby consumption of 1.5 W to the high-efficiency detector with a 0.05-W standby consumption. Implementing the more efficient motion detectors resulted in a final energy saving of 6,986 kWh per year. The all-encompassing EDP concept defined the standards for the use of very efficient devices and guided the gradual replacement of existing devices. The latter guaranteed that devices recently acquired were only replaced if they significantly exceeded the efficiency criteria. All the measures taken yield CO2 savings of 814,302 t. In addition, the building saves an annual 187 kWh/m2 of final energy. The building has won multiple prizes and was awarded 1,000 points – the maximum number attainable – in the sustainability ­certification system of the Austrian climate protection initiative klimaaktiv. To date, it is the only passive-house renovation that has received the “EnerPHit Premium” certification from the Passive House Institute [2].

c

3

Monitoring Through a comprehensive three-year ­monitoring programme, supervised and evaluated by the Building Physics and Research Department of the TU Wien, the design and effects of the technical ­solutions for increasing energy efficiency were precisely tested, documented, reproduced and improved. The results have ­validated the bundled interventions and have made clear that monitoring r­ epresents an essential part of the energy design and building optimisation. Expanding the concept At present, many large buildings have reached the end of their functional lives in terms of their usability and building ­fabric and must be refurbished. Large ­renovation projects in particular represent significant potential in the push to achieve established climate goals. The plus-energy high-rise can act as a model for energy ­efficiency and sustainability in the building sector. On the basis of a very energy-efficient ­building envelope, the plus-energy stan­ dard can be realised at any given location through comparatively inexpensive (lowtech), but remarkably effective measures such as component replacement (e.g. motion detectors). The project has proven that an 88 % reduction in energy requirements and an extreme increase in efficiency can easily be achieved and are not associated with enormous additional expenses, as long as the reduction in energy demand and sufficiency criteria in all areas and components are factored into the building optimisation.

Sufficient Energy Design

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Robust Building Design Thomas Auer, Bertram von Negelein

The complexity of buildings has been steadily increasing for about 25 years. Along with technological options, the ­profusion of component systems associated with individual building trades has grown, with the result that these systems can deliver a combination of comfort and efficiency only if they interact with one another perfectly. Moreover, this has also caused an increase in construction costs. For non-residential buildings, which make up about 50 % of the area taken up by new construction in Germany [1], numerous publications show that, as a rule, the projected operational energy efficiency is not reached, or would be achievable only after a qualified adjustment phase. In most buildings, quality assurance, for example through a monitoring period for the identification of problems and for system adjustments, is associated with additional expenditure and therefore not put into ­practice. The obvious conclusion is that many new buildings with very ambitious designs c ­ onsume significantly more energy than required, and at the same time, their “promise” of high user comfort is not fulfilled. For every form of energy that does not come from a renewable source, additional consumption translates to the fundamentally avoidable emission of CO2 into the atmosphere. The question thus becomes whether the complexity of buildings, specifically of the building technology, is justified and viable in their construction and operation.

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Added to the mix is the human user, who often acts contrary to the technical assumptions and design measures, or at least does not facilitate them. In such cases the designers speak of “human error”, though one must be allowed to question whether it is really an error on the part of the users and not rather erroneous planning; after all, the presupposition is that people and not technology should be the central focus. Really intelligent buildings and technology exist to support humans in their needs, not the other way around. As a result, through a series of newer buildings developed according to low-tech principles, interest in simpler solutions in architecture and in building technology has flared. “High tech versus low tech” was already a topic of discussion in the 1990s, and has since led to reduced, more natural solutions in building technology, for example in ventilation. Even then, passive strategies, known from traditional building technologies and adapted to the climate zone in question, were showcased as examples for optimising residential quality in contemporary construction using minimal HVAC technology. These passive technologies were mainly a consequence of the fact that machine-based cooling of buildings was not possible before the 1920s. It can be demonstrated on the basis of adaptive ­comfort standards (EN 16 798) that this ­traditional architecture was reasonably comfortable throughout most of the year. Equipping buildings with technology led

1

2  Applied sciences building at the Schubart Gymnasium, Aalen (DE) 2019, Liebel Architekten a components of the main concept b variants for the provision of daylight and roof forms

to their being climate-controllable, though what made them comfortable was not holistic­ally understood. The recognition that there was an urgent need for improvement inspired two ways of thinking: One camp espoused the optimisation of indoor climate technology, while the other tended toward less technology and more passive measures. Passive strategies and passively implemented materials have been steadily improved upon over the past 20 years. According to claims by architects Baumschlager Eberle, the office building 2226 in the Austrian town of Lustenau, which they designed for their own use, runs entirely without heating, ventilation and air conditioning (HVAC) technology (Fig. 1). Clever measurement and control technology ­regulates natural ventilation via motor-driven ­windows, based on the indoor CO2 con­ centration and temperature. “Intelligently simple” comes in many guises.

1  Office building 2226, Lustenau (AT) 2013, Baumschlager Eberle Architekten

Additional equipment, combining a hermet­ ically sealed and highly insulated building envelope with optimised interior climate technology, ultimately yields a passivebuilding standard. At first glance, a passive house appears to be worth aiming for, since it requires so little energy for oper­ ation and seems thus to have a favourable carbon footprint as well. Yet an approach to low CO2 emissions can also look quite different. One such can be seen in the example of the applied sciences building at the Schubart Gymnasium (high school) in Aalen (Fig. 2). After comprehensive ­consideration and the weighing of options, the team from Liebel Architekten were able to make a convincing argument for investing in regenerative energy pro­ duction instead of the originally desired sophisticated and expensive building ­envelope. The result is a very different, comfortable building that has received

“Calatrava” variant

Photovoltaics – regenerative electricity generation Night-time aeration Ventilation Subterranean channel a

“Skylight 2” variant

“Shed” variant

“Chimney” variant

“Skylight” variant

“Scale” variant

Daylight Heating Local heating b

2

Robust Building Design

73

Minimal pressure loss exhaust air installation

LVL 5 LVL 4 LVL 3 LVL 2 LVL 1

Passive concrete ceiling 67% open surface Decentralised facade ventilation panels acoustically insulated ventilation with volume-limited flow Decentralised facade ventilation panels for night-time aeration / cooling without constant-volume flow regulation Overflow in corridor

GF a

b

­ ultiple awards for generating more m energy than it consumes, and that was ­certified as “climate-positive” by the DGNB (Deutsche Gesell­schaft für Nachhaltiges Bauen (German Sustainable ­Building Council)) in 2020. The legislation in the form of ordinances covering energy savings is taking the easy way out by trending unerringly toward this passive-house standard. However, when considering the existing building inventory and, for example, the climate ­protection goals put in place by the German government, and relating these to the renovation quotas that can be achieved, it becomes clear that there will need to be other options. “Simple construction” can certainly provide a solution to this, though it is not the sole solution.

times the control system does things that users do not want at that moment, for example when it comes to automated shading. “Simple” must refer to less sensitive, less “nervous” systems. Simplicity cannot be reduced to passive systems like natural ventilation: Location, the form and materiality of the building and, not least, the type of usage are critical. The following two buildings within the Central European climate zone are relevant examples.

What does “simple” mean? Highly developed passive strategies, especially for the indoor climate and for daylight utilisation, have influenced the development of architecture for more than 20 years. The main aim during this time was less a question of form, but rather the establishment of these topics as relevant in architecture. Passive measures on the building envelope itself and in the installation engineering, for example, were supposed to be optimally controlled, i.e. via complex regulation systems. However, the necessary adjustment often did not work correctly; the quality assurance for optimised building operations is obviously insufficient. In addition, some-

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3

Example project: Federal headquarters for the German Alpine Club (DAV) For the federal headquarters of the German Alpine Club (Deutscher Alpenverein – DAV) in Munich (see Example Project p. 140ff.), the client bought an existing building and used resource-conserving methods to ­revitalise it and add additional storeys.

3+4 Federal headquarters of the German Alpine Club (DAV), Munich (DE) 2021, ELEMENT A Architekten, hiendl schineis architektenpartnerschaft a Exposed concrete floors serve as ­storage mass and facilitate night-time cooling in summer. b Basic illustration of the ventilation concept

4

5 a–b  Ventilation panels in the parapet area, federal headquarters of the German Alpine Club (DAV), Munich (DE) 2021, ELEMENT A Architekten, hiendl_ schineis architektenpartnerschaft

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The concept is based on a desire for sustainability and environmental responsibility. From the outside, the fact that the concrete core of the old building was almost completely preserved is concealed. A new building would have significantly increased the project’s footprint due to a greater consumption of resources. The two added ­storeys are timber constructions. From the very beginning, the concept sought a lowtech approach (Fig. 4). Timber, glass and plants characterise the new building envelope. In many areas of the facades the large windows do without exterior sun protection, since simulations investigated the shading from the surrounding buildings and greenery for each relevant window element. The natural ventilation concept delivers very good acoustic and thermal comfort despite the high sound emissions from the nearby motorway and large wind pressure fluctuations due to the high-rises in the ­vicinity. The solution is a new approach to parapet construction, which has been ­incorporated consistently in all office areas (Figs. 3 and 5). An acoustically insulated ventilation panel transports outside air into the building interior at constant flow ­volume, independent of pressure differentials. Typically, such a panal would be mounted above the window, which can cause draughts in the cooler outdoor temperatures of Munich’s Alpine foothills. The low-tech solution found for this avoids the use of auxiliary energy and electrical

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control and regulation elements. Instead, the designers made use of physical prin­ ciples and came up with a very robust system: The ventilation elements are incorp­o­ rated into the facade near floor level, but in such a way that, in case of a breakdown of the heating system, the cold outdoor air flows past the convector. This prevents the convector from freezing, thus obviating the need for frost protection. In normal operations, thermal lift in the ­convection shaft provides for the flow of replacement air from outside and from the lower portions of the rooms. Warmed in this way, the fresh incoming air prevents draughts and cold feet. The outgoing air is centrally collected in the shafts and discharged through the roof via exhaust vents. The functioning of this system was verified by airflow simulations and tested successfully in a 1:1 mock-up using smoke trials. The exposed floors support the night-time room cooling strategy during the summer. During hot weather periods, ceiling fans provide increased air movement and user comfort. Air conditioning and machine ­cooling were avoided. Only the electronics and IT area is subjected to active but not conventional cooling: Two cryocoolers using water as the coolant. This is inexpensive, efficient, non-toxic, non-flammable and non-ozone-depleting and has a global warming potential of zero. In winter, the waste heat is fed into the heating system. The building is also supplied by district heating.

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Example project: Alnatura The organic grocery chain Alnatura has selected a site of about 50,000 m2 at the ­former location of the Kelley Barracks in Darmstadt for its new company head­ quarters (see Example Project, p. 152ff.). The centrepiece of the Alnatura campus is the 500-workplace office building, currently the largest in Europe that features a rammed earth facade. The three-storey working enviroment is ­subdivided into office, conference and ­restaurant areas. Aside from the expect­ ation of a good indoor climate, the emphasis lay especially on simplicity in the sense of robustness: Greater quality through reduction. During the design, efforts were made to ensure that passive measures kept the cost of technical installations as low as ­possible. Even the embodied energy of the new building was evaluated (i.e., the amount of energy needed for the production, transport, warehousing, sales and ­disposal of the building materials) and resource-conserving solutions were chosen for the building components The result is a high-performance, energyefficient building with optimised indoor comforts provided by recyclable and /or natural materials, such as the timber structure of the gable roof and the clay facades (Fig. 6). The foundations, the basement, the cores and the floors are of reinforced concrete. The thermal mass of the floor slabs con­ tributes significantly to protecting against summertime heat, while the solid clay walls – together with the timber roof construction – serve to passively regulate the humidity. The windows in the clay walls are shaded externally. The east and west facades are fully glazed and combine optimally with the north-facing skylight to flood the atrium and its light-coloured surfaces with daylight. The path of the sun was taken into account in the layout of the space, so that the whole building would benefit as much as possible from the natural influx of light. Artificial lighting is regulated depending on usage and daylight. Areas near the facade are natur­ ally ventilated. Because of the depth of the building, the inner areas are mechanically

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supplied with fresh air. In this process, fresh air is preconditioned in a subterranean channel and then drawn into the office spaces via displacement diffusers in the four stairwell cores. The users can open the windows. Controllable openings in the roof of the atrium provide for ventilation and air extraction. The system is equipped with CO2 sensors. The rooms are cooled in summer by flushing with night-time air, thereby reducing the temperature of the thermal mass. In addition, a radiative system integrated into the interior sides of the clay walls serves as heating and cooling. The building is supplied with heat and cooling via geothermal wells, while photovoltaics on the roof generate electricity (Fig. 7). Conclusion “Simple construction”, “low tech” and “robustness” are terms that, for various ­reasons, have again begun increasingly to determine the discussion centred on more

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6 a–c  Rammed earth facade, Alnatura office building, Darmstadt (DE) 2019, haas cook ­zemmrich, Studio2050

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Exposed thermal PV mass with integrated system acoustic elements

Interior sun and glare protection Skylight, High-efficiency triple thermal insulation glazing, can be opened Daylight-dependent artificial light regulation

Wallintegrated heating/ cooling

7 Energy concept, ­Alnatura office building, Darmstadt (DE) 2019, haas cook ­zemmrich Studio2050

Note:  [1] Statistisches Bundesamt (Federal Statistical Office) 2021

Exterior manoeuvrable sun protection Triple glazing Insulated opaque facade Window ventilation Light-coloured surfaces, daylight reflection Light-coloured exterior surfaces/daylight reflection

Heating requirements (e.g. kitchen, etc.) Heating + cooling: Gas-fired kitchen heat geothermal boiler waste heat pump energy

Core air supply

Heating of office areas: Internal wall subterranean loads heating channel

intelligently executed architecture. It is important to ask how this differs from the discourse of the 1990s, during which ­disciplines and terms such as climate ­engineering, climate design and climatecompatible architecture emerged. These were often translated into buildings with a lot of glass and “intelligent” facades. What is new now is a narrower focus on materiality with a view to life cycle assessments and thus the issue of the climatic efficiency of construction materials in combination with decisions regarding the building form. This development is very welcome in terms of residential quality, energy consumption, grey emissions and deconstruction, and it is ultimately economically feasible. Rammed earth buildings are frequently boiled down to the thickness of their walls. In fact, however, the interplay between geometry – particularly aspects such as room height (good daylight with smaller ­proportional window area) – and materiality (exposed thermally and hygroscopically effective building mass) is of great import­ ance. “Simple” clearly implies something other than merely less technology. Rather, simplicity leads to a different, more conscious choice of materials, which in turn has functional and formal consequences. Different, novel typologies are created. Though the “novel” often borrows from traditional architecture, it represents a further

Subterranean channel for comfortable ventilation and bypass with aerator and heating elements 7

step in answering the question as to whether sustainable architecture is capable of developing an independent formal expression. Even more relevant is the fact that ­sustainable architecture is becoming more multifaceted and increasingly state of the art. This is evident in how existing buildings are treated, of which the DAV building is representative (p. 74ff.). In this context, the present discourse about “high tech versus low tech” goes beyond the considerations of the 1990s – the earlier visions of a holistic utopia seem to have arrived in reality. The projects demonstrate that the topic has the potential of being more than just a fad. An office building such as Alnatura’s creates the connection between an “exotic” lighthouse project and a reality-based construction endeavour and shows how consciously designed sustainability can actually change the build environment. If the foundations of Climate Engineering and climate-responsible architecture were developed in the 1990s, then maybe today’s reflections on simplicity and robustness in construction and building technologies represent the establishment of Climate Engineering 2.0.

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Low-tech Focus: Materials Choosing Sustainable Building Materials Edeltraud Haselsteiner

The construction industry is one of the most resource-intensive sectors in the world. In Germany, for example, about 90 % of all mineral commodities consumed are used in the production of building materials [1]. Especially during the production of cement and concrete, large quantities of CO2 are emitted. About 8 % of all the greenhouse gas emissions in the world can be attributed to the production of cement [2]. Building materials are only rarely reused. Composite building materials make a separation by type difficult, and in the best-case scenario, building waste undergoes low-grade utilisation in road construction. In recent years, natural building materials such as clay, timber and straw have established themselves to an increasing degree. The properties of natural materials and commodities can be used in construction, e.g. structurally, and also for functions such as thermal storage, air conditioning, etc. When natural materials are incorporated in keeping with their natural characteristics, without industrial processing, the environmental footprint can be minimised. Yet the modulating properties of natural materials also have positive effects on indoor climate and well-being. In addition, the centurieslong existence of historical timber, stone and clay buildings is evidence for their robustness and durability. The physical properties of materials critic­ ally determine the energetic quality of ­buildings. Materials that minimise the flow of heat make possible a significant reduction

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in energy requirements and the energy ­necessary for operations. The production, maintenance and disassembly of a material involve embodied energy. Finally, energetic ­processes are initiated by care and main­ tenance during the usage phase that have, when viewed over their lifetime, consider­ able energetic and environmental ramifications [3]. The following examples provide a small window into the many uses to which natural materials can be put. It is apparent that it is not only important to employ the mate­ rials according to their properties and as much as possible in their natural state, but also to be mindful of the long-term recyclability of structures and to plan for recycling or reuse at the end of their service life. It is already possible to produce buildings with a high percentage of recycled materials. Recognising the building industry and construction activity in general as part of a comprehensive circular strategy, as shown in “Recyclable Construction and Renovation” (p. 86ff.), is the dictate of the moment. Natural building materials and renewable bio-materials Different material characteristics such as the moisture-regulating effect of clay, the excellent thermal insulation properties of timber or the weather-resistance and easy availability of natural stone make these ­natural building substances the preferred construction materials of historical local

a 1 a– b Office and event building Kulturkraftwerk oh456, Thalgau (AT) 2014, sps-architekten Low tech: Clay storage heater, use of natural materials (e.g. Swiss pine ventilation vents, rammed earth walls, clapboard facade, solid wood floor) and manual techniques, sufficient overall building concept, high building standard (plus energy building) with autonomous energy supply

2 a–c Green Centre administrative building, Immenstadt (DE) 2016, f64 architekten Low tech: Regionally renewable building materials (timber), disconnectable fasteners, rammed earth wall as thermal reservoir and for regulation of humidity, night-time and window ventilation, daylight design

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building culture. Plant-based raw materials like straw, reed, flax, hemp, etc., the avail­ ability of which varied according to climate conditions and the management of agricultural land, complemented the traditional building methods in applications such as insulating material or roof coverings. All these materials are still found in nature or could easily be cultivated again in the pres­ ent day. Especially materials such as timber or clay exist almost everywhere and can be used immediately just as they appear in nature. When paired with a return to manual techniques, various locally available natural materials form the basis for new building concepts with a considerable saving of embodied energy, geared toward a sustainable and resource-conserving future. The two timber buildings described below ­follow the examples described in previous chapters of buildings made from different natural materials.

small hydroelectric power plant and a photovoltaic system on the roof. Furthermore, as a pilot project of the Austrian energy research programme “Haus der Zukunft” (House of the Future), the building was designed to showcase future-oriented methods for en­­ vironmentally sustainable construction and serve as a prototype to test new components and also old artisan techniques [4]. The basic structure is formed by unre­ inforced tamped concrete walls and crosslaminated timber panels. Timber also dom­ inates the rest of the building design: Ventilation vents of Swiss pine, a clapboard facade and solid timber floors demonstrate the broad applications of this construction material. The building is heated by means of a clay storage heating system (Fig. 1).

Office and event building The three levels of the Kulturkraftwerk oh456 building provide space for individual and shared offices as well as an event ­centre. The structure occupies the site of a former timber mill. The necessary energy for the resident companies is delivered by a

Administrative building in Immenstadt The commission to design an administrative building in which forestry, timber and agricultural offices would combine their expert­ ise made timber a natural choice for the primary material (Fig. 2). The diverse building material was used for aesthetic, economic and structural purposes. The slight slant of the facade serves not only to convey a plastic effect but primarily functions as structural wood protection. An important aspect of the project was to work with local companies and with locally available mate­ rials. Interior walls and ceilings are therefore clad in native timber species. A rammed earth wall 40-cm thick provides the building with an equalising storage mass and has a moderating effect on the humidity. Central areas and corridors are lit and ventilated from above via the atrium. Optical and acoustic signals in the offices indicate when windows should be opened.

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Recycled materials In order to broadly reduce the embodied energy of manufacturing processes, the ­further use or repurposing of existing buildings should always take precedence over the complete demolition of a building or the construction of a new replacement. If a building is taken down, it is possible to reuse the accumulated materials from the construction site. To keep the amount of waste that must be disposed of as low as possible, it is a critical facet of design to plan for the complete future deconstruction and recycling of the building materials and substances. The ­following factors facilitate or complicate the reuse or recycling of a building material: •  Homogeneity of the materials used •  Material selection / variety • Separability and connection details between substances and materials • Material/substance labelling and ­documentation

cooperation with the municipality and with the participation of the local population. Through the active involvement of the community, it was possible not only to create a consciousness-raising showcase project for the reutilisation of resources, but simultaneously to establish a unifying and identifying structure for the locals. Recycled materials from the 2012 Olympic and Paralympic Games in London make up 80 % of the building (Fig. 3). Nine former athletes’ locker rooms made of steel frames and plywood were reassembled and connected with one another to form a steel structure. The boxes have also been insulated and equipped with ventilation. In addition, numerous reused objects and elements designed by the local community can be found throughout the building. The facade is partially composed of fences from the Olympic park and recycled aluminium panels; local artists and a group of students designed and made the various lamps [5].

The possibilities for the reuse of individual substances have been continually increasing over recent years, not least due to technical advances. Construction waste, which previously underwent mostly low-grade ­reutilisation in road construction, can now be used in the manufacture of recycled concrete thanks to improvements in recycling processes. The following examples illustrate how successful new architecture can be created from demolition, everyday and waste materials.

Three social enterprises in Vienna magdas hotel, magdas kitchen and VinziRast-mittendrin are social organisations in Vienna for which the idea of reusing various materials and the participation of the future residents became part of the agenda (Fig. 4). VinziRast-mittendrin is a housing and employment project started by students for formerly homeless people. A large part of the conversion work was done together with the affected parties, students and other volunteers, some of whom now also live in the building. The house was primarily furnished with donated items and materials. Things that are usually thrown away, such as fruit and vegetable crates, recycled coffee sacks and even door handles, which serve

Community centre in London Hub 67 is a temporary community centre designed for three to five years of use. The building was built as a communal project in

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3 a–b  Community centre Hub 67, London (GB) 2014, LYN Atelier Low tech: Construction using recycled mate­ rials, 80 % of the employed materials sourced from buildings used at the 2012 Olympic Games

as bag hangers along the bar, have been made maximal use of within this context of limited financial means. magdas hotel and magdas kitchen are both social enterprises run by Caritas Wien. magdas hotel offers shelter to refugees, while food for nursing homes and nursery schools is prepared by magdas kitchen. In both ­projects, the interiors were furnished with ­demolition waste and reused materials. Lamps from a torn-down office building, ­former ceiling panels and parquet floors repurposed as wall decoration and cladding were used to make rooms in which a new life could be created, not only for the mate­ rials but also for people with a difficult past.

4 Social enterprises a–b magdas kitchen, Vienna (AT) 2019, ATP c–d magdas hotel, Vienna (AT) 2015, AllesWirdGut Low tech: Reuse of ­discarded items

Building with mass Building with (storage) mass was used in traditional construction in order to condition rooms naturally without technological means. The principle is based on the effective storage capacity of building components. When heat energy is incident, heat is stored in the component mass and causes an increase in the surface temperature. Depending on the temperatures of room and surface, heat is transferred between the surface and the air. When the room temperatures are low, the surfaces lose heat to the ambient air.

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The use of building mass as a thermal ­reservoir is especially relevant in con­ nection with the passive solar house concept. Completed examples show that the ­constant improvements in building mater­ ials and an optimal interaction among solar influx, storage-capable building mass and o ­ ptimised architectural form have now made it possible to construct buildings without conventional heating ­systems. With the aid of computer simulations and relevant calculation programs, the storage behaviour of building masses and the projected room temperatures throughout the course of the day / year can be calculated quite accurately already in the design phase (see Example Project, p. 136ff.). The big challenge lies in the improvement of the thermal properties of the mass without an increase in quantity. In the pursuit of this goal, two strategies have established themselves: The thermal activation of ­building components and the simulation of mass storage capability by means of phase change materials (PCM). Phase change or viscoelastic materials can reverse changes in their aggregate state in response to ­temperature, electric potential or magnetic fields, absorbing or emitting heat in the ­process. Paraffins or salt hydrates, for example, begin to extract heat from their surroundings at a set temperature and then discharge it again after the phase change (see “Passive solar energy facades”, p. 60f.) [6]. The second strategy, component activation, functions by strengthening the thermal properties of mass without increasing the mass. Exemples of this date back to the hypocaust systems and the building components heated by hot air in Roman baths. Furthermore, the traditional construction methods in Arab and African regions, that is, in regions with a predominantly hot and dry climate as well as very large day-to-night temperature differences, are rife with examples of how heat is tem­ porarily stored in massive ceiling, wall and floor components until it can be dissipated later into the cooler night air. The modern timber building uses this principle to protect

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against summer heat: Storage capacity through surface-adjacent layers (storage mass) combined with ensured heat removal (cooling-efficient air exchange). In contemporary component activation systems, the storage capacity of the building mass is raised through carrier media such as air or water, and heat is primarily dissipated by radiation from the activated surfaces. ­Component activation is used for both the heating and cooling of rooms [7]. School complex in Vella A passive solar energy concept was chosen for the design of a new school complex in Vella (Fig. 5). The new building possesses neither a conventional heating system nor solar collectors. Just one displacement ventilation mechanism and one heat exchanger form a supplementary building technology system. The solid concrete construction represents a good storage medium. In ­addition, the storage effect is enhanced by a flagstone floor of native Vals quartzite throughout the entire school building. The underside of the ceiling was expanded by a ribbed concrete construction that acts as an absorption surface. Large window openings with reveals bevelled upward and south and west at 45 ° facilitate an ­optimal influx of light and passive solar energy utilisation. In the classrooms, a controllable, adaptable louvre system on the inside of the windows allows daylight to be deflected into the depths of the space and radiative heat to be directed into the ribbed ceiling [8].

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heat is generated without a conventional heating system solely from internal energy sources and storage-capable mass (Fig. 6). Thick outer walls, solid floors and ceilings as thermal reservoirs ensure that little heat is diffused through the walls. The 80-cmthick solid exterior walls are composed of conventional vertically perforated bricks laid in a double-skin construction – with no insulation. This, combined with natural ventilation (CO2-sensor-regulated 2226 operating system, see Example Project, p. 138), a compact building form with optimised facade openings, natural shading, simple construction and building method using conventional ecological materials (bricks, timber), daylight, sufficient building equipment and flexibility of usage, makes the building a pioneering project of contem­ porary low-tech construction.

5 a– b School complex Vella GR, Lumnezia, Vella (CH) 1997, Valentin Bearth & Andrea Deplazes Low tech: Reduced heating and building technology (no conventional heating ­system): Passive solar energy concept, optimisation of storage mass efficiency through material choice and design

Office building in Lustenau In Haus 2226 by Baumschlager Eberle Architekten, completed in 2013, indoor

Clay house in Vorarlberg Clay is created through the weathering ­(disintegration) of rock layers as a consequence of geological processes and erosion effects, e.g. from water, frost, wind and temperature changes. Clay is avail­ able and usable everywhere, though its processing is very time-consuming. Now, however, prefabricated clay components allow for a streamlined construction process even

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6 a– b Office building 2226, Lustenau (AT) 2013, Baumschlager Eberle Architekten Low tech: No heating system: Room heating from internal energy sources and bound in storage mass, CO2 -sensor-controlled ­natural window ventilation, compact building form with optimised facade openings and natural shading

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7 a–c Single-family clay house, House Rauch, Schlins (AT) 2008, ­Boltshauser Architekten, Martin Rauch Low tech: Ecological construction method and choice of mate­ rials, reutilisation of excavated soil, recy­ clable, untreated ­natural materials, documentation of incorporated materials

in larger projects. The Rauch clay house is a solid rammed-earth construction (Fig. 7). To build it, all of the excavated material was first screened and then reused in the form of rammed earth for structural and pre-­ fabricated walls, floors and drainage waterproofing. The clay walls were kept largely untreated both inside and out. The building is considered a successful experiment and showcase project for innovative clay construction. Clay brick orphanage Volontariat is an NGO that sponsors and ­initiates social projects. The goal of the ­project in Pondicherry, India, is to provide inexpensive and environmentally-friendly ­living solutions for homeless children. These homes are designed to house fifteen children and five foster parents. The result is a prototype of “baked” clay (Fig. 8). The technique was developed by Ray Meeker and Golden Bridge Pottery and adapted by the architect Anupama Kundoo: The clay houses were first constructed with handformed mud bricks and clay mortar. Afterwards, the entire structure was “baked” so that it would acquire the strength of bricks. In this final step, the interior of the buildings was filled with more mud bricks or other ceramic products (such as tiles) and functioned as a kiln.

8 a–c Volontoriat Home for Homeless Children, Pondicherry (IN) 2012, Anupama Kundoo Low tech: “Baked” clay construction

Innovative building materials All over the world, pioneering architects have tested experimental structures made from alternative materials. This has led to the rediscovery of bamboo as a high-­ performance building material, but even designs made from paper and cardboard have already been realised. Since the mid1980s, the architect Shigeru Ban has been

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developing various construction systems using paper tubes. In his work, tubes that have been inexpensively fabricated from waste paper are employed as a structural elem­ent and joined to form simple building ­systems. Architect Wang Shu and his wife, architect Lu Wenyu (Amateur Architecture Studio) prefer to incorporate recycled materials in their buildings. The Ningbo History Museum, for example, was constructed from the demolition waste of trad­itional ­Chinese buildings in the surrounding region (see figure on p. 36). An equally innovative development based on biomaterials is on the rise. Self-growing biomaterials are based on microorganisms (e.g. bacteria or fungi) that grow in a suit­ able nutrient medium. In the process, the original medium is changed to such a degree that a new material is created. The only requirement, aside from the suitable nutrients (otherwise usually considered waste products), is the maintenance of a specific moisture and temperature level over a given time period. The biomaterials grow independent of location, that is to say, they can be cultivated where they will be used, so that long transport routes become unnecessary. In addition, the ­materials are predominantly organic and absorb CO2 during their growth phase. Another advantage is that these substances can be readily composted after use, or can be reused in another cycle. Even though developments in this sector are still relatively recent, a few products now exist that are well on their way to becoming market­ able commodities. Emergency shelters made from paper tubes After the Kobe earthquake, Shigeru Ban developed simple and inexpensive houses as emergency shelters. They are made ­primarily of various surplus and donated materials. The foundations consist of beer crates filled with sandbags. Paper tubes with a 4-mm wall thickness and a diameter of 106 mm form the walls, while the roofs are covered with tent material (Fig. 9). For insulation, waterproof sponge tape with adhesive backing was inserted between the paper tubes. The material costs for a single

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9 Emergency shelters, Paper Log Houses, Kobe (JP) 1995, Shigeru Ban Low tech: Simple and inexpensive construction using available and donated materials (beer crates, cardboard tubes, etc.), resource efficiency, disassemblycapable and recyclable

52-m unit are less than €1,860. The units can be easily and quickly built and disassembled by laypersons and are completely recyclable. 2

Seaweed house The design by Vandkusten Architects revitalises a local building tradition. Seaweed may already have been used as a roof ­covering on the island of Læsø in the 17th century. This building tradition developed due to a scarcity of timber and straw, as both were needed for other purposes. ­Seaweed is abundant in the coastal waters. The architects used it as roof covering, for facade cladding and for insulation (Fig. 10). On many occasions, the implementation of this unusual concept required manual workmanship. For the roof, the material was stuffed by hand into knitted sheep’s wool nets and then attached to larch battens on the outside of the roof using long cords. The project proceeded under scientific supervision by the Danish Institute for Marine Biology in order to gather more ­information about the physical properties of the plant. Knowledge of how to handle the material was requested by the inhabitants [9].

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10 Single family residence, Modern Seaweed House, Læsø Island, (DK) 2013, architectural studio Tegnestuen Vandkunsten Low tech: Economical construction, innovative and experimental use of inexpensive regional materials, revitalisation of local building tradition

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b 11 a–b MoMA Pavilion PS1, New York (US) 2014, The Living, David ­Benjamin 12 a–b Tecla 3D Habitat building modules, Ravenna (IT) 2021, Mario Cucinella Architects, Wasp Low tech: 3-D printed clay construction

Notes  [1] Pichlmeier 2019  [2] energiezukunft.eu   [3]  Hegger et al. 2007  [4]  nachhaltigwirtschaften.at  [5] Detail 3/2016  [6] Haselsteiner 2011   [7] Zement + Beton 2016  [8] Luchsinger 1998  [9]  Detail Green 1/2014 [10]  Detail 6/2015

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“Self-growing” biomaterials The company Ecovative, which actually specialises in packing materials, has devised a method for replacing plastics with a material based on fungi. The original intention was to develop an alternative to conventional, oil-derived insulating mate­ rials. The innovative material is produced from agricultural waste, such as corn straw or other harvest residuals, and a substance called mycelium, which is an underground fungal network. The mycelium acts as a self-generating adhesive that can bind ­various materials. A small demo house was created to demonstrate the stability of the material. Within its timber construction, a fixed insulating layer was cultivated using the mycelium. The stability of this insulating layer was such that the house could be built without the need for add­ itional stiffening constructions. For an ­exhibition at the Museum of Modern Art (MoMA) in New York in 2014, a proprietary mushroom brick was developed with which architect David Benjamin (The Living) ­created an accessible tower sculpture (Fig. 11). The advantage: Fungi are easy to cultivate and the mushroom bricks, produced using a low-tech process, are fully compostable [10]. 3D-printed clay building Innovations are not limited to the realm of materials – new technologies such as 3D printing also demonstrate alternatives for the economical processing of natural building or waste substances. Architect Mario Cucinella and the 3D printing specialist Wasp developed the prototype of an ecological building that is 3D-printed from clay. The building, called Tecla, was

engineered and constructed using raw earth sourced from a nearby river bed. The two connected dome-shaped volumes comprise 350 stacked layers of 3D-printed clay. According to the developers, this technology allows building modules to be built in 200 hours with an average energy consumption of 6 kW per unit and with prac­ tically no waste. The approx. 60-m2 units have a room height of 4.20 m; they include a kitchen, living area and bedroom and are lit by means of a round skylight in the roof (Fig. 12). Gaia, another building created by Wasp using similar techniques, consists of natural waste materials from rice production; 25 % from excavated materials, 40 % from rice straw and 25 % from rice hulls.

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Recyclable Construction and Renovation Johannes Kisser, Gaetano Bertino

Even though about half of the building materials that come from demolitions and renovations are now recycled, the construc­ tion sector is the source of over one third of all the waste generated in the European Union (EU), and is therefore the greatest waste producer. Cities and settlements are centres of economic activity, but also consume immense amounts of water, food and materials which eventually become sewage and rubbish. Instead of represent­ ing resource sinks, however, buildings, cities and settlements could function as sources of secondary materials, as a resource turn­ table within the circular economy. One important aspect of the circular economy are the omnipresent secondary resources that are always found near human settle­ ments and which can be sorted roughly into two cycles: the technological and the biological. Technological cycles encom­ pass resources that can be used multiple times or are stored in buildings as raw material stock or reserves. Biological cycles include resources that can be composted or are needed for biological processes. In buildings they are continually being metabo­ lised. The approaches to finding solutions for closing technological and biological cycles are distinct. However, recyclable construction goes far beyond the use of secondary materials. From the outset, systemically recyclable buildings are designed to be modular, adaptable, multifunctional and decon­ structable. Solution approaches for recy­

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clable construction follow basic princi­ ples that • view waste as a valuable material ­(nutrient) • use what is locally available (“use what is there”) •  use diversity • see multiple uses and multifunctional usage as fundamental precepts • regard city districts and settlements as ecosystems. Nature-based solutions can be employed (see p. 48ff.) to extract clean water and nutrients from the large quantities of waste­ water and compostable rubbish that build­ ings produce daily, and to return them for use in (food) production in surrounding areas. The greening of buildings with all its additional advantages can take on a key role in this effort. This chapter deals with different approaches to recyclable construction solutions, ranging from the utilisation of secondary materials to systemically recyclable architecture to obstacles and opportunities as well as the legal framework and certifications, in order to contribute to the climate resilience of ­cities and settlements. Robust architecture and the circular ­economy Below, robust architecture stands for the use of qualitatively valuable materials as well as their intelligent incorporation into a building or infrastructure. Durability,

r­ eusability and prefabrication as well as modularity or adaptability are the main focus. The quality of materials encom­ passes avoiding toxic ingredients, using mono-materials (in other words, avoiding compound materials) or the ability to sepa­ rate different materials, and construction that allows for materials to be disassem­ bled. The principle of using simple and robust materials helps to keep costs down, increases usage options and maintains material value. At the same time, robust architecture also means creating intrinsic system re­­ silience. This is achieved by the flexibil­ ity and modularity of incorporated build­ ing fabric on the one hand, and through ­sufficiency and self-sufficiency on the other. The first approach scrutinises tech­ nological cycles in buildings; the second, possible biological cycles. Following the basic principles of cradle to cradle, the ­origin of the modern circular economy, buildings are capable of fulfilling similar functions as trees. They can provide living space for various species and simulta­ neously render additional services such as cleaning air and water. Nature-based solu­ tions are the method of choice, in which advantage can be taken of the many bene­ fits that plants and green building walls or roofs offer.

Recovered material ru ctu re

St

Production

En

ve

Se

rvi

lop

e

ce

s

Ro

Resource investment

om

Assembly

Th

60–300

15–60

7–30

s 3–7

Use

0–5

ing

Years 1  Service life (in years) of various parts of a building

Disassembly

1

Recyclable construction and ­renovation The circular economy in the building ­sector is often associated with new con­ struction. Yet there are many existing ­buildings that are supposed to be refur­ bished in a “renovation wave” (see the planned strategy of the European Green Deal, p. 13). This means that we should focus even more on renovations in future so that the ambitious climate goals can be met. Basics The circular economy in the building sector can be defined as a path towards reaching sustainable development targets that is based on business models which, stated simply, aim to transform one-time waste into valuable materials. Key to this goal are recyclable design [1] and reuse, recy­ cling and recovery of materials [2] in the production, construction and usage of buildings [3]. The transition to a circular economy also depends on how valuable materials can be reused in order to return them to the loop. Disassembling or demolishing a building requires large machines such as excavators, cranes with wrecking balls and other heavy equipment [4]. The way materials are incorporated is ultimately the deciding factor for how recovery can be made (economically) feasible. Lifetime In general, all components are concealed under or behind a clean surface. Floors are often made from concrete, either poured in situ or in the form of precast elements that are bonded on site with a layer of fresh concrete. The products of these construction meth­ ods must necessarily be destroyed at the end of their service life and cannot be ­disassembled [5]. Often, materials are strongly bonded to one another, which makes deconstruction, reuse and recyc­ ling difficult. This approach to building must therefore change. Wet construction methods, such as pouring concrete on the building site and employing wet seal­ ants, must be broadly avoided [7]. It is

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­ ossible to construct building components p in such a way that they can be taken apart again the same way that they were put together [8]. During the usage phase, buildings are refurbished, repaired and maintained. At the end of the life cycle, the linear economy has only three available options for the man­ agement of waste from the demolition of a building: recycling, recovery of the ener­ getic content of the organic substances through incineration and disposal of the ­discarded products [9]. In all these options, a large portion of the value imparted during the manufacture of products and building components is lost. Preserving value Qualitatively valuable materials that can be deconstructed as entire building com­ ponents and are thus reusable retain a greater residual value at the end of a life cycle [10]. In addition, recyclable build­ ings can be amortised over a longer time period (Fig. 2). Aside from the savings in material disposal costs and the local socio-economic as well as environmental advantages, this retention of value can thus also be entered in the books. Together with suitable business models, the preser­ vation of asset value can contribute con­ siderably to making the advantages of the circular economy appealing to other interest groups [11]. The value can be obtained and recorded via a building material passport, for ex­­ ample on the Madaster platform, in which ­individual materials are listed [12]. There are already numerous examples of build­

88

ings in the Netherlands, Germany and ­Switzerland, such as the Triodos bank building in Driebergen-Rijsenburg and the Circl in Amsterdam, that have been built using this method [13]. In similar recycla­ ble projects, a combination of the Building Circularity Passport, which represents a profile of the building and its properties [14], and some chosen form of certification would provide an interesting option. Deconstruction, reuse and recycling An important role in the circular economy of buildings is taken on by deconstruction, which is understood to be “reverse con­ struction”, i.e. the capability of disassem­ bling a building piece by piece without damaging it, with the expectation of recoup­ ing its value through reuse in other con­ texts [15]. This contrasts with classic demo­ lition, which tends to be an arbitrary as well as destructive process. Though demolition is faster, it generates substantial amounts of waste and all the associated negative side-effects such as CO2 emissions, loss of value and additional costs for disposal in landfill. Construction and demolition waste that is not taken to landfill make up about 20 – 40 % of the total waste stream (of which 90 % is produced during demoli­ tion, and only 10 % during excavation and construction) [16]. Also, compared to a con­ ventional demolition process, deconstruc­ tion allows for a significantly greater degree of reuse and recycling of materials: Up to 25 % of the materials of a conventional resi­ dential building can be reused without diffi­ culty, while up to 70 % can be recycled [17]. In an orderly deconstruction, considerably

Building deterioration Renovation 2  Comparison of building depreciation: a linear b recyclable

Value

Value

Conventional

Recyclable Building deterioration Renovation

Renovation

Renovation

Time a

Waste disposal costs

less material ends up in landfill and fewer new resources must be produced; also, compared to demolition it is a cleaner and more sustainable process in which fewer pollutants make their way into the atmos­ phere and bodies of water [18]. After dis­ assembly, building components can be reused in new contexts and life cycles [19]. Of course, before their reuse they must achieve a quantifiable and certifiable quality level so as to ensure their safety during construction and use. Thanks to ambitious environmental policies and the improve­ ment in waste treatment methods, the build­ ing industry today is confronted with the availability of secondary recycled materials that are suitable as regionally accessible alternatives to primary commodities [20]. New digital markets and platforms are opening up for secondary materials which simplify decision-making during the entire life cycle of a building and adhere to the core concept that materials on the openly traded market should be recovered, reused or recycled. Challenges and opportunities The challenges and opportunities can be roughly sorted into two categories: econom­ ics and politics. Economics, material quality and education The most important economic obstacles concern the quality control of waste and the delay in generating data from the evalu­ ation of implemented concepts of the circu­ lar economy in various life cycle phases [21]. The challenges that impact the utilisation of recycled materials in new products are

Time b

2

often their insufficient quality and the dis­ continuation of the supply. In order for them to be successfully brought to market, sec­ ondary materials must, at a minimum, fulfil all necessary product requirements [22]. It is understandable that the market accept­ ance of products fabricated from waste can be guaranteed only if their production costs are lower than those for new mate­ rials. This theoretical price advantage is com­ plicated by high labour costs in industrial­ ised countries, while primary commodities can still be sold with externalised costs (that is, without stating the true costs) [23]. The new approach is often perceived as an obstacle to designers [24]. To make use of secondary building materials, the design must accordingly be based on what is available. Knowledge of the quality and existence of surviving materials is a pre­requisite. In this respect, digitisation plays an important role, if only in making it possible to learn when and where which materials will be available [25]. It may be assumed that future technological innova­ tions and especially new business models will further strengthen the utilisation of sec­ ondary raw materials [26]. Political framework Thus far, current legislation has lent only ­limited support to the circular economy in the building sector. Strategies such as the “renovation wave” [27], which were developed as part of the EU’s Green Deal, describe a series of planned, more concrete actions which were or will be put in place between 2020 and 2024 [28]. One of these measures is the “New European Bauhaus”

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3

3  Upcycled shipping container as a guest house, San Antonio, Texas (US) 2010, Poteet Architects Low tech: Innovative use of materials (e.g. recycled telephone poles or a pallet for the

HVAC unit made of recycled lemonade bottles inside a steel frame), outdoor lighting from parts of a ­tractor’s disc plough, composting toilet, roof garden irrigation with used shower water

In this regard, appropriate measures are also required for the renovation or new ­construction of buildings; a well-organised listing may be seen for example in the EU Taxonomy Compass [31]. The Austrian Recycling Building Material Ordinance [32] was an advance at the ­Austrian level toward the expert deconstruc­ tion of large buildings and towards quality requirements for the recycling of construc­ tion materials. At the EU level, the materials

generated in the demolition of buildings are otherwise subject to the Waste Frame­ work Directive [33]. This includes descrip­ tions of non-binding rules and best-practice ­procedures [34]. In the development of secondary resource streams and of reuse in construction, stand­ ards, experience and guidelines are impor­ tant to guarantee quality. In addition, the Extended Producer Responsibility (EPR) is not yet mandatory in the construction sector and associated standards [35] are not yet ap­­plicable to building products with long service lives. That means that the roles and responsibilities of the various actors are not yet fully clear. On top of this, missing data flows along the value-added chain nega­ tively impact trust in the quality of the mater­ ials that have been recycled or are to be reused. The lack of available documentation regarding the provenance of the resources can raise doubts about their quality. This problem weakens the chances of obtain­ ing a CE certification (a declaration by the producer or distributor stating that the prod­ uct meets all the EU-wide requirements for safety, health and environmental pro­ tection), since the applicability of the har­

4

5

initiative [29], which is intended to strengthen a sustainable and inclusive form of com­ munal living with appropriate buildings. The EU Taxonomy for Sustainable Activ­ ities [30] envisions investment only upon achievement of specific associated environ­ mental goals in the following categories: •  climate protection •  adaptation to climate change • sustainable use and protection of water and ocean resources •  transition to a circular economy • avoidance and reduction of environmental pollution • protection and restoration of biological diversity

90

4  De Gouverneur residential building, ­Rotterdam (NL) 2006, Architectuur MAKEN Low tech: Bricks from recycled industrial waste (ceramics, glass, clay), narrow building about 4.50 m wide (and four storeys high) 5  Collage House, ­Mumbai (IN) 2015, S+PS Architects Low tech: Facade made of doors and windows from demolished buildings, use of other materials (100-year-old stone columns, floors and beams of old houses, textile scraps, slag and old cut stone, among others)

6 gugler* building, near Melk (AT) 2000/2017, a left: Printing shop with offices and administration, Ablinger, Vedral & Partner; right: Media building extension, pos architekten b interior of the printing shop with walls of rammed earth Notes   [1] Rios Cruz, Grau 2019   [2]  Zhang et al. 2020  [3]  Rahla, Mateus, ­Bragança 2021  [4] Elias-Özkan 2002   [5]  Kanters, Jouri 2018   [6]  Chini, Buck 2014   [7]  Bertino et al. 2021  [8]  Generalova, ­Generalov, ­Kuznetsova 2016   [9]  Hart et al. 2019 [10]  Bertino et al. 2019 [11] Acharya, Boyd, Finch 2020 [12]  Madaster 2022 [13] Jackson, Livingston 2001 [14]  Changelab! 2020 [15]  see note 7 [16] Bohne, Wærner 2014 [17]  Akinade et al. 2015 [18]  Minunno et al. 2020 [19]  see note 7 [20] Pedersen, Zari 2014 [21]  see note 9 [22]  Gepts et al. 2019 [23] te Dorsthorst, ­Kowalczyk 2002 [24]  see note 6 [25] Carra, Magdani 2017 [26] Sánchez Cordero, Gómez Melgar, Andújar Márquez 2020 [27] EU Commission 2020 [28] EU Commission Annex 14.10.2020 [29] New European Bauhaus 2022 [30] Regulation (EU) 2020/852 [31] EU Taxonomy Compass 2022 [32] BGBl. II No. 290/2016 [33] Directive 2008/98/EC [34]  Environment 2022 [35]  ISO 14025:2006 [36]  see note 26

a

monised product standards does not extend to waste-derived materials. The certification is a means for ensuring that the products comply with legal standards. Therefore, it can be seen as an important step for a suc­ cessful introduction of building sector sec­ ondary materials to the market [36]. Examples Different projects shown in Figs. 3 – 6 illus­ trate the reuse of various materials and building components. The longtime head­ quarters of a media company in the vicinity of Melk is the first cradle-to-cradle-inspired plus energy building in Austria that features a timber construction with zero emissions, zero energy and zero waste (Fig. 6). It was awarded 900 out of 1,000 possible points in the Austrian Total Quality Assessment (TQB) certification. 96 % of the building con­ sists of reusable materials, of which 43 % of all the raw materials were recycled. The walls were insulated with paper waste, while the outer facade is made from larch and aluminium printing plates that were used for the media company’s digital printing. The foundations were produced from recycled concrete, the car parks from recycled tar­ mac. Figure 6 b shows the older printing shop with walls of rammed earth and build­ ing cooling through the walls using proprie­ tary well water. Thanks to its own 148-kWp photovoltaic system, waste heat utilisation by the heating, printing press and room cooling by means of a groundwater well, and despite an electric charging station for guests, the plus energy building consumes less energy than it produces. The facade insulation is 100 % recycled glass panels. 28.5 % of the roof surface is greened; the

b

6

roof is insulated with mineral insulating pan­ els of natural raw materials and the windows with sheep’s wool in place of PU foam. The grounds encompass about 17,000 m2 of landscaping with biodiversity for humans and nature. This includes habitat spaces, bird protection and deadwood hedges, nesting boxes for European kestrels on the building and herb and vege­table gardens as well as a raised planter bed for the employee restaurant. Prospects The need to establish the circular economy in the building sector is great. Current strat­ egies in this regard (e.g. The Green Deal, EU taxonomy, circular economy action agendas) show ways in which buildings can be more sustainably designed and also managed. Given the intention of the entire Continent to become climate-neutral by 2050, incremental advances (that is, stepby-step, linear improvements of what exists, as opposed to radical, disruptive innovations) no longer suffice. For that, CO2 in all its forms must be sequestered long-term in buildings, whether as biogenic resources or embodied energy. To accelerate this process and to create trust, the first step must be to launch numerous showcase and lighthouse pro­ jects until they become part of the main­ stream. The public sector must also anchor these basic principles in calls for proposals. The available sustainable financing tools are steadily increasing, but project leaders require further education and support in order to take full advantage of them. Cur­ rently, possible ways to finance this circular economy for Austria, for example, are pub­ lished on the website kreislaufwirtschaft.at.

Recyclable Construction and Renovation

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Low-tech Focus: Renovation Utilising Existing Buildings Edeltraud Haselsteiner

A study done in Germany analyses the development of empty residential properties and predicts an increase in unoccupied housing from about 1.4 million flats in 2016 to just under 3 million in 2030 in Germany alone [1]. Even if there are considerable regional variations and the trends in growing and shrinking areas are not really comparable, the numbers are enormous in light of the sustained housing shortages. It can be assumed that vacancy rates in office real estate, service and factory buildings are significantly higher still. From the environmental perspective, the efficient management of existing buildings and their modernisation should be prioritised, and the topic of low-tech renovation should be given precedence over new building concepts. However, now as before, innovations in and ideas for low-tech measures in renovation are still under-represented. In addition, an energy-efficient refurbishment is usually seen as considerably more complex than a new construction. To develop simple solutions and measures for improving the standard, as well as low-tech strategies for revitalising and repurposing buildings, a great deal more attention must be paid to this topic. The refurbishment and conservation of existing buildings contribute significantly to the achievement of climate goals.

92

Traditional building methods, craftsmanship and historic preservation Combining the preservation of a town’s image and built history with the demands of an energetically modern renovation in a design represents special challenges for both planning and implementation. Listed buildings, the energetic condition of which cannot be improved by means of conventional exterior insulation measures, require innovative concepts that take into account the historic substance while simultaneously providing modern comfort levels in the interior spaces. The ­following examples show that careful renovations in combination with ­significant improvements in thermal quality succeed even without high-tech expend­itures. In all these projects, great respect for the old structures and the perpetuation of their hand-crafted qualities form a central aspect in both design and execution. With this return to manual craftsmanship, the time factor also acquires new significance: The focus is no longer on the short-term economic aspect of the construction project but on its aesthetic character, an intensive engagement with the property and the location and long-term preservation (see Interview, p. 32ff.). Restaurant and conference venue in Sulz Freihof Sulz in Vorarlberg, formerly a country inn, was built around the turn of the 19th century. The core of the building dates

1 a–b  Restaurant and conference venue F ­ reihof Sulz, Sulz (AT) 2006, Beate Nadler-Kopf Low tech: Regenerative and renewable raw materials, low-emission building products, careful renovation of an existing building

a

b

Hotel in Bayrischzell The Tannerhof, a hotel and wellness resort that has served as a sanatorium for natur­ opathic medicine since the beginning of the 20th century, was renovated and expanded by Florian Nagler Architekten with a focus on its listed character. All the additions from the 1950s were removed, and an appearance more in keeping with the original character was restored. The architects adopted proven construction techniques from the historical building and carried them over to the new. Situated above the main house, four new “Hütten­ türme” (cabin towers) were created that serve as special retreats. The functional spaces in the cabins, each constructed on a 6.60 ≈ 6.60 m footprint, were stacked vertically with a view to conserving area and resources (Fig. 2).

2 a–c  Hotel and wellness resort Tannerhof, ­Bayrischzell (DE) 2011, ­Florian Nagler Archi­ tekten Low tech: Reutilisation of traditional building techniques, resourceconserving use of area

back to the year 1796. At the time of the 2006 refurbishment, all the rooms and ­furnishings had largely been maintained in their original circa 1900 state. This initial ­situation formed the basis of a careful ­refurbishment, characterised by the implementation of ecological building materials (timber, insulation made from renewable raw materials, a general avoidance of ­plastics, low-emission products such as paints, coatings and glazes low in solvent and plasticiser content, etc.), the use and improvement of seminal old building techniques and an energy supply from renew­ able energies (Fig. 1). The goal of the renovation was to demonstrate that historical preservation and energy-conserving ecological refurbishment complement each other perfectly. Old construction methods were updated to a contemporary level (acoustic insulation, regulated indoor climate and humidity, thermal insulation, low maintenance, colour and haptics). The ­required heating energy is supplied by a ­biomass-contracting heater and a solar ­system as well as the radiant heat from the historical baking oven.. All renovation steps were comprehensively documented and are available as planning aids to all construction participants [2].

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b

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1

House in Soglio In Alpine regions, the decline in agriculture has increasingly left many former farm buildings derelict. Barns and stables about 10 ≈ 10 m in size, with stone roofs, corner columns of natural stone and sides of round timbers, for example, are part of the typical appearance of many mountain villages in Graisons [3]. The architect Armando Ruinelli

2

Utilising Existing Buildings

93

a

b

converted one of these buildings, an unused stable, into a holiday home (Fig. 3). In this process, the important ­historical building elements of timber and stone were preserved and carefully supplemented with unrefined tamped concrete elements. Oak in the ceiling and built-in furniture, ­likewise left in a rough-sawn and untreated natural state, combines with concrete and steel and a perfect artisanal finish on all materials to convey a harmonious confluence of old and new.

building worth safeguarding and the ex­­ ploitation of the energy-­technological opportunities of the present day: Thermal indoor quality was improved through 16-cm thick internal flax insulation in the area of the timber framework on the upper floor, in the west through the glazed connecting wing in the front in the basement through accompanying building component temperature control. The historical box windows were replaced with imitations comprising an exterior single glass pane and interior heat insulation glazing. An especially interesting part of the renovation concept is the use of the access wing as a buffer zone and energy reservoir: By means of different ventilation circuits, warm air is brought into the house; in summer the heat is stored in the stone. In winter, the stone thermal reservoir is ­aerated naturally by airflows from opened windows and doors and the heat is partially recovered (Fig. 4) [4].

Residential building in Silz The Zeggele house is one of the oldest buildings in the Tyrolean community of Silz. It was built in two phases; the core of the building dates back to the 14th century. The house had been unoccupied for some time and had to undergo a general renovation. Under the aegis of the Austrian energy research programme “Haus der Zukunft”, this building became the model for the first overall energy-technological concept implemented in accordance with the requirements of historical and town image preservation and the building fabric. The innovative aspect of the project lies in the way it combines the preservation of a listed Heating operations: natural airflow through the opening of windows and doors on the ground floor and upper floor, heat recovery through forced ventilation of the stone heat reservoir

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94

Stone storage mass in the foundations

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3 a–c Residential / vacation house, Soglio (CH) 2012, Ruinelli Associati Architetti Low tech: Use of vacant building fabric, resource-conserving use of area

Low-tech components for building ­optimisation Everyday classical Modern and especially post-war Modern buildings are only slowly gaining the respect and the pro­ tection that is their due. In terms of authen-

Anterior glazed ­connecting passage

b

4

4 a–b Haus Zeggele residential building, Silz (AT) 2007, Peter Knapp Low tech: Improvement in thermal quality within the constraints of historical preservation requirements, optimised box windows, ventilation concept based on stone heat reservoir

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b

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5

5 a–c Revitalisation of social housing, Tour Bois le Prêtre, Paris (FR) 2011, Frédéric Druot Architecture, Lacaton & ­Vassal Low tech: Low-tech renovation strategy, conservatories as ­climatic buffers and ­living space expansion, ­daylight concept

tic materials, these buildings are usually less stringently dealt with in renovations than their historical predecessors. Pre­ serving their architectural stylistic elements is nevertheless one of the most important tasks during their renovation. At the same time, buildings of this period in particular have poor energy efficiency and are comprehensively in need of modernisation. To accomplish this, Maja Lorbek and Gerhild Stosch developed a concept they call “architecturally nuanced, energetic renewal” (ADE renewal), a renovation concept and a catalogue of interventions in which components important for conveying the style of the early 1960s are retained, while others provide energetic balance thanks to their higher energy standards [5]. On the basis of a case study of the open-air school in Vienna Floridsdorf (built between 1959 and 1961 according to a design by Wilhelm Schütte, and a unique example of a belated implementation of the school building typology based on Neues Bauen (New Objectivity) and classical Modern ideas) they proved that this component-oriented concept could lower the school’s energy consumption to 41 kWh/(m2yr) while still taking into account historical preservation criteria and the architectural character of the building. The concept of component-oriented renovation was developed further in a “modernisation catalogue”, which is a compendium of techniques and building modules for facade and open-space modernisation in high-rise buildings of the 1950s and 60s [6]. The renovation of the building envelope is among the most important renovation measures. Unfortunately, the conventional method for energetic facade renovation using a thick layer of a composite insulation system is

linked to stylistic and structural problems, especially when it comes to refurbishments of buildings of this era [7]. One simple and thermally efficient alternative approach to this can be the addition of another building envelope. Social housing in Paris At first, the plan was to demolish the 16-­storey, 96-flat residential high-rise that had been built on the Paris ring road in the early 1960s. Only after the residents had been polled, and after the architects Frédéric Druot, Anne Lacaton and Jean-Philippe Vassal had conducted extensive research provided not only that a renovation of this long-in-the-tooth social housing complex was supported, but also that the costs of converting the existing building fabric were much less than those for demolition and a new construction, was a revitalisation considered. The architects developed a refurbishment concept in which the facade, which was characterised by small windows, would be removed and replaced by a s­ elf-supporting construction with large openings in front, conserv­ atories and continuous balconies (Fig. 5). The conservatories add floor space to the flats, allow more ­daylight into the interior and simultaneously function as buffer spaces that improve thermal conditions. The facade structure was built using pre­ fabricated elements, so that the residents could stay in their flats while the construction work was completed. Social housing in Mannheim The Technical University of Darmstadt developed an innovative renovation strategy for a 1950s residential building that was

Utilising Existing Buildings

95

6 Conversion of a stable to a two-family residence, Bergün (CH) 1997, Daniele Marques and Bruno Zurkirchen Low tech: Utilisation of locally available building materials, simple prefabricated construction

beginning to show its age. The building had been constructed in the post-war years using brick chippings or poured concrete (Fig. 7). These materials are problematic from a structural point of view, but their properties make them eminently suitable as storage mass for energy generation. This led to the idea of a climate-active facade. Flats were combined and their ­balconies glazed so that they now function as energy gardens. Polycarbonate panels were installed as a second, translucent envelope, which serves as a climatic buffer. Air warmed by the sun is collected and ­distributed via the roof. In the cellar, stones were stacked in former storage rooms to store heat, and to contribute as needed to cooling during the summer by extracting or releasing thermal energy to the ambient air. In a potential future deconstruction of the building, the polycarbonate panels can simply be removed, unlike a composite thermal insulation system. Repurposing and redensification Dealing with derelict commercial or industrial buildings in peripheral and rural areas is a matter of similar urgency as that of unoccupied or rarely used buildings in central and urban environments. A purported lack of flexibility with respect to new uses or the complexity of the building project are often put forward as excuses, but successful examples show that beyond ideological barriers, these problems are eminently solvable through the application of innovative ideas. Stable conversion in Bergün In Bergün, a mountain village in Grisons, architects Daniele Marques and Bruno

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Zurkirchen executed a very thorough renovation project with a house-within-a-house concept (Fig. 6). A prefabricated timber cube has been inserted into the preserved rubblestone facade of a former stable. This new building volume is both enclosed by the old building and integrated into its irregularly perforated solid masonry. The new construction was built using a lowenergy method and energetically incorporates the old rubblestone masonry building fabric. Repurposing vacant sacral buildings According to a study by North Rhine-­ Westphalia, experts predict that the decline in church attendance will lead over the

Climate concept in winter

7 a–c Revitalisation of social housing, Mannheim (DE) 2012, TU Darmstadt, Günter Pfeifer, Annette Rudolph-Cleff Low tech: Low-tech renovation strategy with passive technologies and climate-active facade elements

Climate concept in summer

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7

8 8 St Elisabeth Church, conversion to office and event spaces, Aachen (DE) 2017, ­digitalHUB Aachen  / Landmarken 9  St Sebastian Church, conversion into a day care centre, Münster (DE) 2013, Bolles + Wilson 10  St Boniface Parish Church, conversion into a publishing house, Münster (DE) 2005, agn Niederberghaus & Partner 11  St Alphonsus Abbey and Church, conversion into an office building, Aachen (DE) 2008, ­Kaiser Schweitzer Archi­ tekten and Glashaus Architekten 12  Church of the Sacred Heart of Jesus, conversion into a ­residential building, Mönchen­gladbach (DE) 2011, B15 Archi­ tekten Notes [1] BBSR and ­Waltersbacher, ­Neubrand, Schürt 2020 [2] nachhaltigwirt­ schaften.at [3]  Detail 12/2012 [4] nachhaltigwirt­ schaften.at [5] Lorbek, Stosch 2003 [6] Lorbek, Stosch et al. 2005 [7] Hülsmeier, Petzinka in: Detail 6/2001 [8]  Bathen 2022 [9]  Detail 5/2014

long term to a church building vacancy rate of 25 to 30 % [8]. Now, interim usage concepts are being used to explore new options. An example of a successful interim usage is Hotel Total in Aachen. Over a time period of 15 months, the spaces were first adapted and then run for a three-month active phase as a “space for art, culture and l­iving”. After this interim usage, the former church was permanently converted to digitalChurch, a digitalHub with co-working office stations. Since then, it has offered a broad array of office, conference and meeting rooms as well as event venues (Fig. 8). The discussion and implementation of repurposing concepts for churches that are no longer needed for liturgical ­purposes goes back quite far, even in Germany [9]. In 2005, St Boniface ­parish church in Münster was converted into a publishing house by the architects agn Niederberghaus & Partner (Fig. 10); in 2008, St Alphonsus Church in Aachen was transformed into an office building by architects Kaiser S ­ chweitzer und Glas­haus (Fig. 11); and in 2013, BollesWilson even adapted St Sebastian church in Münster into a ­daycare centre Fig. 9). The Church of the Sacred Heart of Jesus in Mönchengladbach, converted in 2011 by B 15 Archi­tekten, is now in use as a residential building (Fig. 12). Other European countries have already progressed further in this regard. In England, for example, where the repurposing of sacral buildings for ­residential use began significantly earlier, the architects of SUPRBLK Studio, who ­specialise in the revitalisation and use of existing spaces, transformed a 1866 neoGothic chapel in London into a comfortable holiday apartment.

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Utilising Existing Buildings

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Renovation Strategies and ­Concepts for Existing Buildings Andrea Klinge, Eike Roswag-Klinge

Despite many initiatives and stricter laws in most EU countries, it can be observed in recent years that buildings are being demolished after increasingly shorter ­lifetimes. This affects not only buildings erected in the 1950s and 60s; more recent buildings, too, are being demolished, often after having been in s­ ervice for only a few years, in order to make room for something new and sup­posedly better. Waste quantities that can be attributed to the construction sector in Germany ­provide alarming evidence of this: 218.8 million tonnes of building and demolition waste were produced in the year 2018 [1]. Frequently, the reasons given are the ­targeted energy efficiency, which cannot be achieved through a reno­vation, or else a lack of financing to make a renovation economically viable. But what is achieved with such an approach? Are we really ­creating new buildings that bring longterm improvements and will once again remain in use for centuries, or are we ­putting unnecessary strain on resources and generating further waste for which we simply lack the landfill space? It is generally agreed that an approach based solely on energy efficiency and economic viability falls woefully short. What is ­missing is a holistic view of what already exists, a view that takes into account the evolved structures among residents and also encompasses the architectural, ecological and socio-cultural values of older buildings and recognises the planetary

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l­imits within which we live and act. If we as a society want to reach the climate goals set in Paris, if we want to preserve an environment worth living in for future generations, and for our own as well, we need suitable renovation strategies that ­creatively extend and transform existing structures. In concrete terms, this refers to approaches that value existing buildings and respect their users, that simply and ecologically convert and expand the buildings and design them to respond robustly to future requirements and living conditions. Here, circular low-tech concepts come into play, which focus on the use of CO2-lowering, low-emission mate­ rials in recyclable constructions, question the conventional standards and learn from ­mistakes. The latter refers mainly to the ­“performance gap” identified by many experts, that is, the discrepancy between the energy consumption measured in the usage phase and that calculated during the design phase which arises through a combination of user behaviour and complex technologies [2]. Low-tech building system Low tech is the dictate of the moment. But what does this actually mean, and does it really provide solutions to the challenges posed in dealing with existing buildings? In order to comply with the European energy efficiency goals, our buildings have not only become increasingly airtight, but the degree of mechanisation and the complex-

1  Renovation of a town house, Wismar (DE) 2014, Ziegert I Roswag I Seiler Architekten ­Ingenieure a Condition before renovation b Condition after ­renovation

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ity of the systems, particularly that of ventilation technology, has been steadily growing. Low tech relies instead on passive strategies, so that active building technology can be avoided. Low-tech building systems are based on climate-adapted architecture and the utilisation of hygroscopic, low-emission natural materials such as timber, clay, straw or other natural fibres that have the special ability to absorb humidity from and release it back to the indoor air. These can be employed either as renewable resources or as reused building materials or components. When combined with a breathable, highly insulated building envelope, a suitable proportion of glass and natural ventilation, these materials have a positive effect on the indoor climate and can regulate it. The suitable proportion of glass (between 40 and 60 %, depending on the orientation) is of central importance, since it is what mediates among desired heat gains in ­winter, unwanted solar influx in summer, as well as a year-round optimised supply of daylight. Its presence can significantly reduce or even eliminate the need for costly and failure-prone ventilation technology. Because of their high specific heat capacity, clay and natural fibres positively impact the ability to protect against summer warmth. Furthermore, clay is capable of absorbing pollutants from the indoor air, further reducing the need for ventilation technology. This concept is relevant to new constructions, but also to the renovation of existing buildings, if the latter possess a breathable

building envelope with an appropriate amount of glass as well as sufficient air ­volume. The targeted use of natural building materials as a means to reduce technical equipment not only makes buildings more robust, but also saves money, since the ­renovation cycles of building technology are much shorter as well as much more expensive. Using local resources, whether from regenerative sources or as reused components, conserves finite raw materials and lowers transport-related CO2 emissions. Timber and clay materials are particularly suitable for recyclable construction. As an intrinsically circular building substance, clay can be reused indefinitely; that is to say, it is 100 % recyclable and requires barely any energy for processing. Timber is a climate-positive material in that it sequesters more CO2 than its harvesting and processing into a usable product release. In addition, timber allows for dry joining, and because of its relatively low self-weight, it supports reversible connections a great deal more easily than do reinforced concrete or masonry bricks, for example. Its potential for direct reutilisation is therefore distinctly greater. The following example projects illustrate how the concept can be applied in different contexts. Town house in Wismar — KfW efficiency 85 in a listed building The historic centre of the Hanseatic city of Wismar in Germany has been a UNESCO World Heritage Site since 2002. Lübsche

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Straße, first mentioned in 1260, is characterised mainly by gable houses and is now one of the central residential and commercial streets of the old quarter. The goals of the refurbishment of this town house were to restore it to its 1930s condition and to make it usable again as a four-flat residential building. The main focus lay in the longterm conservation of the building fabric and in the historically and materially appropriate restoration of the facades as well as the internal structure. For the energetic renovation, the upper-­ storey ceiling and the new ground slab were insulated, and the entire building was outfitted with interior insulation to meet the “KfW efficiency house 85” standard. From a purely numerical standpoint, its entire energy consumption is thereby limited to 85 % of the annual primary energy requirement mandated by the Building Energy Law (Gebäudeenergiegesetz (GeG)). ZRS Architekten Ingenieure developed the floor plans based on the space partitioning of 1860 and then optimised it to account for the difficult light conditions due to the building’s depth. The ground floor of the refurbished main house is divided by a central hallway typical of Wismar, which provides access to two separate residence units as well as the Kemladenwohnung (a two-storey courtyard annex of a Dielenhaus (hallway house)) and the courtyard itself. The upper storey of the main house was expanded to accommodate a generous flat, which is accessed via the historical staircase. All the elements that form part of the historical character of the building, such

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as many of the windows, interior windows, reveal linings, skirting boards, interior doors and floors, were restored whenever possible and reused as original ­components. A new, floor-length window on the south facade with an outsidemounted egress improves the connection with the outdoors and allows for optimised lighting. Large portions of the two-storey Kemladen had been buried and inaccessible when construction began. It was separated to form a detached residence, gutted under archaeological supervision and furnished with a new staircase to internally connect the floors. The additional air volume of the opened-up attic now visually enlarges the formerly very low upper floor. The ­living areas on the ground floor were combined into a generous open-plan living room and kitchen. New openings to the south connect these to the newly landscaped garden by way of a terrace. This allowed the historic eastern facade with its baroque features to be preserved in its unchanged state. The most important aspect in choosing the reconstruction approach was to reach a high energetic standard with traditional and, where possible, ecological building materials while taking into account the ­historic preservation requirements. To invigorate the footings and provide a shallow foundation for the refurbished lower wall areas, a reinforced concrete ground slab was introduced on which the interior half-timbered walls were retroactively established. Damaged infill was repaired

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2 a–c  Renovation of a town house, Wismar (DE) 2014, Ziegert I Roswag I Seiler Architekten ­Ingenieure

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3  Peat shed, Schechen (DE) 2015, Ziegert I Roswag I Seiler Archi­ tekten Ingenieure

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with newly laid clay bricks. The horizontal waterproofing in the masonry walls was completely redone. Because of their high salt content, historically valuable wall surfaces with the affected paint compositions were desalinated using cellulose ­compresses. On walls with less valuable rendered surfaces, multiple treatments of clay dehumidifying plaster were used for desalination. The roof of the Kemladen was newly shingled with plain roof tiles following historical models. In refurbishing the facades, the designers tried to preserve the his­torical renders as much as possible. The colour scheme was reconstructed based on paint findings. The street facade of the main house and the Kemladen facades were insulated with fibreboard panels or with s­ ilicate board in the damp areas. The half-timbered gable, which had been improperly renovated in the 1990s, was planked with soft woodfibre boards, the infill areas (the fields bordered by beams) were stripped and blown in with cellulose in place of masonry. The roof of the Kemladen was insulated with ­cellulose between the rafters, as was the timber beam ceiling above the upper floor in the main building. The designers had the historic box windows overhauled and strengthened, while the single glazing was furnished with a second, internal layer of insulation glass. The new timber windows are triple-glazed. Radiant panel heating was installed in the walls of the top floor. The ground level is

heated via floor heating. Heat is generated by a micro combined heat and power plant (CHP). Through the comprehensive ­insulation measures and the careful improvements to the windows, a KfW efficiency house standard was achieved with an annual primary energy requirement of about 30 kWh/m2. The breathable building method, combined with the sorptive clay plaster surfaces, ensures natural regulation of the indoor climate. Therefore, despite the impermeable building envelope, a ventilation system was not necessary. Living and working in a peat shed, Schechen The historical peat shed, originally built for the drying of peat, stood in the grounds of the old spinning mill in Kolbermoor in the Bavarian Alpine foothills, where it was used for willow storage (see Example ­Project, p. 158ff.). When an investor took over the largely derelict property in 2006, the two-­storey building was slated for removal. Master basket maker and carpenter Emmanuel Heringer and master smith Stefanie Heringer recognised the value of the building, which was in danger of demo­ lition and thermal recycling. In collabor­ ation with ZRS Architekten Ingenieure, they dismantled the threatened peat barn in ­Kolbermoor, repaired it thoroughly, and rebuilt it reversibly and true to the original at a new site (Fig. 5, p. 103). Historical wood joinery as well as ambitious clients made this scheme possible, which

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is rather unusual these days. Damaged building components were repaired using traditional timber joinery techniques. Only the foundations were adapted to the new usage requirements with the laying of a ground slab. In order to be able to use the barn as a ­residence and workshop, its slatted facade was supplemented with a well-insulated building shell. The two-storey house-andworkshop combination sensitively merges into the historical structure as a house-inhouse concept, respectful of the existing substance. It is clearly offset from the loadbearing axes of the shed, thus allowing them to be largely preserved. On the south and west side, the arrangement creates a gap that allows the longitudinal and transverse dimensions of the old building to be experienced and that is characterised by the play of shadows from the historical vertical slats. To the east, the white-rendered solid juts out from the front of the historical structure. On the north side, a storage area for willow and other weaving materials abuts the house volume and thus continues the historic usage form. The new building relies on low tech and therefore on hygroscopic natural substances like timber, clay and wood fibre in order to do without ventilation technology despite its highly impermeable building envelope. The exterior and interior walls were integrated into the old building using timber beam construction and clad with fibreboard panels. This decision greatly simplified the development of the connections between the historical structure and the new building. The outer walls are highly insulated with blown-in cellulose, while the

interior walls are infilled with clay bricks. Both wall systems are rendered with clay plasters and finished with a thin layer of clay. Because the exterior walls are ­protected by large roof overhangs and are offset from the historic slat facade, the use of clay finishing plaster was pos­ sible on the outer wall surfaces, as well. The consciously open-pore finish of the soaped fir floors and the oiled structure are intended to keep these components sorptive (capable of absorbing and releasing moisture). Suitably large glazed surfaces open the floor plan in the directions of the historical door openings and provide a balanced solution to the challenging lighting situ­ ation that the house-within-a-house concept entails. They mediate between daylight optimisation designed to operate ­year-round and unwanted solar gains in summer. The ground floor plan is oriented towards the east through floor-length openings and is connected to the garden by way of a terrace. An exterior curtain shades the generous window area and ensures that temperatures stay comfortable even in summer. The central living area on the top floor faces south through a large glass pane and is also lit via glazing in the roof ridge. The ­windows of the new construction are arranged so that cross-ventilation and nighttime cooling are possible. Thanks to their positions at the outer wall, the bathrooms can also be naturally aerated. Heat is regeneratively produced by a ­central wood-burning heating system and a thermal solar collector. The building’s ­primary energy requirements are limited to

4 a–d  Disassembly, reassem­ bly and addition, peat shed, Schechen (DE) 2015, Ziegert I Roswag I Seiler Architekten ­Ingenieure

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2. robust timber structure 1. natural resources

3. disassembly abandoned (2006)

storage (2006)

Kolbermoor

90 m3 timber 6. use

4. reassembly

new life for an old structure (2015)

5  Preservation through relocation and reassem­ bly of the building, peat shed, Schechen (DE) 2015, Ziegert I Roswag I Seiler Archi­ tekten Ingenieure

5. conversion

Schechen 15 km

reuse of the old structure (2012)

integration of the lowenergy house

Schechen

storage area and workshop 5

18.3 kWh/(m2yr), which is 30 % below the 2009 Energy Saving Ordinance (Energie­ einsparverordnung or EnEV) mandate. The result is a naturally ventilated low-energy house that is regeneratively run. The design concept was developed in collaboration with the clients and its implementation was largely self-built. Renovation of a zoo building in Berlin In 1955, the East Berlin “Tierpark” or zoo opened on the grounds of the former Schlossgarten Friedrichsfelde palace park, in direct competition with the Zoologischer Garten in West Berlin. Today it is the largest zoological park in Europe. After reunification, the two zoos, which each have distinctive features and strengths, began to cooperate with one another. Damage to the facade of the administrative building in Friedrichsfelde caused draughts, overheating in summer and radiative cooling in winter, making use of the building impossible. For this reason, the GDR skeleton structure from the 1960s was vacant for several years. In 2017, the zoo decided to refurbish the three-storey building. The focus of the

r­ enovation measures were the energetic refurbishment of the building envelope and the building technology equipment. In the interior, sanitary facilities were renewed, but the original interior construction was preserved as much as was deemed fea­ sible. The goal of the measures was to deal carefully with the old building and, in the interests of recyclable construction, to preserve as much of the existing fabric and hence also its embodied energy as possible. The concept of the building – the skeleton structure and the separation of components of varying service lifetimes as well as reversible component connections – facilitated this approach. The renovation proceeded in a mostly climate-neutral manner with CO2-sequestering natural materials. The non-bearing outer wall, which was ­created in the 1960s from innovative, pre-­ fabricated sandwich panels and mounted cement fibre board, could be disassembled without necessitating an intervention into the building structure. The new wall construction, conceptualised as prefabricated, highly insulated timber panels, takes up the grid pattern of the anchor points on

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CO 2 equivalent over 50 years [t]

Calculation without phase C3 with thermal utilisation

Calculation including phase C3 with thermal utilisation 1,006.58

1,100 900 700 500 355.86

300 100 26.39 0

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the existing facade and is reversibly connected to the structure. Future changes in usage and refurbishment cycles will thus be fairly easy to execute. The rear ­ventilation plane and the vertical arrangement of the painted larch sheathing ex­­ tend the lifetime of the building component compared to that of composite thermal insulation systems. The tongue-andgroove sheathing also obviated the need for weather-resistant facade membranes and, consequently, plastics in the con­ struction. The lower self-weight of the new wall construction made it possible to implement the measure without having to supply supporting documentation for the entire building’s structural stability. The building also has load reserves, which yield the potential for increasing its height. Lightweight timber construction could therefore be used to create further usable floor space on the existing building footprint. On the inside of the building, the main work consisted of repairs to make the rooms usable again. The interior construction, typical of its time (such as veneered furnishings in the management rooms and gypsum tile acoustic ceilings, but also simple wooden built-in cabinets), was largely preserved. While the sanitary areas had to be refurbished, simple renovation measures sufficed for the wall and ceiling surfaces. The floor coverings were contaminated with PAH (polycyclic aromatic hydro­ carbons) and therefore had to be mostly

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Scenario 1: Partial demolition + renovation

Scenario 2: Partial demolition + renovation (conventional)

replaced. However, encapsulating the tarred boards with insulating film made it possible to safely leave the contaminants in the building, and thus not to burden either diminishing landfill space nor the environment with them. Small interventions were used to bring the room structures in line with the present-day needs of the zoo, providing accommodation for office and conference rooms as well as functional spaces such as archives and storage. Fire safety was improved to meet contemporary standards. The modernisation of the building tech­ nology involved the complete replacement of heating, sanitary, ventilation and electrical equipment. Though the building envelope is very airtight, the use of hygroscopic building materials and vapour-­ permeable superstructures in the exterior walls largely obviated the need for ventilation technology. Only the sanitary cores were equipped with mechanical ventilation with heat recovery. Relatively small interventions in the existing building substance allowed the administrative building to be restored to its original function. The entire renovation process reduced the global warming potential (a value reflecting possible contributions to the greenhouse effect) of the building to under 30 t CO2-equivalent over 50 years. This is about 980 t CO2-equivalent less than would have been emitted by a conventionally built replacement structure.

Scenario 3: Complete demolition + new construction (conventional) 7 6  Renovation of the ­exterior facade, admin­ istrative building at Berlin Tierpark (DE) 2019, ZRS Architekten Ingenieure (Phase C3 = waste management in Life Cycle Assessment Module C “Disposal” according to DIN EN 15 978) 7  Global warming poten­ tial (GWP) calculations for three scenarios, administrative building at Berlin Tierpark (DE) 2019, ZRS Architekten Ingenieure

Notes  [1]  Wilke 2013 [2] Auer, Franke 2020, p. 40–52; Klinge 2020, p. 82–97

8  Renovation strategy for the administrative building at Berlin Tier­ park (DE) 2019, ZRS Archi­tekten Ingenieure

1960 GDR panel building

Prefabrication / processing /reutilisation (Recovered) timber is processed to yield prefabricated facade elements or load-bearing building components.

Material resources Building components — composed of renewable raw materials — sequester tonnes of CO2 during their growth.

Conclusion These projects illustrate in various ways that suitable transformation processes can be employed to expand existing buildings and adapt and operate them in accordance with modern requirements in a mostly climate-neutral manner. The Wismar project shows that the com­ bination of renovation measures necessary to the basic structure, known as ­“anyway measures”, together with energetic interventions, can often make very high energy standards possible even in ­historical preservation, without damaging the historical building fabric but in fact ­protecting it. In the integration of the new shed construction into the historical timber structure, the choice of hygroscopic materials, the conceptualisation of the superstructures, the

2018 resource-saving preservation The preservation of the flexible original skeleton structure conserved significant resources and saved the characteristic interior furnishings from destruction.

appropriate proportion of glass as well as the night-time cooling all contribute significantly to a comfortable and healthy indoor climate. Therefore, despite the imperme­ able building envelope and a very high energetic standard, the installation of a ventilation system was not necessary. In addition, the modernisation and conversion of the historical building illustrates the future-oriented potential of old timber structures and the recyclability of reversible constructions. The same is true for the renovation of the zoo building in Berlin, which demonstrates that even modern buildings exhibit potential for recycling, and that they can be refurbished and adapted to today’s standards in climate-neutral ways by employing lowtech concepts and carbon-sequestering or reused building components.

2059 potential new use Materials separated by type and reversible connections make simple construction and deconstruction and thus the reuse or further utilisation of timber components possible.

Deconstruction and reconstruction The element-based building method is easy to disassemble and can be reassembled elsewhere.

2019 new appearance Through minimal interventions into the existing building fabric, the building was returned to its original function and gained a new appearance even though the character of its facade was preserved.

2018 recycling, reusing, refurbishing The removal of the original facade is followed by a separation by type of the materials and, where possible, recycling of the raw materials. 2019 construction and retrofitting The element-based construction method using reversible connections allows for diverse conversion and use concepts and uncomplicated upgrades. 8

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Assessments

Low Tech in the Context of International Building Evaluation Systems and Standards 108   Low-tech criteria as facets of sustainability standards109   Low-tech matrix: Corresponding standards in BREEAM, LEED and DGNB110   Low tech and the goals of regenerative and sustainable development115  Low-tech criteria compared with the LBC rating system and the UN’s 17 Sustainable Development Goals (SDG)115 Building Evaluations and Life Cycle Assessments 118   Target values and criteria for low-tech buildings118   House of Learning120  Summary123

Rauch House, Schlins (AT) 2008, Roger ­Boltshauser and Martin Rauch (clay construction: LehmTonErde Baukunst)

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Low Tech in the Context of ­International Building Evaluation Systems and Standards Edeltraud Haselsteiner

Containing the impact of climate change urgently requires a reduction of emissions in all economic sectors. The construction sector is responsible for one third of greenhouse gas emissions worldwide [1]. To usher in an energy transition, more effective measures are critically needed for new construction in particular. In addition, a significant increase of the renovation rate from the current EU level of just 1 % is absolutely essential. Low-tech design as such does not define any requirements for a more sustainable or more energy-efficient building concept. Rather, it expresses a critical view toward growth and efficiency paradigms in connection with technological developments and questions their effectiveness as the supposedly sole long-term means of confronting the climate crisis. This perspective is based on the conviction that a more comprehensive and holistic approach is needed to meet the challenges of climate change. Low-tech design and regenerative sustainability shift attention from a ­narrow focus on individual issues such as energy efficiency, renewable materials or sustain­ able technologies towards the creation of an auto-regenerating social and ecological system [2]. This also includes involving people as actors within and designers of their environment and strengthening their ties to nature. Furthermore, there is a point to be made about the rising costs in the construction

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sector, which can be attributed p ­ rimarily to the growing demands on the technical building equipment (TBE) [3]. E ­ fficiency ­criteria, which are used to evaluate subsidies, are driving not only the demands on building technology but also the price spiral. Though high investment costs are weighed against lower energy consumption costs, the latter in turn encourage greater consumption (rebound effect). In addition, the usability of the buildingtechnical components is increasingly impacting the service life of real property. While the building fabric of a structure will last for a life cycle of 50 years or more, the longevity of technical additions is only about ten years, and for information and communications technology in general only five years or so [4]. This results either in high cost projections for repair and maintenance or – as is unfor­tunately often the case – a significant decrease in the average usage lifetime of buildings and a further rise in the already numerous vacant properties in certain regions. Sustainability certification is given great importance in the implementation of inno­ vative building concepts [5]. A perusal of the literature shows that there are more than 600 different building and materials certificates in use to date [6]. Apart from the prevalent international assessment tools such as the British certification system BREEAM (Building Research Establish-

ment Environmental Assessment Method), the LEED (Leadership in Energy and ­Environmental Design) system of the US Green Building Council and the seal of the DGNB (Deutsche Gesellschaft für Nachhaltiges Bauen e. V.), increasing numbers of national and institutional evaluation schemes are being added. The latter are intended especially to support national ­regulations or institutional strategies and intentions in reaching their goals. Beyond these, various alternative rating systems have arisen that put more emphasis on the social aspects of sustainability and on issues such as health and well-being and social responsibility [7]. While the ­rating schemes known as Green Building ­Certificates (BREEAM, LEED, DGNB, Green Star, etc.) place their sustainable building focus on environmental data and, in particular, on the energy performance of buildings [8], other systems such as ­Living Building Challenge (LBC),

One Planet Living, WELL and Cradle to ­Cradle (C2C) concentrate more heavily on regenerative principles in the built ­environment. It is important to qualify this by noting that even here, building cer­ tificates primarily function as marketing tools for the construction and property ­sectors. Their goals are quantitative and qualitative evaluation and the establishment of benchmarks. Low-tech criteria as facets of sustainability standards In the chapter “The Sustainable Low-tech Building” (p. 22ff.), a matrix (Fig. 8, p. 30f.) was developed that comprehensively reflects various low-tech design strategies as the basis of an overall concept built on sustainable principles. These requirements are contrasted and compared in Fig. 2, p. 110ff. with three frequently employed Green Building Certificates (BREEAM, LEED, DGNB).

1  Designed in accordance with the Cradle to Cradle concept, research institute in Wageningen (NL) 2010, Claus en Kaan Architecten

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Low-tech matrix: Corresponding standards in BREEAM, LEED and DGNB Low-tech matrix — criteria

Corresponding criteria in the building assessments of BREEAM (DE 2018 / residential construction), LEED (v4.1, 2021) and DGNB (v2018 / new construction)

A  Ecological quality ECOSYSTEM — climate, regeneration, resilience site-based, regenerative and ecological design approach, utilising the eco-dynamic whole of a location and the interrelationships between people, buildings, nature and the ecosystem to achieve a holistic solution Climate

Holistic, ecological and regenerative design approach based on local resources and conditions, such as (micro)climatic factors (e.g. sun, ­bodies of water, air currents, vegetation), geology (e.g. ground consistency), topography (e.g. terrain, ground surface), etc.

BREEAM: Not specified LEED: Not specified DGNB: Not specified

Regeneration Measures taken as a positive contribution to the restoration / improvement of a functioning (regenerative) ecosystem; that is, to avoid negative impact on and interference with functioning ­environmental cycles (e.g. land use, biodiversity, vegetation, water)

BREEAM: Land use and ecology (8.68 %) • site selection • ecological value of the site and protection of ecological values • minimisation of impact on existing ecology at the site • improvement of ecology at the site • long-term impact on biodiversity LEED: Sustainable sites / site quality (9.1 %) • avoidance of environmental pollution through construction ­activities 1) • site development /assessment • conservation or reestablishment of the biosphere • free space • rainwater management • reduction of heat islands • reduction of light pollution DGNB: Ecological quality (22.5 %) • life cycle assessment of the building • risks to local environment • responsible extraction of resources • potable water supply and wastewater • area consumption • biodiversity at the site

Resilience

BREEAM: Transport (7.5 %) • access to public transit • proximity to relevant amenities • alternative modes of transportation • maximum parking capacity • mobility concept • home office LEED: Location and traffic (14.6 %) • neighbourhood development • protection of sensitive soil • high-priority sites (e.g. historic towns, brownfield rehabilitation) • surrounding density and mixed zoning • access to quality transportation (e.g. public transit) • bicycle-friendly facilities • reduced parking footprint • electric vehicles DGNB: Site quality (5 %) • micro location • look and influence on the neighbourhood • access to transit • proximity to user-relevant objects and facilities

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Sufficiency and resilience based on climate, ­location, geography and existing infrastructure (e.g. regionalism, building density, connection with and utilisation of existing infrastructure, ­inclusion in local economic cycles)

RESOURCES — form, energy, recycling systems Energy-efficient and ecological construction based on a sufficient use of technology, use of simple active principles and nature-based solutions for supplying renewable, regionally available resources, minimisation of embodied energy and avoidance of CO2 emissions throughout the entire life cycle Form

Energetically optimised form and orientation (e.g. micro-climatic adaptation of the form / surface / facades, amount of glazing – storage mass) Use of climatic / site-specific factors for thermal, hygienic and acoustic comfort and for natural ­lighting

BREEAM: not specified LEED: not specified DGNB: not specified

Energy

Supply (heating, cooling, ventilation) based on ­natural, renewable and regionally available ­(environmental) energy potentials (sun, earth, groundwater, wind, internal heat sources, heating / cooling through seasonal / diurnal rhythms, etc.), observing a sufficient use of technology and optimised energy characteristics (heating requirements [kWh/m2a], heating load of the ­building [W/m2], primary energy reference value [kWh/m2a])

BREEAM: Energy (17.03 %) • reduction of energy consumption and CO2 emissions • monitoring of energy consumption • exterior lighting • low CO2 design • energy-efficient chilling and cold storage • energy-efficient transportation systems • energy-efficient laboratory systems • energy-efficient equipment • drying space for laundry LEED: Energy and global environmental impact (30 %) • fundamental commissioning and monitoring 1) •  minimum energy output 1) •  energy measurement at the building level 1) •  fundamental management of cooling agents 1) •  improved commissioning •  optimisation of energy output •  expanded energy measurements •  demand response •  renewable energy generation •  improved management of cooling agents DGNB: Technical quality (22.5 %) • acoustic protection • quality of the building envelope • use and integration of building technology • easy-to-clean building structure • ability to deconstruct and recycle • protection against immissions • mobility infrastructure

Recycling systems

Formation and use of possible supply and removal cycles in the building, taking into consideration ­surrounding buildings and the location (exhaust heat – heating / cooling, combined heat and power (CHP), rain / wastewater – service water, etc.)

BREEAM: Water (11.58 %) • water •  water consumption •  water monitoring • identification and avoidance of water leaks •  water-conserving equipment LEED: Water efficiency (10 %) • reduction of outdoor water consumption 1) • reduction of indoor water consumption 1) • water meters at the building level 1) • cooling tower water consumption • water meters DGNB: Drinking water supply and wastewater (environmental quality)

1) 

2

Prerequisistes / must-have criteria

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B  Economic quality ROBUSTNESS — life cycle costs, homogeneity, quality Robust overall concept executed with a view to longevity and long service life, high-value ecological and economical building standard with durable (proven manual) building techniques and structures, observing sufficient resource and commodity consumption with low life cycle costs Life Cycle Costs

Minimisation of embodied energy and avoidance of CO2 emissions during the life cycle through short transport routes, avoidance of emissions or increased technological expenditure during ­construction (e.g. excavation, technical costs for ­cellar and underground floors), sufficiency in resource and material use, etc.

BREEAM: Material (15.44 %) • impact on the life cycle •  landscaping and edge consolidation •  responsible sourcing of materials •  insulation •  design for longevity and resilience •  material efficiency LEED: Reduction of impact on building life cycle 1) (materials and resources) DGNB: Economic quality (22.5 %) • building-related life cycle costs •  flexibility and convertibility •  marketability

Homogeneity Use of simple, proven (manual) and durable building techniques and structures, simple building details and superstructural components, do-it-­ yourself and prefabrication options, etc. Material homogeneity, reduced complexity in ­material choice and sufficient use of materials

BREEAM: Not specified LEED: Not specified DGNB: Not specified

Quality

BREEAM: Management (10.61 %) • project description and design • life cycle costs and longevity planning • responsible construction practices • commissioning management and hand-over • after care LEED: Integrative design process (0.9 %) DGNB: Process quality (12.5 %) • quality of project preparation • safe guarding of sustainability aspects in calls for tender and awards • documentation for sustainable management • procedure for urban development and design concepts • construction site / construction process • quality control during construction • orderly commissioning process • user communications • facility management-friendly design

Quality-ensuring measures for the prolongation of the (service) lifetime of building components by way of passive / structural building details (e.g. moisture and UV radiation protection, etc., planning for the “ageing” and “care” of surfaces, structural shading)

SIMPLICITY — functionality, maintenance, servicing Interdisciplinary and integrally coordinated simple and robust building concept, designed with user-friendly control and regulation as well as easy repair and maintenance Functionality Low-complexity building technology and electrical cabling (e.g. installation requiring no structural ­engineering, open cable trays)

BREEAM: Not specified LEED: Not specified DGNB: Not specified

Maintenance Simple upkeep and care, simple replacement and maintenance of individual components (e.g. standard components) without dedicated ­technical tools or the need for specialist assistance, minimisation

BREEAM: Not specified LEED: nNot specified DGNB: Easy-to-clean building structure (technical quality)

Operation

BREEAM: Not specified LEED: Not specified DGNB: Exercise of influence by users (socio-cultural and ­functional quality); user communication (process quality)

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simple, intuitive operation, manipulation, control and regulation by users or the provision of (automated) control and regulation via environmental ­factors (e.g. wind, temperature fluctuations, light intensity, humidity)

C  Social quality SUFFICIENCY — minimisation of requirements, area consumption, intensity of use Economical and resource-conserving size and equipment (area, room volume, interior finish, home technology, appliances, etc.), ­minimal use of space and avoidance of additional ground sealing (with precedence given to the utilisation of existing buildings), increase in usage intensity Minimisation Utilisation of existing buildings and materials of needs ­(revitalisation, conversion, recycling, upcycling, use of construction waste and secondary raw ­materials, etc.)

BREEAM: Not specified LEED: Not specified DGNB: Not specified

Area consumption

Minimal use of area, e.g. through a compact and optimised A/V ratio

BREEAM: Not specified LEED: Not specified DGNB: Area consumption (ecological quality)

Usage intensity

Need-based area, floor plan and equipment concept (e.g. zoning of the floor plan, climate /  temperature zones, permanent / temporary supply) Taking advantage of multi-use potential and sharing and raising usage intensity

BREEAM: Not specified LEED: Not specified DGNB: Not specified

HEALTH — natural commodities, materials, relationship between humans and nature Selection and economical use of local, ecological, renewable, recyclable and robust materials with long lifetimes that contribute to health and well-being Natural raw materials

(Re-)use of locally available renewable resources and materials with high-value recycling and recy­ clable properties and minimal transport costs

BREEAM: Responsible sourcing of materials (materials) LEED: Materials and resources (11.8 %) • storage and collection of valuable substances 1) • planning for construction and demolition waste management 1) • reduction of impact on the building life cycle 1) • disclosure and optimisation of building products — ­environmental product declarations • disclosure and optimisation of building products — acquisition of raw materials • disclosure and optimisation of building products — material ingredients • disposal of construction and demolition wastes DGNB: Life cycle assessment of the building (ecological quality)

Materials

Efficient utilisation of the characteristics of existing natural building materials in a sufficient and robust building concept to minimise resource ­consumption (e.g. thermal storage, cooling, easy recyclability, etc.), a healthy indoor environment (e.g. hygroscopic properties) and a long lifetime (e.g. durability)

BREEAM: Not specified LEED: Not specified DGNB: Not specified

Relationship between humans and nature

Measures taken to improve the connection between people and nature as a contribution to quality of life, health and well-being (thermal, hygienic and acoustic comfort, natural lighting, natural humidity, vegetation, indoor, outdoor and recreational green spaces, etc.)

BREEAM: Health and well-being (18.16 %) • visual comfort • indoor air quality • thermal comfort • building and room acoustics • accessibility • natural dangers • private free spaces • water quality LEED: Indoor (air) quality and comfort (14.5 %) • minimum indoor air quality 1) • tobacco smoke monitoring of the surroundings 1) • improved strategies for indoor air quality • materials with low contaminant content • plan for managing air quality in the construction sector • evaluation of indoor air quality • thermal comfort • interior lighting • daylight • quality aspects • acoustic performance

1) 

Prerequisites /must-have criteria

2

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DGNB: Socio-cultural and functional quality /comfort (22.5 %) • thermal comfort •  indoor air quality •  acoustic comfort •  visual comfort •  exercise of influence by users •  indoor and outdoor quality of occupancy •  safety •  accessibility D  Participation /process quality RECYCLABILITY — flexibility of use, deconstruction, documentation Building concept, structure and material connections that permit easy replacement of individual components and make separated ­reutilisation, deconstruction and re- /upcycling of building materials or a partial or entire conversion possible Flexibility of use

Open usage area concept with maximal flexibility with regard to expansion and changes in usage; design /additional planning for retrofitting, expansion or dismantling and including adaptation options through simple (non)structural means and modest technological expenditure

BREEAM: Hypothetical expansion; functional adaptability (waste) LEED: Not specified DGNB: Flexibility and convertibility (economic quality)

Deconstruction

Building parts and /or materials with detachable ­connections that can be disassembled and sorted by type, enabling them to be utilised further as ­products or in some other manner

BREEAM: Waste (3.86 %) • management of construction wastes • recycled aggregates • operational waste • hypothetical expansion • adaptation to climate change • functional adaptability LEED: Storage and collection of valuable substances 1) Planning for construction and demolition waste management 1) (Materials and resources) DGNB: Ability to deconstruct and recycle (technical quality)

Documentation

Documentation of resources, materials and decision paths employed in the production process

BREEAM: Not specified LEED: Not specified DGNB: Not specified

RESPONSIBILITY — adaptation to climate change, (building) culture, equity Responsible overall concept as a regenerative contribution to climate change and to social equity, the promotion and advancement of quality in building culture and participation Adaptation to climate change

Precautionary measures taken against regional ­climate change phenomena to ensure optimal responses to environmental conditions and their changes Future-oriented, innovative concepts to contribute positively to climate stabilisation and regenerative sustainability goals (e.g. carbon-sequestration in buildings)

BREEAM: Environment (7.13 %) • impact of cooling agents • NOx emissions • run-off of surface water • reduction of nocturnal light pollution • pollution control BREEAM: Innovation, adaptation to climate change (waste) LEED: Innovation (5.5 %) LEED: Regional priorities (3.6 %) DGNB: Not specified

(Building) culture

Inclusion /observance of experiential knowledge ­represented in regional / historical building traditions Promotion and advancement of quality in building culture Participation and inclusion of users and affected ­parties

BREEAM: Not specified LEED: High-priority sites (e.g. historic towns, brownfield rehabilitation) (Location and transportation — infrastructural connectivity of the site) DGNB: Not specified

Equity

Equitable distribution and social responsibility, such as avoiding building materials that have the potential to endanger food availability or ­biodiversity, etc.

BREEAM: Not specified LEED: Not specified DGNB: Not specified

1) 

Prerequisites / must-have criteria

114

2

2 Low-tech matrix: ­Corresponding standards in BREEAM, LEED and DGNB 3 Low-tech criteria compared with the LBC ­rating system and the UN’s 17 Sustainable Development Goals (SDG)

The comparative overview (Fig. 2, p. 110ff.) shows that particularly charac­ teristic criteria for a low-tech concept, such as robustness, simplicity, sufficiency and location and climate-adapted form, as well as the utilisation of building material properties as functional parts of the building concept, are nowhere to be found in any of the Green Building Certificates presented. Likewise, aspects of social and societal responsibility and future-oriented measures to adapt to climate change receive little or no attention.

Low tech and the goals of regenerative and sustainable development The Living Building Challenge (LBC) ratings system from the USA claims to strive for very ambitious and regenerative sustainability goals. However, a comparison between the low-tech criteria and the LBC reveals that, though significantly more of the rejected criteria are represented in the ratings system, calls for the minimisation of requirements and for simplicity are absent. Finally, Fig. 3 contrasts the low-tech criteria with the 17 Sustainable Development Goals of the United Nations (UN).

Low-tech criteria compared with the LBC rating system and the UN’s 17 Sustainable Development Goals (SDG) Low-tech matrix — criteria

Corresponding criteria in building assessments LBC (Living Building Challenge 4.0, International Living Future Institute, June 2019)

Corresponding criteria in the UN’s 17 Sustainable Development Goals (SDG)

ECOSYSTEM — climate, regeneration, resilience

LOCATION: Reestablishing a healthy relationship ­between nature, location and community •  ecology of the location •  urban agriculture •  exchange of biospheres •  living on a human scale

11. SUSTAINABLE CITIES AND COMMUNITIES; Designing cities and settlements to be inclusive, safe, resilient and sustainable 14. LIFE BELOW WATER: Preserving and sustain­ ably using oceans, seas and marine resources with a view to sustainable development 15. LIFE ON LAND: Protecting, reestablishing and promoting the sustainable use of terrestrial ecosystems, sustainably managing forests, com­ bating desertification, stopping and reversing soil degradation, putting an end to the loss of biological diversity

RESOURCES — form, ­energy, recycling systems

WATER: Creating systems that function within the water budget of a given location and climate •  responsible use of water •  net positive water ENERGY: Relying on renewable raw materials •  reduction of energy and CO2 •  net positive energy

6. CLEAN WATER AND SANITATION: Ensuring the availability and sustainable management of water and sanitary provisions for all 7. AFFORDABLE AND CLEAN ENERGY: Securing access to affordable, reliable, sustainable and modern energy for all

MATERIALS: Building with products that are safe for all species over the course of time •  responsible materials •  Red List •  responsible sourcing •  Living Economy sourcing •  net negative waste

8. DECENT WORK AND ECONOMIC GROWTH: Promoting sustained, inclusive and sustainable economic growth, full and productive employment and decent work for all 9. INDUSTRY, INNOVATION AND INFRASTRUCTURE: Building resilient infrastructure, promoting broadly effective and sustainable industrialisation and supporting innovation

A  Ecological quality

B  Economic quality ROBUSTNESS — life cycle costs, homogeneity, quality

SIMPLICITY — functionality, maintenance, servicing

4. QUALITY EDUCATION: Providing inclusive, egalitarian and high-quality education and ­promoting opportunities for life-long learning for all 3

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C  Social quality SUFFICIENCY — minimi­sation of requirements, area consumption, intensity of use HEALTH — natural com­ modities, materials, ­relationship between humans and nature

12. RESPONSIBLE CONSUMPTION AND ­PRODUCTION: Safeguarding sustainable models for consumption and production HEALTH & HAPPINESS: Promoting environments that optimise physical and psychological health and well-being •  healthy indoor climate •  healthy indoor performance •  access to nature

3. GOOD HEALTH AND WELL-BEING: Ensuring a healthy life for all people of all ages and pro­ moting their well-being

D  Participation /process quality RECYCLABILITY — flexibility of use, decon­ struction, documentation

MATERIALS: Building with products that are safe for all species over the course of time •  responsible materials •  Red List •  responsible sourcing •  Living Economy sourcing •  net negative waste

6. CLEAN WATER AND SANITION: Ensuring the availability and sustainable management of water and sanitation for all

RESPONSIBILITY — ­adaptation to climate change, (building) culture, equity

EQUITY: Promoting an equitable world •  general accessibility •  inclusion AESTHETICS: Celebrating design that raises the human spirit •  aesthetics and biophilia •  education and inspiration

1. NO POVERTY: Ending poverty everywhere and in all its forms 2. ZERO HUNGER: Ending hunger, achieving food security and better nutrition and promoting sustainable agriculture 5. GENDER EQUALITY: Achieving gender equality and empowering all women and girls to practice self-determination 10. REDUCED INEQUALITY: Reducing inequalities within and between countries 13. CLIMATE ACTION: Taking immediate action to combat climate change and its consequences 16. PEACE, JUSTICE AND STRONG INSTITUTIONS: Promoting peaceful and inclusive societies for sustainable development, providing access to justice for all and building ­effective, accountable and inclusive institutions at all levels 17. PARTNERSHIPS FOR THE GOALS: Strengthening the means for the implementation of goals and reinvigorating global partnerships for sustainable development 3

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3 Low-tech criteria compared with the LBC ­rating system and the UN’s 17 Sustainable Development Goals (SDG) 4  Clay house, Falkensee (DE) 2019, Gereon Legge

In summary, this analysis shows that – together with the method introduced in the chapter “Building Evaluations and Life Cycle Assessments” (p. 118ff.) – the fully elaborated low-tech matrix can also be used as an assessment gauge, and in ­particular can be helpful as a supplemen-

tary framework for a sustainability evalu­ ation. The weighting of individual aspects is determined by the specific challenges of the building task and its social and societal embedding. This can be dynamically and changeably defined and designed as needed.

Notes [1] Global Status Report 2017 [2] Brown et al. 2018; Cole 2012; Reed 2007 [3]  Endres 2020 [4]  Daniels 2000 [5] Haselsteiner et al. 2021 [6] Reed et al. 2009; SBi GXN 2018 [7] Forsberg, de Souza 2021 [8] SBi GXN 2018; Berardi 2012

4

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117

Building Evaluations and Life Cycle Assessments Bernhard Lipp, Ute Muñoz-Czerny, Thomas Zelger

In order to evaluate and optimise low and high-tech solutions, as well as to facilitate the development of robust and directionally stable low-tech buildings in both the new and revitalised construction sphere, it is helpful to formulate these methods and practices as socio-technical systems, that is, as social practices used in engaging with technologies and buildings. Essentially, this entails expending scientifically sound efforts in technical as well as social (and communicative) subsystems so that versions with varying “technological contributions” can be compared with one another within complete systems for thermal comfort, user satisfaction, life cycle costs and climate compatibility. In many cases, high tech can be compensated for by intelligent planning, a considered choice of materials, a solid basic ­technical supply and its sensible application. Buildings are long-lived commodities, and low-tech buildings in particular are more strongly coupled to local climate ­conditions: Today’s low-tech concepts should already contain provisions that vouchsafe quality thermal comfort without excessive operational or personal cost for predicted future warming (according to the climate projections from the German Weather Service DWD). Because of this, low-tech concepts tend to favour technologies that have low repair and maintenance costs, which often react more slowly than the high-tech solutions with their greater facility man­

118

agement intensity and quicker adjustability. On the other hand, factors such as design participation, the ability to understand and adopt building technology concepts and the increase in personal responsibility engage the users more intensively and allow them to forge a closer connection with the building they occupy. The “honest” involvement of the users obviates or sig­ nificantly reduces the need for complicated regulation systems and the associated building technologies, though the direct efforts required of the users increase. Engaging users extends the comfort range boundaries and raises subjective satisfaction levels. Compared to conventional approaches and high-tech concepts, low-tech concepts move costs out of operations and maintenance into the construction and ­renovation phase. The more intensive engagement of the users lowers the oper­ ating costs further by expanding the comfort range and avoiding technical regulation expenditures. Target values and criteria for low-tech buildings In a currently active research project run by the Austrian Institute for Building and Ecology together with the University of Applied Sciences Technikum Wien and Wohnbund:consult, and commissioned by the German Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR), an evaluation matrix

and target values were developed for future-oriented low-tech concepts. A comprehensive literature review yields the following findings about the relationship between low-tech concepts and user behaviour: • Low-tech buildings can achieve the same level of user satisfaction as high-tech buildings (though not the same comfort levels). • Greater opportunities for interaction translate to greater satisfaction. • The expectations of the indoor conditions in a low-tech building differ from those in a high-tech building. Based on these observations as well as the adaptive comfort model and the discussion concerning climate-compatible energy supply concepts, a compact evaluation set for low-tech buildings was developed that contains the following main and sub-criteria regarding expenditure for the construction or renovation of buildings: • Building technology: Expenditure for ­production, maintenance, repair, degree of complexity, external energy for equipment (e.g. auxiliary power for ventilators, pumps, measurement, control and regulation technology) • Structural engineering: Expenditure for manufacture and repairs • User “activity”: effort expended on the part of users for regulation etc., and degree of complexity of equipment servicing

Apart from the expenditure, the following qualities are also evaluated: • Deviations from the comfort range limits and from good indoor air quality •  Energy consumption, climate load Based on the technical assessments, research on low-tech concepts and surveys, the following overall evaluation for sustainable low-tech buildings is proposed: Must-have criteria: (100 % = high-tech building) • Building technology criterium ≤ 20 %: Modest expenditure for building technology in manufacture, maintenance and repairs, a low degree of complexity and robust building technology are prerequisites for low-tech buildings. • Low energy consumption / climate load  ≤ 20 %: Low-tech buildings are futureproof only if they can be supplied with 100 % renewable energy or are climate-­ neutral. Should-have criteria: • Deviations from comfort limits defined in EN 16 798-1 ≤ 40 %: If the users are wellinformed and expect low tech, the comfort limits differ from those of fully climatised high-tech buildings. • Effort of “active” users ≤ 80 % (no effort = 0 %, fully manual = 100 %): The participation of users is usually more necessary in low-tech buildings. The users must be “well-informed” in order to fully exploit

Building Evaluations and Life Cycle Assessments

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100

60 40

Low tech High tech

Building technology [%]

80

Late 19thcentury building

20 -60

-40

-20

0 -20

20

-40 -60 -80 -100

40

60

100 80 Energy use / climate load [%]

Comfort [%]

-100 -80 Users “active” [%]

1

the comfort and energetic potential of the building. Professional assistance is required when users take possession of the building but also during operations; coordination with occupational health and safety authorities etc. is advisable. Informational criteria: • Structural engineering expenditure: This is given as information. There is no upper limit for a positive categorisation of a building as “low tech”. This is due for the most part to the usually long usage phase and the modest maintenance costs of the structural components as compared to those of building technology components. Figure 1 shows the results and target values for three typical buildings. In fixing the limiting values, the decision was made to forgo any differentiation of the boundary conditions on the basis of building depth, occupancy density and floor plan design. The same goes for the influence of the local climate (city centre, countryside and climate zone) on comfort and renewable supply. These boundary conditions must be integrated into the weighting of the individual criteria whenever they are not “automatic­ ally” included in the detailed assessment. (For example, according to the adaptive model, the outdoor temperature moving average is incorporated into the comfort assessment, which means that in warmer locations, higher perceived temperatures are accept­able in the achievement of a

120

given quality class.) In the following passages, typical results are discussed and robust low-tech concepts are formulated using a case study as an example. House of Learning The House of Learning was built in 2018 in St. Pölten as an education and advisory centre for GESA (Gemeinnützige Gesell­ schaft für Entsorgung, Sanierung und Aus­ bildung). The three-storey, cellarless building is of passive-house standard and has a gross floor area of 1,485 m2 with office, conference, seminar and communal spaces. GESA is a non-profit socio-economic organ­ isation that provides unemployed persons with advice, qualifications and on-the-job training during their reintegration into the workforce. The House of Learning is a sustainable building in several respects: The integration of unemployed persons into the construction process helps qualify them for the labour market. At the same time, the use of ecological materials and the choice of an optimal building concept keeps impact on people and the environment to a minimum.. The sustainability concept encompasses reduced energy consumption, the buildingecological material aspect as well as the flexible use of the building. Materiality In the selection of materials, their separ­ ability, reusability and/or recyclability and regionality were all taken into account. The

1 The project variant ­rectangle must lie within the must-have target rectangle and should also be within the should-have target rectangle. The limits of “users active” are determined on an individual building basis.

2 House of Learning, education and advisory centre of GESA, St. Pölten (AT) 2018, MAGK architekten ­aichholzer I klein a Timber workshop b Access c–d  Installation of the straw bale insulation e–f  Wall heating on the building site  /during construction

a

b

interior was finished through self-build work by personnel of the GESA programme in cooperation with a contractor (Fig. 2). The primary structure is made from timber. Inside, cross laminated timber (CLT) panels form the stiff core of the building. A skeleton construction spans the transverse axis, providing flexibility for a possible re-grouping or conversion. The timber frame walls are insulated with straw bales and plastered with clay on the inside. The exter­ior of the outer envelope is covered with a breath­ able render on the lower floors and features

larch planking at the attic level. In the offices, the skeleton construction was left fully exposed, as were most of the cross laminated timber walls and ceilings. Straw bales were used as thermal insulation in the roof construction, as well. The building materials used by all the par­ ticipating building trades were drawn from a surrounding radius of about 200 km. The cross laminated and glued laminated timber panels were delivered from the ­production shed to the construction site on a just-in-time basis. The roof panels

c

d

e

f

Building Evaluations and Life Cycle Assessments

2

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100

60 40

High tech

Building technology [%]

80

Low tech House of Learning Should-have borders Must-have borders

20 -60

-40

-20

0 -20

20

40

-40 -60 -80 -100

60

80 100 Energy use / climate load [%]

Comfort [%]

-100 -80 Users “active” [%]

3

were equipped with the straw insulation at the carpentry shop to ensure that the on-site assembly would be quick and independent of weather conditions. Only the installation of the exterior wall elements proceeded “unfilled”, since the insulation work represented part of the training programme of the GESA. All in all, 55 % of the employed materials are renewable, 38 % can be reused or ­recycled and 8 % are non-renewable or recyclable. Though construction had to be preceded by an archaeological ­survey and a building site inspection for wartime ordinance because of the site’s proximity to the train station, the costs for this project remained at the low end compared to other building ventures of the same volume.

Building technology The very small heating energy requirements are met by a groundwater heat pump. Heat is delivered via low-­temperature heated surfaces (in the walls and floor). Automated room ventilation with high-efficiency heat recovery min­imises ventilation losses. The building features two central ventilation systems suitable for a passive house with heat recovery and automatic bypass. Communal rooms with highly fluctuating occupancy (social and classrooms) are equipped with variable volumetric flow controls that are operated via CO2 sensors in the relevant rooms. This makes it possible to keep the moving hourly average CO2 level in those spaces below 1,000 ppm. During business hours, the offices are

3  Evaluation of the House of Learning by means of the Low-tech Readiness Indicator (LowTRI)

4  House of Learning. Low values in the Lowtech Readiness Indicator (LowTRI) constitute favourable assessments in terms of the low-tech approach: The goals are less ­technical expenditure, lower climate load, smaller deviations from agreeable comfort ­levels. a Comparison of energy usage b Allocation of energy usage

33

33

20

38

10

10

25

15

20

10

29

43

33

52

Heating (with WW)

Cooling

Total

74 Ventilation

122

18

9

50

a

31

14

Low-tech Readiness Indicator (LowTRI) [%]

Low-tech Readiness Indicator (LowTRI) [%]

100 80 60 40 20 0 -20 -40 -60 -80

-100

b

Ventilation

Heating Cooling (with WW)

Total

Deviations from comfort range limits Energy use / climate load Users “active” Structural engineering Building technology 4

­ entilated at a near constant flow volume v that has been adjusted for average occupancy. Outside of business hours the equipment is operated at the minimum ­ventilation setting. The ventilation system for the training workshops is run as needed and is shut off ­completely outside of business hours. The users can also aerate the rooms by opening the windows. The exterior shading can be controlled via buttons inside the rooms. Assessments In the assessment of low-tech buildings, the general situational conditions as determined by climate zone, building orientation, local energy resources, floor plan layout and window openings must be taken into account. In addition, the potential of involving the users in the design process and during the operational phase must enter into the assessment. The room-by-room regulation of CO2 on the upper floors results in a relatively high ­technological expenditure for ventilation. A photovoltaic system on the roof with a ­nominal output of about 25 kWp would help keep the energy consumption /climate

load value below the upper limit of the ­targeted range. Though the system has not yet been installed for budgetary reasons, the necessary cabling for it is already in place (Figs. 3 and 4). Summary There is no such thing as “the” low-tech building – just as there is no “the” hightech building. It is rather the individual measures that can be described as ­low tech. For this reason, an evaluation ­regarding low or high tech requires the assessment and allocation of a plethora of data points and parameters, which can make the evaluation very complex. However, two important characteristics deserve emphasis: • The incorporated technology must be as robust and long-lived as possible. • The involvement of the users is essential. If the goal is to achieve similar accep­ tance levels with less building technology and to keep the satisfaction of the occupants at least the same, it is necessary to invest in an integrative, site-specific design (ideally with the engagement of the users) and reduced but robust and easily operated technical equipment.

5 Facade with main entrance, House of Learning, education and advisory centre of GESA, St. Pölten (AT) 2018, MAGK architekten aichholzer I klein

5

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Best Practice

Low-tech Focus: Design, Concept, System House in Trallong, United Kingdom — Feilden Fowles Agricultural Centre in Salez, Switzerland — Andy Senn Architektur Low-tech Focus: Building Technology Residential Building in Dornbirn, Austria — Baumschlager Eberle Architekten Administrative Building in Munich, Germany — ELEMENT A. Architekten,   hiendl_schineis architektenpartnerschaft 

Sands End Arts and Community Centre, London (GB) 2020, Mae Architects

126 130

136 140

Low-tech Focus: Material Information Centre in Böheimkirchen, Austria — Architekten Scheicher  Ecological and Energy-Efficient Building Concepts: Straw Bales for Sustainable Architecture — Robert Wimmer Headquarters in Darmstadt, Germany — haas cook zemmrich Studio2050

150 152

Low-tech Focus: Renovation Residence with Workshop in Schechen, Germany — Ziegert I Roswag I   Seiler Architekten with Guntram Jankowski Conversion of a Flarz house in Bauma, Switzerland — Oecofakta Saikal Zhunushova

158 164

Low-tech Focus: Overall Concept Lecture Hall and Administrative Building in Landshut, Germany — pos architekten Community Centre in London, United Kingdom — Mae Architects

168 172

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All project information was provided – unless otherwise specified – by the featured architecture firms or other design participants. The low-tech category evaluations were performed using a points system based on the low-tech matrix shown in this book (see “The Sustainable Low-tech Building”, p. 22ff. and “Low-tech Matrix”, p. 27ff.). The allocation of points was determined by the editor in agreement with the publishing company and the individual architecture firms. If a project meets all of the criteria within a low-tech category, it is awarded five points on the scale; one point means that it barely meets any of the criteria in the category.

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Between Tradition and Low Tech House in Trallong, United Kingdom

Like a well-shaped building block, lacking any projections or recesses of note, this geometrically accurate house stands on a lonely property on the edge of the Brecon Beacons National Park in South Wales. ­Conceived as a traditional longhouse and constructed with impressive precision in its details, it exemplifies sustainable residential architecture. It combines the use of passive solar radiation, the incorporation of ­natural materials from the region and a traditional building form.

Text: Steffi Lenzen

Concept The house, called Ty Pren – which trans­ lates as “House of Wood” – stands in a nature preserve on the edge of the Brecon ­Beacons National Park in Wales. This sen­ sitive context demanded a clever design approach to satisfy the local licensing authorities and simultaneously promote an architecture that was intended to be seen as a sustainable showcase project. The result is a two-storey longhouse without roof over­ hangs, based on the traditionally dominant building form. The orientation of the building and the facade design are based on the cardinal compass points. The long southern

126

facade, clad in larch wood, has many open­ ings that afford views of the expanses of Pen Y Fan mountain, while slate protects the roof and the exposed, mostly closed northern facade from the rough weather. Logically, this design principle is carried over into the interior. All the services, storage rooms, bathrooms, stairs and the pantry are located on the long north side. On the south, the communal rooms such as the kitchen, living room, dining area and office- / bedrooms are arranged in a row. An open gallery spatially connects the ground and first floors with one another, with only the flexible-use rooms on the upper floor partitioned off.

Architects: Feilden Fowles Client: Gavin Hogg Structural engineering: Momentum Structural Engineers

Site plan Scale 1:3,000

Construction and materials The building, which does without a cellar, rests on a foundation of reinforced concrete. The structure consists of self-supporting, thermally insulated panels known as SIPs (structurally insulated panels), which attach to the floors and ceilings via special fastening systems of timber web girders. In order to achieve a low U value in the walls, a secondary insulation of a sheep’s wool blend was added on the inside. The use of SIPs in combination with insulated double-glazed windows guarantees a highly airtight building envelope and very small heat losses. The highest-priority goal for the materials was employing local, contaminant-free and resource-conserving materials. The ­horizontal larch planking on the south, west and east facades is intended in its rain-­ protection function as a sacrificial layer. The timber comes from an estate about 3 km away that is owned by the client. Eight larch trees were planted on the estate after con­ struction to replace the cladding after its predicted lifetime of 25 years. The north facade and the roof are covered in recycled Welsh slate. Indoors, the floor is of limestone and Welsh oak floor boards. The partition walls of the utility rooms in the north are of sustainably grown birch plywood. Through­ out, Ty Mawr lime plasters and paints were used.

Low tech The Ty Pren house is consistently conceived based on the principles of solar construc­ tion. The compact structure is 20 m long and 6 m deep and forms a closed box that has generous openings only towards the south. Here, deep window reveals and manually operated sliding shutters prevent excessive solar gains in summer, while the few small north-facing windows are set flush into the facade and thus permit an unim­ peded influx of daylight. To the south, the large glass surfaces invite a lot of natural daylight and high solar gains in winter. The open floor plan and the modest room depth

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also allow for optimal cross-ventilation throughout the building. The floor plan offers maximum flexibility. Essential rooms are wheelchair-accessible and thus guarantee usage with changing requirements over generations. The structure and the material connections were designed so that individual building components could be easily replaced, and the entire building could be completely deconstructed and its parts separated by type for recycling or reuse at the end of its useful life. Easily detachable connec­ tion details and good construction documentation are therefore part of the design standard. Consciously chosen local materials such as the recycled Welsh slate, native timber species and limestone as well as lime

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­ lasters p and paints lend4 low-tech inspired 2 a 5 support to a made-to-last traditional con­ struction method. The on-site solar collectors supply the entire 5 house with hot water. A wood-burning stove in the living area directly and efficiently heats the adjacent spaces, and also provides hot water for a buffer tank installed in the north wall. This services the floor heater, which together with the stove provides warmth throughout the whole house and can also accommo­ date surplus hot water from the solar col­ lectors. A mechanical ventilation and heat recovery system ensures that all rooms are efficiently aerated in the winter months.

a Section3• Floor plans Scale 1:250 1 Entrance 2 Living room 3 Office / bedroom 4 Eat-in kitchen 5 Terrace 6 Pantry 7 Air space 8 Bedrooms

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  9 20 mm slate roof covering 25/50 mm battens 50/50 mm counter battens vapour barrier prefabricated ceiling element consisting of: 15 mm OSB panel 112 mm thermal insulation 15 mm OSB panel; glued element joints; 100 mm sheep’s wool ­thermal insulation 12.5 mm plasterboard 10 Internal rain gutter 11 24/46 mm rough-sawn larch ­cladding 50/100 mm larch post breathable house wrap Prefabricated exterior wall panel consisting of: 15 mm OSB panel 112 mm thermal insulation 15 mm OSB panel glued element joints

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80 mm sheep’s wool thermal insulation (installation level) 25/50 mm lathing 12.5 mm plasterboard 12 25 mm oak plank flooring raised floor consisting of: 25 mm OSB panel 250 mm timber web girder 100 mm cavity insulation 15 mm plasterboard 13 Window: Double glazing in a ­timber/aluminium frame U = 1.6 W/m2K 14 40 mm limestone panel flooring in a mortar bed 100 mm heating screed separating layer 80 mm rigid foam impact sound insulation with aluminium facing on both sides 200 mm reinforced concrete ground slab waterproofing membrane 100 mm blinding layer 15 150/220 mm concrete block plinths around perimeter

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Low Tech All Along the Line Agricultural Centre in Salez, Switzerland

The agricultural centre in Salez near St. Gallen sets an example for successful architecture and sustainability: The hybrid timber building utilises the material properties of concrete, hardwood and softwood through their ­specific implementations. Natural lighting and ventilation as well as wood chip heating, electricity from its own photovoltaic system and structural wood protection and sun shading round out the holistic low-tech concept.

Text: Steffi Lenzen

Concept On the Rhine river meadows in the Swiss canton of St. Gallen, on the outskirts of the little town of Salez, the newly constructed extension of an agricultural training centre stretches out before an imposing mountainous backdrop. New generations of agricultural professionals have been traditionally educated here since the 1970s. The intention was to provide additional rooms for educational activities and for the boarding school dormitories and to build a new cafeteria. The new L-shaped timber block completes the existing administration and workshop buildings so that a generous central courtyard is formed between the old and new structures. Construction and materials Because of the poor load-bearing condition of the ground, the building stands on a foundation of reinforced concrete piles; the

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basement and ground slab are likewise of reinforced concrete. Atop these, a clearly organised, tranquil timber structure blends naturally into the surroundings. The entrances to the new construction are at the intersection of the school and dormitory wings as well as at the head of the long main block. The extended two-storey area housing the agricultural vocational training classrooms comprises a pure skeleton structure of spruce glued laminated timber with a 2.14-m grid. This allows for large spans between floor joists and considerable flexibility in the long term. The ceilings are ­timber-concrete composite constructions consisting of a three-layer board with a top concrete layer, which guarantee the necessary stiffness for the ceiling spans of up to 8.50 m. In addition, their high mass supports the acoustic protection requirements and serves as a thermal reservoir to prevent overheating. At the southern end of this wing is a large open space for the cafeteria, which is spatially separated from the central hallway only by the bearing columns. When needed, the doors of the auditorium across the hall can be fully opened, making it possible to use the entire transverse building width. Construction of the shorter, three-storey dormitory wing comprises cross laminated timber panels and accommodates 28 twin rooms. Here, too, t­imber-concrete composite ceilings provide the necessary rigidity, the required storage mass and

Architects: Andy Senn Architektur Client: Canton of St. Gallen Structural engineering: merz kley partner HVAC design: Richard Widmer, Hans Schär Electrical design: Bölle & Partner Structural engineering, energy design: Lenum Landscape architecture: Mettler

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­structure are built with softwood that good acoustic protection. In addition, in comes predominantly from the surroundthe interests of acoustic insulation, the bearing walls between the rooms are doubleing forests. Large vertical windows up 16 to 2.80 m high4provide optimal6lighting 6 skinned and separated, as are the ceilings, 8 by a joint. and afford open views toward the broad Arbours provide structural su- and rain expanses of the Rhine valley on entering ­protection for the facades. The areas that the building. In summer, when these 16 6 6 are exposed to wind and weather are 16 ­windows are closed with sliding shutters in hardwood, while all other parts of the to protect against solar gains, continuous

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17 Vertical section of the education wing Scale 1:20 17 Roof construction: extensive green roof; 40 mm substrate 2≈ 4 mm filtering fleece, drainage mat, bitumen sheet 30 mm rock wool thermal insulation 2≈ 4 mm bitumen sheet 180 mm cross laminated timber 160 mm rock wool thermal insulation breathable membrane 140 mm cross laminated timber 18 Silver fir with triple insulating fixed glazing 19 Flap for manual ventilation 20 Insect screen 21 180/200 mm glued laminated timber beam 22 Silver fir timber window with triple insulating glazing 23 Education wing floor construction: 5 mm casein primer; 70 mm screed PE film separating layer 20 mm rock wool impact sound insulation 35 mm levelling insulation timber-concrete composite ceiling: 100 mm reinforced concrete 60 mm flat ceiling slab of spruce cross laminated timber, triple-layered 24 Acoustic ceiling: 18 mm untreated silver fir battens, attached with spacing; black fleece 60/150 mm spruce beams, interleaved with 30 mm rock wool acoustic insulation 25 50/100 mm oak handrail 26 120/80 mm oak boards 40/100 mm oak squared timber polymer support; 100/160 mm oak girder

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bands of 1.25-m-high windows above them ensure an unobstructed influx of ­daylight. Low tech Thanks to sophisticated design and the involvement of its users, the building ­manages with only a minimal amount of technology. Only the laundry room and the professional kitchen require mechanical ventilation with heat recovery. For the most part, the occupants are responsible for manually operating the controls for ventilation, lighting and cooling in all the other areas themselves. A well-thought-out concept for cross-ventilation, however, facilitates the natural influx of fresh air via vents below the transom window bands and the Ecosystem 5 Responsibility

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discharge of stale warm air through openings in the upper area below the ceiling. These lead into a permanently open but covered air exchange space that runs ­centrally along the full length of the main wing of the building. As a consequence, the weather poses no issues and the glazed ventilation flaps located there can be opened at any time. The 4.40-m height of the rooms also allows for good air circu­ lation. The cross-ventilation option exists in the classrooms on both floors and in the communal rooms. Natural daylight enters into the spaces through generous openings oriented as needed and through the transom window bands above, while heat is intended to be kept outside by multiple layers of structural sun protection. A staggered series of shading measures consisting of deciduous trees in front of the building, deep arbours and manually operated sliding shutters directly outside the lower portions of the window areas provides considerable sun protection in summer, while allowing the rays of the low winter sun to find their way into the building. An on-site photovoltaic system covers most of the electricity demand. Thermal energy comes from the local wood chip heating facility. Heating ducts, radiators and the hand cranks used to operate the ventilation openings are easy to use and surface-mounted throughout, providing guaranteed reliable access for maintenance and repair.

Note: The source of specific information beyond that provided by the architecture firm is the publication “Landwirtschaftliches Zentrum St. Gallen in Salez” (St. Gallen ­Agricultural Centre in Salez), published by the Building Department of the Canton of St. Gallen, St. Gallen Building Authority

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1 2≈ 8 mm LSG roof glazing with ventilation openings in aluminium clamping profile 2 Roof construction: extensive green roof; 40 mm substrate filtering fleece, drainage mat 2≈ 4 mm bitumen sheet waterproofing 360–250 mm rock wool thermal insulation, tapered 160 mm rock wool thermal insulation breathable membrane 60 mm cross laminated timber 3 90/20 mm rough-sawn silver fir cladding 25/60 mm battens 50/50 mm counter battens; underlay 70 mm mineral wool thermal insulation 160 mm cross laminated timber 4 25/200 mm spruce fins 5 Silver fir tilt windows with triple insulating ­glazing 6 2≈ 4 mm bitumen sheet waterproofing 30– 80 mm rock wool thermal insulation, tapered 100 mm rock wool thermal insulation breathable membrane 100 mm cross laminated timber

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2226 – Durability Instead of Technology Residential Building in Dornbirn, Austria

Dornbirn in Austria‘s Vorarlberg region is known beyond its city limits for innovative architecture and new ­construction incentives. It is not surprising, therefore, that the architects, who hail from nearby Lustenau, took the ­daring step of transposing their proven radical energy concept from building 2226 into residential con­ struction. “Concept 2226”, which is by now traded as a proprietary system, describes a construction method that ensures indoor temperatures between 22 and 26 °C, which most people consider comfortable, without conventional heating but using only building mass, internal heat sources and proprietary software. Text: Steffi Lenzen

Concept The two-storey, eight-unit residential building lies at the north-eastern city limits of Dornbirn. The multi-family building responds to the mixed development typology in its vicinity with a reduced use of stylistic elements. Following a clearly orthogonal geometry, the three slightly offset structural blocks are staggered along the slope. Each pair of three-room flats is accessed via a classic shared entryway. The east-west orientation of the flats allows for an optimal use of daylight. An associated underground garage is integrated into the slope. Construction and materials The materials used in the building and the structure itself are designed for longevity and thermal storage capacity. Lightweight constructions were purposely avoided. The main thermal mass lies in the floors of reinforced concrete, a material which was otherwise used only to build the underground garage. Ninety per cent of the entire building mass consists of insulated bricks and, to a small extent, of timber and glass for the deeply recessed windows. Lime plaster covers the outside of the exterior brick walls of the building, which are approximately 50 cm thick. The plaster is vapour-permeable and acts as a fungicide, guaranteeing unhindered vapour diffusion and preventing fungal growth on the facades. Thanks to automated ventilation controls, the humidity of the indoor air fluctuates between the desired 40 and 60 %.

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All the materials are regionally sourced, and most of them are constructed in a way that allows them to be disassembled and recycled. The use of composite materials was generally avoided and industrial products were only minimally utilised.

Architects: Baumschlager Eberle Architekten Client: Graf Immobilien Structural engineering: Mader & Flatz Building physics: T.A.U.

Low tech The basic idea of “Concept 2226” is to avoid the use of technology for air conditioning. Now, for the first time, this principle is being transferred to a residential building which will thus function without conventional heating, cooling or ventilation. Here, too, the heat emitted by the residents and the appliances used in the house, taken together with high thermal storage masses,

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a balanced window ratio and automated ventilation flaps, will yield the desired ­temperature range of 22 to 26 °C. Easy-­ to-use software, the 2226 Operating System, controls the heating budget, the humidity and the CO2 concentration of the b indoor air via automated ventilation flaps. These can also be opened manually as needed. In general, the thermal storage capacity of the construction allows the internal heat a to be absorbed and then radiated uniformly 1 throughout the day. In contrast to Office Building 2226, in this case there is2a photo3 voltaic array on the roof to provide hot water b and control the building temperature, since 4 the heat supplied by people, computers and other appliances and lighting fix5 tures in private residences is significantly

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less than in an office or commercial ­building that is fully occupied all day. a The generated energy of the photovol1 1 a taic array is not fed into the municipal 2 but3is instead stored in a grid, however, refrigerator-sized device in the garage, to use for building-­ specific needs such as 4 for infrared panels which supply additional 5 rooms. This gives the heat in individual building with a form of “environmental backup insurance”. a Through this construction method, in com­ 1 bination with efficient regulation of the energy flows, the total energy requirements for running the buildingb– and the associated demand for resources – is reduced to a minimum, which has a noticeable economic impact. The costs for maintaining technical hardware are also avoided.

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Vertical section Scale 1:20 6 Bitumen sheet waterproofing, double-layered 2≈ 100 mm PUR thermal insulation 150 –180 mm tapered EPS insulation vapour barrier ceiling element: 180 mm in-situ concrete 60 mm prefabricated reinforced concrete ­component, prestressed 5 mm lime plaster levelling primer 7 365/250 mm U-shaped brick filled with concrete and reinforced

  8 3 mm lime plaster levelling primer 7 mm lime cement exterior undercoat render 490 mm masonry 15 mm lime cement interior undercoat render 5 mm slaked lime plaster   9 10 mm oak parquet floor 60 mm cement screed 100 mm cement-bonded fill 180 mm in-situ concrete floor 60 mm prestressed ceiling element 5 mm lime plaster levelling primer 10 Window: triple glazing in timber frame U = 0.6 W/m2K 11 Aluminium window sill 7

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Revitalisation of the Highest Calibre Administrative Building in Munich, Germany

An aging administrative building has been given a new lease of life for the German Alpine Club (Deutscher Alpenverein or DAV). Revitalised in a resource-conserving manner and increased in height by two storeys, the new timber-hybrid building in the centre of Munich‘s Parkstadt Schwabing district defies the monotone office architecture of its surroundings. Rigorous low-tech design and an intelligent ventilation concept made it possible.

Text: Steffi Lenzen

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Architects: ELEMENT A. Architekten (work stages 3– 8), hiendl_schineis archi­ tektenpartnerschaft (work stages 1–2) Client: Deutscher Alpenverein Structural engineering: Karlheinz Kovacs (solid construction) Merz Kley Partner ­(timber construction) Energy consulting: transsolar Energie­ technik Landscape architects: t17 Landschaftsarchi­ tekten

Site plan Scale 1:5,000

Concept In the very north of Munich, conveniently located between the Middle Ring and the A9 motorway, lies the so-called House of the Mountains, a green oasis in the otherwise quite colourless office building dreariness of Parkstadt Schwabing. The former administrative building of the Langenscheidt publishing company had four storeys and an underground garage and was built in two phases in the early 1970s and 1980s by Kurt Ackermann und Partner. At first, its projected use as the ­federal headquarters of the German Alpine Club with a correspondingly extensive ­spatial allocation plan seemed unrealistic. The general refurbishment based on a rig­or­ ous low-tech concept succeeded thanks to an intelligent extension in timber and ­timber-hybrid construction and a clever ventilation scheme. Construction and materials Hardly recognisable from outside, the concrete structure of the old building now hides behind the inviting facade of the new DAV headquarters. The special way the existing building was dealt with and the resourceconserving revitalisation have caused a steep drop in the net environmental footprint of this structure. The two full storeys added have been constructed in timber. Thanks to the intrinsic material properties of timber, the additional structural loads and the embodied energy have both been kept in check – wood is considered a sustainable building

material, since it binds CO2 in the structure over the long term. The access cores of the two added storeys are likewise timber constructions. The ground floor was extended with the addition of a new conference room on the west side. In the course of the revitalisation, the entire building gained a new post-and-beam facade of timber that highlights the vertical dimension and features large glazed areas that allow full utilisation of daylight in the interior. In many sections, exterior sun protection is unnecessary thanks to the shade from the surrounding buildings; at the few unshaded points, manually operated textile roller shades in a greenish yellow provide colourful accents on sunny days. On the long sides, a timber construction about 1.5 m deep covers the full five-storey height of the building but reveals the former structural volume within. The construction is equipped with planter boxes and is gradually greening up. It also serves as structural sun shading and provides access for maintenance and cleaning of the facade. To furnish access, the building was extended on the north side to include an atrium with an open stairwell that extends over all storeys. Timber, glass and plants determine the architecture of the building – not only on the facades, but in the interior as well. The timber-sheathed ventilation panels in the parapet area, installed room modules and wood furniture as well as lightweight

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timber-and-glass partition walls, which attach to the facade following the grid of the existing concrete structure, furnish a bright, inviting atmosphere. The concrete ceilings in the old building and the timberconcrete composites in the extension have been left exposed. Cabling is mostly surface-­ mounted, ensuring easy accessibility for maintenance. Low tech A natural ventilation concept was required that would provide optimal acoustic and thermal comfort despite the high sound protection demands due to the noise pollution from the surrounding traffic and the considerable wind pressure fluctuations due to the exposed location. The modular style of the interior constructions allows for long-term flexible use of the space. The passive cooling is a result of a clever idea on the part of the engineers, who redesigned a series-produced ventilation panel and relied on proven physical prin­ ciples instead of electrical control and ­regulation. The acoustically insulated ventilation units are controlled in situ and are consistently installed as parapet panels in the facade close to the floor in all the offices, thus ­preventing uncomfortable draughts. During normal operation, outside air and room air near the floors is pulled inward by the thermal lift effect of the convection shaft, providing for an influx of fresh warmed air. The exhaust air overflows into the core area, where it is centrally collected in two shafts and expelled through exhaust fans in the roof. Even in winter, the cold outdoor air is

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drawn through the convector by thermal uplift. If, however, the heating performance of the convector should fail due to a tech­ nical defect, the frigid outside air will safely flow past below the convector so that the unit does not freeze. The exposed concrete ceilings act as ­thermal reservoirs and allow for optimum night-time cooling. Permanently installed ceiling fans improve air circulation as needed and raise thermal comfort levels in summer. The entire building thus runs without active mechanical ventilation or ­cooling. Only the electrical and IT areas require additional cooling in the form of two chillers, though these employ environmentally friendly water as a cooling medium. The waste heat of these machines is used in winter for heating.

Note See “Robust Building Design”, p. 74ff.

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  1 Extensive green roof, 100 mm substrate filtering fleece, 20 mm drainage mat bitumen sheet waterproofing 250–120 mm tapered EPS thermal insulation 100 mm EPS thermal insulation vabour barrier, 120 mm reinforced concrete ­ceiling   2 Zinc sheet roofing   3 160/30 mm larch sun protection louvre   4 160/160 mm larch glulam facade column   5 30 mm steel girder with fire-resistant solid ­timber cladding   6 6 mm carpet, 34 mm raised floor panel 86 mm raised floor support /air cavity timber-concrete composite floor: 120 mm ­reinforced concrete 245/280 mm glued laminated timber beam   7 Window: triple insulating glazing in timber frame, U = 0.7 W/m2K   8 30 mm spruce multilayered board cover   9 Ventilation element with integrated acoustic insulation for fresh air supply 10 Post-and-beam facade: 2 mm powder-coated steel sheet with slits for fresh air supply, 45 mm rear ventilation breathable housewrap, 180 mm mineral wool thermal insulation, 25 mm insulation 140 mm (pre-existing) reinforced concrete 19 mm spruce multi-layered board cover convector heater, 15 mm cement-bonded ­fibreboard, 50/50 mm fi galvanised steel sheet subconstruction 12 6 mm carpet, 34 mm raised floor panel 86 mm raised floor support /air cavity 200 mm pre-existing reinforced concrete floor slab

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Low-tech as Design Principle Information Centre in Böheimkirchen, Austria

The S-House in the Lower Austrian town of Böheimkirchen is part of a research and technology programme entitled “House der Zukunft” (House of the Future) run by the Austrian Ministry of Mobility, Innovation and Technology. The goal of this programme is to demonstrate how sustainable construction of residential and office buildings can succeed, preferably by realising ground-breaking projects. The S-House serves as an information centre for sustainable construction.

Text: Steffi Lenzen

Concept Located in the middle of a garden space, the building is considerate of the preservationworthy old-variety fruit trees that surround it. In accordance with solar construction, the building is oriented strictly by the car­ dinal compass points, with a mostly closed facade to the north and large glass openings to the south. The eastern side features an open terraced area beneath the large overhang of the roof. In order to meet the criteria for what is called a “factor 10 house”, ambitious sustainability goals were pursued. Exclusively regional and non-hazardous building materials of renewable resources were used in its construc-

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tion. At the same time, the structure was designed right from the start to be capable of deconstruction and recycling in its endof-life phase. An integrative process contributed to its successful implementation. All participating firms were involved from the outset, so that environmental and functional solutions could be cooperatively developed by a careful consideration of options. Construction and materials The so-called S-House is a compact, ­red-painted timber cuboid that has been inserted between an elevated floor and an overhanging roof slab. Slightly slanted

Architects: Architekten Scheicher Client: Technische Universität Wien, GrAT (Gruppe angepasste Tech­ nologie) Structural engineering: JR Consult Timber construction: Florian Hager Energy consulting: Robert Wimmer

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hinged supports carry the roof and increase its stability against laterally acting forces. The ground slab is supported on individual footings and suspended about 30 cm above the ground. As a result, there is no excavated area, less ground sealing and a smaller use of resources than for a foundation with a basement, since the demand for concrete is considerably reduced. The inside of the wall construction consists of load-bearing cross laminated timber panels with a 50-cm-thick insulating layer of straw bales. Because of their high insulating ­performance, these make even a passivehouse standard possible. A clay render applied to the outside of the insulation provides the necessary fire protection, and even the sound insulation values of this highly efficient exterior wall design lie above the standard requirements. To guarantee deconstruction capability, special screws made of a biosynthetic material were developed and manufactured via injection moulding. They also allow for attachments without thermal bridges to the counter battens of the rear-ventilated facade. The shape of the screws was optimised using bionic criteria to achieve the best strength values for the least amount of material. The screws can be removed and re-used or, like the straw bales, reintroduced after the use phase into the biological loop. Low tech Apart from the compact building geometry and its optimal orientation for the passive

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utilisation of solar energy, the regulation concept employs renewable resources with minimal material expenditure. The building services system uses air as its only heat-conducting medium, and short ducts keep conduction losses perman­ ently low. The controlled supply of fresh and removal of exhaust air occurs via a geothermal heat exchanger and timber ­ventilation ducts. A solar collector on the roof supplies the energy for hot water, and a passive-house-capable biomass storage furnace integrated into the heat and ­ventilation distribution system covers the peak heating loads. Glass panes set into the roof overhangs admit natural daylight, but prevent excessive direct solar gains in the summer.

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Vertical section Scale 1:20   1 Extensive green roof substrate, filtering fleece 40 mm drainage mat 1.3 mm root-resistant rubber ­waterproofing 110 spruce cross laminated timber   2 2≈ 8 mm LSG roof glazing in aluminium clamping profile   3 Powder-coated aluminium coping   4 120/120 mm | hinged larch support, ­widening to 180/180 mm | cross-shaped at half height, with grooves along all four corners   5 30 mm waxed spruce hardboard 20 mm lime plaster 500 mm straw bale thermal insulation 110 mm spruce cross laminated timber   6 Window: double glazing in larch wood frame, U = 0.79 W/m2K   7 20 mm rough-sawn spruce cladding 50/120 mm batten, affixed to straw bale with biosynthetic screws 20 mm lime plaster reinforced with jute 500 mm straw bale insulation 7 110 mm spruce cross laminated timber   8 30 mm Douglas fir solid timber floorboards, fastened with wooden dowels onto 50/80 mm battens, interspersed with straw pellet fill, separating layer 20 mm impact sound insulation 110 mm spruce cross laminated timber   9 60/30 mm natural stone flooring, bonded into a 40 mm bed of crushed gravel with lime casein glue, separating layer 20 mm impact sound insulation 110 mm spruce cross laminated timber 500 mm straw bale insulation 80 mm spruce cross laminated timber 10 30 mm thermally treated ash floorboards 2≈ 80/80 mm solid wood beams

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Ecological and Energy-efficient ­Building Concepts: Straw Bales for Sustainable Architecture

Text: Robert Wimmer, GrAT (Gruppe Angepasste Technologie, Vienna)

A relatively large part of energy and resource consumption is attributable to the building sector. Renewable resources represent the potential for considerable improvement in this regard. They also ­contribute to the reduction in construction waste which is difficult to dispose of. For this reason, it is logical to use materials that are easy to recycle or discard. In addition, the utilisation of regional, renewable resources for insulation and other building materials presents a sustainable solution for achieving climate protection goals. Materials such as straw, reeds, hemp, flax and timber absorb CO2 during growth and then serve as CO2 stores when they are used in construction. The energy required for their production is ­usually low and, after their use, they can be returned to the natural cycle. The low ­primary energy content raises energy ­efficiency by a factor of about 10.

forms better by up to a factor of 10 in all environmentally relevant evaluation cat­ egories. In the Austrian project Stroh-Cert, straw bales were officially recognised by the authorities as a certified insulating ma­­ terial, and an integrated logistical analysis from straw harvest to compression of the bales to their warehousing, as well as a concept for quality control to ensure their uniformly high quality, were developed. As a seasonal agricultural product, straw (or straw bales), like other renewable raw materials, can only be produced within a short window between the end of June and the end of August. However, as an insulating material it is needed throughout the year. For this reason, appropriate storage capacities are needed. Currently, the lack of incentives to produce straw bales means that after the grain harvest, most straw is left on the fields. With the development of a logistics model for straw bales, existing

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Straw bales are therefore well-suited as building blocks of sustainable architecture. In contrast to conventional insulating materials, they store CO2 and therefore make a valuable contribution to climate protection. The important properties of straw bales are their high insulation per­ formance (λ value 0.045 W/mK), their poor flammability (fire resistance class E) and the modest resource and energy demand for their production. A comparison between a straw wall construction and a conventional wall shows that the straw wall per-

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2 LIFE Cycle Habitation, Böheimkirchen (AT) 2014, Architekten Scheicher Low tech: Materials of renewable commodities (straw, t­ imber, clay), high building standard (plus-energy building) with self-­ sufficient energy supply, recyclable materials in their natural, untreated state

capacity for transport, warehousing and processing can be used, jobs can be secured even outside the agricultural sector and important regional economic incentives can be created. Using this standardised insulating product, architects and designers can position themselves in the market for sustainable buildings. Because of the regulations and standards in the construction sector (passive house or low-energy standard, obligatory energy performance certificates, etc.) thermal ­insulation has taken on particular importance. Given supply bottlenecks for fossil fuel-based commodities and increasing ­climate awareness, regionally sourced renewable materials have advantages such as supply security and resource efficiency, which are ultimately reflected positively in the costs. The official certification of straw bales as insulation, which has already taken place in Austria, ensures the availability of bales of uniformly high quality and secures market acceptance. The fact that an increase in the use of renewable resources is a critical strategy for sustainable management is undisputed. Especially in construction, intelligent util­ isation of materials can create synergies between optimal functionality and the avoidance of environmental and waste disposal problems. The goal is to meet the needs of users in the best possible way without saddling future generations with enforced reuse or leaving them to deal with disposal difficulties. The industrial prefabrication of building components makes it possible for even small and medium-sized businesses to compete internationally. It allows not only for more economical production, but can guarantee and effectively monitor the maintenance of a uniform product ­quality level. The industrial prefabrication of building parts and functional modules achieves the best possible resource efficiency and allows for precisely designed production processes as well as short onsite construction times. However, standard­ isation and prefabrication do not mean that all houses will be the same. Quite the

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opposite: Efficient serial manufacture of individual components such as the building services system frees up resources to address the specific wishes of clients and allow for an original facade design, for example. In the S-House, the Factor 10 concept was implemented in the construction (resource consumption was reduced to one tenth of current values) and the criteria for sustainable building were met. The continuing project LIFE Cycle Habitation (Fig. 2), which was realised with the LIFE+ funding programme of the European Union, relies on an innovative building concept that uses regionally available, highly energy-efficient renewable materials in modular prefabri­ cation. Various straw bale construction techniques (structural and prefabricated, non-bearing modules) as well as a highly innovative energy supply system were implemented. The building concepts are being optimised with the aid of dynamic simulations, both to reduce the heating needs of the residential units but also to minimise summertime overheating and thus to raise the thermal comfort of the residents. Promotions such as trial living allow the new concepts to be experienced so that the energy supply system can be subjected to real-time testing and optimisation.

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Added Value through Clay Headquarters in Darmstadt, Germany

The new headquarters of the organic food manufacturing company Alnatura in Darmstadt was intended to be close to nature, resource-conserving, inviting and to have optimal working conditions for employees. The result proves how rewarding it can be to set high goals: Using natural and resource-conserving materials, an office building was created that is largely naturally ventilated and illuminated, consumes little energy and provides optimised indoor comfort. This is what built and experienced sustainability looks like.

Text: Steffi Lenzen

Concept The new headquarters of the organic food producer Alnatura is the centrepiece of the 55,000-m2 campus located at the site of the former American army barracks in southwest Darmstadt. The company grounds border a large pine forest and ­feature kitchen and teaching gardens as well as a public nursery school. The fore-

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most goal for the new headquarters with high-quality working conditions for the approximately 500 staff was the creation of an all-around resource-conserving ­building that would establish a connection to nature and use mostly available resources. The compact geometry of the three-storey building is entered through comparable

5 Site plan Scale 1:5,000 1 Headquarters ­building 2 Pond 3 Vineyard 4 Allotment garden plots 5 Nursery school 6 Car park

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Architects: haas cook zemmrich Studio2050 Client: Campus 360 Structural engineering: Knippers Helbig Clay construction: Lehm Ton Erde Baukunst Energy consulting: transsolar Energie­ technik Landscape architects: Ramboll Studio Dreiseitl

large entrances on the two building ends. The interior immediately reveals the openness and generosity that characterises the design. Flooded with daylight via skylights, an atrium stretches across the entire building length of about 95 m and upward to the roof. The working areas of the individual departments and the conference rooms occupy the long sides and are accessed by means of central stairs as well as open ­galleries that are stepped back with height. Only very occasionally are individual areas – for meetings, for example – firmly partitioned off by glazed walls. ­Basically, the building consists of a single large space, which can be flexibly organised and made use of by means of acoustically insulating curtains. The ­free-form occupancy options of the spaces are intended to promote open ­interdepartmental communication. The ­predominant materials of timber, clay and untreated concrete combine with the daylight concept in contributing to a ­natural, friendly atmosphere.

Note The source of some of the information beyond that provided by the architecture firm is the publication “Gewerbebauten in Lehm und Holz – Mehrwert durch Material“, published by the Deutsche Bundes­ stiftung Umwelt.

Construction and materials The structural design harks back to academic research on different variants of resource-conserving construction. In the design, criteria such as the energy needed for transport, manufacture and disassembly played a major role, as did recyclability and indoor climate requirements. The ­materials employed, namely timber, clay

and concrete, were found to represent a very reasonable and cost-effective com­ bination. The structure comprises a classic reinforced concrete skeleton and four stiffening sanitary and stairwell cores on a basement of reinforced concrete. Self-supporting facade panels of rammed clay 69-cm thick alternate with glazed post-and-beam sections to form the long walls, while the ends are conceived purely as post-and-beam facades. The clay facades have extra ­features, as they possess additional core insulation in the form of a 17-cm thick layer of recycled foam glass gravel between the rammed clay layers as well as integrated panel heating. At six points of the facade, the backs of the clay walls are anchored to the floor slabs and the edge beams of the roof structure.

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In order for the life cycle assessment of 2 the clay to remain unencumbered, it had to 2 4 be regionally sourced. In this case, it came 3 from the inexhaustible supply of excavated material from the major Stuttgart 21 construction site about 160 km away, a distance that certainly still leaves room for improvement. The incisive roof construction is divided into two structurally independent parts by the continuous band of skylights running from east to west. Glued laminated timber gir­ders, each supported on two pillars, are connected on their top sides by OSB panels for shear stability. Despite its open structure and its unclad ceilings and walls, the building’s acoustics are pleasant. This is owed in large part to the open surface structure of the clay walls. In addition, recyclable foamed concrete

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absorber strips were embedded into the exposed concrete ceilings. The strips do 5 6 5 not negatively impact the thermal storage function of the concrete slabs. The underside of the enormous roof is also equipped a with an acoustic slatted timber cladding, as are the window reveals. The four stairwell and sanitary cores are sheathed in microperforated cladding. Low tech In the pursuit of a resource-conserving ­construction, a building technology and energy concept using natural materials was developed that would provide maximum heating, cooling, ventilation and lighting performance with minimal consumption. This succeeds thanks to various factors. First, the orientation of the building plays a very important role. The continuous east-to-

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  1 1 mm standing seam aluminium sheet 160/24 mm sheathing, 80 mm rear ventilation breathable underlay, 25 mm sheathing, 80/280 mm squared timbers with 280 mm ­mineral wool thermal insulation between, breathable membrane; 18 mm mineral-bonded fire-resistant panel, 100 mm mineral wool acoustic insulation; 57/18 mm solid spruce slat   2 Aluminium sheet box gutter   3 380 mm prefabricated rammed clay element 250 + 100 mm mineral wool thermal insulation, breathable membrane, 140 mm glulam beam   4 330/140/12 mm steel ∑ profile anchor plate, hot-dip galvanised   5 15 mm lime mortar pointing   6 Insulation concrete joist, B500 B reinforcing steel; longitudinal and shear reinforcement Ø 8 mm each   7 30 mm foam glass thermal insulation   8 Layer of trass lime   9 380 mm prefabricated rammed clay element + 170 mm foam glass gravel thermal insulation + 140 mm rammed clay with integrated wall heating 10 Plastic geogrid 11 6.5 mm carpet 38 mm calcium sulfate raised floor panel 1.5 mm acoustic fleece; 152.5 mm air cavity 300 mm reinforced concrete floor slab 12 Mineral waterproofing slurries 13 80 mm prefabricated insulation concrete ­element; aluminium sheet bracket subconstruction, 200/100/10 mm stainless steel profile, 100 mm wide; aluminium sheet sheathing, filterstable ­geotextile, dimpled drainage sheet bitumen sheet waterproofing; 560 mm lightweight concrete prefabricated plinth element 14 Filter-stable geotextile, dimpled drainage sheet, 140 mm foam glass thermal insulation bitumen sheet waterproofing 350 mm reinforced concrete outer wall 15 18 mm cable duct of mineral-bonded fire-­ resistant board 16 33 mm silver fir acoustic panel, slotted and painted 17 125 mm Ø drainwater pipe 18 Clay backfill 19 Mineral wool thermal insulation

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west band of skylights admits a uniform influx of northern light, ensuring reliable daylight use without generating unwanted solar heating. Ventilation is provided mainly through ground ducts in the basement, which take in air at the nearby ­forest edge, pre-temper it with stored geothermal heat and supply it to the interior spaces via displacement vents at the four concrete cores. This makes positive use of the fact that the average temperature of the ground at that location provides ­cooling in summer and heating in winter. Exhaust air is driven upward towards the roof by natural thermal lift and expelled through automated openings in the skylights. Thanks to the pre­conditioning of the intake air, the additional heating and cooling needs of the building are kept to a minimum. In rare weather situations, the fans in the ground channels must be powered up in order to boost the chimney effect; however, these run on internally ­generated energy from a photovoltaic system on the southern part of the roof. The windows can also be individually opened as needed to provide fresh air to the offices at any time. The central atrium guarantees sufficient air removal and natur­ ally supports this type of cross-ventilation. The clay walls contribute substantially to a stable temperature level in the building. Together with the concrete ceilings, they represent an enormous storage mass, and even on hot summer days, the evaporative cooling of the clay in the very tall rooms is

enough to prevent overheating even without mechanical cooling equipment. In winter, heating coils in the clay walls provide efficient supplementary radiative heat. These are embedded into the clay and are supplied with hot water from regenerative sources such as the geothermal wells and recovered waste heat generated by kitchen appliances.

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New Use for an Old Structure Residence with Workshop in Schechen, Germany

Preserving value with a relocation: The old peat shed from Kolbermoor has moved to a new neighbourhood 15 km away in Schechen, where it now serves as a residence, workshop and warehouse. Built and expanded entirely with the natural construction materials of timber and loam, it blends harmoniously into the former railway grounds. The respectful treatment of the existing building and the ­surrounding natural space results in an impressive indoor quality.

Text: Steffi Lenzen

Concept Schechen is a community of 1,200 souls in Upper Bavaria, about 50 km southeast of Munich. Right next to the refurbished old railway building stands a former peat shed, which has found a new use in this town as a workshop with a studio and two residential units. The shed was originally part of an old cotton spinning mill in Kolbermoor, 15 km away. But when the plans of investors called for its demolition, the client and his wife simply bought the supposedly worth-

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less barn, which the wickerwork designer had already been using as a ­perfect storage place for his materials. Together with a few carpenters, he dis­assembled the shed piece by piece and warehoused the segments while he searched for a ­suitable property for its planned future use as a workshop and ­storage place. The main goal during the search was to avoid sealing any new greenspace areas for the ­project. Therefore, the brownfield site in Schechen directly adjacent to the

Architects: Ziegert I Roswag I Seiler Architekten with Guntram Jankowski Client: Stefanie and Emmanuel Heringer Structural engineering: Ziegert I Seiler ­Ingenieure Clay construction: Ziegert I Seiler ­Ingenieure

Site plan Scale 1:2,000 Note Additional source: https://www.faz.net/ aktuell/wirtschaft/ wohnen/bauen/neuehaeuser/neue-haeusernaechster-halt-alte-torf­ remise-15037439.html

f­ormer railway station seemed ideal, especially as, after acquiring the property from Germany’s national railway company, the community wished to densify this area in the village centre and convert it to mixed residential and commercial use. The idea of revitalising an old barn fit perfectly into this objective. Because the 365-m2 footprint of the shed was so huge, the eventual design concept went beyond the original plan involving a workshop with warehouse space to incorp­ orate an inserted residence with two units, as well. Today, the old barn blends perfectly into the existing surroundings next to the old railway station and another railway service building. In contrast to the original plans, the inserted timber structure now accommodates the workshop of the basket weaver, which is separated from the living area to prevent any machine noises from causing a disturbance. The natural surroundings remained largely untouched during the implementation of the construction project, and existing trees were respected. Construction and materials The historic shed was faithfully reconstructed atop a new ground slab. All damaged parts of the existing building were repaired and manually replaced; any added building components are made of the traditional natural timber and clay ­ma­­terials. This allowed for breathable con-

struction, which together with the natural, manual airing guarantees a natural ­regulation of the indoor climate and permits the building to operate without a ventilation ­system despite its high energetic standard and airtight implementation. The new residential construction is placed inside the open, historic envelope as an ­individual, self-heated volume. It is asymmetrically offset to the old structural shell of the barn and projects out from it on the eastern side. This creates a space on the southern and western sides in which the historic timber skeleton structure of ­columns, struts and cross beams can be clearly recognised. Here, the impressive dimensions of the shed – a length of 27.50 m and a height of 4.20 m in the Ecosystem 5 Responsibility

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Note See “Renovation Strat­ egies and Concepts for Existing Buildings”, p. 98ff.

1 Original building before disassembly a foundations b historical timber structure 2 Reconstruction at new location c new foundation and ground slab d new terrain e reassembly of the historical timber structure 3 Integration of the ­low-energy house f doubling of roof U-value: 0.15 W/m2K g exterior wall U-value: 0.13 W/m2K h triple-glazed timber window U-value: 1.0 W/m2K i floor U-value: 0.1 W/m2K j hot water collector k stratified storage l wood-burning stove m area heating for heat distribution

ground floor interior rooms – can be truly experienced. In addition, the timber slat facade of the old shed provides natural structural shading as well as a lively play of light and shadow on the light-coloured lime plaster of the new construction. The outer walls of the highly insulated and heated residential volume are of breath­able timber frame construction that was infilled with wood fibre insulation and given a finishing coat of lime plaster. The ­latter is suitable for the exterior walls of the new building because of the sufficient weather protection provided by the roof overhangs and the house-within-a-house construction method. The floors are of soaped fir. Low tech Through the revitalisation of a brownfield site as well as the reuse of an old barn structure and the associated value preservation of the building substance, this project already fulfils certain critical low-tech criteria. In addition to the use of natural, resource-conserving materials, lighting and heating play important roles in the design concept. To the south and east there are large windows, as well as well-designed skylights and a long strip of glazing along the ridge. The openings are oriented to the cardinal compass points and the ­historical door openings of the barn. The new construction protrudes a little from the old barn roof, allowing the contours of old and new to be readily perceived from the

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outside there, as well. All the bathrooms lie on the outer periphery and are thus ­naturally lit and ventilated. Heat is regeneratively produced by a central wood-burning stove and a thermal solar collector. A panel heating system supplies a comfortable indoor climate. Through the conscious use of the natural building materials timber, cellulose and

clay, a highly insulated, exclusively regeneratively operated low-energy house was created. Sorption capacity and breathability of the building components ensure a naturally ­regulated indoor climate. The highest ­energetic standard and an airtight implementation are therefore possible without a ventilation system.

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Section • Floor plans Scale 1:400   1 Living and dining area   2 Bedrooms   3 Building services   4 Workshop   5 Storage   6 Air space   7 Gallery   8 Living and dining area   9 Bedrooms 10 Office

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13 Vertical section Scale 1:20 11 Tile roofing 60/40 mm roof battens 100/40 mm counter battens 60 mm breathable fibreboard 160/240 mm rafters, with 240 mm wood fibre thermal insulation between 22 mm OSB panels, joints sealed with adhesive 12.5 mm plasterboard 12 15 mm lime thin-layer coating on lime finishing plaster 60 mm fibreboard 60/240 mm solid timber frame construction, with 240 mm wood fibre insulation between 40 mm fibreboard 40 mm interior clay plaster with integrated panel heating 13 220/180 mm original timber beam 14 29 mm soaped fir floorboards 22 mm fibreboard impact sound insulation 18 mm OSB panel 220/180 mm original timber beam, with 115 mm gravel fill between, 18 mm OSB panel 50 mm fibreboard 12.5 mm plasterboard 15 Window: triple glazing in timber frame U = 1.0 W/m2K 16 50/50 mm original slats 17 150/130 mm original timber beam 18 250/20 mm original planking 19 20 mm soaped fir floorboards 60/60 mm floor sleepers, with clay panels with integrated floor heating between 35 mm OSB panel 120/60 mm elevated timber construction, with 636 mm cellulose thermal insulation between bitumen sheet waterproofing 260 mm reinforced concrete ground slab 20 200/220 mm reinforced concrete plinth

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Flarz Today Conversion of a Flarz house in Bauma, Switzerland

An intelligent overall concept ensures the successful refurbishment of a historical Flarz house in Bauma in the Zürcher Oberland (Zurich highlands). The conversion involved a lot of self-built work, very much in line with tradition, and though it runs without a technical ventilation and heating system, it nevertheless f­ ulfils very high demands of indoor quality. The resident family thinks of the centrally positioned new fireplace as the heart of the house.

Text: Steffi Lenzen

Concept The construction method of what is known as Flarz houses developed out of the clever circumvention of existing building regulations by the residents of the Zurich highlands. Formerly, less well-to-do people were not allowed to settle in the community. However, the sons of families that were already established there were permitted

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to share an existing house or to add onto it. Thus, through extension of their gable sides, single houses often gave rise to row houses. Flarz houses are usually two-storey timber plank-post constructions with somewhat flatsloped roofs, low floor heights and long bands of windows. Kitchen, fireplace and water mains connections were typically l­acking in

Sections • Floor plans Scale 1:200 1 Threshing floor 2 Kitchen and dining area 3 Living room 4 Office / work room 5 Bedroom 6 Antechamber 7 Air space

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the original buildings. Since tradesmen could build these simple constructions themselves, they were generally cost-­ effective. Working and living were often done under the same roof. The Flarz house in Bauma was built in or about 1832. It is one of the registered historical cultural buildings of the community, so the renovation had to preserve the character of the house. The architect used its orig­ inal simplicity as her design principle. The greatest challenges were the existing structural stability and fire and acoustic protection requirements with respect to the neighbouring residential units, since these were originally separated from the house by only a simple wall.

Architects: Oekofacta Saikal Zhunushova Building physics: BWS Bauphysik Historic preservation: Heinz Pantli

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Despite the modest approx. 6.75-m width of the house, the entire 11-m length of the ­interior was formerly divided into a living and a commercial area by means of a ­timber framework wall with an infill of straw and loam. This division has been mostly preserved in the renovation; the walls were merely covered with new lime plaster. In the upper storey, the room subdivisions of the floor plan largely follow these historical guidelines, while the infill on the ground floor walls was removed to allow for a more generous spatial effect. However, the offset in height and the remaining plainly visible timber columns ensure that the historical spatial composition remains apparent.

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Construction and materials The materials used were limited mainly to timber, clay and natural stone. Much of the work could be completed in DIY mode. In order to provide fire safety with respect to the neighbours, the two ­longitudinal walls were equipped with internal cellulose insulation and clad in fibrous plaster panels. Thanks to their moisture-­ regulating properties, base and finish layers of lime plaster provide for a comfortable indoor climate. The floors in the kitchen and living area of the ground floor were covered in solid ­timber boards of soaped larch wood 23 mm thick. Slate flagstones on the floor of the f­ormer work area serve as thermal

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storage mass and, particularly in winter, as passive collectors. The floors on the first floor are of 10-cm thick glued laminated timber and all the thresholds are of durable oak. Low tech The Flarz house functions without a com­ plicated technical ventilation and heating system. In order to generate a significant amount of passive solar energy, the house opens up large surfaces toward the south and allows unlimited influx of sunlight in ­winter to extract warmth from the low-lying sun. At the same time, the large roof canopy holds off the steeply inclined rays of the summer sun and protects from overheating. A large, highly efficient fireplace of natural stone occupies the centre of the floor plan. It heats the entire house on the few foggy days of the year in Bauma on which the passive solar gains are not enough. Cleverly positioned thick slate flagstones on the ground floor provide a sufficient amount of thermal storage mass. The glazing was replaced by high-efficiency insulating glass windows and some of it was slightly enlarged; all the portals and doors were glazed as well, so that enough daylight could be brought into the spaces, some of which are more than 10 m deep. In addition, the roof acquired nine flushmounted skylights so that full use could be made of daylight without changing the character of the house through the addition of dormer windows.

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Newly Interpreted Tradition Lecture Hall and Administrative Building in Landshut, Germany

The new lecture hall and administrative building for the campus expansion of Landshut University of Applied Sciences was the winning design in a two-stage open architectural competition. The red ceramic facade of the three-storey compact cuboid references the special brick architecture of some of the historical buildings in Landshut. To a large extent, the building manages without mechanical ventilation.

Text: Steffi Lenzen

Concept The university campus is located about 4 km northeast of the Landshut city centre near a reservoir of the Isar river. Because of the unexpectedly large numbers of matriculating students in the past few years, the campus is in the process of expanding. The lecture hall and adminis­

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trative building represents the entryway into the university’s campus expansion plans. The neighbouring cafeteria ­building was recently completed, so that the lecture hall/administration and ­cafeteria ensemble can now justly claim their status as the Landshut campus ­gateway.

Architects: pos architekten Client: Free State of Bavaria, Staatliches Bauamt Landshut Structural engineering: ISP Scholz Building physics: Österreichisches Institut für Bauen und Ökologie

Site map Scale 1:2,500 Sections • Floor plans Scale 1:600   1 Lecture hall and administrative building   2 Canteen   3 Library   4 Multidepartmental building   5 Foyer   6 Seminar room   7 Lecture hall 1   8 Lecture hall 2   9 Office of the ­President 10 Office 11 Office of the ­Chancellor 12 Kitchenette 13 Meeting room 14 Common area 15 Roof terrace 16 Air space

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The compact, three-storey cuboid of the lecture hall building was designed with a passive-house envelope. A foyer with a ­continuous air space connects all the ­building sections. Flexibility of use is para­ mount here. The two lecture halls on the ground floor can be separated by movable partition walls or, if needed, connected via the foyer with the five seminar rooms on the same level to form a large event space, for example for exhibitions or ­symposiums. Less public areas for offices and meeting rooms are located on the first and second storeys. The compactness of the cuboid dissolves toward the interior, where an air space across the three storeys links the various parts of the building and admits daylight. An open access concept with galleries throughout the three levels lends the traf­ ficked areas a pleasant atmosphere and invites users to linger and interact freely. On the roof of the lecture hall on the second storey there is a garden atrium. Thanks to the clever positioning of air and light shafts, the atrium not only provides the upper offices with daylight, but ensures that all the rooms and hallways all the way down to the ground floor receive natural lighting even in winter. Construction and materials The building is designed as a classic re­­ inforced concrete construction with a partial basement. In reference to the historical Landshut brick architecture, the facade

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Horizontal section • Vertical section Scale 1:20 1 Photovoltaic panel 2 60 mm pebbles, protective fleece, PE waterproofing membrane; 340 mm avg. thickness sloped EPS thermal insulation vapour barrier; 300 mm reinforced concrete slab; 2 mm gypsum primer 3 Adjustable sun protection louvres 4 Window: Triple insulating glazing in a timber / aluminium frame, U = 0.9 W/m2K 5 40 mm ridged ceramic facade element 20/60 mm ¡ aluminium subconstruction 80 mm rear ventilation vapour-permeable housewrap 200 mm rock wool thermal insulation 220 mm reinforced concrete 102 mm installation level

comprises a skin of ceramic elements. These can be easily detached at the end of their service life and are completely ­recyclable. Individual building components, such as an external staircase tower and the con­ necting bridge to another building on the first storey, are of steel and can also be separated by type and recycled. Since the building site is located near the River Isar in a flood channel, the construction ground was improved with vibro replacement col­ umns. This procedure made it possible to lay foundations without excavating the soil.

Note The source of some of the information beyond that provided by the architecture firm is the IBO (Austrian Institute for Building Biology and Ecology GmbH) Proceedings of the Wiener Kongress für zukunftsfähiges Bauen (Future of ­Building Congress in Vienna) 2015

Low tech The design calls for a compact volume with a facade that meets the passive-house standard. Thanks to an intelligent overall concept, the building runs mostly without mechanical ventilation or cooling. High rooms, large storage mass and external sun protection prevent overheating in ­summer. The three-storey entrance foyer, together with the roof garden carved out of the ­second storey, plays a central role in the cooling of the building and functions as a type of ventilation chimney for the ­adjacent spaces. The targeted positioning of the openings, the external sun protection and the storm­ proof and burglar-proof ventilation and shad­ ing options provided by the office windows and in the foyer keep the heat outside and make cooling and mechanical ventilation obsolete. Large glazed sections of the

15/15 mm fi galvanised steel sheet ­subconstruction; 12.5 mm plasterboard   6 25 mm parquet floor, 60 mm heating / cooling screed; separating layer, 25 mm impact sound insulation; 45 mm cement-bonded insulating fill 300 mm reinforced concrete slab 2 mm gypsum primer   7 Aluminium post-and-beam facade with triple insulating glazing   8 70 mm insulated aluminium panel suspended porch ceiling   9 35 mm polished mastic asphalt 90 mm heating / cooling screed; 25 mm impact sound insulation, vapour barrier 160 mm thermal insulation 40 mm cement-bonded insulating fill 300 mm reinforced concrete slab 10 30/10 mm stainless steel grate in a stainless steel trough

facade near the entrance are recessed in accordance with the concept of structural sun protection and are thus shaded by the storey above. Because of their intermittently high occupancy densities, the two lecture halls and the seminar rooms on the ground floor are the only spaces equipped with mechanical intake and exhaust ventilation with high-efficiency heat recovery and adia­ batic cooling. A part of the energy demand of the building is covered by its own roofmounted photovoltaic array. With regard to primary energy consumption, even a plusenergy standard is achievable if the entire roof ­surface is covered with photovoltaics.

Ecosystem 5 Responsibility

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Resources

3 2 1 Recyclability

Robustness

Simplicity

Health Sufficiency

Lecture Hall and Administrative Building in Landshut (DE)

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Neutral Spaces for the Community Community Centre in London, United Kingdom

The new community centre blends into its historical surroundings in London’s South Park in a completely harmonious way. The land was once occupied by the largest family-owned plant nursery in Europe. Inspired by the style of the former greenhouses, the building ensemble follows a simple cubature. In its materiality it references the Victorian brick wall that encloses the park and simultaneously distinguishes itself in a subordinated manner from the preserved old lodge, which forms the centrepiece of the new complex.

Text: Steffi Lenzen

Concept For a long time, the old park lodge in the north-west corner of South Park in the ­London Borough of Hammersmith and ­Fulham stood vacant, because it has been many decades since the 8-hectare green space has had a keeper. The park has a long history. Before it was opened in its ­current form as a public recreational space in 1903, the entirety of the estate had served as a garden nursery and for fruit ­cultivation since the middle of the 19th ­century. The unpretentious architecture of the current community centre references the greenhouses that existed there previously. The long building blocks with

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Resources

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Robustness

Simplicity

Health Sufficiency

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their flush-mounted shed roofs are grouped in a loose arrangement around the restored old lodge behind the still-standing brick boundary wall of the park. The ambitious requirement put forward by the city council was to create a community facility that would promote social integration within the community. In addition to a café, the new buildings accommodate functionally neutral spaces for social and educational exhibitions, ­ceremonies and events as well as appro­ priate sanitary facilities. The old building was gutted, so that even this part of the ensemble can be used flexibly. A large, lockable steel gate in the old park wall provides access to the grounds, where visitors are automatically directed into the lobby that forms the corner connection between the two building wings. The intelligent way in which the buildings are pos­ itioned on the grounds results in a logical sequence of courtyards, squares and rooms that interweave structures and landscape tightly with one another. Construction and materials The individual long building volumes are designed as frame constructions of cross laminated timber with steep shed roofs that open up toward the street and facades that are clad in light, cream-coloured bricks. These bricks were developed especially for this project by a Dutch company. They are a recycled product and consist of ground mineral demolition waste and clay. In order

Architects: Mae Architects Client: London Borough of Hammersmith and Fulham Council Structural engineering: Elliot Wood Building services: Max Fordham Landscape architects: J & L Gibbons

Site plan Scale 1:2,500

Community Centre in London (GB)

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Sections • Floor plan Scale 1:500

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  1 Lobby   2 Café   3 Kitchen   4 Function room   5 Storage   6 Kitchenette   7 Utilities   8 Changing room   9 Common room 10 Small multipurpose room 11 Large multipurpose room 12 Cloakroom 13 Old building

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b foundations to a minimum, to reduce the the lightweight timber structure was 7 designed in collaboration with structural 7 8 engineers to be as efficient as possible. The ground slab is therefore only 175 mm thick. Of great importance during the entire design and execution process was the ease of deconstruction and reuse at the end of the building’s service life. For this reason, detachable plug-in and screw connections were almost always used. The large window bands facing the street run the entire length of the rooms and are of post-and-beam construction. The windows reach from the middle of the facade up under the roof ridge, and

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on the northwest side are equipped at their tops with fanlights that can be opened. 8 Their parapet height lies considerably above the Victorian border walls and, from the outside, is reminiscent of the eye of a periscope. Not only does this elevated positioning of the window bands make the community centre recognisable from afar despite the surrounding wall, but it also guarantees an influx of natural daylight into the rooms beyond. Timber determines the materiality of the interior. While the beams and panels of the cross laminated timber roof construction remain in their untreated state, green-stained walls and sliding doors and dark window frames provide colourful accents.

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Low tech The building ensemble has highly insulated facades and double insulating glazing and was designed according to passive-house principles. Accordingly, a single boiler suffices for the full-scale operation of the floor heating system. More than 35 % of the building materials are recycled – above all the cream-coloured facade bricks. Since the manufacture of these bricks is very expensive, they were laid on edge to conserve material. The high-ceilinged rooms encourage good air circulation. In addition, the clever arrangement of the windows allows

for natural cross-ventilation; fresh air is admitted via the lower facades on the ­courtyard side through the ground-level ­windows there, while exhaust air is vented through the ­opening fanlights in the streetfacing ­window bands. These fanlights are mechanically operated and ensure passive natural ventilation. In summer, they can be opened completely to facilitate nighttime cooling. The facades to the west are equipped with exterior sun protection louvres of Douglas fir. Optimised use of ­daylight was one of the principal goals of the design. 1

Vertical sections Scale 1:20 1 992/1650/35 mm photovoltaic system 50 mm aluminium subconstruction 6 mm fibre cement corrugated roofing panel, attached with self-drilling screws with sealing washer, 40/65 mm battens 40/40 mm counter battens breathable underlay 150 mm wood fibre thermal insulation vapour-proofing, 100 mm spruce glulam 30 mm subconstruction/rear ventilation acoustic ceiling element of 18 mm mineral wool insulation and 25 mm fibreboard 2 210/100/65 mm recycled brick masonry, secured with masonry anchors 75 mm rear ventilation 2≈ 100 mm rock wool thermal insulation breathable membrane, 100 mm spruce glulam

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  3 335/245 mm cement block lintel element   4 Sprung floor construction: 22 mm timber floorboards 48/45 mm battens, 15 mm elastic pad 85 mm screed with integrated floor heating 2≈ 100 mm rigid foam thermal insulation with aluminium facing on both sides waterproofing membrane 200 mm reinforced concrete ground slab   5 Drainage gutter   6 22/210 mm Douglas fir sheathing 55/55 mm battens breathable underlay 35 mm particleboard 150 mm wood fibre insulation 160/320 mm spruce glued laminated timber beam   7 50/280 mm Douglas fir louvre   8 Window: Double-glazing in an aluminium frame   9 1.5 mm waterproofing membrane 150 mm wood fibre thermal insulation vapour barrier, 12 mm particleboard 50/90 mm tapered battens on 50/38 mm battens 100 mm spruce cross laminated timber 10 160 mm spruce cross laminated timber wall ­panel 11 2.5 mm linoleum flooring 85 mm screed 285 mm rigid foam thermal insulation with ­aluminium facing on both sides waterproofing membrane 200 mm reinforced concrete

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Community Centre in London (GB)

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Strategies

Planning and Design Strategies  180   Urban and space planning – Low tech begins with building site designation180   Low-tech parameters and design criteria182   Low tech in calls for tender and implementation 190   Regenerative design strategies for a climate-positive future  190

Administrative building, Vienna City Administration (MA31), Vienna (AT) 2016, ­Rataplan Architektur

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Planning and Design Strategies Edeltraud Haselsteiner

Urban and space planning – Low tech begins with building site designation Making low-tech designs possible in construction starts with the designation of the building site. Spatial planning also means energy planning. There are pioneering ­projects that illustrate this in Switzerland, for example. There, energy (structure) plans ensure that a spatial infrastructural analysis is already available. Detailed options for individual city districts or communities are gathered for, among other things, locally available renewable energybased heating options (e.g. from potential sources such as waste heat, geothermal heat, solar energy and biomass) and used to ­create guidelines for the development. Such energy (structure) plans are useful for identifying potential and efficient utili­ sation of environmental resources for lowtech buildings. For low-tech buildings, respect for the ­location, the natural environmental context including micro-climatic impact (and ­therefore the optimisation potential for the entire range of building supply and waste disposal factors that can be derived from it) are considered prerequisites. Without a ­precise analysis of the site and the local environmental resources, a low-tech building concept is unthinkable. In the trad­ itional design process, however, both ­instrumental methodologies and financial means for this analysis are lacking. Climatic environmental conditions and their inter­ actions with finished or planned structures

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can currently be recreated and simulated quite realistically using software models, but because of cost considerations, these are rarely used. Of course, low-tech concepts go far beyond the consideration of climatic con­ ditions. Local resources, which include not only materials available nearby but also local knowledge and skills, can only be effect­ively used in close coordination processes with people and analyses at the site. Short transport routes and buildings that are laid out and built in accordance with local building traditions and thus with local resources and local expertise are distinguishing features of sustainable construction that are especially relevant to low-tech design. Solar architecture stands out clearly as the most energy-saving and sustainable construction method [1]. The direct utilisation of solar influx via transparent building elements and the storage of ambient heat in the walls and floors of the interior for later use in warming spaces are some of the pioneering achievements of energy-­ saving architecture. Examples show that well-functioning solar architecture can ­provide sufficient indoor comfort throughout the entire year even in the absence of a conventional heating system [2]. The only prerequisites are a location and a building site designation that allow for this optimised construction method, though a clever de­­ sign makes this option available even in densely built-up urban areas. Examples of

1 a–b Residential building, Kolding (DK) 1998, 3XNielsen

2 a–b Ideas for a honeycomb house to minimise area use, Axel Stelter, Hannover (DE) 1974

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high-density residential developments that link area-conserving construction with ­best-possible utilisation of solar energy demonstrate that both can be realised in combination (Fig. 1). In contrast, single-family houses not only occupy a lot of area in themselves, but they also occasion the need for disproportionately large associated infrastructures such as roads and various municipal ­supply and waste connections, and con­ sequently cause additional sealing of the soil. Different ideas were developed to gain greater acceptance for high-density housing without having to forgo the ­qualities of a ­single-family house. In 1974, Axel Stelter first described his reflections on a construction system of honeycomb ­elements (Fig. 2). Using a model, he ­demonstrated the possibilities of stacked series-produced concrete room modules. During assembly, these are connected with steel screws and waterproofed. In their fully-constructed state and with a ­separate entry for every individual unit,

they were meant to convey to the residents the feeling of living in their “own house”. The architect Peter Haimerl has now d ­ eveloped a similar concept of a ­honeycomb structure, with the goal of ­offering an alternative to the single-family house that provides greater residential ­quality than conventional multi-storey buildings. The building comprises individual ­honeycombs, several of which can also be combined to form larger clusters for communal use. Because of the unusual shapes of these spaces, suitable furniture for them is fabricated with 3D printers. The project was finished in Munich in 2022. As a pure concrete building, it is more properly categorised as high-tech architecture, but work is being done to develop a version made of recycled materials. Aside from the limitations like the reduction of space or the need to make one’s own furniture, the idea of developing attractive multi-storey residential models to make experimental or alternative housing options available should nevertheless be seen as positive.

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Planning and Design Strategies

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All further building proliferation in the form of single-family residential developments stands in direct contradiction to the lowtech goal of not only minimising the sealing of the soil, but of bringing about a regenerative balance in the ecosystem with every construction measure. For these reasons, the activation and use of existing buildings takes on extra importance and urgency. Many rural communities are struggling with vacant buildings in the village or town centres. Commercial, residential and production floor areas in central downtown locations lie derelict, while ground is being earmarked for new construction in the surrounding countryside. Worries about difficult and expensive renovations of old buildings as well as the high demands of contemporary construction standards – in addition to the already complex ownership structures – often complicate the development of ­existing building resources even more. ­Self-build initiatives and engaged groups that make simple adaptations for their own needs and renovate spaces cheaply with innovative ideas and with modest ­comfort requirements would represent a low-threshold alternative for putting usage of at least a temporary nature into practice (Fig. 3). In urban areas it is the ground floors in particular in which low-tech refurbishment and conversion concepts can be implemented to revitalise city or village centres and strategically counteract vacancies and urban sprawl. Low-tech parameters and design criteria “How little is enough?” This question was the central theme in a preparatory study for the expansion of the Federal Ministry of the Environment in Berlin. Elisabeth Endres, architect and teacher of passive strategies at the intersection of architecture and technological systems, developed decisionmaking documentation and parameters in the run-up to an architecture competition for the design of a “building with few components that runs with as little control technology as possible” [3]. The specifications apply to the building envelope as well as to the building services concept. The

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facade is to comprise the appropriate materials and the window area and orien­ tation is to be chosen so as to minimise the danger of overheating. Automated and motor-driven sun protection is to be avoided. Area heating and cooling is to be controlled in a manner separate from the structure and, where possible, throughout the year and independent of outdoor temperatures and users. Ventilation is to be natural, except in spaces with high ­occupancy density, specifically the assembly hall and conference room. Construction of the winning entry by the architecture firm C. F. Møller is still underway. The design calls for a multistorey timber building with solar panels integrated into the facade, glazed atria, roof gardens and a branching building structure embedded in green spaces (Fig. 4). An even more rigorous implementation of the theme “How little is enough?” is the ­conversion of an industrial building in the small town of Apolda in Thuringia that Egon Eiermann had expanded in the 1930s (Fig. 3). From the beginning of the 18th ­century until German Reunification, Apolda was considered an important industrial ­centre. Today, most of these production

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3 a–b Egon Eiermann Building, Apolda (DE) 1939/2018, IBA ­Thüringen (Project management: Katja Fischer)

4 Design sketches for the building expansion of the Federal Ministry of the Environment, Nature Conservation and Nuclear Safety (BMU), Berlin (DE), under construction, C.F. Møller

halls stand empty. For occupancy and usage, an unusually simple room-within-aroom concept was realised in coordination with the IBA (Internationale Bauausstellung (International Building Exhibition)) of Thuringia. Small greenhouses and “boxes” that can be individually heated as needed via infrared lamps were placed into the enormous hall. In the main space, radiator panels on the ceiling generate air temperatures of at least 15 °C. The boxes can be self-built. They are not only an inexpensive upgrade variant but are also easy to dis­ assemble and reuse. A parameter study addressing the question of whether and how an energy-efficient optimisation of office buildings can be implemented with passive measures ­(thermal mass, high insulation standards, reduced proportional window area, optimised and controlled natural ventilation) but with no active heating, cooling and ­ventilation systems and with no loss in ­comfort, yields interesting conclusions regarding “robustness”: If no technological components are employed in the building services and facades, then according to the currently valid standards the usual indoor comfort levels cannot be ensured continuously throughout the entire year. Nevertheless, the use of simple technologies and single elements (e.g. external sun protection, mechanical ventilation, building component activation) shows ­considerable potential for optimisation. An important finding is also that, given the current state of development of the building envelope, the winter climate has

4

taken on a subordinated role, while protection from summer heat, which can be influenced by design and passive measures, has become much more important [4]. The building’s orientation and the type of glazing are the parameters with the greatest impact on heat protection in summer, followed by the thermal mass and, only in fourth place, the total area of the windows. However, in terms of energy requirements, the window area and the building’s orientation lead the remaining parameters by a wide margin [5]. Elisabeth Endres takes stock of what her research has revealed about “How little is enough?”: “The simplification of the ­technical equipment of buildings, a con­ version to an effective distribution of ­regeneratively produced electricity in local grids during construction, operation and deconstruction, changes in the per capita-based reference value of area for a population, and the considerations of entire material cycles all require fundamental changes in directives, standards and laws. Intensifying individual approaches will not be enough. The task over the next years is rather to achieve a radical societal change in thinking, to completely reassess customary principles and to simplify the existing state of standards and laws. L^ast but not least, with regard to standardisation and legislation, the key to taking a holistic view and thus successfully adapting and designing structures that meet the requirements of tomorrow’s society lies in the answer to the question “How little is enough?”. [6]

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Parameters for robust architecture and low-tech design An analysis of built examples shows that many of the solutions for a reduced use of technology do not have to be researched from scratch; often, it is enough to look back to the early years of energy-saving construction, before ­climate engineering and climate design and technological approaches to building efficiency became widespread (see “Robust Building Design”, p. 72ff.). ­However, experiential knowledge about passive strategies for indoor climate regu­ lation comes especially from traditional or indigenous building methods. One study that employs a literature review to track the contributions of autochthonous structures to climate-adapted building comes to the conclusion that the structures provide valuable and emulation-worthy experience not only through “a conservative approach to resources”, but also “through [their] ­sensible incorporation into the geograph­ ical and topographical context” [7]. The work-up and scientific analysis of this is as yet underrepresented and consequently incomplete especially in the German-­ speaking world. What can be clearly observed in the his­ torical development, however, is a recurring intensive examination of the topic of ­climate-adapted construction. In early ­discussions about “light, air and sun” and forms of “new construction” in the 1920s, architect Alexander Klein grappled with the question of how to make good ­sunshine, lighting and ventilation possible in residential buildings. He argued in favour of building types that would take into account not only economic considerations but also indoor climate requirements. If the results of his numerous insolation and ventilation analyses, as well as his ­suggestions for passive indoor climate ­regulation, were modernised through contemporary building simulation methods and up-to-date ­climate data, they would constitute an ­exciting foundation for lowtech design. Using examples, for instance, he explained how a three-storey residential building in the form of north-south oriented

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row housing would have to be constructed in various ­climate zones in order to respond optimally to the associated climatic conditions (Fig. 5). With this, Klein also demonstrates that a good facade design must be developed not only on the basis of stylistic considerations, but also in line with climatic requirements. [8] An important criterion for a successful lowtech design is “integrative planning”. In the design phase, basic decisions are made concerning the building form, orientation, floor plan typology and openings, and these are then used to determine efficient resource and energy-optimisation factors. However, this sequence creates conflicts within the building-technology step of the process, which in the usual design scheme occurs only after the architectural plans are in place. At this stage, building services or energy experts can only make reactive “building technological” adjustments to optimise the existing design, but they are not actively involved in designing the overall energetic concept. In this respect, too, lowtech design requires a change in approach during the early design phase toward integral and interdisciplinary planning. Figure 6 lists the various potential of robust architecture and low-tech design and refers readers to the appropriate chapters in this book. Floor plan

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Sketches by Alexander Klein of a residential building and climatespecific passive adaptations (floor plan and facade design, size of openings, room height) to produce an agreeable indoor climate. The different locations are: a Haifa b Tel Aviv c Berlin d Oslo

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6 Potentials for robust architecture and lowtech design Design indicators

Low-tech criteria (see matrix p. 30f.)

Robust design / low tech (examples)

Location and form

ECOSYSTEM — climate, regener­ ation, resilience RESOURCES — form, energy, recycling systems SUFFICIENCY — minimisation of requirements, area consumption, intensity of use RESPONSIBILITY — adaptation to ­climate change, (building) culture, equity

• Geometry of the structure (see “Climate- and location-optimised ­building form”, p. 40f.) • Orientation to allow for best use of natural environmental resources (see “Sun houses”, p. 58ff.) • Building form to utilise microclimatic conditions (see “Natural ventilation”, p. 61ff.) • Arrangement and orientation in alignment with the natural environment (see “Vegetation, greening and cooling”, p. 65ff.; “Nature-based ­Solutions”, p. 48ff.) • Limited sealing of the soil (see “Repurposing and redensification”, p. 96f.; “Renovation Strategies and Concepts for Existing Buildings”, p. 98ff.) • Avoidance of embodied energy through minimised excavation

Building envelope

ROBUSTNESS — life cycle costs, homogeneity, quality

• Storage-capable (thermal) mass (see “Building with mass”, p. 81ff.; ­“Climate and location-optimised building form”, p. 40f.; “Ground plan and temperature zoning”, p. 42f.) • Sun protection, structural design strategies (see “Climate-sensitive ­Construction”, p. 52ff.; “Simple construction”, p. 43f.; “Vegetation, ­greening and cooling”, p. 65ff.) •  Solar heat gains (see “Sun houses”, p. 58ff.) •  Daylight (see “Daylight”, p. 64f.)

Construction

ROBUSTNESS — life cycle costs, homogeneity, quality RECYCLABILITY — flexibility of use, deconstruction, documentation

• Robust and recyclable structure (see “Recyclable and versatile con­ struction”, p. 46f.; “Traditional building methods, craftsmanship and historic preservation”, p. 92ff.; “Low-tech ­components for building ­optimisation”, p. 94ff.) • Construction details (see “Simple construction”, p. 43f.; “User-optimised design, self-building and adaptably sized houses”, p. 44ff.) • Passive design and construction strategies (see “Low-tech Focus: Design, Concept, System”, p. 38ff.; “Vegetation, greening and ­cooling”, p. 65ff.)

Floor plan

SUFFICIENCY — minimisation of requirements, area consumption, intensity of use

• zZning for use based on temperature requirements (see “Ground plan and temperature zoning”, p. 42f.) • Multiple use and flexibility of use (see “User-optimised design, self-­ building and adaptably sized houses”, p. 44ff.; “Recyclable and ­versatile construction”, p. 46f.; “Repurposing and redensification”, p. 96f.)

Materials

ROBUSTNESS — life cycle costs, homogeneity, quality HEALTH — natural commodities, materials, relationship between humans and nature

• Untreated materials, material properties, etc. (see “Low-tech Focus: Materials”, p. 78ff.) • Local materials, avoidance of embodied energy and transport (see “Low-tech Focus: Materials”, p. 78ff.)

System

ECOSYSTEM — climate, • Simple active principles and sufficient dimensioning of systems ­regeneration, resilience (see “Building Technology”, p. 56ff.; “Simple construction”, p. 43f.; RESOURCES — form, energy, “Eco tech, low tech, high tech”, p. 10ff.; “Sufficient Energy Design”, ­recycling systems p. 68ff.; “Robust Building Design", p. 72ff.; “Climate-sensitive SIMPLICITY — functionality, ­Construction”, p. 52ff.) ­maintenance, servicing • Use of environmental conditions and material properties for efficient LOOP-COMPATIBILITY — flexibility of ­operation (see “Recyclable and versatile construction”, p. 46f.; “Sun use, deconstruction, documentation houses”, p. 58ff., “Natural ventilation”, p. 61ff.; “Vegetation, greening and cooling”, p. 65ff.; “Low-tech Focus: Materials”, p. 78ff.) 6

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Elements of passive indoor climate ­regulation Low-tech design relies on the direct use of environmental potential and therefore on passive climate regulation whenever possible. For this to succeed, basic design factors must be considered. Location and building form Depending on the particular climate region it is planned for, the building concept is subject to a very varied set of requirements. While design strategies in the ­central European continental climate zone are characterised by protection from the cold during the winter months, buildings in Mediterranean climate zones are oriented toward keeping out the heat and providing sufficient ventilation in summer. At the micro-climatic level, altitude, wind exposure, frequency of fog, availability of ­sunshine and topography all impact the energetic behaviour of a building [9]. The choice of location already lays out ­fundamental decision paths for the energetic concept. A climate-sensitive plan for the building form does a great deal toward optimising the energy demand (see “Climate-sensitive Construction”, p. 52ff.). Solar radiation for passive energy and heat gains; wind conditions as a basis for a natural ventilation concept, including their interactions with the surrounding ­vegetation; green and open spaces and bodies of water as elements of natural ­cooling and humidity – these are environmentally efficient potential approaches to passive air conditioning. Low-tech design is characterised by nature and bio-based loops in the supply and waste removal for buildings. At the same time, an important sustainability goal is the use of regenerative measures as a counterweight for constructive interventions and as a contribution to the improvement of the ecosystem. The increased value placed on the relationship between humans and nature and the creation of opportunities to experience nature in its pristine state are also part of the environmental approach of low-tech design.

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Building envelope Minimising the building surface by means of a compact building form can significantly improve energy efficiency. The more surface area a building has, the greater the possible thermal transmission losses. Structures with modest building depth admit more daylight and facilitate natural ventilation. The building envelope is a substantial means of energy storage (thermal mass) on the one hand, and provides area for heat and energy generation (transparent surfaces) on the other. Hence, individual facades should be designed differently depending on conditions at their location and on their orientation. Passive temperature control measures to gain or save energy, such as transparent building components, structural sun protection and natural ventilation and shading, are essential ingredients of a robust building design. The organisation, proportional arrangement and orientation of the storage mass, the window surfaces and other transparent areas regulate the heat gain and protect from overheating. The variation in the incident angles of solar rays between the summer and winter half years at central European latitudes make structural sun protection easy to implement. As the different examples in Part B – Analysis (see p. 37ff.) show, however, even simple measures such as curtains are sufficient if the design has already taken the risks of overheating into account. Construction The array of solid building components for heat storage and transparent surfaces for passive solar energy gains are chosen based on location and determine the basic structure of a building designed along low-tech principles. Depending on the type of construction – solid, lightweight or hybrid – the thermal reservoir function can be performed by interior and exterior walls, floors or ceilings. In order to improve the efficacy of a ceiling surface as a storage mass and to extend its function to include passive conditioning, the absorptive area can be increased by the addition of formed cavities, such as ribbed or honeycombed constructions

(Fig. 5 b, p. 82). Since warm air rises, the height of the rooms also influences the heat flow. In tropical and subtropical climate zones, high-ceilinged rooms are useful for moving hot air upward. In climates with greater heating needs, the opposite applies, namely, the danger of heat losses due to tall rooms must be considered [10]. Structural building details and the quality of their implementation determine the robustness of a building in many ways, but also dictate the possibility of a separation by type and of reuse of individual parts if deconstruction should prove necessary. A conservative approach to resources also encourages the appropriate rather than overdimensioning of structures. Floor plan Along with the facade, the floor plan and its functional internal partitioning play an important part in passive climate design. Floor plan zoning according to daily and seasonal fluctuations allows for a slender or even partially eliminated building services design or one that is restricted to heating with a manually operated heat source. In addition, all rooms should be provided with natural lighting and ventilation capabilities. Depending on the type of use, different lighting, heating and daylight requirements predominate. The delineation of core and buffer zones and rooms that are used to suit the seasons allow for varying temperature levels according to need. The incorporation of atria makes it possible for natural daylight to reach even low-level building areas and for natural ventilation concepts to be implemented. A need-adapted floor plan can be intensified through flexible design or overlaps in usage. Their adaptability allows flex­ ible floor plans to be used over the course of generations.

7 (on p. 188/189) Functional principles for using low-tech design strategies

Material Selecting materials on the basis of their life cycle costs simultaneously takes into account their embodied energy. Viewed over their life cycles, natural regionally sourced materials such as timber, clay or plant fibres require significantly smaller quantities of energy [11]. Avoiding long transport routes by preferentially choosing

regionally available materials, reusing existing b ­ uilding substance and recycled materials and employing robust and long-lasting materials raises the ecological added value. In addition, positive material properties and their beneficial impact on the indoor climate, such as the hygroscopic characteristics of clay, become effective only via an untreated n ­ atural surface. ­Further considerations are as homoge­neous, resource-conserving and contaminant-free a choice of materials as possible, sepa­ rable material connections and material ­quantities that are reduced to what is necessary. System The primary goal with regard to the requirements of a building-technological system can best be characterised as simplicity. In a building designed along low-tech principles that has been given a location-adapted building form and furnished with passive measures to regulate the indoor climate, building-technological equipment will ­usually have been reduced to a minimum, perhaps to provide electricity and water. Added to this is the requirement that operation, maintenance and upkeep be simple and user-friendly. This requirement is supported by running cables in as open and accessible a manner as possible, as well as by installing standard components that can be replaced easily without the need for specialists. Another essential characteristic of a rigorous low-tech design is control left in the hands of the users – whether it be through opening windows for ventilation or operating individual stoves for additional heating in the colder seasons.

Building components and environ­ mental potentials for low-tech design strategies In the analysis presented thus far, many building components were identified that provide support for a low-tech design ­concept (see “Analysis”, p. 37ff.). Without claim to completeness, Fig. 7 (p. 188f.) lists a summary of the most important components and provides diagrams illustrating their functional principles.

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Building components and potentials

Functional principle

HEAT GAINS •  internal heat gains

people, lights, appliances

•  passive solar heat gains

direct solar influx

sun-activated components

activated building components

time-delayed radiation of heat collector facade (Trombe wall, air collector, window panel collector)

solar chimney

winter

summer

solar buffer spaces / conservatories

HEAT STORAGE (building components with high thermal storage capacity / thermal mass) • solid building components (walls, ceilings, floors) • surface coatings • increased surface area

activated building components

time-delayed radiation of heat COOLING •  evaporative cooling

surrounding vegetation

•  greening of the facade, interior, roof • greened roofs or floors

water surfaces, fountains or water sprayers

188

•  night-time cooling

temperature differences in connection with storage mass

day

night

natural cross-ventilation

south

north

thermal effects (atria, chimney effect)

wind towers

(mechanically / manually operable) ventilation flaps (e.g. top-hung windows)

SUN PROTECTION

vegetation

structural sun / weather protection vertical (horizontal)

pergolas

movable sun protection elements: Venetian blinds, awnings, shutters, curtains, roller blinds, etc.

HUMIDITY

•  hygroscopic materials • water surfaces • plantings

LIGHTING / DAYLIGHT

• floor plan design optimised for ­daylight • window areas • atria 7

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8

Low tech in calls for tender and imple­ mentation The comparison between low-tech criteria and the categories evaluated in sustain­ ability certificates also shows up which points as yet garner little attention in the practice of design (see “Assessments”, p. 107ff.). If a low-tech construction method is definitely desired, it is important to appropriately detail these points in the call for ­tender and to consider them when evalu­ ating the offers. The low-tech matrix (see p. 30f.) can serve as a basis for decisionmaking in order to refine the targets and set appropriate priorities. Also, overarching goals can be defined and concrete proposals and ideas for solutions can be demanded as to how those goals can be achieved, among other things, with a minimum use of technology. A simplified specification profile reduced to its critical points should nevertheless take into account the most important environmental, economic, social and participative criteria. The most significant points include: • a location-based environmental and resource-conserving design approach optimised for its interaction with its surroundings (local resources, life cycle costs, minimisation of embodied energy, etc.) • reduced overall concept oriented toward necessary requirements (designs, materials, area use, thermal comfort, etc.) • simple, preferably robust functions based

190

8 Though the facades are mostly glazed, their timber brise-soleil is evocative of the pre­ vious building. Con­ version of a barn into a library, Kressbronn (DE) 2018, Steimle Architekten

on passive components, renewable energies and natural recycling systems and operated mainly by hand (heating, cooling, ventilation, daylight) • high quality standards in all building ­components and technologies in terms of robustness, longevity and reusability • responsible selection and integration of materials and resources designed for ­recyclability, health and long service life (untreated natural materials, material properties, etc.) • a participative guiding principle based on personal and/or social responsibility and regenerative sustainability goals In its demand for simplicity, low-tech design occasionally stands in opposition to recognised rules of technology, standards or directives. This issue should be carefully examined in advance, and possible mutually exclusive formulations in the introductory remarks of the tender documents should be reconciled [12]. The better the collaboration and the communication among the individual building trades – or with the future users – is during the design and construction phases, the greater the probability that the implementation of the low-tech design goals meets with practical success. Regenerative design strategies for a ­climate-positive future In a report issued in 1987, the World Commission on Environment and Development,

9 Renovation of a multifamily residence, Casa di Luce, Bisceglie (IT) 2016, Pedone Working Studio. Solar greenhouses and the kinked geometry of the facade facilitate the influx of sunlight and simultaneously prevent overheating in summer. The innovative use of hempcrete and tufa for the outer and partition walls supports an optimised indoor climate.

Notes   [1]  Sölkner et al. 2014  [2]  Rüdi, Watter, Schürch 2016  [3] Endres 2020  [4] Endres 2019  [5]  Endres 2017, p. 60   [6]  see note 3, p. 80  [7]  Krause, Leistner, Mehra 2020, p. 184 –195   [8]  Oswalt 1994, p. 55  [9] ibid. [10] ibid. [11] Erber, RoßkopfNachbaur 2021 [12] ibid. [13]  Brown et al. 2018

9

also called the Brundtland Commission, ­formulated the definition of sustainable development that is still broadly recognised today: Sustainable development “meets the needs of the current generation without endangering the chances of future generations to satisfy their own needs and choose their own way of life.” In reality, our economic development and our construction industry in particular are only inad­ equately geared toward a long-term regeneration of a functioning ecosystem. With its 40 % share of energy and water consumption and carbon dioxide and waste gener­ ation, the building sector is a significant ­contributor to climate change. Despite the fact that binding climate protection goals have been agreed upon and repeated assurances have been made that harmful impact on the climate will be minimised, actual advances have been extremely ­modest. Therefore, a paradigm shift in construction also requires a more comprehensive sustainability approach that focusses less on the “energy performance” of a building and instead actively contributes to the regeneration and improvement of the en­­ vironment. The goals of such restorative and regenerative sustainability are defined here: “Restorative sustainability” aims to regenerate a socially and environmentally balanced and healthy ecosystem. In ­practice, this means using the capabilities of the built environment to positively influence health, well-being and quality of life.

An important c ­ ornerstone of the approach is to strengthen the connection between humans and nature. “Regenerative sustain­ ability” broadens this requirement so that the regenerative design process not only allows for the preservation of balanced ­ecosystems, but an improvement occurs for both the biotic (living) and abiotic (chemical) components of the environment. Regenerative buildings result from holistic thinking that considers the built physical as well as the natural environment, encompassing location, water, materials, energy, plants, microbes, humans and culture [13]. Many of the examples presented in this book show that low-tech design follows a “regenerative” design approach much more closely than does conventional energy-­ efficient architecture. It also incorporates the idea that construction should be decoupled from growth and efficiency paradigms and oriented toward a circular economy that fosters strong engagement at the local level. Many of the prerequisites for a climate-­ positive tomorrow are created by using places, people, ecology and culture as a design basis; by prioritising human actions, health and sense of responsibility toward future generations; and by setting the goal to exist harmoniously with the local economic and natural ecosystems.

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Image Credits The editor, authors and publisher would like to extend their sincere thanks to ­everyone who assisted in the production of this book by providing images, granting permission to reproduce their work and supplying other information. All of the drawings in this book were custom-­created by the publisher. Despite intensive efforts, we have been un­able to i­dentify the copyright holders of some images. However, their claim to the copyright remains unaffected. We ask to be informed of such claims.

A. INTRODUCTION p. 6  Philippe Samyn + Partners Low Tech — Utopia or Realistic Option? 1 from: Rüedi, Andrea; Schürch, Peter; Watter, Jörg: Solararchitektur – Häuser mit solarem Direktgewinn. Zurich 2016, p. 23; www.faktor.ch/fachbuchreihe 2 a Susanne Völlm 2 b Susanne Völlm 3 a from Detail 6/1992, p. 579 3 b from Detail 6/1992, p. 580 4 a Matti Östilling / Lindman photography 4 b Åke E:son  Lindman / Lindman photo­ graphy 4 c Åke E:son  Lindman / Lindman photo­ graphy 5 a home4students / Barbara Mair 5 b Daniel Hawelka Fotografie 6 proprietary illustration based on Luo, Maohui et al.: The dynamics of thermal comfort expectations: The problem, challenge and implication. In: Building and Environment. Vol. 95, 2016, p. 322–329 doi:10.1016/j.buildenv.2015.07.015 7 a agsn 7 b agsn 8 proprietary illustration based on Schnitzer, Ulrich; Meckes, Franz (eds.): Schwarzwaldhäuser von gestern für die Landwirtschaft von morgen. Workbook of the Landesdenkmalamt Baden-­ Württemberg. Stuttgart 1989 The Sustainable Low-tech Building 1 a Artan HOXHA 1 b Valdrin XHEMAJ 2 Edeltraud Haselsteiner 3 Edeltraud Haselsteiner 4 Edeltraud Haselsteiner 5 Edeltraud Haselsteiner 6 Peter Kytlica 7 a Lucas van der Wee 7 b Lucas van der Wee 8 Edeltraud Haselsteiner Building with Natural Materials and Local Resources 1 GABRICAL / Gabrijela Obert 2 GABRICAL / Gabrijela Obert 3 GABRICAL / Gabrijela Obert

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B ANALYSIS p. 36 Iwan Baan Low-tech Focus: Design, Concept, System 1 Kurt Hoerbst Design Strategies 1 a Ruiz Larrea y Asociados 1 b Ruiz Larrea y Asociados 1 c Ruiz Larrea y Asociados 2 ritchie*studio 3 a Grüne Erde GmbH 3 b Grüne Erde GmbH 4 proprietary illustration from Kazuhide Doi Architects 5 a Adrià Goula 5 b Adrià Goula 5 c Adrià Goula 6 www.solardecathlon.at 7 a Jakob Schoof 7 b Sebastian Schels / Pk. Odessa 8 a Philippe Ruault 8 b Philippe Ruault 9 a Rasmus Norlander 9 b Rasmus Norlander 9 c Rasmus Norlander 10 W. Koenig 11 a BeL Sozietät für Architektur 11 b Götz Wrage 11 c Veit Landwehr 12 a Barbara Bühler 12 b Barbara Bühler 13 a David Grandorge 13 b David Grandorge 14 Rasmus Hjortshoj 15 a Stijn Peolstra 15 b Stijn Peolstra Nature-based Solutions 1 Robert Six rb6 2 a caitao /123RF.com 2 b syrnx / Alamy Stock Photo 3 TagTomat / Mads Boserup Lauritsen 4 Ramboll Studio Dreiseitl Singapore Climate-sensitive Construction 1 a proprietary illustration based on www.stadtklima-stuttgart.de, solar position calculation 1 b proprietary illustration based on www.stadtklima-stuttgart.de, solar position calculation 2 a Hertha Hurnaus 2 b Rauhs / WWFF 2 c Rauhs / WWFF Low-tech Focus: Building Technology 1 proprietary illustration based on https://www.arkd.at/wp-content/ uploads/2017/10/solar.pdf 2 Edeltraud Haselsteiner Energy Potential of the Environment 1 from Sabady, Pierre Robert: BiosolarArchitektur. In: Werk — Archithese. Zeitschrift und Schriftenreihe für Architektur und Kunst. Volume 65, 1978, Issue 19–20: Bilanz 78, p. 18

2 a proprietary illustration based on https://reinberg.net/projekt/purkersdorfwintergasse-53-wohnprojekt/ #&gid=2&pid=2 2 b proprietary illustration based on https://reinberg.net/projekt/purkersdorfwintergasse-53-wohnprojekt/ #&gid=2&pid=2 3 a by martin loosli, ch-lenk i.s. 3 b by martin loosli, ch-lenk i.s. 4 a Clément Guillaume 4 b Clément Guillaume 5 a Thermocollect 5 b Thermocollect 6 Gaston Wicky 7 a–c  from Hegger, Manfred et al.: Energy Atlas. Nachhaltige Architektur. Munich 2007, p. 100, Fig. B 4.88 8 Illustration based on Steele, James: An Architecture of People. The complete Works of Hassan Fathy. London 1997, p. 176 9 proprietary illustration based on Oswalt, Philipp: Wohltemperierte Architektur: Neue Techniken des energiesparenden Bauens. Heidelberg 1994 10 a Peter Cook / View 10 b Arup Associates 11 a ATP / Thomas Jantscher 11 b ATP / Thomas Jantscher 11 c Passivhaus Institut 12 a atelier GROENBLAUW 12 b atelier GROENBLAUW 13 a Jasmin Schuller 13 b Jasmin Schuller 14 proprietary illustration based on Pohl, Wilfried et al.: Entwicklung eines ‘Licht­ fängers’ für tageslichttransparente, hochenergieeffiziente, mehrgeschossige Gebäude. Final report. Berichte aus Energie- und Umweltforschung 22/2014. Vienna 2013, p. 21 15 Paul Raftery / view / artur 16 Jørgen True 17 Adrià Goula 18 RATAPLAN 19 Christian Kandzia 20 Christian Flatscher Sufficient Energy Design 1 Schöberl & Pöll GmbH 2 TU Wien, Building Physics Research Department, adapted by Schöberl & Poll GmbH 3 a Schöberl & Pöll GmbH 3 b Schöberl & Pöll GmbH 3 c Schöberl & Pöll GmbH Robust Building Design 1 Jakob Schoof 2 a from Transsolar Energietechnik GmbH 2 b Transsolar Energietechnik GmbH 3 a Sebastian Schels, Markus Lanz / Pk. Odessa 3 b from Transsolar Energietechnik GmbH 4 Sebastian Schels, Markus Lanz / Pk. Odessa

5 a Sebastian Schels, Markus Lanz /  Pk. Odessa 5 b Sebastian Schels, Markus Lanz /  Pk. Odessa 6 a Transsolar Energietechnik GmbH 6 b Transsolar Energietechnik GmbH 6 c Transsolar Energietechnik GmbH 7 from Transsolar Energietechnik GmbH Low-tech Focus: Materials Choosing Sustainable Building Materials 1 a Kurt Hoerbst 1 b Kurt Hoerbst 2 a Nicolas Felder 2 b Nicolas Felder 2 c Rainer Retzlaff 3 a Jill Tate 3 b Jill Tate 4 a ATP / Florian Schaller 4 b ATP / Florian Schaller 4 c AllesWirdGut Architektur / Guilherme Silva Da Rosa 4 d AllesWirdGut Architektur / Guilherme Silva Da Rosa 5 a Ralph Feiner / feinerfotografie 5 b Ralph Feiner / feinerfotografie 6 a Eduard Hueber 6 b Eduard Hueber 7 a Beat Bühler 7 b Beat Bühler 7 c Beat Bühler 8 a Javier Callejas 8 b Andreas Herzog 8 c Alka Hingorani 9 Hiroyuki Hirai 10 Helene Hoyer Mikkelsen 11 a BarkowPhoto 11 b  Ray Wang 12 a  WASP 12 b WASP Recyclable Construction and ­Renovation 1 alchemia-nova based on an illustration by Arup and others 2 a, b  alchemia-nova, based on principles from Madaster, Building Circularity ­Passport, Drees & Sommer 3 Chris Cooper 4 Ossip van Duivenbode 5 PHOTOGRAPHIX — Sebastian Zachariah 6 a gugler* Rupert Pessl 6 b gugler* Rupert Pessl Low-tech Focus: Renovation Utilising Existing Buildings 1 a Lukas Schaller 1 b Lukas Schaller 2 a Stefan Müller-Naumann 2 b Stefan Müller-Naumann 2 c Stefan Müller-Naumann 3 a Ruinelli Associati Architetti 3 b Ruinelli Associati Architetti 3 c Ruinelli Associati Architetti 4 a proprietary illustration based on Heiß, Daniel; Walser, Silvia; Ortler, Alexandra: Haus Zeggele in Silz. Energietechnische Sanierung eines historisch erhaltenswerten Wohngebäudes. Berichte aus Energie- und Umweltforschung 6/2009. Published by BMVIT. Vienna 2008 4 b Energie Tirol

5 a 5 b 5 c 6 7 a 7 b 7 c 8 9 10 11 12

Frédéric Druot Architecture Frédéric Druot Architecture Frédéric Druot Architecture Ignacio Martinez from Detail green 1/2015, p. 52 Claudius Pfeifer Claudius Pfeifer digitalHub Aachen e. V. Markus Hauschild Christian Richters Hans Jürgen Landes Hans Jürgen Landes

Renovation Strategies and Concepts for Existing Buildings 1 a ZRS Architekten Ingenieure 1 b Mila Hacke 2 a ZRS Architekten Ingenieure 2 b ZRS Architekten Ingenieure 2 c ZRS Architekten Ingenieure 3 Malte Fuchs 4 a Emmanuel Heringer 4 b Malte Fuchs 4 c Ziegert I Roswag I Seiler Architekten ­Ingenieure 4 d Ziegert I Roswag I Seiler Architekten ­Ingenieure 5 Ziegert I Roswag I Seiler Architekten ­Ingenieure 6 ZRS Architekten Ingenieure 7 ZRS Architekten Ingenieure 8 ZRS Architekten Ingenieure C ASSESSMENTS p. 106  Beat Bühler Low Tech in the Context of International Building Evaluation Systems and Standards 1 Christian Richters 2 Edeltraud Haselsteiner 3 Edeltraud Haselsteiner 4 Gui Rebelo Building Evaluations and Life Cycle Assessments 1 Thomas Zelger, Ute Muñoz-Czerny, ­Bernhard Lipp 2 a Rupert Steiner 2 b Rupert Steiner 2 c © MAGK 2 d © MAGK 2 e E. Schwarzmüller 2 f E. Schwarzmüller 3 Thomas Zelger, Ute Muñoz-Czerny, ­Bernhard Lipp 4 Thomas Zelger, Ute Muñoz-Czerny, ­Bernhard Lipp 5 Rupert Steiner D BEST PRACTICE p. 124  Rory Gardiner p. 126, 127  David Grandorge p. 128 top, centre  Feilden Fowles p. 129  David Grandorge p. 131—135  Seraina Wirz p. 137—139  René Dürr p. 140—145 Sebastian Schels, Markus Lanz / Pk. Odessa p. 146 —149 Architekten Scheicher p. 150 left, right GrAT — Gruppe Angepasste Technologie

p. 151  Architekten Scheicher p. 152  Brigida González p. 153  Brigida González p. 154  © Vitra, Foto: Eduardo Perez p. 155  Brigida González p. 157 top  Roland Halbe p. 157 second from top  Marc Doradzillo p. 157 third from top  Emmanuel Dorsaz / Lehm Ton Erde Baukunst GmbH p. 157 bottom  Emmanuel Dorsaz / Lehm Ton Erde Baukunst GmbH p. 158—159  Malte Fuchs p. 160 top  Stefanie Heringer p. 160 bottom  Ziegert I Roswag I Seiler Architekten Ingenieure p. 161 top left  Ziegert I Roswag I Seiler Architekten Ingenieure p. 161 top centre  Emmanuel Heringer p. 161 top right  Emmanuel Heringer p. 161, Fig. 1–3  Ziegert I Roswag I Seiler Architekten Ingenieure p. 162  Malte Fuchs p. 163  Ziegert I Roswag I Seiler Architekten Ingenieure p. 164  Philipp Stäheli p. 166 left, right  Saikal Zhunushova p. 167 top left  Philipp Stäheli p. 167 centre left  Saikal Zhunushova p. 167 top right  Philipp Stäheli p. 167 bottom  Philipp Stäheli p. 168—171  Peter Litvai p. 173  Rory Gardiner p. 174 all  Mae Architects p. 175—177  Rory Gardiner E STRATEGIES p. 178  Anna Stöcher Planning and Design Strategies 1 a Ivar Mjell 1 b from Detail 6/2002, p. 758 2 a from Detail 6/1974, p. 1051 2 b from Detail 6/1974, p. 1051 3 a IBA Thüringen, photo: Thomas Müller 3 b IBA Thüringen, photo: Thomas Müller 4 C. F. Møller Architects 5 a–d  from Klein, Alexander: Der Einfluss des Klimas auf die organische Gestaltung von Grundriß und Ansicht. In: Journal of the Association of Engineers & Architects, Vol. 5, No. Feb. / Mar, 1942; cited in Oswalt, Philipp: Wohltemperierte Architektur. Neue Techniken des energiesparenden Bauens. Heidelberg 1994, p. 55 6 Edeltraud Haselsteiner 7 Edeltraud Haselsteiner; proprietary illustration based on Manzano-Agugliaro, Francisco et al.: Review of bioclimatic architecture strategies for achieving ­thermal comfort. In: Renewable and ­Sustainable Energy Reviews, Vol. 49, Sep. 2015, p. 736—755, doi: 10, 1016/ j.rser.2015.04.095 8 Brigida González 9 Sergio Camplone

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RESTORE_booklet_print_END.pdf (last accessed 01.05.2021) Cole 2012 Cole, Raymond J.: Regenerative design and development: current theory and practice. In: Building Research & Information, Vol. 40, No. 1, 2012, p. 1–6 doi:10.1080/09613218.2012.617516 Reed 2007 Reed, Bill: Shifting from ‘sustainability’ to regeneration. In: Building Research & Information Vol. 35, Nr. 6, 2007, p. 674– 680 doi: 10.1080/09613210701475753  [3] Endres 2020 Endres, Elisabeth: Hightech versus ­Lowtech oder einfach nur robust?. In: Lowtech im Gebäudebereich: Technical symposium TU Berlin 17.05.2019. ­Bundesinstitut für Bau-, Stadt- und Raumforschung (Federal Institute for Research on Building, Urban Affairs and Spatial Development). Published by the Federal Institute for Research on Building, Urban Affairs and Spatial Development. As of January 2020. Bonn 2020, p. 74 – 81  [4] Daniels 2000 Daniels, Klaus: Low-Tech — Light-Tech — High-Tech. Building in the Information Age. 1st corrected edition. Basel et al. 2000, p. 218   [5] Haselsteiner et al. 2021 Haselsteiner, Edeltraud et al.: Drivers and Barriers Leading to a Successful Paradigm Shift toward Regenerative Neighborhoods. In: Sustainability, Vol. 13, No. 9, 2021, Art. No. 9, doi: 10.3390/su13095179   [6] Reed et al. 2009 Reed, Richard et al.: An International Comparison of International Sustainable Building Tools. European Real Estate Society (ERES), eres2009_331, Jan. 2009. https://ideas.repec.org/p/arz/wpaper/ eres2009_331.html (last accessed 02.03.2021) SBi, GXN 2018 Statens Byggeforskningsinstitut (SBi); GXN (eds.): Guide to sustainable building certifications. Copenhagen 2018   [7] Forsberg, de Souza 2021 Forsberg, Mara; de Souza, Clarice Bleil: Implementing Regenerative Standards in Politically Green Nordic Social ­Welfare States: Can Sweden Adopt the ­Living Building Challenge? In: Sustainability. Vol. 13, No. 2, 2021, Art. No. 2, doi: 10.3390/su13020738   [8] SBi, GXN 2018 (see note [6]) Berardi 2012 Berardi, Umberto: Sustainability Assessment in the Construction Sector: Rating Systems and Rated Buildings. In: Sustainable Development, Vol. 20, No. 6, 2012, p. 411–424 doi: https://doi.org/10.1002/sd.532 E STRATEGIES   [1] Sölkner et al. 2014 Sölkner, Petra Johanna et al. 2014.: Innovative Gebäudekonzepte im ökologischen und ökonomischen Vergleich

über den Lebenszyklus. Publication series Berichte aus Energie- und Umweltforschung 51/2014, Vienna 2014 (last accessed 29.11.2021) https://nachhaltigwirtschaften.at/resources/hdz_pdf/ berichte/endbericht_1451_innovative_ gebaeudekonzepte. pdf?m=1469660917&   [2] Rüdi, Watter, Schürch 2016 Rüdi, Andrea; Watter, Jörg; Schürch, Peter: Solararchitektur: Häuser mit solarem Direktgewinn. Zurich 2016  [3] Endres 2020 Endres, Elisabeth: Hightech versus ­Lowtech oder einfach nur robust? In: Lowtech im Gebäudebereich: Technical symposium TU Berlin 17.05.2019, 1st edition, as of January 2020, Bundes­ institut für Bau-, Stadt- und Raumfor­ schung, eds. Bonn: Bundesinstitut für Bau-, Stadt- und Raumforschung, 2020, p. 74–81  [4] Endres 2019 Endres, Elisabeth: Parameters to Design Low-Tech Strategies. Presentation at the Powerskin Conference. Delft Jan. 2019 http://pure.tudelft.nl/ws/files/69585347 /679_3_679_3_10_20190325. pdf#page=289 (last accessed 30.09.2021)  [5] Endres 2017 Endres, Elisabeth: Parameterstudie LowTech Bürogebäude. Technical University of Munich. Chair of Building Technology and Climate Responsive Design. Munich 2017, p. 60 https://docplayer.org/165733295Parameterstudie-low-tech-buero­ gebaeude.html (last accessed 30.09.2021)   [6]  see Note [3], p. 80   [7] Krause, Leistner, Mehra 2020 Krause, Pia; Leistner, Philip; Mehra, Schew-Ram: Einsatz und Auswirkung von Vegetation bei autochthonen Bauten. In: Bauphysik 4/2020, p. 184–195 doi: 10.1002/bapi.202000015  [8] Oswalt 1994 Oswalt, Philipp: Wohltemperierte Architektur. Neue Techniken des ­energiesparenden Bauens. Heidelberg 1994, p. 55  [9] ibid. [10] ibid. [11] Erber, Roßkopf-Nachbaur 2021 Erber, Sabine; Roßkopf-Nachbaur, Thomas: Low-Tech Gebäude. Prozess Planung Umsetzung. Commissioned by the Climate and Energy Committee /  Environmental Commission of the International Lake Constance Conference IBK, Constance 2021 [12] ibid. [13] Brown et al. 2018 Brown, Martin et al.: Sustainability, Restorative to Regenerative. An exploration in progressing a paradigm shift in built environment thinking, from sustainability to restorative sustainability and on to regenerative sustainability. COST Action CA16114 RESTORE. Vienna 2018

Authors Edeltraud Haselsteiner Edeltraud Haselsteiner studied architecture at TU Wien and earned her doctorate in the theory of architecture. She is a project leader, researcher, exhibition curator and an architecture journalist for sustainable architecture, urban planning and mobility. She is the founder of the research institute URBANITY, which equally addresses issues of gender, participation, the history and theory of architecture and art. Thomas Auer Thomas Auer is Professor of Building Technology and Climate Responsive Design at TU Munich and an executive at Transsolar. He works with renowned architecture firms all over the world on prize-winning projects that are characterised by innovative design and integral energy concepts. In his research he focuses on resource consumption, residential quality and robustness. He is a member of the Akademie der Künste (Academy of Arts) and of the Bundesstiftung Baukultur (Federal Building Culture Foundation) convention. Gaetano Bertino Gaetano Bertino studied structural engineering and architecture with a specialisation in forensic engineering. He is currently a project manager at alchemia-nova and is completing his doctoral degree at the University of Natural Resources and Life Sciences in Vienna on the topic of circular solutions for sustainable architecture. Anna Heringer For Anna Heringer, architecture is a tool for improving living conditions. Her buildings in Bangladesh, Ghana, Austria, Germany and other locations represent a global strategy for sustainability that is based on the utilisation of local resources. Among other places, she has taught and is teaching at Harvard University, ETH Zurich and the University of Art and Design in Linz and is the recipient of numerous prizes including the New European Bauhaus Award, the Obel Award and the Aga Khan Award for Architecture. Johannes Kisser Johannes Kisser studied technical chemistry. In 1998 he began working in the waste industry, and was soon dedicating himself to circular economy solutions. He has initiated many projects, and is also an evaluator, consultant and lecturer. After many years as the CEO, he was made Technical Director of the alchemia-nova group in 2019. His strong ­systems approach combines innovation with inspirations from nature and with social transformation. Andrea Klinge Andrea Klinge is a Professor of Circular ­Construction at the University of Applied

­ ciences and Arts in Basel. Her teaching and S research are focused on recycling-­oriented low-tech construction based on ­natural building materials. Andrea Klinge worked in various architecture firms in L ­ ondon, Rome and Berlin for over ten years, after which she established the research ­division at ZRS Architekten in 2013. Steffi Lenzen Steffi Lenzen studied architecture at the RWTH Aachen University and in Paris. She worked as an architect for several years before she completed practical training at DETAIL, where she has since worked as an editor. In 2019, she became team leader of the editorial department. Her special interests include timber construction and topics connected with sustainability. Bernhard Lipp Bernhard Lipp studied technical physics at TU Wien. He is the managing director of the Austrian Institute for Building Biology and Ecology (IBO) and founding member of the ÖGNB, as well as a member of the klima­aktiv executive committee. He researches comfort and stress and develops quality assurance concepts for buildings and envir­onmental criteria for residential funding. Ute Muñoz-Czerny Ute Muñoz-Czerny is an architect and an anthropologist. She conducts research in the areas of indoor air quality, user comfort and energy efficiency. In 2013, she completed her education as a specialist in clay at the Handwerkskammer Koblenz. Ute MuñozCzerny is qualified to issue building certifications (klimaaktiv, ÖGNB). Eike Roswag-Klinge Eike Roswag-Klinge is a professor at TU Berlin and has been the director of the Natural Building Lab there since 2017. He is a founding member of ZRS Architekten Ingenieure in Berlin (2003). For more than 20 years he has been working with communities of different cultural and climatic backgrounds to create futureproof, climate and resource-oriented architecture based on natural raw materials. Ursula Schneider Since 2000, Ursula Schneider has been the director of POS architekten. For over 30 years, her focus has been environmental and climatesensitive architecture. Starting in 2001, she has increased her work in the areas of innovative and applied building research and consulting on the topics of passive houses, daylight architecture, the plus-energy standard, CO2-neutral construction, Cradle to Cradle, recyclability, user comfort and the greening of buildings. In the context of her active engagement as a teacher and lecturer she communicates her values for a future-oriented architecture.

Helmut Schöberl Helmut Schöberl has been working in building physics for over 25 years. Schöberl & Pöll GmbH is one of the major building physics firms in Austria, and has been doing pioneering work in numerous passive house projects for more than 20 years. Helmut Schöberl is active on technical standards committees at Austrian Standards and has received many prizes, among them three Staatspreise (national awards), which are among the highest distinctions conferred by the Republic of Austria. Bertram von Negelein Bertram von Negelein has a diploma in biology and is employed in the public relations department of Transsolar. Robert Wimmer Robert Wimmer studied mechanical en­­ gineering and process engineering at TU Graz and TU Wien and earned his ­doctorate with a thesis entitled “Flex-Fuzzy Logic Expert System, ein integrativer Ansatz zur Bewertung von technischen Systemlösungen aus dem Gesichtspunkt nachhaltiger Entwicklung” (Flex-Fuzzy Logic Expert System, an integrative approach to the evaluation of technical system solutions from the perspective of sustainable development). He is the director of the scientific research ­association GrAT – Gruppe Angepasste ­Technologie (Adapted Technology Group). Robert Wimmer coordinates (inter)national development and demonstration projects with an emphasis on system solutions for ­sustainable development through adapted technologies. He also does consulting work for businesses and agencies and teaches at various universities. Maria Wirth Maria Wirth studied Environmental Technology & International Affairs at TU Wien. She is currently a project manager and researcher at alchemia-nova, specialising in the use of nature-based solutions for improvements in urban water management as well as circular food systems. Thomas Zelger Thomas Zelger has held an endowed professorship for energy-efficient and user-friendly buildings and neighbourhoods at the University of Applied Sciences Technikum Wien since 2016. Before that, he did research and practical work for over 20 years at the Austrian Institute for Building Biology and Ecology (IBO) in the fields of passive house construction, plus energy construction, building ecology, comfort research and building physics. Thomas Zelger publishes on the topics of comfort, building ecology, plusenergy neighbourhoods and environmental passive house building part catalogues.

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