The Future Envelope 3 : Facades - the Making Of [1 ed.] 9781607506720, 9781607506713

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Research in Architectural Engineering Series Volume 10 ISSN 1873-6033 (print) ISSN 1879-8225 (online) Previously published in this series: Volume 9. U. Knaack, T. Klein (Eds.) The Future Envelope 2 - Architecture-Climate-Skin

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Volume 8. U. Knaack, T. Klein (Eds.) The Future Envelope 1 - A MulƟdisciplinary Approach Volume 7. M. Eekhout, F. Verheijen and R. Visser (Eds.) Cardboard in Architecture Volume 6. M. Veltkamp Free Form Structural Design – Schemes, Systems & Prototypes of Structures for Irregular Shaped Buildings Volume 5. L. Bragança, C. Wetzel, V. Buhagiar and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of ExisƟng Urban Building Envelopes – Facades and Roof Volume 4. R. di Giulio, Z. Bozinovski and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of ExisƟng Urban Building Envelopes – Structures Volume 3. E. Melgaard, G. Hadjimichael, M. Almeida and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of ExisƟng Urban Building Envelopes – Needs Volume 2. M.T. Andeweg, S. Brunoro and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of ExisƟng Urban Building Envelopes – State of the Art Volume 1. M. Crisinel, M. Eekhout, M. Haldimann and R. Visser (Eds.) EU COST C13 Glass and InteracƟve Building Envelopes – Final Report

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

UIF!GVUVSF!FOWFMPQF!4

Copyright © 2010. IOS Press, Incorporated. All rights reserved.

Gbdbeft!.!Uif!Nbljoh!Pg

fejufe!cz! Vmsjdi!Lobbdl!'!Ujmmnboo!Lmfjo

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

© 2010 IOS Press and the Authors. All rights reserved. ISBN

ISBN 978-1-60750-671-3 (print) ISBN 978-1-60750-672-0 (online)

Published and distributed by IOS Press under the imprint DelŌ University Press Publisher

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Editors Ulrich Knaack Tillmann Klein

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Reviewing commiƩee Prof. Dr. Wim Poelman, University of Twente, NL Prof. Dr. Dirk Henning Braun, De Monƞort Leicester, UK Prof. Dr. Patrick Teuīel, DelŌ Technical University, NL Layout & bookcover design Usch Engelmann

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Photography cover and content Copyright by the respecƟve authors unless indicated otherwise. Legal noƟce The publisher is not responsible for the use which might be made of the following informaƟon. All rights reserved. No part of the material protected by this copyright noƟce may be reproduced or uƟlized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informaƟon storage and retrieval system, without wriƩen permission of the author. This publicaƟon is based on the contribuƟons to the The Future Envelope, a Symposium held on 14 May 2009 in DelŌ. This symposium was organized by the Faculty of Architecture, DelŌ University of Technology (Chair Design of ConstrucƟon) in cooperaƟon with VMRG (Vereniging Metalen Ramen en Gevelbranche) and FAECF (FederaƟon of European Window and Curtain Walling Manufacturers AssociaƟons).

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

PREFACE

Copyright © 2010. IOS Press, Incorporated. All rights reserved.

The association of the book title with the Ƥlm industry is intentional. A documentary about the creation of a movie can be more exciting than the movie itself. With the background information provided we understand the Ƥlm and its intention in a diơerent way, and develop a diơerent relationship with it. Once a friend said that that one should never watch the “Making Of” before having seen the movie, but we don’t just see ourselves as spectators, but rather as directors in the world of building envelopes. A director needs to master the technique of making Ƥlms. An institute for research and education not only has to know the state of the art, it also needs to direct its eơorts to explore future developments. At any rate, there seems to be suƥcient new material related to facade technology. The requirements keep rising, not only in terms of energy consumption. New materials, foil technology for example, evolve from customized solutions to established systems. New production methods such as rapid manufacturing generate questions about the future of traditional techniques. On one hand, existing methods and technologies are being optimized, and on the other, new ones are Ƥnding their way into the market. All of these developments are both a blessing and a curse. Of course they provide unknown possibilities and the term innovation alone makes your heart beat faster, but the developments are also a burden, because they force us to keep pace. We need to comprehend them and react accordingly. The facade is a topic that is and will remain one of the most exciting parts of building technology, and for us the book series “The Future Envelope” is one of the tools to stay on top. However, it might be interesting for the reader to know that the book is based on an annual conference at our faculty with the same title. It combines research, education and practical application of architecture and facade construction. Professors and students from our partner universities use it as a meeting event. With its accompanying workshops it is a Ƥxed part of the curricula of the Facade Master programs in v

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Lucerne, Switzerland, Detmold, Germany, and in Delft. Here, the focus lies on practical applicability, which also provides the beneƤt for the industry. Our goal is not merely to gather and learn what is technologically and scientiƤcally cutting edge, but to create a relationship between those who currently deƤne the business and those who aim to do so in the future. We thank our partners VMRG and FAECF for their support and the trust they place in our work. We are also grateful to those companies and institutions that have become Ƥrm partners in our research activities and are therefore instrumental in the development of the contents of this book.

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Ulrich Knaack Design of Construction Faculty of Architecture Delft University of Technology

vi

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INTRODUCTION

The goal is to sketch a picture of the future building envelope. Which trends can be seen, what drives these developments and what does that mean in practice? Building envelopes are a broad topic and “The Making Of” refers to all the aspects necessary to produce a facade, from the design to the Ƥnished product. This is mirrored by the selection of authors from various disciplines, who contributed to this publication. The book is divided into four chapters, which will cast a light on areas of future developments from diơerent points of view.

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Materials and Technologies Surely we can expect new developments coming from the area of materials. Acrylics for example are widely used in interior design but not for exterior use. Matthias Michel shows with a number of executed projects what it takes to use this material in facade constructions. The structural designer James O´Calaghan is pushing the limits of the application of structural glass in the Apple Store New York by transferring production technologies from the aerospace industry. Only in the last few years have textile facades developed from experimental projects to an accepted technology. Jan Cremers from SolarNext reports about the latest developments in this Ƥeld. New Structural Facade Concepts The implementation of radical new facade concepts is a big challenge. A chain of inherited dependencies and responsibilities has to be circumnavigated that deƤne the way we are building today. The development of a new suspended facade with loadbearing composite cables is in the focus of Mick Eeckhout's paper. He explains in detail the potential of this approach and the risk bottlenecks that had to be tackled. The second contribution of Tillmann Klein shows a method to analyse and develop facade structures. A number of student designs are presented that radically depart from the way facades are built today and oơer new possibilities.

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Industry and StandardizaƟon Today, industrial standards are actually deƤning the way most facades are built. Jeroen Scheepmakers from Alcoa Architectural Products explains how system suppliers are trying to raise the benchmark for standardized systems. Bert Lieverse is head of the European branch organization for aluminium facade producers. He writes about the experience with a new market concept for the facade industry. How testing becomes an integral part of the implementation of new structures is the third contribution to this chapter by Daniel Meyer from the University of Applied Sciences, Lucerne.

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Architecture, Design and Engineering The constantly rising requirements for energy saving and user comfort, lead to the use of new design tools for simulation and calculation and inevitably to a stronger integrated design approach. In order to illustrate an exemplary design approach, the architect Oliver Kühn uses the new headquarter building for the Süddeutsche Zeitung as a case study. Jan Knippers shows the role of the structural engineer while designing glazed grid shells. In the Ƥnal contribution “Form follows Energy”, Brian Cody explains how he sees new design parameters emerging.

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CONTENTS Materials and Technologies Acrylic Facades - Three Case Studies MaƩhias Michel, Imagine Structure / Structural design

1

Thinking Big with Structural Glass James O'Callaghan, Eckersly O'Callaghan / Structural Engineering

15

Designing the Light — New TexƟle Architecture Jan Cremers, HFT StuƩgart / Hightex Group

27

New Structural Concepts Development of a Super Slim Facade System for InHolland Polytechnic, DelŌ Mick Eekhout, TU DelŌ / Octatube, Peter van der RoƩen, Octatube

39

Scenarios for Future Building Envelopes - Student Designs Tillmann Klein, TU DelŌ / Facade Research Group

55

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Industry and StandardisaƟon Architectural Mass ProducƟon Jeroen Scheepmaker, Alcoa Architectural Systems / Industry

71

Experiences aŌer the IniƟal Launching of the Living Facade Bert Lieverse, General Secretary FAECF

81

Test-based Facade InnovaƟon Daniel Meyer, University Luzern / Facade Technology

91

Architecture, Design and Engineering Form Follows Energy - Energy Eĸciency in Architecture and Urban Design Brian Cody, TU Graz / Arup GmbH

101

The Constant of Change Oliver Kühn, GKK+ Architekten

107

Recent Developments in the Design of Glazed Grid Shells Jan Knippers, Thorsten Helbig, Knippers Helbig / Engineering

117

The Making Of - A Summary Tillmann Klein, TU DelŌ / Facade Research Group

127

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Structural engineer Dipl.-Ing. Matthias Michel is specialist in steel constructions, digital workƪow and 3 dimensional geometric structures. He is co-founder of the oƥce imagine-structure. During his career he was responsible for the structural design from large scale buildings down to the level of sculptures. Especially the examples about acrylics he is showing in his paper where Ƥrst used by him for the design of trade fair stands and later with this experience transferred into architectural applications.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-1

ACRYLIC FACADES ͳ THREE CASE STUDIES

MaƩhias Michel

IntroducƟon

Imagine Structure / Structural Design

Poly(methyl 2-methylpropenoate) is known as PMMA, Plexiglas, Perspex or just acrylic. Acrylic glass is a wide spread substitute to glass, having excellent optical behavior, low tendency to splitter, light weight, good chemical resistance and so on. In many kinds of products acrylic has taken the place of glass long ago. How about facades? The choice of transparent materials in buildings is focused on glass. A low price, durable surface and inƪammability are key advantages of glass. The pros of acrylic like noise protection, robustness and low weight do not trump the beneƤts of glass – today.

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For advanced building application acrylic oơers features that glass cannot provide. Good deformability without loss of optical qualities is only one oft the advantages of acrylic. Easy machining like CNC cutting or CNC engraving of light directing textures, uncomplicated use as structurally activated building members and the possibility to integrate active electronic devices are features of acrylic that are rarely exploit – today. In the following paper, I present three projects focused on the work with the material acrylic from the technical and structural point of view. It reƪects a personal learning process, beginning with acrylic as a nonstructural cladding and closing with the self-supporting transparent shell structure made of acrylic.

Case I – BMW Clean energy Bubble The Clean Energy Bubble designed by Bernhard Franken for the International Automobile Ausstellung in Frankfurt 1999 resulted from a two-year-old design, a won competition for the same event 1997. However, it was not realized until BMW’s automotive design was found to be conservative and out fashioned, so a progressive architectural language should help to polish the companies image and to introduce their hydrogen technology. The Bubble contained an exhibition of the upcoming technology without showing any car in the vicinity. 1

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The project was realized under very limited time conditions and the planning team suơered through an abrupt change of the structural concept and a complete recommencement of production a few weeks before the exhibition’s opening. For the Ƥrst concept a totally self-supporting acrylic shell without supporting primary structure was planned. The second concept featured a primary aluminum structure of ƪat aluminum ribs with 8 mm acrylic panels as cladding. The Įrst concept The architectural form of two water droplets merging into each other showed qualities to be realized as a self supporting shell. The structural analysis resulted in a stress level low enough to try a realization by using acrylic panels that are glued together from individual pieces. The acrylic panels of 25 mm thickness were heat formed over cncmilled foam blocks and cooled outside the fabrication site. After cooling, the foam block was milled down to the next geometry and reused.

Fig. 1 One of the hardest to solve design quesƟons was how to enter the Bubble Image: Bollinger + Grohmann, MaƩhias Michel

The panels were trimmed by a 5-axis router and prepared for bonding. However, it was found that the manufacturer was not able to comply with the demands for optical and structural quality at all.

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The issues that Ƥnally lead to a full stop of the manufacturing were lack of continuity of the surface and bondage strength. The curvature of the individual panels changed after production because of internal stresses, which resulted from a rapid cooling after deformation and the diơerence between the inner and outer surface temperature during the cooling.

Fig. 2 The panels were deformed on milled foam blocks Image: Bollinger + Grohmann, MaƩhias Michel

The bonding was made by a polymerization process in order to join two pieces in a similar way like welding. The same material is used as glue and the same process is applied to cure the seam as it is used to produce the adjacent parts themselves. However the process does not require heat. The strong shrinkage of the glued seam results in high internal stress around the seam. Tempering the seam will relieve these stresses. As a controlled polymerization and especially the tempering is diƥcult to be accomplished in situ, the test results of the bonds were below expectations. Second Concept Due to the poor results in manufacturing and with no time to start all over with a diơerent manufacturer, the second concept was created.

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The outer shells surface was sliced along a one meter rectangular grid. The ribs result from this projection process. They consisted of three layers of 8 mm aluminum sheets, with two of them being structurally required and one to allow gaps. Each layer of the ribs was individually intersected with the master surface resulting in a stepped outer edge, that adapts better to the facades curvature, also in cases of glancing intersections between rib and skin.

Fig. 3 The cladding Įnally was 8mm thick warm formed acrylic Image: Bollinger + Grohmann, MaƩhias Michel

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The cladding was now manufactured from 8 mm acrylic sheets that were held on the ribs by individual small bars, bolted into the narrow side of the aluminum. For the doors 25 mm panels were used, mounted on rails to slide out. The BMW Bubble is an archetype of the digital architecture because of it’s form. It’s materials and because it’s simplicity of construction, Ƥnally resulting from a lack of time to become more complex. The crucial experience made in this project: • Heat forming acrylic requires a good amount of production time and experience. Cooling must be slow. • Compensation of the mould’s geometry is required to obtain a good surface continuity in the case of thick panels. • The use of glue to bond complex curved panels along their edges may be considered as extremely diƥcult especially if structural qualities are wanted.

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Case II – Kunsthaus Graz Skin The early design concept of Peter Coock and Colinf Fournier for the Kunsthaus Graz featured a multifunctional facade with a many features like transparency or media eơects. In accordance to the many functions the facade was named “skin” by the architects. During planning of the skin some features were omitted while others survived. Finally the technical demands for the outer skin cladding material crystallized:

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• The skin should be translucent and of high quality surface Ƥnish • The outer skin was designed to be elevated over the water proving inner skin • It should be realized by point supported panels of individual form and size • The facade had to withstand high snow- and wind loads • Temperatures were expected to be very high on the top of the building • The shell material was supposed to be ƪame retardant or Ƥre resistant • The lifetime of the shell was required to be at least 20 years

Fig. 4 The structure’s geometry was derived from the panel size of the acrylic Image: Bollinger + Grohmann, MaƩhias Michel

Soon in was evident that the demands would bring any material at it’s technical limits. And it became obvious that there would be no material on the market to meet all requirements. Although acrylic was the favoured material, research was done towards thermoplalstics as well as duroplastics. The latter, like composite of polyester resin and glass Ƥber, are better suitable to the demands than thermoplastics like acrylic. A semi transparent 4

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

composite panel was developed by a company in Germany for the project, that was temperature resistant enough, hat good mechanical qualities and a B1 Ƥre retardant certiƤcate. Unfortunately the material did not meet the budget, so the realization process Ƥnally focused on the acrylic. Engineering the acrylic All geometric dimensions of the skin and it’s structure were limited by the maximum available panel size of acrylic, resulting in standard panel sizes of about 1,40 by 2,80 meters. Every panel is point supported at six spots in a two by three layout. Because of this statically indeterminate support, the panel is under strain if it’s inside and outside temperature diơer, causing it to ƪex like a bimetal.

Fig. 5 The acrylic skin covers a triangular steel structure Image: Bollinger + Grohmann, MaƩhias Michel

As the skin is elevated over the roof seal by ca. 40 cm, temperatures as high as 80°C in the space between were predicted at the ƪat roof top, resulting in a temperature range of 100°C that hat to be taken into account for planning. Temperature diơerences between inside and outside layer were expected to be about 40°C, leading to a signiƤcant deformation of the panels and evoking the strain mentioned above. Acrylic tends – as every thermoplastic material – to relaxation, meaning that persisting loads result in a persisting deformation. The tendency to relaxation is more critical under high temperatures.

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The admissible stress in the material depends on the time of exposure to a load and it depends on the temperature range. The admissible stress for persistent loads was found to be about 10% of the breaking strength without risking relaxation. For initial dimensioning values about 5 KN/cm2 for permanent loads and 1,3 kN/cm2 for short term loads can be used as admissible design stress for cast acrylic sheets. Cast acrylic material should be preferred because extruded material is not as durable but more sensitive to chemical exposure. Fig. 6 The eīect of long-term relaxaƟon was visualized by raytracing a cloud map on a surface, that is deformed according to the Įnite elemente analsysis’ results Image: Bollinger + Grohmann, MaƩhias Michel

No Ƥre retardant certiƤcate (i.e. “B1” according to German standard) can be obtained for acrylic sheet products. The material is ƪammable particularly on the edges. For some ƪame retarding eơect, chlorines are added to the acrylic mixture that was developed for the skin. This is also practiced for the material of noise protection walls. As a side eơect, chlorine reduces the temperature resistance and the mechanical strength of acrylic. It is also said to reduce the lifespan of the material. Finding the right properƟes Testing was made to adjust the parameters of the customized acrylic for the skin to get the maximum of ƪame retardant substances without taking risk concerning the thermal and mechanical stability. 5

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Once a specimen was produced and a data sheet was issued, a test of inƪammability was made. Finally, to ensure the mechanical properties, the ƪame retardant substances were reduced to a minimum, resulting in a material that did not fully satisfy the Ƥre police. In the Ƥre department’s test, the acrylic would continue to burn on the back, inside the facade’s interspace, after extinguishing with water from outside. A fully automatic sprinkler system was installed with outlets on both sides of the acrylic. Although costs of a sprinkler system have a substantial eơect on every project’s budget, in this case the additional costs of the facade were less than 5%. Once the material conƤguration was set up it took long term testing to judge the eơects of extreme heat and shock cooling on the quantity of relaxation, that may result from the strained support arrangement of a heated panel.

Fig. 7 AŌer exƟnguishing this mockup from the outside, the inner side would conƟnue to burn Image: Bollinger + Grohmann, MaƩhias Michel

In 100 cycles a hot summer day with 80°C material temperature was simulated. At the end of each heating cycle the specimen, that was clamped in the test arrangement in a strained way and set under load, was shock cooled on one surface like a sudden thunderstorm rain or hail would cool the outside surface of a panel while the inner side remains hot.

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The Ƥrst test cycles produced most of the lasting deformation, that was abating with every cycle. Based on the test’s data the persistent deformation could be estimated and visualized by the use of a lower Young’s modulus in the analysis model. The resulting deformation under permanent loads was transferred to a ray tracing software. The rendering of the distortions of a cloud reƪection was used as a decision-making aid for the clients whether the amount of relaxation is acceptable. Point supports The design of the point supports – brought in by the contractor – features a rather basic technology that Ƥnally did it’s job. However, the participants probably would decide to keep more inƪuence on the contractors planning in a future project. The dimensioning of the point supports was based in the knowledge and the analysis results of the material study and lead to rather large diameters of the point holder base and the countersunk head plate. The edges of the countersink have a parabolic rim section to minimize the stress and the risk of cracks.

Fig. 8 The point holder assembly as it was realized by the contractor Image: ARGE Kunsthaus, Schiīer

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To avoid strain around the point supports, dual layer EPDM elastic point supports were chosen. Thermal expansion was calculated to be about +- 6 mm. As the support’s diameter was large enough, slotted holes were cut directly into the support’s arm. The degrees of freedom were arranged similar to point supported glass facades. The facade was Ƥnished in 2003 and is in good shape until today, after more than Ƥfe years, with no panel having been replaced yet, although all kinds of extreme weather condition showed up in the recent years.

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Fig. 9 Forming the nozzles from 25 mm strong acrylic was demanding for the manufacturer

The crucial experience made in this project • Flame retardant modiƤcation and structural qualities diƥcult to combine – especially under hot conditions • Strained support arrangement of facade panels should be avoided • Special care must be taken in the design of point supports • Thermal expansion of acrylic is often underestimated • Expect the presence of a sprinkler system if large amounts of acrylic are used in a building project (also the Bubble had a sprinkler system)

Case III – BMW Hourglass for 7 Series PresentaƟon The knowledge gained by the two preceding cases resulted in the solution found for the BMW 7 series hour glass. The hour glass debuted summer 2008 at the Red Square in Moscow. A 7-series car was suspended in the upper half, covered with “sand” that ran out continuously, giving view to the new car. 7

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The object is designed by an advertising agency that usually designs print media products for it’s clients. The BMW hour glass is an object that was created to be put into urban public space like one would compose a photoshop style collage in communication design. The eơect of it’s presence shall result from press photos in magazines. Only for the day of the presentation spectators on site are of interest.

Fig. 10 The iniƟal design of the BMW hour glass

I took care of the entire design of the object in the pitch phase, working on the design as well as solving the engineering questions. The pitch was won by our team basically because our proposal to build the hour glass without any primary facade structure like steel proƤles. The concept to use a self supporting acrylic shell structure was created based on Ƥndings of the preceding projects in mind:

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• Acrylic is a decent structural material • Bonding is not be considered for shell structures • The production techniques of curved panels are known and can be handled • Strain coming from temperature changes must be totally avoided Some further regards lead to the self supporting design concept:

Fig. 11 The structural principle of the acrylic shells

• The hour glass’ upper and lower half are rotational symmetric like a cupola or dome • A dome activates radial and ring forces • A hanging cupola has the same inner as the standing forces, but in opposite direction • The two shells do not need interconnection to be stable • A cupola can be reduced to a system of beams in radial, ring and diagonal direction • The beams can be inscribed into panels that are connected to each other 8

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

• Interconnections between panels close ring forces and transport the radial forces • One panel may be imagined as if it contained a set of beams in ring and radial direction plus braces • Interconnections must handle the shear forces between the panels The above regards lead to a concept of two almost identical self supporting acrylic shells, one standing and one hanging. They consist of individual double curved panels which are joint by connectors in the gap. Connectors are orientated in ring and in radial direction and provide some shear stiơness as well as they clamp together the panels to get a ƪush surface. The stress level in the acrylic panels is rather low as the forces spread, as it is characteristic for shells. Also the sensibility to buckling was found to be low as the position of the connectors were chosen to have a large distance from the panels edges, the potential weak point for loss of stability.

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Fig. 12 Stress concentraƟon occur only around the connectors

The elementary design goal for the connector was to allow individual thermal elongation in adjacent panels and prevent resulting strain between two connectors. A connector being entirely stiơ to shear forces would lead to lasting deformation or buckling resulting from thermal strain, as shear loads between two panels would sum up along a gap. No shear coupling on the other hand would make entire the shell instable. Fig. 13 The connectors are arranged to carry ring and radial forces

While a stiơ coupling is wanted in ring and radial direction in order to get a rigid shell and avoid excessive deformations, the shear stiơness of the connector should be low. Stiơ enough though to ensure 9

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

stability, yet soft enough to let the panels deform individually under diơerent temperatures, as it might result from partial exposure to sunlight. Finally the connector must be designed to Ƥt universally all the diơerent curved panels of the shell. The resulting connector couples the ring and radial forces by a ƪat steel bar and countersunk point supports, containing a rotating pin to adopt to the individual bending situation. In longitudinal direction the connector has high a stiơness. To couple the shear action between two panels, pins are provided that intrude into a slot in both acrylic panels, interlocking them. Each pin has a soft EPDM ring warped around that allows a certain movement under temperature. A countersunk plate forces the panels together for a lateral stability.

Fig. 14 The connector in detail

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All steel parts are separated from the acrylic by EPDM layers to prevent direct contact. A 5-axis router milled the connector’s foot print into the curved panels during the trim process. Excellent surface quality of the cut and milled areas is essential to provide a sound joint that can bear high loads without structural failure.

Fig. 15 TesƟng of the connector under tension and shear

Testing was done for the entire system and extra testing was performed for the bore and the point support. The reason for the extra testing was that the margin of safety for the dimensioning of the acrylic is rather large compared to steel. The steel parts failed far before the acrylic did break. The breaking force for bore proved to be around 60kN, giving a margin of safety of factor 10 and more. 10

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Assembly was successfully tested in Germany and was also uneventful in Moscow. The resulting glassed space inside the lower hour glass is very particular as it’s facade is almost immaterial or even invisible. The hour glass did it’s job well, and 180,000 silver colored balls that represented the sand, were rushing through the hour glass, unveiling BMW’s new top model to the public. The following 5 days nearly 100,000 spectators used the opportunity to climb the stairs to have a good overview over the red square and, by the way, to have a glance at the car. Fig. 16 FabricaƟon of the panels

Conclusion

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Technical design of facades and transparent shells fabricated of acrylic is strait forward if elementary design rules are followed. Engineering will usually require testing and close collaboration with a producer. Although acrylic is no alternative material to glass in every day building, it allows a wide range of application where the use of glass may be too expensive or too complicated.

Fig. 17 The Įnished object in Moscow

The true limiting factor is the inƪammability, which requires a sprinkler system or other special measures. Although Ƥre retardant substances may be used, their use is not recommend indoors. UnmodiƤed acrylic burns without toxic gasses and it produces very little fumes at all. Fire retardant modiƤcation does not prevent the material from burning, but produces toxic fumes.

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Fig. 18 The immaterial transparent shell generates a great spaƟal impression from the inside. What a pity there is no public entrance!

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Alternatives to acrylic are Polycarbonate (PC) and Polyethylene Terephthalate (PETG). Both materials may be considered similar to acrylic and may replace it. Both materials have a ƪame retardant certiƤcate for certain product types. On the down hand, PC is diƥcult to deform as it may store water inside it’s matrix that can produce vapor bubbles during heat forming. Milling and cutting is diƥcult as the material is more brittle. PETG has excellent deformation and milling properties, but it is softer than acrylic and it’s heat stability is lower, limiting the outdoor use. If in doubt if the use of acrylic is feasible from the structural point of view, it may be helpful to compare the material to other better known ones. The mechanical properties and design stress of glass i.e. are similar to those of aluminum (at least some sorts of it). Acrylic may be compared (with some limitations) to birch or beech tree plywood. Once you consider a design feasible in plywood, chances are good to get the job done in acrylic of similar dimension.

Fig. 19 For the show down 180.000 silver balls were rushing down in 4 minutes, unveiling the new 7 series model

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Acknowledged as an authority on the structural use of glass, BEng CEng MIstructE James O´Callaghan is perhaps best known for his highly innovative glass stairs, bridges and other structural elements in a range of Apple’s ƪagship retail stores including New York, London, Tokyo, Sidney and Beijing. Glass is still one of the most important materials in building envelopes and the structural boundaries still do not seem to have reached their limits.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-15

THINKING BIG WITH STRUCTURAL GLASS

James O'Callaghan

IntroducƟon

Eckersly O'Callaghan / Structural Engineering

It is the continuing aspiration of the writer to use glass to its maximum potential, to stretch the fabrication boundaries of glass such that less becomes more. It is inevitable that glass projects on a scale larger than the current fabrication limitations will result in the need for connections. While these connections can be sympathetically detailed, they detract from the writers ultimate goal of pure glass - less is more. It is with these ideals in mind that the subject of this paper came to be. The paper records the explorations and utilisations the writer has been involved during the development of concepts for oversized glass panels formed by recently inspired lamination techniques. The paper also discusses this technology and illustrates its use through projects built within the last few years.

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The paper then goes on to describe the on-going work the writer has been involved with in relation to structural glass stairs focusing on the scaleability of examples previously presented in papers.

Fig. 1 Apple Cube, New Zork

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Finally the paper will conclude with a discussion on the limitations of structural glass design and the appetite for change in this area, the challenges faced with respect to fabrication/realisation of projects and the increasing focus on economic justiƤcation.

The Big Glass Concept The concept for Big Glass was born out of need for a project in New York documented previously by the writer. The Fifth Avenue Apple Store entrance glass cube now stands a landmark in the city and its success as an example of a glass structure is demonstrable by its subsequent frequent references (Fig. 1).

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The structure of the glass box consists of a series of 10m glass columns supporting a grillage of glass beams supporting a glass panelled roof. The Ƥns also provide lateral support for the glass walls which are subject to wind loads. This being the case, it was concluded early in the design that the Ƥns would need to act monolithically and ideally would be a constructed as monoliths themselves. The fabrication limitations for glass at that time (2005-2006) were such that it was very diƥcult to source raw glass larger than 6m and no fabricators had autoclaves of any greater length than the maximum raw glass sizes. Why would they! So it came to be that early concepts of how to achieve large monolithic glass Ƥns were developed by the glass contractor Seele through discussions with the writer and the chosen glass fabricator BGT in Germany. The concept of creating 10m Ƥns with layers of 6m glass was developed by oơsetting each glass panel from its adjacent laminate, similar in eơect to the way plywood is made. This step lamination process of Ƥve glass plies ensures at least two layers of glass continue over a joint in the Ƥnal sheet (discounting any compression, tension or shear passing through the butt joint itself). The whole assembly of these oơset glass layers would be bound together by bolts between the plies, and reinforced by the interlayer for post-failure integrity, thus creating a monolithic structural element. The main challenge with this concept is that an autoclave of at least its total length was required to create it - at the time this was not available from within the glass industry. Not to be arrested by this limitation BGT investigated options outside of the glass industry and discovered that the aircraft industry catered for large laminations as a result of the need to laminate aircraft wings. In fact their autoclaves typically start at about 10m. Through testing and mock ups the techniques was perfected by BGT and then successfully implemented in the design and construction of the cube. These have now been installed for over three years and there has been no evidence of lamination deƤciencies. 16

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Advancing Big Glass A couple of projects which hit the drawing board after the cube in New York, also for Apple, presented opportunities to take the concept to the another level, both structurally very diơerent challenges but both had the similar ideal need for large glass panels with minimal glass-to-glass connection. The Apple Store Atrium in Sydney, Australia, encloses three storeys of a redeveloped tower block with a 4.5m roof across 20m of the building face (Figure 2, Figure 3).

Fig. 2 Apple Sydney atrium, internal Fig. 3 Apple Sydney atrium

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So the idea of developing panels up to 13.5m x 3m was explored. Again the concept of step laminating came to the fore in these explorations and it was conceived that three layers of heat strengthened glass of up to 8m x 3m raw sheets would be laminated to create the mega sheets of monolithic glass (Figure 4). While it was architecturally acknowledged that there would be a visible butt joint between the panels at controlled heights, this was an aesthetically superior alternative to splitting the glass with visible silicone joints. Critically, the glass itself acts as a structural shear wall, with shear shared between panels through the Ƥttings, which provides the lateral restraint. Crucially for the aesthetic, the ability to create these monoliths mitigates the need for mechanical connections within the height of each panel which the shear wall requires.

Fig. 4 Apple Sydney atrium, exploded splice connecƟons and laminaƟon

The Apple Store, Boston, MA, (Figure 6) has a very ambitious structural glass facade hanging from the roof of the building. As a consequence of this design the Ƥns are Ȟ, or hockey stick, shaped (Figure 5) to allow them to project from the building structural line and create a glass box gallery. These Ƥns are 13m tall and again because of their signiƤcant structural function it was deemed 17

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advantageous to form them as single monolithic elements. Using the same concepts and arrangement of Ƥve layers of heat strengthened glass of up to 8m tall were cut and laminated (Figure 7). The resulting Ƥns being too large to ship in a container, had to be shipped as open top cargo.

Fig. 5 Apple Boston hockey-sƟck Įns Fig. 6 Apple Boston facade

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In a departure from the structural principles of the Ƥns in the Cube and Sydney, where the splices are mechanically created through bolt holes in the glass, the interlayer plays a much greater role in Boston. The use of SGP in the hockey stick Ƥns is key in relieving high stress concentration over the laps and in the “knee”. This shear transfer between plies minimises the work done by the splice bolts to virtually zero, allowing the creation of Ƥns that would otherwise lose the purity of uninterrupted glass. The contractor for both these projects was again Seele and prior to the designs above being conceived they took the commercial decision to invest in fabrication facilities themselves. This lead to a new factory and an autoclave of 12m long. The unfortunate timing consequence of this autoclave delivery was such that it was not suƥcient for the fabrication for the panels needed for the Sydney project. Sedak, the company formed by Seele to fabricate glass, reacted quickly and ordered a newer larger autoclave of 15m to accommodate the panels cited for Sydney. A brave and bold move on their part and fundamental to the success of the Sydney glass facade. Two of the signiƤcant challenges of such large glass elements beyond fabrication is shipping and installation. Clearly, these panels are of signiƤcant value and as such particular attention to the way

Fig. 7 Apple Boston facade, exploded splice connecƟons and laminate panels

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they are handled is imperative. Seele invested in new glass handling equipment that had to be designed from the ground up to handle such large elements - in itself an engineering marvel. Transportation to Sydney via deck cargo for the mega panels took three months which had huge implications on the fabrication schedule and the replacement theories.

Stairs Over the last Ƥve years the writer has been working with Apple on the design and realisation of glass stairs in their retail stores throughout the world. This has been well documented in previous papers and as such this section of paper acts an extension to these previous recordings. We developed a circular stair design for the Apple Store on Fifth Avenue that supported itself using a series of glass hockey stick column/cantilever Ƥns, primarily to allow the central core of the stair to house a glass elevator. The stair negotiates two levels between the basement level store and the street level exit.

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Another project in New York on 14th Street and the project previously mentioned in Boston followed, both of which had the need for a stair that negotiated three levels, the ground, Ƥrst and second ƪoors (Figures 8-10). The architectural layouts favoured a circular stair and to that end, the design team was presented with a challenge to engineer a double height structural glass helical stair.

Fig. 8 Double height helical stair, Apple 14th St, New York Fig. 9 Double height helical stair, Apple Boston, MA., fully loaded

The structural approach to a helical stair that negotiates more than one level diơers in that the designer needs to be conscious that any supporting system cannot interfere with the ƪow of the stairway above. This means the system of cantilevered Ƥns used in the Fifth Avenue staircase would not be possible due to the interference 19

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the vertical Ƥns would have in the stairway itself. A hung stair was also considered but ruled at the time due to the challenges of the diơerential movements both lateral and vertical, between ƪoors.

Fig. 10 Stair landing: canƟlever beams span out of the central core, picking up the outer stringer

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Given these challenges and limitations a structure was devised whereby the stair would be primarily supported via a central glass core and the outer glass stringer supported via a series of cantilevering glass beams using the glass walls of the core as their fulcrum. The central core is gravity supported at its base and therefore in order to accommodate the diơerential deƪections between ƪoor levels the glass landings had to be devised and detailed such that they would pivot between the core and the ƪoors. The ƪoor supporting the stair was locally rebuilt or designed accordingly to resist the higher vertical loads imposed by the stair and minimise deƪections to an absolute at the base. The basic structural principle of the stair, that of transferring vertical loads into the ground ƪoor slab, is as follows: a) vertical (crowd) loads applied to the glass treads (Figure 11) which span between the central glass core (Figure 14) and outer glass stringers (Figure 12); b) glass stringers simply span between glass beams (Figure 13) as two mechanically spliced panels; c) glass beams cantilever out from the glass core, with push/pull support from the near and far edges of the core; d) uplift and downward forces transfer through the glass core into ground anchors. Lateral stability for the stairs is achieved through direct connection to the slab through the landing panels and through stainless steel collars at intermediate landing levels which mechanically splice the curved chemically tempered laminated glass panels. These collars are designed to transfer direct vertical load from panels above and 20

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Fig. 11 Glass tread, simple span Fig. 12 Mechanically spliced glass outer stringer, simple span

Fig. 13 Glass beams, canƟlever Fig. 14 Glass core, Įxed base

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accommodate increased loads as overturning moments (imbalanced loads), storey drift and torsion loads are resisted by the core. Principally all the glass elements that form the glass structure are joined via stainless steel Ƥttings and load bearing holes in the glass. A great deal of research in to the bearing capacity of holes in various glass types has been undertaken by Seele and as designers we have limited loads transferred via this method safely within these boundaries. The performance of glass holes in bearing is an interesting subject in itself and something that remains inconclusively documented. To that end we have to be cautious in our approach to take in to account the limited data and the results we model in FEA software. On this point, for holes of a critical nature or those carrying large pivotal loads, it is essential to carry out solid modelling to predict stress concentrations through the body of the glass and compare this to test data. 21

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Having completed these types of studies, we also limit stress within the parameters suggested by the code in which we are working. This is not necessarily straight forward because codes such as ASTM in the US do not consider direct bearing (particularly through tension) within a bolt hole, and do not suggest reduction factors that we know come in to play when considering bearing through holes. Experience over time has taught us how to best interpret the spirit of the various codes and apply them appropriately to glass structures. More work needs to be done in this area with codes needing to be developed in a uniform and comprehensive manner. When designing stairs of this and other natures it is also important to keep an eye on the predicted frequency of the stair. The goal is always to have the natural frequency above 4Hz as a minimum and often we Ƥnd the structures close to this limit. The helical stairs less so as their inherent rigidity and compact nature facilitates a reasonable response. However, many of the straight stairs are much harder to keep above 4hz and detailing becomes critical to ensure that actual performance of the stairs does not deviate signiƤcantly below the response predicted through design.

A QuesƟon of Scale

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The writer has been pushing the boundaries of scale over the last few years and the projects described in this paper demonstrate the limit state today. While this has been a worthy pursuit and it has enabled the glass fabricators to think outside of the boxes they normally think within, it needs to be questioned further.

Fig. 15 Delivery of a 15m autoclave

All the glass used in the examples comes in a raw state, which we know is from the ƪoat line. Therefore the Ƥrst limitations are those of the ƪoat glass producers. The length and width that glass is cut to is normally limited in the region of 6m x 3m, some now are making sheets available at larger sizes up to 8m and a very few up to 12m.

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These larger sizes are very rarely produced, perhaps twice a year and for good reason. They are not typical and are not in high demand, further the handling of these sheets is very diƥcult and results in frequent breakage. More producers could run the 12m sheets if demand increased, most are actually limited by the overhead cranes they have to move the glass around. Clearly, in most instances these could be upgraded at a relatively modest cost. Secondly there are the limitations of glass processing. The tempering ovens have gradually increased in size over the last few years such that there are facilities that can temper to 8m in Europe and up to 14m in China. Limitations on width tend to be typically at the 2.7m mark with a very few touching 3m max. Laminating autoclaves have not grown dramatically industry wide, but the writer and the projects sited prior have resulted in at least one fabricator scaling up to signiƤcant autoclave sizes at 15m x 3m.

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Handling and shipping are a signiƤcant challenge the larger glass becomes and this frequently becomes a limiting factor. Overhead cranes and glass handling equipment is not typically scaled for glass greater in size that the limits of the tempering oven – why would it be! Shipping glass is generally limited to container sizes, which at 15m is close to the size of some of the glass elements used in project described prior. Further, open deck cargo can be an option but with glass that big the risk of breakage during transit becomes signiƤcantly more costly to insure and manage the consequences of.

Fig. 16 Jumbo glass installaƟon

Finally comes the Ƥnancial viability factor. While there are a few clients in the world that are interested in pushing these boundaries, the are fewer who are prepared for the cost. With increased scale comes more complex fabrication, longer lead times for raw glass, 23

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limited suppliers, increased shipping and handling risks, increased breakage during fabrication. All these factors conspire to result in much higher end costs and the need fordeep pockets. For the reasons above and particularly in these challenging economic times there are few who can meet the challenge of larger glass elements and hence glass structures. The appetite has been slowly growing and there are people interested in sponsoring such developments, but the writer suspect these ambitions will be slightly curtailed to be in line with the move towards more the sustainable and eƥcient developments of the future.

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Despite this and the challenging times ahead the writer remains determined and focused on innovative structural glass design and looks forward to reporting on his adventures in this arena at future conferences.

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Textile building envelopes – foils and membranes - are becoming increasingly applied as many projects show, such as the new roof for Wimbledon court, the new football stadia in South Africa and the swim stadion in Beijing. Prof. Dr.-Ing Jan Cremers is Director Technology at Hightex GmbH, one of the leading companies in architectural foils and membranes. Since 2008 he is also Professor at the Faculty of Architecture, Hochschule für Technik Stuttgart. He describes the development of this rather new technology and gives and outlook over the potential of this approach.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-27

DESIGNING THE LIGHT ͳ NEW TEXTILE ARCHITECTURE

Jan Cremers

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HFT StuƩgart / Hightex Group

Besides glass, a variety of other translucent and transparent materials are just as highly attractive to architects: plastics, perforated metal plate and meshing, but maybe most of all membrane materials which can also withstand structural loads. Earlier applications of textile materials have served the purpose to keep oơ the sun, wind, rain and snow while oơering the advantage of enormous span widths and a great variety of shapes. The development of high performance membrane and foil materials on the basis of ƪuoropolymers, e.g. translucent membrane material such as PTFE-(poly tetraƪouroethylene) coated glass Ƥbres or transparent foils made of a copolymer of ethylene and tetraƪuoroethylene (ETFE) were milestones in the search for appropriate materials for the building envelope. The variety of projects that oơer vastly diơerent type and scale shows the enormous potential of these high-tech, high performance building materials which in its primordial form are among the oldest of mankind. Their predecessors, animal skins, were used to construct the very Ƥrst type of building envelopes, namely tents. Since those days, building has become a global challenge. Usually building structures are highly inƪexible but long-lasting and they account for the largest share of global primary energy consumption. It is obvious that the building sector has to develop international strategies and adequate local solutions to deal with this situation. Principally, building envelopes as facades or roofs are the separating and Ƥltering layers between outside and inside, between nature and adapted spaces occupied by people. In historic terms, the primary reason for creating this eơective barrier between interior and exterior was the desire for protection against a hostile outside world and adverse weather conditions. Various other requirements and aspects have been added to these protective functions: light transmission, an adequate air exchange rate, a visual relationship with the surroundings, aesthetic and meaningful appearance etc.

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Accurate knowledge of all these targets is crucial to the success of the design as they have a direct inƪuence on the construction. They determine the amount of energy and materials required for construction and operation in the long term. In this context, transparent and translucent materials play an important role for the building envelope as they not only allow light to pass through but also energy. In the last few decades, rapid developments in material production types (e.g. laminates) and surface reƤnement of membrane materials (e.g. coatings), along with advanced CFD and other computer simulation methods, have been constant stimuli for innovation. As a result, modern membrane technology is a key factor for intelligent, ƪexible building shells, complementing and enriching today’s range of traditional building materials.

Modern membrane materials for building envelopes and second skin facades – a real alternaƟve to glass

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The Centre for Gerontology, a spiral building in the South of Germany, houses a shopping area on the ground ƪoor and provides oƥce space on the upper ƪoors (Fig. 1).

Fig. 1 ETFE Second Skin Facade, Centre for Gerontology (GTZ), Bad Tölz © Copyright Hightex, D-RimsƟng

A special characteristic is the horizontal walkway arranged outside of the standard post and rail facade which forms the thermal barrier. The walkway is protected from the weather by a secondary skin. The complex geometry, the creative ideas of the architect and the economical conditions have been a special challenge and led to the implementation of a highly transparent membrane facade with 28

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

high visibility between the inside and the outside due to its much reduced substructure. Moreover, because of this ‘climate envelope’, an energy saving intermediate temperature range is created as a buơer, which can be ventilated naturally by controllable, glazed ƪaps in the base and ceiling area. This secondary skin has a surface area of approximately 1550 m2 and was constructed by the Hightex Group as a facade with a prestressed single layer ETFE membrane with a specially developed Ƥxing system using lightweight clamping extrusions. This was the Ƥrst implementation of this type of facade featuring a second skin made of single layer stressed ETFE membrane anywhere in the world. Project-Data: Centre for Gerontology (GTZ), Bad Tölz, Germany Architect: D.-J. Siegert, Bad Tölz Year: 2004

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Printing the transparent membrane with a silver dot fritting pattern serves as light scatter and sun protection. The ƪouropolymer-plastic ETFE used, which until then was mainly used for pneumatically prestressed cushion structures (e.g. the Allianz-Arena in Munich), has a range of outstanding properties which predestinates it for building envelopes: - The life expectancy is far beyond 20 years if the material is used according to speciƤcations. - The ETFE-membrane is ƪame retardant (B1) according to DIN 4102 and other international standards. Tests have shown that, due to the low mass of the membrane (which is only between 0.08 and 0.25 mm thick, with a density of approx. 1750 kg/m3); there is minimal danger of any material failing down in the event of Ƥre. - The ETFE membrane is self-cleaning due to its chemical composition, and will therefore retain its high translucency throughout the entirety of its life. Any accumulated dirt is washed oơ by normal rain if the shape and the connection details are designed correctly. - The material is maintenance-free. However, inspections are recommended in order to Ƥnd any defects (for example damage caused by mechanical impact of sharp objects) and to identify and repair such damage as early as possible. It is also recommended that the perimeter clamping system and the primary structure are regularly inspected. - The translucency of the ETFE membrane is approximately 95 % depending on the foil thickness, with scattered light at a 29

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proportion of 12 % and direct light at a proportion of 88 %. Compared to open air environment, the dangerous UV-B and UV-C radiation (which causes burning and is carcinogenic) is considerably reduced by Ƥltration. - ETFE membranes can be 100% recycled. Additionally, this membrane system is extremely light (about 1/40 of glass). The ETFE system is unmixed and therefore separable. - With suƥcient production quantities this material may also be supplied in a range of colours. - In order to reduce solar gain or to achieve speciƤc designs while maintaining the transparency, two dimensional patterns can be printed on the membrane. - Because of the zero risk of breakage, unlike glass, no constructive limits have to be considered when used as overhead glazing.

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The outstanding properties of this membrane material ensure a constant high-quality appearance lasting over decades. This also applies to PTFE coated glass fabrics which can not only be applied on large roof structures but also on translucent facade areas to proƤt from the high light design quality. One of the most famous examples of such an application is the large PTFE/glass facade of the Burj al Arab Hotel in Dubai (executed by Hightex in 1999). Of course the materials can be mixed according to design and functional requirements. The 900 m2 facade of a new building in Switzerland showcases this option: For the Miroiterie Flon Lausanne, unique triangular membrane cushions have been combined with smaller glazed areas (Figs. 2, 3). The building is designed to house high level commercial shops and the pneumatic four layer structure with a very low U-Value of only 1.3 W/m2K also features extremely high light transmission due to the innovative material mix within the cushions: The outer skin of PTFE/ Glass is combined with three highly transparent inner ETFE layers. The cushions are run at two diơerent internal pressures and can be illuminated from inside during the night. Generally, light is an important design feature which enriches the unique possibilities in shape and emphasises the immateriality of the delicate skins in membrane architecture.

Fig. 2 PTFE/Glass and ETFE cushions, Miroiterie Flon Lausanne, Lausanne © Copyright Hightex, D-RimsƟng

Fig. 3 PTFE/Glass and ETFE cushions, Miroiterie Flon Lausanne, Lausanne © Copyright Hightex, D-RimsƟng

Project-Data: Miroiterie Flon Lausanne, Lausanne, Switzerland Architect: Brauen & Wälchli architecture, Lausanne, Switzerland Year: 2007 The project ‘Oasis’ gives evidence of this beautiful eơect: The outer ETFE skin is printed with silver dots (Ø 4.2 mm, cover ratio 65%) to provide reƪection (Fig. 4). 30

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Project-Data: OASIS - Lifestyle Building Sculpture Architects: LiteHouseOne, Munich Year: 2007

Fig. 4 Lifestyle Building Sculpture OASIS - Exterior view at night ©Copyright LiteHouseOne, DMünchen

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A modular approach to membrane and foil facades Most projects incorporating textile constructions are prototypes and have an extremely high share of innovative aspects, which have to be solved and also impose a certain risk to the designer and the executing companies. Therefore it looks promising to closely look into the options of following a modular approach. Most of the activities are still in an R&D phase, however, a Ƥrst important building has been realised: For the Training Centre for the Bavarian Mountain Rescue in Bad Tölz a modular facade has been developed together with the architect Herzog+Partner which comprises of approx. 400 similar steel frames with a single layer of pre-stressed ETFE foil. The project is depicted in Figs. 5-8.

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Fig. 5 Modular ETFE Facade, Training Centre for the Bavarian Mountain Rescue / Bad Tölz © Copyright Hightex, D-RimsƟng

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Project-Data: Bergwacht Bayern - Training Centre for the Bavarian Mountain Rescue / Bad Tölz Architect: Herzog + Partner BDA, Munich Year: 2008

Figs. 6, 7, 8 Modular ETFE Facade, Training Centre for the Bavarian Mountain Rescue / Bad Tölz Fig. 7 © Copyright Hightex, DRimsƟng Figs. 8 & 9 © Copyright Verena Herzog-Loibl, D-München

Flexible photovoltaics integrated in translucent PTFE- and transparent EFTE-membrane structures: ‘PV Flexibles’ Hightex is working together with its sister company SolarNext on signiƤcant innovations to improve building with advanced membrane material. Among them are new ‘PV Flexibles’ that are applied on translucent membrane material or fully integrated

Fig. 9 ETFE cushion with PV Flexibles © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

in transparent foil structures (Fig. 9). The technology being developed is ƪexible amorphous silicon thin Ƥlm PV embedded into ƪouropolymer foils (Fig. 10) to be used on PTFE membranes and ETFE foils. These complex laminates can be joined to larger sheets or applied in membrane material and be used on single layer roofs or facades. They can also be used to replace for example the toplayer in pneumatic cushions. Fig. 10 ETFE encapsulated photovoltaics: PV Flexibles © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

Fig. 11 PV Flexibles on membranes: solar shading and power supply © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

PV Flexibles do not only provide electricity - in an appropriate application in transparent or translucent areas it might also provide necessary shading which reduces the solar heat gains in the building and thereby helps to minimise cooling loads and energy demand in summer (Fig. 11). This synergy eơect is very important because it principally helps to reduce the so called balance of system (BOS) cost for the photovoltaic application. In a report, the International Energy Agency gives an estimation of the building-integrated photovoltaic potential of 23 billion square meters. This would be equivalent to approx. 1000 GWp at a low average eƥciency of 5%. Up to now solutions for the integration of photovoltaic in free spanning foil and membrane structures have not been available, although these structures are predestined for the use of large scale photovoltaic applications (shopping malls, stadium roofs, airports etc., cp. Figs. 12 & 13).

Fig. 12 PV Flexibles integrated into texƟle membrane material, StuƩgart Stadium (Rendering) © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

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Fig. 13 The membrane roof of StuƩgart Stadium (status quo) © Copyright Hightex, D-RimsƟng

PV Flexibles allow addressing market segments of the building industry which are not accessible to rigid and heavy solar modules in principle. The basic PV cell material is very thin (only approx. 51 Ɋm) and lightweight (Fig. 14). Therefore, it is predestined for the use in mobile applications. But as it is fully ƪexible at the same time, it is also an appropriate option for the application on membrane constructions. Fig. 14 Flexible a-Si thinĮlm PV on polymer substrate (51 ђm) © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

PV Flexibles can be directly integrated in ETFE and PTFE membranes for the generation of solar energy, for PTFE see Figs. 15 and 16. First applications have been executed successfully in the South of Germany and are currently monitored with regard to their output 33

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

performance (Figs. 17 and 18).

Figs. 15, 16 PTFE/glass texƟle membrane with PV Flexibles © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

Figs. 17, 18 ETFE cushion with PV Flexibles, Oĸce Building, RimsƟng © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

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Highly eīecƟve translucent thermal insulaƟon for membranes Compared to glass, pneumatic supported and tensile membrane structures have the big advantage of their unequal lower weight. Thus the material complexity and therefore the visual appearance of the supporting structure can be reduced strongly. Nevertheless a principle problem of membrane structures is the low material thickness of partly less than 0.2 mm. Therefore, despite the low thermal conductivity of plastics, thermal insulation properties are limited. If required the solution lies either in the construction area (multiple layer constructions with air cavities between layers) or in the use of insulation materials such as conventional mineral Ƥbres or transparent/ translucent thermal insulation as a light transmitting variation. As high light transmission is a key factor in choosing membranes, opaque insulation materials are rarely desired. Hence in our opinion, one of the most promising solutions is the use of translucent silica-aerogel (Fig. 19). This innovative material is available as granulate or blankets. Both options can be used as translucent thermal insulation in membrane structures. The light transmission degree of an aerogel layer is approximately 80% per cm layer thickness installed, while the insulation property is twice as good (l= 0,018 W/mK) compared to polystyrene foam (Fig. 20). Additionally, the aerogel material is Ƥre-proof, environmentally friendly, recyclable, thermally stable up to 600°C, UV-stable, hydrophobic, durable, and is once again, predestined for use in the building sector.

Fig. 19 Granular silica aerogel, Nanogel® by Cabot CorporaƟon © Copyright Cabot CorporaƟon, USA

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Fig. 20 InsulaƟon values of exisƟng building insulaƟon products (Values are per 1 Inch/25 mm of material): R-Value: North America (hr•Ō2F/ Btu) U-Value: Europe (W/m2K) © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

For the competition entry of the Georgia Institute of Technology in the Solar Decathlon 2007 (Fig. 21), SolarNext developed and completed together with Hightex a concept for a highly insulating, translucent ceiling structure, featuring both, outstanding energetic and aesthetic properties.

Copyright © 2010. IOS Press, Incorporated. All rights reserved.

Fig. 21 Aerogel insulated ETFE roof (top view)

To be able to design the constructive elements of the ceiling as simple as possible, the structure is parted into two, function based, separated levels. The lower level consists of insulated panels, which act as the ceiling, while the upper level is the skin that provides the weather protection. The lower level consists of nine ceiling panels with a size of approx. 4 x 1.5 m. These are made of a cross-sectional optimised, thermal split framework structure Ƥlled with aerogel. The result is a light ceiling with a homogeneous appearance at a transmission degree of approximately 20% and a U-value of less than 0.3 W/m2K, cp. Figs. 21 - 23. Project-Data: Contribution to the international competition ‘Solar Decathlon 2007’ Architect: Georgia Institute of Technology, Atlanta, USA Year: 2007

Fig. 22 Aerogel insulated ETFE roof (interior view)

Fig. 23 Aerogel insulated ETFE roof (principle secƟon) images Figs. 23-25 © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

FuncƟonal coaƟngs for membranes The development of functional coatings on membrane material has a special impact also. In the past this has led to the development of low-E-coated and translucent PTFE-Glass fabric (emissivity less than 40%) which has been applied for the Ƥrst time by for the new Suvarnabhumi Airport in Bangkok, Thailand which was opened at the end of 2006 . The development of transparent selective and low-emissivity functional layers on ETFE Ƥlm consequently has been the next step to allow accurate control of the energy relevant features of the material (Fig. 24). The Ƥrst project to make use of this newly developed type of material will be the large shopping mall "Dolce Vita Tejo" near Lisbon in Portugal with a roof area of approx. 40,000 m2 (Fig. 26). Here, the transparent, selective low-E-coatings together with the speciƤc north-shed-like geometry of the foil cushions help to realize the client's wish to have as much light as possible but reduce the solar-gains at the same time: Customers shall feel like being outside but in an environment of highest climate comfort (Fig. 25).

Fig. 24 ETFE foil with transparent selecƟve low-E coaƟng © Copyright SolarNext AG/ Hightex Group, D-RimsƟng

Project-Data: Shopping Mall "Dolce Vita Tejo", Lisboa, Portugal Architect: Promontorio Architects, Lisboa, Portugal Year: 2009

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Fig. 25 Building Envelope Concept, Shopping Mall Dolce Vita Tejo, Lisboa, Portugal © Copyright Promontorio Architects, P-Lisboa, and Transsolar, D-StuƩgart

Fig. 26 Shopping Mall Dolce Vita Tejo, Lisboa, Portugal (Rendering Interior) © Copyright Promontorio Architects, P-Lisboa

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Impact on the design process of building envelopes

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The variety of new technologies developed in the Ƥeld of foil and membrane construction and materials are deƤnitely expanding and enriching architectural design options to realize advanced technical solutions and new shapes. However, a solid background of know-how and experience is needed to derive full advantage of the innovative and intriguing oơers. As an architect or designer you can only feel comfortable with technologies of which you have at least a basic understanding. This actually poses a great challenge to the educational system for architecture but also to the membrane industry, which is a comparable small sector. At the end, every new product and technology has to be introduced to the market and made known to the architects and designers, which needs resources for marketing activities and promotion. Also, it requires a great deal of pre-acquisitional activities of direct consulting to planners in early design stages to enable the development of functional and technical sound and also economical solutions. Therefore, it will be a long (but still very promising) road to follow until the technologies described here will be commonly used in the building sector and become something that could be called a 'standard'.

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As a specialist in facade design and the execution of special constructions, Prof.dr.ir Mick Eekhout describes the development of a new facade that includes structural composite materials. Mick Eekhout is head of the chair Product Development at the TU Delft, Faculty of Architecture, and his company Octatube has executed many famous buildings in glass, steel and composite materials.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-39

DEVELOPMENT OF A SUPER SLIM FACADE SYSTEM FOR INHOLLAND POLYTECHNIC, DELFT Mick Eekhout

Abstract

TU DelŌ / Product Development

Design, engineering, prototyping, production and realisation of an innovative insulated facade system with integrated prestressed cable stabilisation with application for a polytechnical school INHolland with a laboratory for composite materials in Delft, NL. The process consisted of 4 major phases:

Peter van der RoƩen Octatube InternaƟonal b.v.

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• • •

The experimental (‘Sia Raak’ subsidy) design phase; The experimental design and engineering phase; The production and realization phase of the commercial facade system; • The production and realization of the original composite facade system. The initial conceptual ‘wild idea’ for the INHolland project by architect Rijk Rietveld, New York, was elaborated through diơerent design brainstorms towards a radical innovative system for ultra-slim glass facades. In this facade system insulated glass panels of a depth of maximum 50 mm are integrated with internal pre-stressed structural composite cables, stabilising the facade against wind forces. Dead weight to be taken over by vertical deadweight rods in between the vertical silicone seams between the panels. The insulated glass panels are sealed by composite spacer frames. Many diơerent solitary tests were done with the sealing and the carbon Ƥbre components, with adhesion of silicone sealant on the carbon Ƥbre frames and on the perforation of the carbon Ƥbre used through the frames. In the actual engineering phase structural analysis was performed and tests on several levels were executed. The composite frames were substituted by conventional metal frames. The system is suited for facades of 14 m high. Under wind loading the facade system deƪects as a sail membrane, with the deƪections at the perimeter taken up by adequate detailing at the sides so that no breakage occurs and the membrane facade is regarded as fail safe system. A prototype of the corner was constructed and tested for practical approval. Due to the refusal by the glass panel manufacturer to supply a guarantee on inadequate number of tests with inadequate quality, the integrated system had to be changed into a duo-system with internal pre-stressed cables and integrated dead weight suspension rods. The project consisted of 2 large facades executed in this manner and one more narrow segment facade exactly in the experimental mode, for performance evaluation. The facade had to keep in pace with the progress on site. The building was opened in September 2009. 39

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

IntroducƟon All-glass facades for larger spans need stabilising systems for wind and deadweight loadings. Frameless facades show ultimate visual lightness as daylight is not hindered by obstructing steel purlins and aluminium framing proƤles. In an experimental process of design and development of a composite facade for the INHolland Polytechnic in Delft a system was selected and developed in which pre-stressed cables were developed for taking up horizontal wind forces while deadweight suspension rods transfers the vertical deadweight of the system. Both types of pre-stressed cables and suspension rods were initially designed to be located within the thickness of the insulated glass panels. The pre-stressed aramide cables are located inside the tubes in the inner spaces of the double glass units, while the suspension rods are located in the end zones, seams, between the panels. The development of the process highlights the many hindrances and risks involved in this dense integration of the two independently developed ‘alien’ components: the double glass units and the pre-stressed cables. The experimental design scheme and the realistic engineering answer on that are described in this contribution.

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FIRST PHASE: THE EXPERIMENTAL SIA-RAAK DESIGN PROCESS The INHolland Polytechnic has a Composites Laboratory that wishes to pronounce itself to the world. In 2007 an experimental design process was started to design a composite glass facade system with the aid of members from the Polytechnic School, the Composites Laboratory (dr.Michiel Hagenbeek), two professors of the Delft University of Technology (prof.dr.Ulrich Knaack and prof.dr.Mick Eekhout) and a number of industries (Octatube and Asahi Glass Company) and advisory engineers. A major role was played by the project architect of the new Polytechnic School in Delft Rijk Rietveld of New York (www.rietveldarchitects.com) who challenged the development team, by his very design of the School building, to design an innovative composite glass facade system, as the facades in his design could function as the zero-series of application. See Ƥg.1. However, the architect had ‘wild ideas’ that in combination had a too high number of experimental challenges that in the Ƥrst phase hardly could be met. This experimental process started after the award of a Dutch research grant ‘SiaRaak’, to stimulate research at Polytechnical Schools. The immaterial goal of the approved Sia Raak research program of INHolland was to promote the use of composites in architecture and to transfer and adapt the knowledge of these materials by designing a glass-composite facade system. A challenging starting point was: 40

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Fig. 1 Impression of the living composite glass facade (image Rietveld Architects).

“which knowledge and experience has to be gained to come to applications of composites in glass facades for architecture?”

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Composites oơer a combination of durability, freedom of creating shapes and a high strength and stiơness per unit weight. In the last 2 decades in architecture particular interest arose for facades without metal window frames. This makes it possible to create highly transparent glass facades, leading to transparent architecture. Material goal of the research program was to develop a facade system with a new combination of glass and composites. The initial idea of the architect was to introduce solid composite rods of 50 x 300 mm in between glass panels in half-brick fashion to improve the structural stability of the facade panels and of the facade as a whole. But this suggestion did not prove to be useful for a realistic invention, even after further development. The ambition of the INHolland Sia Raak-program was to research the feasibility of glass-composite facade systems. In this process the transfer and adaptation of knowledge on composites between design and engineering companies, co-makers and knowledge institutions was foreseen. After the initial phase the target became to develop building concepts, as well as spreading the knowledge, best and bad- practices. And to improve the education on composites. Parties involved were INHolland architect Rijk Rietveld, TU Delft, TNO Gluing Institute of TU Delft and Syntens, Octatube International, and Asahi Glass Company and others. The grant enabled the development team members to brainstorm for a year with changing success to develop a more of less realistic scheme for an integrated composite facade as a compromise between the 41

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

wishes and capacities of the architect, the Composites Laboratory and the building industry members During the process many meetings did not produce a leap forward, due to the contradictory demands and wishes of the team members involved and the general shyness in these brainstorms, caused by uncertainties of the global experiment. The Ƥnale came into sight when the suggestion was seriously drafted on the whiteboard to integrate the supporting and stabilising cables inside the air volume of the double glass units. They were seen as sealed oơ by a composite framework of four spacers in stead of the usual metal spacers. The composite spacers themselves were integrated with composite tubes for the penetration of the composite cables. These composite elements formed the point of invention. This composite glass construction had to be developed intelligently and with care so that from this originally ‘wild idea’ a solid and trustworthy technical solution could be developed on this idea. On behalf oơ the development team a patent application was Ƥled by INHolland, with the penetration of the cables through the air cavity as its primary invention. The usual and quite linear product development methodology as described in the book ‘Methodology for Product Development in Architecture’ [Ref. 1] showed many loops and feedbacks.

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The central design concept resulting from the Ƥrst phase of experimental design was to stack the double glass panels, have them penetrate by vertical cables spaced 600mm carrying the wind load and with a suspension system of steel rods through the vertical joints between the glass panels. See hand sketch in Fig. 2.

Fig. 2 The set-up of the experimental facade concept

Figs. 3, 4: Sketches from brainstorm sessions.

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Fig. 5 Sketches from the brainstorm sessions

The experimental design also contained a large number of small scale prototype tests of the glass panels, the adherence of the sealant to the composite spacers, the air-tightness of tubes and tubular end connections and Ƥnally a full scale prototype of a segment of the designed facade application in the new premises: 6.0 m high and 4.5 m wide facade segment with pre-stressed cables and penetrations of aramide cables through composite spacers in double glass units. The experimental aspects resulting from the Ƥrst experimental design phase to the prototyping development phase were threefold (see Fig. 3 and 4): • The insertion of the composite tubes, penetrating trough top and bottom spacers ; • The perforated weakness of the spacers and the overall stiơness of the glass panels; • The bonding of the silicone and other sealants to the composite and glass surfaces.

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Fig. 6 Overall view of the mock-up.

Because the cables penetrating the spacer of the insulated glass special holding carbon tubes are foreseen, sealed oơ air-tight, to create an air-tight box of the insulated glass. The architect was attracted to the high tech look of the resulting system and was inclined to compromise many of his further wishes. The second function of the tubes, in a part of the facade, is to transport the dead weight of the facade to the foundation as the tubes would stick out through the insulated glass panels and the deadweight would be transferred by stacking the glass panels on top of each other. In this way two functions are integrated in these tubes: holding the cable and leading oơ deadweight. It was foreseen that the dimensions of the tube, cable and spacer are synchronized with extremely small tolerances. The composite spacers had to be developed to obtain a real overvalue of the composite spacers over the metal ones. The end of the Ƥrst experimental design phase was in fact the full size mock up in the factory of Octatube, on the other side of the street as the actual INHolland building under construction. See Ƥg.5 The mock-up was used for obtaining experience with pre-stressing of the aramide cables and stacking and tolerances of the glass panels. See Fig. 6 and 7.

Fig. 7 Detail of the mock-up

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EXPERIMENTAL ENGINEERING AND PROTOTYPING PHASE

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After the initial design phase in summer 2008 Octatube, up to then one of the design team partners, was asked to make a quotation for the designed system. At that moment free brainstorming Ƥrst phase changed into a potential dangerous engineering and prototyping second phase. Now it became really serious and Octatube took up the challenge Ultimately the client expected a fully guaranteed facade system, developed up to a trustworthy level of maturity. The process was now connected with the execution of the building of INHolland as the prime application. Deadline of the building was foreseen as opening in September 2009, the starting date of the new school year. Wind loading on the facade as a whole was to be taken up by vertical pres-stressed cables. As these cables are ƪat and quite in contradiction with the usual engineering practice of stiơ structures, the system would work as a linear cable system with no structural depth, acting as a sail as it were. It would have large deƪections as a consequence. The structural action of the individual glass panels would be to bend in a polygonal line under wind loading, the glass panels would act as stiơ members in a vertical chain. In the detailing the degree of movement between the glass panels was to be regarded carefully, not to lead to breakage of any kind in the glass panels. The individual glass panels were regarded as multiple supported against wind force by the continuing cables in horizontal direction. The development of the carbon Ƥbre tubes through the panel frames was for a long time quite insecure. Hence at that moment in time it was decided that the deadweight would be transferred though vertical tensile action to the top of the facade, rather than via a downward action to the foundation. This was reached by the introduction of vertical stainless steel suspension rods in between the vertical seams, within the central space to be sealed oơ from both sides with silicone sealant and hence invisible. Fig. 8. The consequence of stacking these cables was the vertical seams had to be in line, contrary to the brick-mode proposed by the architect, which still was kept in the full-size prototype. The principal of the 13,2 meter high facade is based on a sail. The insulated glass panels have at the horizontal seams the freedom to rotate slightly under wind loading. The glass panels are tied in vertical direction like a chain around the aramide cable. The horizontal wind loads are transferred by these cables to both end: the top of the building and the bottom, near the foundation. With extreme wind conditions, appearing statistically only every 50 years, the facade is supposed to deform 330 mm maximal inward and 330 44

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

mm outward without any problems. After investigation on the market the composite cable was selected. Phillystran HPTG cables consisting of a high modulus elasticity yellow aramide Ƥbre core in parallel construction, protected by a black extruded polyethylene jacket. The cables have an excellent resistance for Ƥre and changing loads. The common contemporary applications are bridges, towers and rigging for sailing yachts. The idea was conceived that during installation of the facades the glass panels are temporarily attached to a complete scaơolding on the inside of the building. The feeding of the cables would occur from the top downwards. The pre-stressing and certiƤcation of suƥcient pre-stress would follow later. Fig. 8 Engineering set-up of aramide cables inside the double glass panel

By placing the cables in the spacer of the glass the system is, structurally seen, very eƥcient for the glass panels. Structurally each glass panel has multiple supports by the cables. Therefore deƪections and stresses in the glass planes are quite low. Out of reasons of safety all glass panels are not chosen to be fully tempered only, but laminated form two fully tempered glass panels. This system would result in a facade with a super minimal thickness of only 50 mm! Outside nor inside the two glass planes there would be no structure, both sides of the facade were thought to be totally smooth.

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ADDITIONAL TESTING The velocity of a real construction process is ruthless for experimenting engineers. Every uncertainty has to be tested and tests take time, especially when also long term behaviour has to be imitated. The obvious choice is often to go back to tested and certiƤcated elements and refrain from new and unknown elements in the construction, or in case of selection of new elements to test these and come to a certiƤcation level in a short time, testing only individual aspects one after the other. Some hesitation on the part of Asahi Glass Company (AGC) as the nominated glass panel producer concerned the connection between composite tubes and the metal spacer frame. In practice AGC was familiar with other examples of composite spacers, however they always had a steel backing for the vapour tightness and proper sealing oơ. The glass producers refrained form using composite spacer frames and went back to metal frames, as the sealing around would give a trustworthy airtightness and the tests of composite gluing did not appear to be satisfactorily enough for the supply of all usual guarantees on the glass panels. The client hesitated as the INHolland Composited Laboratory was not amused at all by this manoeuvre, although it was obvious that further tests were necessary for the certiƤcation process, which would make it hard to have the facade ready parallel to the actual building process. Prof. Ulrich Knaack TU Delft was 45

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

asked for a second opinion on the degree of innovation of the proposed facade scheme with metal frames. After having received his positive advice that the proposal of Octatube had a high degree of innovation the client, INHolland Real Estate department, decided to use the experimental facade system with metal spacers as a launching customer. The atrium consists of three facades. It was agreed in this stage that the two large facades would be executed as proposed by Octatube/Asahi with the metal spacers and the third, more narrow facade of only one glass panel wide and 13,2 m high, would be executed as per original design completely in composite spacers. The narrow composite facade would demonstrate the innovation possibilities with composites in architecture. The further developments and realization of the two main facade were all executed directly by Octatube, the composite facade was executed under responsibility of the INHolland Composite lab, but produced and built also by Octatube.

STRUCTURAL ANALYSIS OF THE REALIZED FAcade SYSTEM

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The facade is a planar one-way cable system which stabilize the glass facade through the resistance to deformation of the pre-tensioned cables. The facade system has large service deƪections for the maximal wind load event. The lateral deformations are necessary for the system to transfer the (wind)loads and are resisted by the tendency of each cable to return to its straight line conƤgurations between supports. The maximum deƪection of the facade is L/40 of the facade its height. In this project the facade is 13200 mm height, the deƪection is maximal 330 mm, inward and outward. This lead to rotation angles in the horizontal facade seams of approximately 1 degree . This protected the integrity of the glass and sealants and minimized a perception by the buildings occupants. A Ƥrst impression of the forces in the cables of the facade can be determined with a very simple rule mentioned in Ƥgure 9. With the wind load the height of the facade and the maximal allowed deƪection the vertical and horizontal forces can be calculated.

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Fig. 9 First determinaƟons with simple formula

• Wind load eơect on deƪection of the wall • First movement small force needed, deformation is necessary to obtain routing of forces, the cables have no bending stiơness • Number of elements determine the deƪection: constraint stiơness, stiơness cables, pre-stressing cable, wind loads. The critical design goal is limiting deƪections through adjusting axial stiơness of the cables, and the pretension; • This also have inƪuence on the own frequency of the facade • No vortex at the edges so that the wall does not resonate / swing relative high preload so that the deformation of the recessed construction not become too high during wind Every days deƪections of L/150 = 13200/150 . The wall components are (oơ course) designed to accommodate this movement without compromising wall performance. The cable of aramide has excellent durability qualities • The tensioning of the cables must be accomplished with all cables. This requires rigorous methodology frequently involving sophisticated hydraulic jacking gear. Compensating adjustments in the tensioning can be computed and implemented. The trick of the cable structures is in the tension: Ƥrst determining appropriate theoretical cable pre-tensions with respect to the boundary conditions, then realizing those tensions exactly in the Ƥeld on site. Any adjustments must be systematically and not locally. • In practice cable structures are remarkably forgiving as they are designed to move. They can deform many times the deƪection criteria of conventional steel or aluminium structures without any permanent deformation or failure.

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THIRD PHASE OF PRODUCTIONS AND REALIZATION Leading the deadweight to the surrounding structures has been deliberately separated from taking care of the wind loads on the facades. The wind loads were taken over by vertical aramide cables The deadweight of the separate panels is guided by means of tensile stainless steel rods, in the space between two adjacent double glass panels. The rods are provided by supporting steps, made of POM, to carry the glass units. The suspension rods and steps are located within the joints of the glass units, to be sealed oơ later. Gravitational loads are carried by the suspension rods, because it is hard to make mechanical node attachments on aramide cables . The upper structure had to be provided with the proper suspension provisions, which were not present in the main steel structure due to the late decision for the experimental facade. In the concrete foundation structure at the bottom of the glass facades, the usual drillings had to be made, this time in large holes of 300 mm diameter which was complicated because of the heavy reinforcements and the uncertainty with the actual location of reinforcement bars. On the inside of the facade a complete scaơolding was to be build up with clamps on the outrigging elements, so as to enable temporary purlins to be attached. On these purlins the individual glass panels are temporarily attached, stabilised against wind loadings, while the deadweight is already carried by the suspension rods and saddles. The glass panels are positioned in alignment of the vertical and horizontal seams on the one hand, but even more precise will be the alignment of the tubes, through which the cables will be fed. This was the situation of development in spring 2009. In the mean time the reaction forces, not only from the suspension rods, but mainly from the pre-stressed cables had an important stiơening eơect on the substructure of the roof, from which the cables were stressed. The substructure had to be redimensioned. See Ƥg.10 and 12. The 2 corners of the glass facades presented a further engineering challenge as during wind compression both facade corners would bend inward 330mm and damage each other. This is the reason why the facade corners were provided with a hollow lens form to allow the inward movement without breakage. Yet these lensformed openings were to be closed oơ. This was done in a rounded deformable form and in a rubber sandwich. The two glass planes of the 2 facades can move outward both as well as inward, 330 mm from the neutral position. The largest deƪection would be in the middle, decreasing towards the top and bottom of the corner . The material is a double rubber membrane with a rubber insulation material as a sandwich in between. See Ƥg. 11.

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Fig. 10 3D view of overall structure with aramide cables

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Fig. 11 Inside view and outside view of the Ňexible corner

Fig. 12 Detail of the glass structure as realized

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In this experimental process also the production appeared to oơer more unsuspected problems: the glass panel manufacturer had discovered that the tests did not provide satisfactory results as to the air tightness of the tube-to-frame connections and the airtightness of the carbon Ƥbre tubes themselves. Asahi would not issue the normal guarantees of the glass panels in this case. This appeared in the month of May, just before production of the glass units. This potentiality, however, could easily lead to the necessity of the complete replacement of the entire facade when the insulated glass panels would indeed show air leakages after some time. The replacement had to be done on costs of the supplier within 10 years and on costs of the client after that date. Both supplier and client saw their own responsibility. In a dramatic week in may 2009, the author took the decision to reposition the cables from the inside of the double glass units to the outside, in the inner space of the building in fact, with the carbon Ƥbre mantle tubes to the inside of the space, adjacent to the insulated glass panels. So with this engineering manoeuvre factory guarantees were given again, but the project had again lost one of its innovative potentialities. So the client also agreed. The architect indicated that Octatube would have to develop the system further as he would want to apply the original integrated glass/cable system in a future building. Other set-backs ware caused by the supplied stainless steel end pieces of the aramid cables that were produced by a yachting supply industry in New Zealand. They appeared the have only 60% of the breaking strength compared with the ultimate expected breaking strength. In an ultra short time these end pieces had to be redimensioned, produced and ƪown in not to cause essential delays in the crucial construction time, where steel structural engineers, concrete engineers, Octatube erection crew en glass producers collided in the planning.

FOURTH PHASE OF PRODUCTION AND REALIZATION OF THE ORIGINAL FAcade CONCEPT The third facade has been executed in the original composite frames, which were produced (cut, glued in the corners and provided with composite tubes) in the Composite Laboratory and under its own responsibility. The solid composite spacers do not have a possibility to contain hydrating material, which usually Ƥll the metal spacers. So separate cylinders of hydrogen are positioned on the bottom spacer with a measuring device to read oơ the air humidity inside of the double glass panel. See Ƥg. 13. The required accuracy of the glass panes versus the composite frames required remounting of the double glass units and re-assembly two times. The installation on site of the aramide cables though the tubes in the very spacers did not provide unforeseen moments. The engineering of the part of 50

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

the facade provided even much more intensive work than the two regular facades. This facade, however, provides the most advanced state-of-the-art technology of integrated composite glass facades in the world to date.

CONCLUSIONS

Fig. 13 Internal and external view of the original experimental facade part with the internal aramide cables inside the air space

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An experimental design and development process best is to be organised separate or preceding to an actual application (or: zeroseries) construction process. Independent team players who have their own agendas are often hard to integrate in the process. In principle it is wise never to combine a highly experimental project with a fast running building construction process. It is worth while to keep incremental steps forward in the development of systems. Small steps each time. In the Ƥrst experimental design phase progress was slow and many times contradictory, until the stage was reached of the integration of pre-stressed cables with insulated glass panels. After a selection it Ƥnally led to a design with an air-tight system not easy to be executed as all construction details had to be solved within the thickness of the 50 mm insulated glass panel. In the feasibility study it appeared that the chosen composite-glass facade was technically possible in conformity with the process on the market for design facades. To explore in this phase already the production of the insulation glass panels in detail a demonstrator of 3,6 by 5,0 meter was realized. The mock-up did not only give a good overview of the production and assembly aspects for the material suppliers and producers, but also gave other technical information. It is possible to make the facade with very small tolerances of less than 1mm.

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In the second experimental engineering and prototyping phase several parts of the concept facade have been developed in more detail and tested in a small parts testing program. Major drivers for the tests were the structural behaviour and the durability. Most important were the temperature and moisture inƪuences on the composites in the facade, the always changing loads and above all the production and assembly processes. An unexpected drawback was formed by the composition of the insulated glass panels where the composite frames had to be substituted by conventional metal frames which have proven performance and guarantees. The composite frames did need much more testing before they could be applied in practice with the usual guarantees from the producer. The third phase of experimental productions and realizations had two problems. One in the engineering and production of the end pieces of the aramide cables. The other, as a result of the testing, inadequate trust in the performance of the air-tightness of the feeding tubes thought the framings of the double glass panels, so that for the two larger facades the cables and tubes were repositioned on the inside of the glass panels. The fourth phase of the original concept was produced with the original composite frames and tubes at the Composites Laboratory on the basis of which the double glass units were assembled with visual hydrogenous material in cylinders. The stacking of the cables through the panel tubes was executed and the system proved to be laborious. But it worked. This facade is being watched regularly as a part of the Composites Laboratory education program.

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The developed facade concept, as a total, with pre-stressed aramide cables, is characterized by its innovative character on multiple levels. The application of composite materials in this type of facades is exclusive. The total picture is an ultra slender, frame-less, facade,

Fig. 14 Today’s state of construcƟon

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

with a height of 13.200 mm. This led to a very slenderness ratio of almost 1:300. But the build facade proves that the original ‘wild idea’, when properly and seriously developed, can be realised within a few years. This is the convincing force of design.

REFERENCES [1] Eekhout, M. ‘Methodology for Product Development in Architecture’, IOS Press, ISBN 978-1-58603-965-3

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Fig. 15 The completed pre-stressed glass facades in exterior

Fig. 16 Interior view with verƟcal cables, glass panels and the rubber corner membrane

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As an architect, facade planner and researcher in the Ƥeld of facades, Dipl.-Ing. Tillmann Klein looks at ways to innovate facade construction. He is leading the facade research Group at the TU Delft and is editor of the book series “The Future Envelope”. The paper is a result of student works from the International Facade Master program at the TU Delft.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-55

SCENARIOS FOR FUTURE BUILDING ENVELOPES ͳ STUDENT DESIGNS

Tillmann Klein

Abstract

TU DelŌ / Facade Research Group

The Ƥrst metal-glass facades where developed about 100 years ago and since than have undergone an incremental evolution. The basic constructional concept and its function have not changed. What has changed is the demand: On the one hand the energy performance and on the other the user comfort. The building envelope of the future will be a like a musical instrument in an orchestra, which is nicely tuned according to the ever changing surrounding conditions. It will contain a large number of technical installations. The paper introduces Product Architecture as a method to analyze and to design constructions. On this basis students of the Facade Design Master Program at the TU Delft have developed four visionary facade designs.

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An experimental approach to facade construcƟon A facade’s main function is to separate the interior and exterior climate. In order to modulate the deviations of the exterior climate according to the requirements of the interior climate we can design the building composition in a way that window openings and areas of shading, as well as the means of construction with its mass have a balancing eơect. However, in many cases this does not prove to be suƥcient and energy is needed to create the desired interior climate; for example by heating, cooling and/or humidifying (Fig. 1).

Fig. 1 Energy is needed to modulate the interior climate. The Ɵghter the limits of the deĮned comfort area are set, the more energy is required.

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The demand for low energy consumption and a raised sense of comfort give the facade an important roll in the building concept. It must not only be extremely well insulated but also adaptive in order to participate in the modulation of the interior climate. Ideally, a facade should be able to adapt its properties such as insulation and transparency on the basis of diơerent time spans. Some functions need to be adapted from minute to minute such as sun protection or transparency to provide an optimum amount of daylight or to prevent overheating. Some functions need a seasonal change; such as the amount of insulation, and others yet need to change within a couple of years, reacting to changing users (Fig. 2).

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Fig. 2 The building envelope must be understood as an acƟve element of the climate concept. The highest possible degree of adaptability is desirable.

The result is an increasing technicalization of the facade. More and more building services components are being integrated into the facade. The facade as an active building services component is not a new idea; but problems such as the combination of various traditionally separate subcontracts such as metal construction and installation are far from being solved. How exactly should building services components be integrated into the facade construction and where are the interfaces? Will these services continue to be provided by separate companies? What does this mean for the design process, for the construction stage and the warranty of the product? All these aspects will have an inƪuence on facade construction. One can say that facades are simply a geometrical arrangement of components as a reaction on a functional proƤle and the current situation of stakeholders and responsibilities. This point of view oơers the chance to look at it in a new way. Instead of trying to optimize incrementally evolved systems, we can try to imagine constructional scenarios and in a second step try to understand what such scenarios could mean for the design and construction process and the involved parties. 56

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Student design scenarios About one year ago we started the Facade Design Master Program at the TU Delft, led by Arie Bergsma. The program is strongly supported by the VMRG (Dutch association of manufactures of metal facade elements) and major facade building companies. In addition to fundamental knowledge about facade technology, the students are being educated to academically research new ideas. In the design studio the students were asked to design a building services integrated facade. On the basis of profound knowledge about facade functions and existing technologies the task was to take a step back and then experimentally develop a completely new approach to facade construction. Naturally, the focus did not lie on a fully functional facade, but a good representation of possibilities. One example: If the task would be to explain how to ƪy to the Moon, the initial planning phase does not require a detailed drawing of the landing gear. An idea of a rocket is needed that gets the astronaut out of the Ƥeld of gravity of the earth. Further a transport module in which he or she can stay during the travel time, and Ƥnally a landing module to approach the Moon’s surface. One can calculate the weight of the spaceship and the fuel needed and think about a suit to survive the low temperatures of the universe. One may not yet have the proper material available, but can certainly deƤne the exact requirements.

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Construction lies in the heart of the matter and on one hand we have materials and on the other architecture. The way it is constructed is responsible of the Ƥnal functionality of a product. Fabrics deliver a good example for everyday use. The base Ƥbre, e.g. wool, is very important for the quality of the fabric, but the way it is spun and woven determines its Ƥnal strength, ƪexibility or usability for a certain purpose. For a shirt we want it to be light and gentle, for a trouser it needs to be robust like jeans. The idea was thus to begin a new approach at with construction and to develop constructional scenarios, departing from the traditional “stick and Ƥlling” idea or at least exaggerate a principle in order to trigger a clearer outcome. The four constructional scenarios: 1. A facade that solely consists out of components, similar to a lego system, without a system of mullions or beams; 2. A grid-like facade, to which all components are attached, that was symbolized by a net; 3. A facade made out of a continuous, graded material into which all functions are embedded. Just imagine a cake and diơerent facade functions like would be raisins. 57

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4. A facade that is made out of diơerent layers with the properties and the arrangement of the layers creating the desired functionality. Here on can picture a jacket with diơerent layers from inside to outside.

Fig. 3 Four construcƟonal scenarios

In order to establish a theoretic background for describing and developing constructions, we used “Product Architecture”. Product Architecture can, according to Karl Ulrich, be described as follows (Ulrich, 1995): 1. The arrangement of functional elements 2. The mapping from functional elements to physical components 3. The speciƤcation of the interfaces among interacting physical components 58

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

We will use a post-beam construction as an example (Fig. 4). This system is highly modular. Unique functions can be assigned to the main components. The mullion has a load-bearing function, the sealing system takes on air and water tightness, and so forth. This can be illustrated by the following function structure (Fig. 5):

Fig. 4 Exploded view of a curtain wall system (Raico).

The sealing system connects all Ƥlling components with the load-bearing structure. It functions as an interface between the components. Ulrich describes this method of connection as a BUS interface. We know this term from the computer industry as a USB hub. Various components such as external hard drives or printers can be connected to the computer via a USB hub. The unique assignment of functions and components and the BUS interface make the construction very modular, meaning its components can be easily exchanged. The product architecture of a post-beam system can be described in a function structure.

Fig. 5 FuncƟon structure of curtain wall system with modular interface

Four student designs Copyright © 2010. IOS Press, Incorporated. All rights reserved.

1.

Fig. 6 Honeycomb

Component facade – Leonie van Ginkel

This scenario is based on the idea that the facade itself does not have a independent load-bearing structure but consists of equal shape components that are connected with each other. The result of a form study (Fig. 7) showed that the optimum shape for such a component is a hexagon. In nature, we Ƥnd hexagons in honeycomb structures that contain maximum amount of honey with minimal amount of bees wax (Fig. 6). The assignment of the functions and components is described in the diagram shown below (Fig. 8).

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Fig. 7 Form study

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Fig. 8 FuncƟon structure of a component facade

In a simpliƤed manner, the diagram shows the assignment of (a selection of) functions to components and the interfaces between them. In principle, each of the components can fulƤll a diơerent function. All of them, however, fulƤll the structural function. The components are divided into sub-components. Since we want to be able to arrange and exchange the components arbitrarily, we need to choose a sectional interface. An example are the modules of kitchen furniture (arbitrary arrangement) or the pimples on Lego bricks. From a constructive point of view, the load must be transferred and leak-tightness guaranteed. The basic deƤnition of the construction is derived from the type of interface and the general requirements. Leonie van Ginkel has schematically examined two possible construction methods for the components: a construction with a aluminum frame and a formed element made of polycarbonate (Fig. 9). Interesting properties show when analyzing this construction: all of the components can be easily exchanged and ensure the adaptability of the facade. Diơerent companies can independently develop and manufacture these components. As new, more powerful products 60

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become available, they can be seamlessly integrated into the system. A suƥciently high demand for such products guarantees continuous innovation. Components could be rented or resold. Fig. 9 SchemaƟc construcƟon of the components with aluminum frame and polycarbonate material

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Fig. 10 PespecƟve view

A proper speciƤcation of the interface between the components is of critical importance. All component manufacturers must adhere to these speciƤcations for you to be able to seamlessly integrate the product into the system. The question of who develops the interface arises. Rights of use could be sold to component suppliers, comparable to the Windows operating system, to which all software developers adjust their applications. However, there is a disadvantage to such a pre-deƤned interface, since it is diƥcult to modify them at a later stage, making them a possible innovation blocker for the entire system. The components among each other and centrally communicate via wireless communication. The information is analyzed at a central location and then converted into action guidelines for each component (Fig. 10).

Fig. 11 Spanish Pavilion, Expo 2005, Foreign Oĸce Architects

The facade design is limited to the composition of the components; whereby the choice is made depending on the type of shell construction, the usage and the climate concept of the building. 61

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From a constructive point of view everything is predetermined by proven building components. Thus the risk is accordingly low. Limited architectural freedom is the biggest disadvantage o this approach, however, the hexagon is currently in vogue again.

Fig. 12 Control concept via wireless communicaƟon

2. Matrix Facade – Nathan Volkers Nathan Volkers´ interpretation of the grid facade is a media matrix. Future climate integrated facades will be equipped with various installations. Energy, water and information data will need to be transported to all areas of the facade. This is the task of the matrix. It can encompass all types of diơerent components (Fig. 13). The function structure shows that all transport elements are subcomponents of the matrix and all other components will be attached to the structural frame of the matrix (Fig. 14).

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Fig. 13 Components in matrix

Fig. 14 FuncƟon structure of Matrix Facade

A BUS interface is needed to make sure that each component with diơerent properties can be installed anywhere within the matrix and is interchangeable. On top of that, each component is connected to a data cable, water supply line, etc. depending on its functionality. 62

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This requires a slot interface. An example for slot interfaces is the motherboard of a computer. For each component such as graphic cards, memory boards, etc. a special and unique connection is made.

Fig. 15 Example for decision making process

Local decision making units (DMU) are located at the cross points of the matrix are located. Together with the central processing unit (CPU) they control all actions. The facade functions as a living organism which constantly adapts to the environment and user needs (Fig. 15). The scale of the matrix depends on the size of the available components. In principle, the grid could be in the range of a couple of millimeters (Fig. 16). The interesting point of this design is that not the facade function is the starting point of the design, but a transportation network for energy, water and information data. The design and construction of this type of facade would be a joint task of a precision engineer, building services designers, structural engineers, electronics specialists and a neurosurgeon.

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Fig. 16 Developing scale and shape of grid and components

Fig. 17 Facade design and detail of matrix

3. Integral Facade – CharloƩe Heesbeen Charlotte Hesbeen explains her approach with the example of a tea cup (Figs. 18, 19). In the Ƥrst cup, every main function is translated into one component. The second cup shows an integral architecture. The question is what an integral approach would mean for the facade construction.

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Her inspiration came from bone structures (Fig. 20). Basically, the entire bone is made from one material, but diơerent zones embody diơerent functional elements. The outer cartilage is soft and ductile and protects the actual bone structure. This is divided into a very massive and a sponge like structure to minimize weight. Figure 21 shows how an integral material could be inƪuenced in order to archive diơerent functionality. Structure as well as insulation properties can be inƪuenced by the mass and porosity of the material. For other functions, the shape can be adjusted or additives, such as embedded reƪective elements, have an enhancing eơect.

Figs. 18 & 19 Modular and integral design of tea cup

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Fig. 20 Cross secƟon through human bone

Fig. 21 Scheme to inŇuence the properƟes of an integral material

A facade design was made based on these aspects (Figs. 22, 23, 24). Mass is accumulated where it is needed for the structure of the building. For insulation purposes the outer area is porous. 64

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Fig. 22 ElevaƟon, horizontal and verƟcal cross secƟon

Fig. 23 VenƟlaƟon through caviƟes in the material

Fig. 24 Embedded light direcƟng Įbers and heaƟng components

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Continuous pores in the inner area can transport warm and cold water. Embedded glass Ƥbers transport light. The beneƤt of an integral design is potentially higher performance, because the product can be adjusted according to its functionality. Standardized interfaces always contain compromises. No physical seams cause leakages between the components. On the other hand, the facade cannot be adapted at a later stage and integral constructions have an inƪuence on the ability to recycle. In order to achieve some degree of adaptability, interfaces have to be introduced to connect components that need to be exchanged. Fig. 24 shows some possibilities, such as an integrated nut into which a bolt can be mounted to attach more functional components. Fig. 25 The connecƟon of adaptable components

The design shows that integral product architecture requires integral design and integral production facilities. 65

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Fig. 26 FuncƟon structure Integral Facade

4. Layered Facade – Jasper OverkleeŌ Examples such as space suits, Goretex jackets and milk containers prove that the combination of layers with diơerent properties can lead to remarkable performance. A space suit is only a few millimeters thick, but can protect against very low temperatures and dangerous radiation. Jasper Overkleeft uses this idea to create the facade’s main functions (Fig. 27).

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Fig. 27 FuncƟon structure of Layered Facade

Unlike the other designs, in his system some of the functions are created by a combination of diơerent components. Insulation properties are achieved by a combination of pneumatic cushions and reƪective layers. The enveloping foil and the pneumatic cushions (working as a structural spacer) in combination with the prestressing under-pressure is used to create stiơness. Flexible warm water capillary tubes are integrated for heating purposes (Fig. 28). All the layers are only temporarily held in place until the application of under-pressure Ƥxes them in place. This also means that the interface is created by a combination of components instead of a deƤned physical interface. Of course, the edge of the facade needs an airtight frame (Fig. 30). The arrangement of the layers can be adjusted according to the user needs, the architectural idea and the direction of the building (Fig. 29).

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Fig. 28 Facade layers

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Fig. 29 Diīerent facade performance through diīerent layer arrangements according to direcƟon of building

Architecturally all kinds of colors, light emitting foils, etc. could be integrated. The facade could be transparent, translucent or opaque. At a later stage the layers could also be rearranged to adjust the facade properties or to add new technologies. This type of facade is lightweight and could be transported in a rolled-up manner. It can be tailored like a sail and brought into 3-D shapes. Fig. 30 Detail of end element

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Fig. 31 Mock-up of Layered facade

Conclusion

Fig. 32 Imaginary facade producƟon in a sail maker’s workshop

When developing new ideas we naturally start with what we already know - architectural conceptions and design and production methods. In contrast, the above described four student scenarios start from four constructive visions. The designs show a prospect of what future facades could look like. To a great extent they could be realized with existing technology. Regarding the posed requirement, for example the possibility to exchange and upgrade components, the work shows remarkable answers.

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In other disciplines, such as software design or mechanical engineering, product architecture as a method is widely used. Our experimental student designs illustrate that this method helps to identify and solve constructive relationships. The tight interrelation of functional requirement, construction and interface becomes apparent. The facade performance as well as the possibilities of standardization depends here upon as well as how suitable a facade product is for future innovation. Just as the functional requirements change (one example is the integration of building services components), so will the architectural requirements. New developments constantly deliver new materials and construction and manufacturing possibilities, for example rapid manufacturing technology. We do not yet know which factors will be decisive in future facade construction, but is it really unlikely, that future building envelopes could be manufactured on the desks of Indian tailors? References Ulrich, K.: The role of product architecture in the manufacturing Ƥrm, Research Policy 24 pp.419-440, Elsevier 1995

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The facade industry is the key factor when it comes to introduce new inventions into the broader market. The system suppliers here have a crucial role. They translate new requirements, architectural desires in standard systems and the standards in Western Europe are the highest in the world.

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Ir. Jeroen Scheepmaker is senior product manager with Alcoa Kawneer architectural systems and he shows what it takes to raise the level of technical standards.

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The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-71

ARCHITECTURAL MASS PRODUCTION

Jeroen Scheepmaker Alcoa Architectural Systems / Industry

The inspiring announcement of Future Envelope; the creation of a facade and building is like a Ƥne musical instrument attuned with the entire orchestra, is really hard to resist. Of course this metaphor makes you think. Yes, we are part of the facade orchestra but who else is involved? And what kind of instrument should we all play as industry? Can we compare our business with other industries, with other orchestras? Answering these questions is challenging but worth a try. The next pages will show a vision of the future envelope done by comparing the facade industry with automotive. But Ƥrst some information regarding aluminium in general, Alcoa and aluminium facades.

Aluminium

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1 Alcoa Corporate: www.alcoa.com

The age of aluminium1 Copper has been in widespread use for over 7,500 years, bronze (copper with tin) for about 4,000, iron and steel for 3,000 years plus. But the age of aluminium is just beginning. It was born in 1886, with the Ƥrst process for smelting aluminium in quantity. It was a long time coming. More than 7,000 years ago, Persian potters made their strongest pitchers and bowls from a clay containing an aluminium oxide; what we now know as alumina. Thirty centuries later, ancient Egyptians and Babylonians were using other aluminium compounds in fabric dyes, cosmetics and medicines. Still, no one knew about aluminium. No one had ever seen it. Though it’s the most abundant metal in the earth’s crust, it doesn’t occur naturally as a metal. Finally, in 1808, Sir Humphry Davy proved the existence of aluminium and gave it its name. Soon after, Danish physicist Hans Christian Oersted managed to produce a few droplets of the metal. Others improved his process until, in 1869, about two 71

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

tons of aluminium were produced. That brought the cost down from $545 to $17 a pound, about the same as silver. A reasonable price for tableware at the French Court, a crown for the King of Denmark, and a cap on the Washington Monument which is still there. It would take a high-volume, low-cost smelting process to open the way for aluminium as a major metal that would outperform its predecessors; and that is the discovery that launched Alcoa.

Fig. 1 The aluminium cap on the Washington Monument

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Fig. 2 The original aluminium pellets shown on a page of handwriƩen minutes - 1890

Alcoa - worldwide2 Nowadays Alcoa is world leader in the production and management of primary aluminium, fabricated aluminium and alumina combined, through its active and growing participation in all major aspects of the industry. Alcoa serves the aerospace, automotive, packaging, building and construction, commercial transportation and industrial markets, bringing design, engineering, production and other capabilities of Alcoa's businesses to customers. The company has 87,000 employees in 35 countries and has been named one of the top most sustainable corporations. More than 70% of the aluminium ever produced is still in use, equalling 586 million metric tons of a total 806 million metric tons manufactured since 1886. Recycling of aluminium Indeed, aluminium scrap can be repeatedly recycled without any loss of value or properties. The energy required is a mere fraction of that needed for primary production, often as little as 5%, yielding obvious ecological beneƤts. A study by Delft University of Technology recently revealed aluminium’s considerable recycling potential in the building sector. Aluminium collection rates from a cross-section of commercial and residential buildings in 6 European countries were found to be in excess of 92%, demonstrating the industry’s commitment to sustainable development.3

2

Alcoa Corporate

Fig. 3 Aluminium scrap ready to be recycled 3

European Aluminium AssociaƟon> www.eaa.net

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4

Source: Facades & Architecture – Just Renckens

Aluminium & Architecture Aluminium adapted by architecture 4 In the beginning of the 20th century the Ƥrst high rise projects were being built in the USA. Due to new building techniques and the invention of the elevator, high rise became more popular. One of the most famous methods for making high rise facades was initiated by architect Mies van der Rohe. Those facades were made of glass and steel beams only. Aluminium had a warm welcome in the high rise. The material is corrosion proof and light weight. One of the Ƥrst buildings with facades completely made of aluminium is the Alcoa Building in Pittsburgh. The facade has been made of aluminium 3D shaped panels and glass. Extrusion The extrusion of aluminium was a logical next step in the facade industry. Extrusion made it possible to create rather complex shaped proƤles for creating lightweight and strong facades. Nowadays extruded and thermal broken aluminium proƤles are common in construction and architecture.

5

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European Aluminium AssociaƟon: www.eaa.net

Figures & Facts In 2006, the building sector in Western Europe used an estimated 2.9 million tonnes of aluminium. Around 1.7 million tonnes were used for proƤles, making this sector the largest market by far for extruded products, accounting for about 50% of all such shipments. A more modest, but still substantial, 1 million tonnes found their way into rolled products, representing approximately 24% of all rolled aluminium shipments. Finally, about 0.2 million tonnes of aluminium were used in castings for a range of building applications, representing approx. 8% of all casting aluminium shipments. 5

AutomoƟve & Architecture AutomoƟve – a young industry Aluminium is a young and new material with high ambitions. Not only in the building and construction industry, but also in other industries like automotive. This industry is also young and with high ambitions. Born at the end of the 19e century the car industry is evaluating rapidly ever since. Many times and at many occasions, advisors and researchers are making comparisons between automotive and architecture. Let me start making a comparison between our facade business and 73

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the automotive. We all understand the car industry is diơerent than our ‘industry’. The car industry is expert in setting trends by creating concepts cars suitable for the nearby future. The car industry creates their market and persuades their consumers. Their marketing is ‘business to consumer’ based and they are focused at you and me. Concept cars The car industry is, generally spoken, master in creating, developing, designing and understanding product development. At exhibitions we can see the newest models and concept cars presented by diơerent brands. The concept cars give the visitors a glimpse into the future. It will give the developers and marketers a clear understanding of the do’s and don’ts concerning the developments that can be produced, and the developments that need to be put on hold.

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Fig. 4 EDAG Light Car – open source EDAG, worldwide provider of engineering services, presented the world premiere of its vision of an environment-friendly, future-orientated vehicle for everyday and leisure use at 2009 InternaƟonal Motor Show in Geneva

Sometimes it’s hard to grasp some of the inventions presented with the concept cars. The shape, the design of the concept cars seems to be at Ƥrst more related to a new Hollywood Ƥlm production than real live. But after a few years, those developments and the design seems to be standard and not science Ƥction anymore. At that time the cars can be found in each country and in some cases at every ‘corner of the street’. Architecture as an industry This approach makes a big diơerence compared to the oƥce and housing ‘industry’. Almost every building has a unique appearance. Not only the facade but also the construction; the back bones are diơerent and almost each time unique. It seems like we do not mind to drive the same car as our neighbour but we prefer not to live in exact the same house with the same ƪoor plan. 74

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With mainly residential exceptions, buildings are being built especially for one ‘individual’. One company, one assigner with speciƤc demands and requests. Those buildings are designed by architects and are custom made. An architect will choose the elements needed to create the required space and looks. The architect as the conductor of the building orchestra. This makes every building a composition of pre-engineered and pre-tested systems; all combined together in a prototype. An ‘acceptable’ prototype that, in general, will not be build twice.

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Fig. 5 Alcoa Architectural Systems – projects in the Netherlands

The complex world of architecture The fact that each building is unique is not only interesting (or necessary) from an aesthetical point of view, but also challenging from an industrial point of view. Not only the aesthetics but also the requirements change with each project. Many parameters, and many of them conƪicting with each other, will be the input during the design of the building and of course the facade. Choices need to be made regarding materials and solutions. This of course is nothing new; it is the same for automotive. It is the challenging part of designing! The car industry collects the required knowledge and has the best people on board to fulƤl this 75

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challenge. And in the architecture? After Ƥnalizing the building we change the winning team and we seem to start all over and begin from scratch. Dynamic role of the facade industry To give a good example, a close look at the facade industry will be helpful. Alcoa Architectural Systems is supplier in the distribution chain and sells facade systems to several facade builders. There is a one to one, a direct business to business relationship. In general the investors (principals), advisors and architects are linked in the organization of realizing the facade. Those parties are all brought together based on, to the project tailored and oơered activities. Each of those parties is bringing in their deƤned input for realizing the total facade and building. When compare with the orchestra; play a piece of music and if produced well, it will result in an attuned music play. The next play however will be with diơerent members and a new producer. Fig. 6 Alcoa Project: Viñoly Tower, Amsterdam, the Netherlands; architect, Rafael Viñoly Architects, van den Oever, Zaaijer & Partners. Facade has been designed and developed in close cooperaƟon with the architect and facade manufacturer.

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Facade system development The changing of the organization makes it challenging for the facade industry to developing systems. Each project and organization will have a speciƤc combination of requirements, demanding a speciƤc facade solution. This solution will generally be created by using a facade system. A system ‘able’ to adapt the changing project requirements and existing of essential components like aluminium, pre-coloured proƤles with tested hardware. Compare it with a supplier for the car industry. Within one developed system, oơering completely diơerent cars like a SUV, sedan, cabriolet e.g. It is obvious that marketing input on a high level is needed to create systems like this. To give answers to questions like: what are the latest legislations; the newest requirements and aesthetical desires? For this input direct links with all the facade-parties is absolutely necessary. We, as facade industry, have to distillate the common thoughts and translate those into trends.

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Trends in facade & architecture Day lighƟng and space One important upcoming trend is the increase of the size of windows started at the end of the 20e century. In many projects windows with the size of doors are desired. Storey high and with a minimum of aluminium on the outside.

Fig. 7 Alcoa Project: Kunstlinie, Almere, the Netherlands; architect: Sejima and Nishizawa Ass. Architects Big glass panels are used for maximum view and daylight.

Open Europe Another important trend is direct related to improved communication through the internet. People are more aware of available systems and products and their performances. If the ‘local products’ are not the right ones why not go abroad? More often facade products are imported and in spite of the fact each country has their habits and regulations, this will increase; starting by architects searching for the newest and best products.

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Sustainability The last important trend which needs to be mentioned is sustainability. Each market, each company is fully aware of the need to adapt sustainability in their daily business. First of all to stop the climate change and second to follow the market. The facade industry has this important topic high at their priority list. One important ongoing development is the improvement of the thermal performance of windows, doors and facades. New techniques and new materials are explored at this moment. Alcoa’s RT 72 HI+ can fulƤl a satisfying Uf value of 1,4 W/m2K at this moment.

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Fig. 8 Alcoa window systems: many choices in diīerent shapes, colours, insulaƟon values. Available with a high insulaƟon value of Uf=1,4 W/m2K.

Sustainable integrated facade Another sustainable development is the upcoming ‘energy neutral’ facade. A facade not only performing like a climate buơer but also direct reacting and perhaps anticipating at outside and inside climate changes.

Fig. 9 Alcoa project: MarƟni Hospital, Groningen, the Netherlands; architect: Burger Grunstra architecten adviseurs. The facade of this ‘sustainable’ hospital contributes at the energy performance.

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A short study will point out those type of facades are already made, but they are still not fully adapted by the market and for sure not common. One of the reasons in my opinion, is the direct link between the ‘new’ necessary techniques and the complex and ever changing relations in the current building distribution chain. Several building disciplines like climate control, construction, esthetical design need to be combined. The integration of all those disciplines on one hand and the integration of the diơerent techniques on the other will be challenging matters. Because of the integration of other disciplines like for example climate control, the facade will be more ‘integrated’ in Ƥrstly the design and secondly the construction of the building and thirdly also the Ƥnal use.

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Fig. 10 Alcoa Concept Research Advanced & integrated facade - an ‘open’ system

CooperaƟon

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With all the parties and their knowledge mixed together, sustainable facade systems can be developed and oơered as a ‘system solution’. Not just one product comparable to the ‘take-it-or-leave-it black Ford’ but an ‘open’ system, due to a ƪexible combination of components and options suitable for diơerent and unique architectural projects. In my opinion this new typology of facades will be interesting for the future. These facades will make our buildings more (energy) eƥcient, more ƪexible and esthetical challenging. The sustainable techniques all integrated in the future building envelope will be eye catching, but is in my believe not really the biggest challenge. One of the key drivers for success will be the new cooperation between facade related companies. Creating the future building envelope is of all our interest. It means not only pushing the facade industry forward, but also changing the facade orchestra. At this moment Alcoa Architectural Systems is with several other innovative partners part of a new facade orchestra. Together with these important ‘orchestra members’ we play Ƥne tuned sustainable music for now and for the future.

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Ing. Bert Lieverse is general secretary of the FAECF (Federation of European Window and Curtain Walling Manufacturers Association). He represents the companies that actually “make” facades. Today facades are not anymore separate building components, but an integral part of the climate concept of a building. The “Living facade” is a model to describe the impact and the chances of climate oriented architecture on the facade industry.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-81

EXPERIENCES AFTER THE INITIAL LAUNCHING OF THE LIVING FACADE Bert Lieverse

IntroducƟon

General Secretary FAECF

In June 2008, I presented The Living Facade concept at the conference The Future Envelope 2. This concept focuses attention on building facades as elements that produce comfort and contribute to the environment. The facade was seen as an installation, responsible for enormous added value because it was attributed multiple uses. The facade industry was challenged to make this concept a reality. At the same time, everyone was aware that this was impossible without designers, architects, consultancies, suppliers, etc. So it would be better to replace ‘facade industry’ by ‘facade sector’ to include facade manufacturers and all experts, specialists and companies involved in creating the ‘Living Facade’.

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The concept was a hit with many people from diơerent disciplines as well as customers and users. However, there was one reaction that struck me as particularly noteworthy. Someone said it was a vague concept, not yet Ƥnished, with too many open endings and not in line with what is going on in construction. I complimented him on his observation, because he hit the nail on the head. After all, we had intended to ‘formulate a comprehensive, challenging and non-restrictive perspective’. The observation that it is not in line with current developments in the construction industry is also a compliment. Because the concept of the Living Facade would perish in the traditional organisation of construction, which is characterised by habits and structures that are ripe for some change. There are concepts for this, too, as Jos Ligtenberg demonstrated at the same conference with Slimbouwen®. In other words, changes in the organisation and structure of the construction industry and the Living Facade actually go hand in hand.

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Today, I will take things a step further. I will place everything in a business context and show concrete examples of innovations that appeal to the Living Facade. Today, I will take the following path: 1. 2. 3. 4. 5. 6.

The facade sector as a company The confrontation with an outmoded ‘building’ process Opportunities and threats for this company in the facade sector The role of innovation Examples Conclusion

The facade sector as a company Our Vision: Every company should have a vision. That vision deƤnes how the company sees the market and the role of the products or services it provides. It will not surprise you that the Living Facade provides this vision, as a reference to the presentation in 2008 and the details added later indicate. It is a look into the near future based on the essential role the sector wishes to play. The facade sector accomplishes the concept of the Living Facade.

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Our Mission: Can we create a signboard, a quick critical publication about what we are here to do and what we can do for all those involved? Using the following elements, the partners in the facade sector can detail their missions, which can then apply to the facade sector as a whole. Our facade systems oơer health, environmental beneƤts and comfort to users and businesses alike. The facade sector challenges, looking for the frontiers of technology, continually developing. Constant innovation and dissemination of knowledge are what drives us. In parallel, our collective and individual expertise is growing. We craft a creative climate in which aesthetics is combined with Ƥrst-rate functionality and responsibility. Our Strategy: Our strategy is a mix of various essential elements. We cannot aơord to let a single direction or working method prevail. Our system geared at achieving successes is a complex one. But all roads to success go by way of knowledge transfer and sharing knowledge about the possibilities of facade construction. Illustrative examples are the work performed by the Kenniscentrum Gevelbouw and the collaboration with Delft University of Technology on the subject of International Facademaster. 82

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We will also support the development of the facade sector through R&D initiatives. A collective programme by Delft and Eindhoven Universities of Technology, the University of Detmold and Polytechnico Milan has been set up, supported by various facade construction organisations in the Netherlands and abroad. The Energiecentrum Nederland (ECN) is involved in a research programme on the adaptive facade, in which we also collaborate. I will discuss innovation later. Together with partners in the Technical (climate) installation engineering industry from all over the world, we will set up a joint venture to manufacture the most complex part of the building: the facade/climate/energy installation. We would like to aơord this combination of companies a separate position in the current archaic construction process in order to concretise this added value for clients. The facade installation will have to be manufactured as eƥciently and industrially as possible and we will have to oơer lifelong service to guarantee the installation’s performance and to ensure that new technological developments (such as new software versions) can be applied on a continual basis. Moreover, we will be visible and transparent, communicating beyond the limitations of projects and restrictive contract relationships. Our ambition is to put the facade sector on the map and make sure that it remains a focus of attention.

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The confrontaƟon with an outmoded ‘building’ process Thinking back to the response to my previous presentation about the Living Facade, in which it was said that this concept is out of kilter with people in the construction industry who have their feet Ƥrmly planted on the ground, brings me to a critical consideration of the ineơective and ineƥcient phenomenon called the construction process. You might think that when there is no shouting and if it is not wet or too short or too long, it is not suited for the building industry. The question for the facade sector is whether they still want to belong to the building industry or whether they should transfer to installation engineering. The answer has been given in the paragraph on strategy – the ‘construction’ part in facade construction does more harm than good.

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This is clear from the following. MarkeƟng Every self-respecting company focuses on the customer. The customer is both a source and a goal. There is not a single industry that can aơord to neglect its customers. But in the construction process, customers immediately become partners to the problems and concerns that may increase or decrease as construction progresses. Every self-respecting company tries to Ƥgure out its customers’ purchasing motives and underlying rationale. It is about the question behind the question. This is what we call marketing. But in the regular construction process, the customer is far away. Customers are often anonymous and facades are delivered to suppliers or intermediaries. It is also said that the construction market is moving from a supply-driven to a demand-driven market, which is diƥcult for an organisational form that was not made for it. The facade sector will have to take care of marketing itself, trying to Ƥnd out and understand what the Living Facade can mean for the users of those facades, whether they are residents, users or manufacturers. Core concepts are: supplying comfort, supplying a high-quality, productivity-enhancing working environment, supplying energy regulation, energy saving, etc.

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In other words, we do all our marketing ourselves. AŌer-sales Focusing attention on the customer does not only mean doing what they think is important; ultimately, it is all about delivering value. Not summing up costs as is customary in regular construction, but formulating the value achieved for the customer throughout the product’s lifetime. According to this lifetime value concept, we must also be there for the customer once the building or facade is ready and functioning. After-sales and the provision of assistance concerning management and maintenance are self-evident notions. So once the facade sector starts to distinguish itself on the demandand user-side of the ‘construction’ and ‘user process’, it will gain a solid and indispensable position. In other words, we take care of the after-sales of our products and provide services.

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The ‘construcƟon’ process itself What remains is the process we all have in mind when we talk about construction: the construction process itself. This only represents a tiny part of the lifecycle of a building and the lifecycle of the products used in it. It is a process that is far from perfect. I will not weary you with discussions about the amount of failure costs. Like the discussion on roles, this is a subject for symposia or conferences. Just check the archives: this has been going on for 30 years and to no avail. But a spring cleaning dictated by the economic crisis is absolutely necessary. And I am not talking about the scale of the ineƥciencies, but about the casualness and resignation with which the phenomenon is accepted. It may be clear that this acceptance is no longer acceptable and no longer beƤtting a modern sector. In other words, we are working with industrialised processes, eƥciently and eơectively, controlling and reducing failure costs. Management and responsibility I believe that modern facades and their results for the user are the direct responsibility of companies that completely understand the concept. These companies deserve a direct relationship with the customer, without intermediaries. This one-on-one relationship between the facade sector and the customer also entails the responsibility that comes with the supply and assembly of this important building installation. The term ‘installation’ already indicates that the installation engineering sector also fully deserves this position. This results in a triumvirate of designer, technical Ƥtter and the facade sector that is responsible for a building’s key functions.

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In other words, we take our responsibility.

OpportuniƟes and threats for this company in the facade sector OpportuniƟes for our company in the facade sector There are plenty of opportunities. Not only in today’s market, but also in tomorrow’s. We will, of course, continue to produce what we are producing now, and there will be more and more sophisticated facade systems, while increasingly modern materials are also Ƥnding their way into the facades. The facade is still a very aesthetic and functional result of the architect’s design palette. But today’s challenges and the opportunities we have of showing the solutions that we can provide are in the following subjects: 85

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• Energy generation • Energy regulation • Automation and independent electronic drive of facade functions • The health demand from residents and users • The ever-increasing demand for comfort • The social forces and politics that encourage us to work on this • The labelling systems that promote recognisability and quality (Energy labelling, Eco labelling, CE marking, etc.) • The international facade market, in which our Western knowhow is leading • The aesthetic assignment that continually renews itself • The facade as example and showcase of modernity and progress • The contribution we can make to productivity enhancement There also are threats and shortcomings, of course: • Fragmentation, thinking in individual elements and lack of a holistic vision • National protectionism • Trade restrictions and bureaucratic behaviour • Holding on to outdated organisational principles • Impractical tools of a pseudo-idealistic nature (e.g. overstated calculation models for environmental eơects that are not transparent and that basically assume the worse-case scenario) • Lack of investment in R&D, innovation and risk-avoidance behaviour • Holding on to Ƥxed positions and unwillingness to launch new forms of co-operation

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The essenƟal role of innovaƟon Judging by all the attention that is being paid to it, it would seem that innovation is a new concept. But it is an indispensible feature of entrepreneurship. Without innovation and creativity, there would be no company and no position in the market. First of all, I will give a deƤnition and an explanation, borrowed from James Canton: A new idea, product, service or process that has the potential to act as an accelerator of competitive advantage for a nation, a region, an industry, an organization or some combination of these categories. An innovation creates new value-growth, solutions, proƤts, increased market share and return on investment.

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Innovations are judged by the market place, simply an innovation has value if it is blessed by customers who are willing to pay for it. .

We use this deƤnition in our sector company and always ask several fundamental questions when we have to decide on investments in innovation. First of all, management creates a climate of innovation, in which originality is appreciated and initiated. Management encourages and supervises the innovation processes, asking the following questions: • • • • •

Can we successfully sell it to our customers? Can we make it? Can we make money from it? Is it an innovation? Does it contribute to our society and our (natural) environment? If these questions are answered in the aƥrmative, the investment is made. I think that today’s and tomorrow’s economy must be economies of innovation. Manufacturing and selling will no longer be suƥcient; it is about the constant creation of concepts and ideas as described above. The facade sector will cherish such a climate and encourage it. Moreover, we must be aware that the lifecycle of innovations and their results may be short. Successful entrepreneurship is innovative entrepreneurship.

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Company policy and sector policy must be imbued with this realisation in order to encourage and motivate all those involved in the facade sector to continually do things diơerently. It is for this reason that the VMRG is working on innovation programmes with 40 companies, aided by the Ministry of Economic Aơairs. It is for this reason that the VMRG deƤnes R&D programmes with universities in the Netherlands and abroad. And it is for this reason that the VMRG works on knowledge distribution and organises creativity sessions. You will understand that, in the near future, we will organise these sessions with architects/designers, with installation companies, facade companies, suppliers, consultants and customers. A broad and varied group of people that will have to deƤne our industrial sector’s new proƤle and that will signiƤcantly inƪuence construction 87

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and the supply of buildings and related services. Everyone who takes this to heart is welcome. So this is also an invitation. An invitation to everyone who sees the importance of joining us on the path of innovative conceptualisation and innovative implementation. This is of vital importance to turning the economic tide and creating an internationally competitive edge.

Conclusion In conclusion, I want to put things into perspective. Of course, we will have to do things diơerently, organise things diơerently. After all, our innovative behaviour will not create respite but rather dynamics and rapid development. Knowledge and knowledge distribution play a key role in this. But like the economy, our discipline is imbued with technical specialisms. Technology, calculation technology, construction technology, etc., are often dominant. Knowledge and the evaluation of innovations are under threat of developing in the same direction. The opinions on a number of research plans by international experts are evidence of this, as is the careless use of an incompletely developed set of measurement tools for environmental standards. Working from experience and demonstrable experience are indisputable and important assets. They are, as it were, the intellectual appreciation and reward for inventions from the past.

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But we cannot work on today and tomorrow using the tools of the past. We must be prepared to take risks. We must be willing to create new areas in which we have no experience. What is more, tools based on experience, on veriƤable demonstrability, are counterproductive and restrictive for innovations and the re-creation of our future. Entering new areas and establishing new ways of working and dealing with new technologies and tools particularly demand working together and creating together. Only when we pay close attention to our relationships and succeed in creating new ways of collaboration between experts, companies and institutes can we be truly innovative. So we are, as a matter of fact, facing a multiple task in which we must all be creative.

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Prof. Dr. Daniel Meyer is director of the consulting company Dr. Lüchinger + Meyer Ltd.

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In addition to the professional work as a structural engineer since 2003, he is professor at the University of Applied Sciences of Lucerne where he leads the facade test centre. In his contribution to this book, Meyer shows that the testing of mock-plays an important part in evaluating calculations. Furthermore he explains that testing should be applied as an active tool for developing innovative facades.

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The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-91

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TESTͳBASED FACADE INNOVATION

Daniel Meyer

IntroducƟon

University Luzern / Facade Technology

In these times of global warming and ever scarcer fossil energy resources, the need for energy eƥ-ciency and sustainability is all the more acute. Of all parts of a building, the facade probably has the greatest potential in the near future for undergoing decisive further development and improvement. Modern facades are therefore one of the most important keys to achieving energy-eƥcient and sus-tainable buildings.

*DIN EN ISO 8402, 1995-08 , Point 2.17 states: “In design and development, veriƤcation concerns the process of examining the result of a given activity to determine conformity with the stated requirements of that activity.”

Facade constructions are among the most complex components in a building. They provide protection against sun, wind and weather and direct any occurring loads reliably to the main load-bearing struc-ture. They are also a signiƤcant factor for determining the appearance of a building and a design ele-ment for the surrounding area. Facades have to perform a multitude of functions in a compact space, e.g. thermal insulation, impermeability to air and driving rain, and sun protection as well as structural safety and serviceability. In the future, entire installation components and supply lines for the building will also be integrated in the facade, as well as photovoltaic installations or solar collectors. Testing is therefore an appropriate and quite useful activity for developing new and innovative facade designs and systems. Tests provide insights, for example, into the behavior of a bond in a composite construc-tion, into the residual load bearing capacity of a new type of glazing system, or into the load-bearing and deformation behavior of an overall system. Tests may have to be run on small building compo-nents and/or large ones depending on the issue being veriƤed*. From the standpoint of the construction industry, facades are actually mass-produced products. Com-ponents or even entire elements are mass-produced. Planning, manufacturing and assembly are in-ternationally oriented activities that extend beyond national borders. Facades are planned and manufactured, then transported and assembled around the world. Although the current trend is for facades and the services associated with them to be exported from Europe, this might not be the case in the future. The risk of the facade, as a Ƥnal 91

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

product, not satisfying the set requirements is increased by this method of production and the multitude of project participants, by the geographic distances in-volved and the various approaches to quality standards prevailing in the world today. Well-documented quality control based on ISO standards is a good idea but steps must be take to ensure that the criteria and actions are appropriate to the complexity of the project and remain so. One helpful activity in a complex international project is to deƤne tests for the speciƤc building and conduct them on facade sections on a scale of 1:1. These tests are documented and any existing risks are eƥciently eliminated.

Tests on a facade tesƟng stand The aforementioned need to verify tests on a scale of 1:1 through testing and to determine an accept-able benchmark is a key step in minimizing the risks for the entire facade system and for the project partners involved. In other words, facades are no longer just planned and manufactured, they are also tested as an entity. This approach eliminates fundamental planning and system errors. The European product norm for curtain walling EN13830 and the normative references in it deƤne the requirements and criteria for testing facade systems. These tests are required to obtain CE certiƤcation for facade systems. Facades specially designed for a given project are tested with less administrative outlay but in a manner that is technically equivalent. The main point of facade testing is to verify the structural safety and serviceability of the entire facade system. In tests designed for a speciƤc project, the inter-faces with the building’s load-bearing structure are also examined.

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The sub-tests and testing cycles as deƤned in the EN 13830 product norm are directed toward the following key criteria: Air permeability test: The air permeability of a facade is a major factor in determining the exchange of air in a building and is directly linked to the building’s energy balance. An uncontrolled or excessive exchange of air is undesirable because the incoming air must be heated or even cooled. Good air impermeability is an essential trait for a facade in these days of rising energy prices. Driving rain impermeability test: Impermeability to driving rain is a central determinant of the serviceability of a facade. The penetration of water through a facade can usually be traced to fundamental construction or assembly 92

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defects. In the facade industry, the occurrence of leaks is considered to be a worst case scenario. Immediate action has to be taken to prevent further structural damage. Test on resistance to wind loads: This testing covers system deformation occurring under service loads as well as structural resistance as it relates to structural safety requirements. The system is veriƤed as safe and serviceable. In addition, the tested facade is loaded to failure following the deƤned normative test cycles. Interesting con-clusions can be drawn by observing the failure mechanisms and can often serve as a basis for further optimizing the system. As a supplement to the deƤned technical tests, architectural aspects can also be examined and as-sessed in the course of large-scale testing of this kind.

Facade test center at Lucerne University of Applied Sciences and Arts The new facade test center at the Engineering & Architecture School of Lucerne University of Applied Sciences and Arts consists of three functional units: a test chamber, a technical booth and a weather simulator.

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There is an opening in the front of the test chamber that is 8 meters wide and 12 meters high. If re-quired, it can be reduced in size to eight by eight meters or six by eight meters. The technical booth houses controls and water and pressure units. The weather simulator consists of a rake system equipped with water jets and a moving blower. The facades being tested are built into the test chamber opening and subjected to rain from the weather simulator. Over or under-pressure states are generated to produce exchanges of air and uniformly distributed loads across the test specimen surface. The new test center allows pressure and suction forces of up to 10 kPa to be cre-ated. It can be subjected to static or dynamic rain with the operator’s choice of 2 or 4 l/(m2 min) and has variably adjustable consoles and ƪoors.

Tests on facade components

Figs. 1a, 1b New test stand Lucerne University of Applied Sciences and Arts

Facade constructions must be dimensioned and designed in a way that guarantees suƥcient safety. The safety considerations made should be documented in a traceable manner whenever possible.

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The existing standards and guidelines do not always suƥce for deƤnitive conclusions to be drawn about behavior under load, structural safety and serviceability, especially in the case of structural glass construction. Component tests are therefore also required. Convenient standard-based dimensioning of the type used in steel and reinforced concrete construction is not fully available for facade and structural glass construction. This situation is exacerbated by the fact that some of the materials and composite materials used in facade construction exhibit brittle failure mechanisms when subject to loading and some behave in a highly non-linear manner in terms of deformation. A great deal of eơort is required for adequately capturing these eơects in an analytical way. There are currently no system-atically veriƤed rating systems for structural glass construction that adequately cover the complexity of the building components and the materials. Until such systems are in place, building component tests will probably remain the most eơective way of minimizing existing risks. Glazing constructions that protect against falling, overhead glazing and walkable glazing, in particular, require careful design and dimensioning and in some cases building component testing. Fall-protection glazing units are usually tested for human impact loads and in the event of damage to the entire pane system, for residual load-bearing capacity. Human impact testing is simulated with a 50-kilogram falling dummy covered in double tires. The maximum drop height of the soft-body impac-tor can be as high as 1200mm depending on the requirements involved.

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Overhead glazing and walkable glazing are also tested for human impact. Hard body impact, veriƤed thus far only in testing, must also be simulated. Steel balls weighing 4.1 kg are used for this hard-body impact test. The drop height varies between one and three meters.

Figs. 2a. 2b SoŌ body impact test and post breakage behaviour of a roof glass

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Example: Full-glass facade at the Leutschenbach School, Zurich The Leutschenbach School project in Zurich involved the construction of a new school building in steel and reinforced-concrete composite construction with large-area glass facades. Consistent use was made of full-glass constructions in which the glazing closing oơ the space is aƥxed to glass load-bearing elements. The gymnasium located in the upper ƪoor is enveloped in a full-glass facade about 9 meters high. The facade is divided by a horizontal joint into a top section six meters high and a bot-tom section three meters high.

Fig. 3 Mock-up of the interior (Source: Ch. Kerez)

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Vertical sword-shaped glazing elements six meters long are used as support surfaces for the 2.5-meter-wide top panes of insulation glass, which are also six meters long. The sword-shaped glazing elements and facade panes are aƥxed using structural silicone by way of interim components that are mechanically detachable. Dimensioning is based on a complex spatial, structural model. Current trade publications and guide-lines were drawn on to optimize the modeling and dimensioning. However, a veriƤcation of material behavior and the failure mechanisms found in the norms was lacking. To verify the breaking behavior and material behavior, a testing procedure for this speciƤc project was devised using building component tests carried out in the Competence Center for Facade and Metal Construction at the School of Engineering & Architecture School at Lucerne University of Applied Sci-ences and Arts. The loadbearing behavior and residual load-bearing behavior of the swordshaped glass elements were tested, as were key local details such as bonding.

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To verify the global load-bearing behavior of the six-meter-long sword-shaped glazing elements, a section of the full-glass facade was set up in the laboratory of the School of Engineering & Architecture School at Lucerne University of Applied Sciences and Arts. In addition to these large test specimens on a scale of 1:1, further test specimens, reduced in scale, were used for local testing of the connec-tion point between the sword-shaped glazing element and the insulation glazing. The large and small test specimens were also ideally suited for making a visual examination of the architectural appear-ance of the facade.

Fig. 4 Lateral view of the test setup

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Fig. 5 Test setup under load and measuring equipment

In accord with the test procedure that had been developed for this speciƤc project, the test specimens were subject to loading cycles and destruction cycles. In the large test specimen, these cycles were continued to the point at which 50 percent of the composite safety glass was destroyed. In the small-specimen tests, the load was increased up to a displacement value deƤned before the test was con-ducted. The structural safety, stability and good residual load-bearing behavior of the full-glass facade were conƤrmed in the largespecimen tests that were conducted. Even after serious damage to the sword-shaped glazing elements, the full-glass facade successfully withstood reduced loading for a period of at least 24 hours. This 24-hour period ensures that suƥcient time remains to take safety actions if the load-bearing glass elements sustain substantial damage (e.g. cordoning oơ the endangered area). The small-specimen tests conƤrmed suƥcient load-bearing strength for the silicone bond and the as-sociated slide mechanism between the screw channel and the fastener.

Fig. 6 Small specimen test

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The Competence Center for Facade and Metal Construction at the School of Engineering & Architec-ture at Lucerne University of Applied Sciences and Arts – documented and interpreted the test results and observations. The facade, as intended to be installed in the building, was veriƤed by the building component tests and meticulously documented. The resulting test report is an important document for everyone involved in the project.

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Fig. 7 Leutschenbach school t fully glazed facade

Example: Autago full-glass roof Autago, a project conducted to mark the 50th anniversary of the School of Engineering & Architecture at Lucerne University of Applied Sciences and Arts, impressively shows how architecture, energy management and structural engineering can be combined to create a single functional and design entity. Simple lightweightconcrete cubes with no additional layers of insulation form two coherent, largely opaque volumes. The lightweight-concrete cubes are covered with a highly transparent glass construction. The facade is opaque and formed seamlessly of a piece. The highly transparent roof is made of surface-bonded pre-fabricated units made of structural as well as insulating glass. This straightforward use of materials characterizes the architectural design. The structure is authentic, a building you can reach out and touch.

Fig. 8 Autago project exterior and interior view

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The Autago project is an engineering challenge. The facade walls, which are more than 70 centime-ters thick, achieve an insulation coeƥcient scarcely better than the compact insulating glass units. Nonetheless, Autago also stands for autonomy. The Autago design works well architecturally and in terms of energy at its speciƤc site, the Engineering & Architecture campus at Lucerne University of Applied Sciences and Arts. A geothermic heating system that draws heat from a depth of 1000 meters is planned for the heating of the Autago pavilion. The thermal energy will be eƥciently supplied to the facade walls via tabs, water lines embedded in the lightweight concrete, thus making the cladding of the building thermally controllable. This eƥcient means of supplying energy opens up the possibility of incorporating bold details of great note technically and architecturally.

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The highly transparent roof membrane gives the Autago pavilion design its characteristic note, along with the opaque building envelope of lightweight concrete, and has no weak spots in terms of energy. In fact, the compact roof membrane has superb insulating values. The solar energy that is produced is rendered controllable and thus useable by the outside shading elements. The enormous span of the transparent roof membrane (over 12 meters) poses the biggest engineering challenge. Although the Ƥrm Glas Trösch set new standards worldwide by extending glazing production and processing to glazing elements with a maximum length of nine meters, these nine meters were too short for this roof glazing.

Fig. 9 Lateral view of a glass beam

The Engineering & Architecture School of Lucerne University of Applied Sciences and Arts teamed up with Dr. Lüchinger + Meyer Bauingenieure AG and Glas Trösch to develop a system for joining the roof girders. The roof girders are made up of four 12-mm thick laminated panes of ƪoat glass with a structural height of 1.6 meters. Obvious mechanical connections or conventional silicone bonding do not satisfy the criteria for absolute transparency and the structural requirements. Virtually invisible adhesive joints were developed instead. As in classic tongue-and-groove joints, the individual 1.6-meter by 9-meter panes of ƪoat glass will be arranged 98

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and laminated together with 12 meter long glass girders. The stacking and laminating of the glass elements creates huge areas of overlap be-tween the individual glass panes. These areas are activated with interlayers as adhesive surfaces. The plan is to use SentryGlasPlus from DuPont instead of conventional PVB interlayers. The SentryGlasPlus Interlayer is many times more rigid and has better adherence and strength values than PVB. The SentryGlasPlus Interlayer is also less sensitive to temperature. However, temperatures as high as 70°C occur for short periods between the glare protection inside and the ceiling pane due to heat buildup. Even the SentryGlasPlus Ƥlms exhibited sharply lower rigidity at these high temperatures.

Fig. 10 Laminated glass beam and the distribuƟon of principal stress

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In a Ƥrst step, the eơects of temperature-related relaxation were assessed in Ƥnite element analyses. The testers modeled the actual joining zone for the girders with volume elements and the other areas of the girders with shell elements. As expected, the maximum main tensile stresses in the glass oc-curred in the glass panes adjoining the but joints. Analogous to the glass stresses, the highest stresses in the composite Ƥlms also occurred near the but joints in calculations at increased tempera-ture. In a further step, small-component tests were used to examine the static behavior of the SentryGlas-Plus Ƥlm in a temperature range of 20°C to 80°C. Glass girders 1.5 meter long and 0.3 meter high joined to SentryGlasPlus Ƥlm underwent a four-point bending test in a climate chamber specially de-signed for the purpose. A suitably designed Ƥnite element model was then used to calibrate with these tests. The derived parameters provided an essential basis for dimensioning and designing the girders.

Fig. 11 Test setup with small specimen in the climate chamber

In the Ƥnal phase of the structural examination, a section of the roof on a scale of 1:1 was integrated in the facade test stand and then assessed for structural safety, serviceability and residual loadbearing capacity using a test procedure designed speciƤcally for the object being tested.

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Prof. Brian Cody leads the institute for buildings and energy at the University of Technology in Graz since it was established in 2004. His focus in research, education and practice is aimed at maximising energy eƥciency of buildings and cities. Along with his work at the University of Technology he continues to serve as a scientiƤc advisor for Arup. He directs his eơort in describing how energy will become a new design parameter for future architecture.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-101

FORM FOLLOWS ENERGY ͳ ENERGY EFFICIENCY IN ARCHITECTURE AND URBAN DESIGN Brian Cody

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TU Graz / Arup GmbH

Today "energy eƥciency" is on everyone’s lips. This term is however unfortunately often misused, abused and confused with the terms "energy demand" and "energy consumption". This is especially true in the building sector, where low energy consumption is often falsely equated with high energy eƥciency and where a lot of eơort in research and practice is directed towards minimising energy demand and too little towards maximising energy eƥciency. This misconception of the term "energy eƥciency" is fundamental and needs to be corrected in order to avoid future misguided developments. Maximising energy eƥciency is more than simply minimising energy consumption. Eƥciency implies performance. Eƥciency is the relationship between output (beneƤt) and input (resources). The key issue is the quality of the beneƤt provided as a result of the energy "consumed". In the context of the thermal performance of buildings, energy eƥciency should be understood as the relationship between the quality of the thermal environment and energy demand. Regulatory devices for the energy eƥciency of buildings currently in use, including the new EU “Directive on the Energy Performance of Buildings“ unfortunately deal only with energy demand and not with energy eƥciency. At my institute we have developed a method, called BEEP (Building Environmental and Energy Performance) which allows the true energy eƥciency of a building design to be determined and thus a real comparison of various building design options. Energy eƥciency is understood here as the relationship between the quality of the internal thermal environment in a building and the quantity of energy consumption required to maintain this environment. A second misconception, particularly frequent in central and northern Europe, is the focus on heating energy. This is probably a result of cultural background. Humans are essentially a subtropical species and for those who arrived in regions like central and northern Europe, where the climate is, at least for a large portion of the year relatively cold, the 101

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climatic challenge in the past was to achieve reasonably warm indoor temperatures for living. This line of thought tends to dominate our thinking still today, even though it has little to do with the reality of the buildings we need and use today. Modern buildings do not only need to be heated but also artiƤcially lit, ventilated and increasingly cooled. This has only partially to do with the architectural concepts employed and largely results from the changed requirements due to modern usage of spaces. Heating energy demand in a modern oƥce building for example accounts for only a fraction of the total energy demand of the building.

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The third misconception in the current discussion is that there is too much emphasis on quantities and not enough on qualities. It is important to consider not only the quantity of energy “consumed” in a speciƤc process but also the quality. Heat energy at a temperature suitable for space heating is for example a comparably low grade energy form. Electricity is a high grade energy form. When comparing energy eƥciency of diơerent options we need to consider the quality of the energy quantities involved. Values for delivered energy or site energy are not suitable for such comparisons. Primary energy consumption or CO2 emissions are better. The exergy concept can also prove useful to understand better the implications of various solutions and compare their eƥciency. In thermodynamics the exergy of a system is deƤned as the potential of a system to do work during a process that brings the system into equilibrium with a heat reservoir, normally its surroundings. A research project at my institute has shown that mechanical ventilation systems with heat recovery systems in oƥce buildings, as employed in many European countries with the intention of saving heat energy do not in most cases make sense in energy eƥciency terms as the heat energy saved is more than compensated for by the electrical energy required to power the ventilation systems. A fourth misconception is that when various alternative solutions in the building context are compared with each other, too often only the energy eƥciency in operation is considered. We need to think more holistically. The total energy eƥciency including manufacture, construction and disposal needs to be considered in most cases. Recent research has for example shown that in many built buildings employing double facades to improve energy eƥciency, the time taken to recover the embodied energy of the second skin via energy savings in operation can be in the order of 25 years. This amortisation period was calculated purely in terms of primary energy, the economical payback period is substantially longer. The low energy and so-called passive house concepts in the residential building sector so loved by the popular media 102

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at the present time are a classical example of this problem. The resources input (increased building volume and embodied energy due to thermal insulation, triple glazing, mechanical ventilation systems etc.) outweighs by far the beneƤt of the reduced heating energy demand in operation. The use of electrical energy to power the mechanical ventilation systems in these buildings with the intention of saving heating energy is also problematic (see above). Furthermore, the starting point for energy eƥciency is in urban design and not in a solitary building.

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The most energy eƥcient building in the world is absolutely ineơective if not integrated into an energy eƥcient urban structure. Optimising urban density must be a key component of any future strategy to maximise energy eƥciency. This has only partly to do with the reduction of transport energy. The present use of land itself is not sustainable. An aspect which is particularly interesting with regard to energy eƥciency in urban design is the possible contribution which tall buildings could make. Results of a research project at my institute indicate a potential for increasing the energy eƥciency of cities by the use of tall buildings in urban developments. We showed that the urban density can be increased by the use of vertical structures by a factor of nearly two compared to traditional European city conƤgurations while avoiding the usual technical problems associated with high rise buildings; daylight access, reduced area eƥciency due to enlarged cores, discomfort at pedestrian level due to environmental winds etc. After proving that high rise buildings can increase density and thus potentially reduce energy consumed by transportation, the next question is whether they can really increase total energy eƥciency. On Ƥrst sight, high rise buildings appear to have inherently low energy eƥciency in their operation. This is mainly due to wind related issues. On account of the increased wind pressures due to height, external solar shading and natural ventilation with operable windows become diƥcult and thus all tall buildings to date employ mechanical ventilation and air conditioning. Therefore, strategies allowing natural ventilation of tall buildings oơer signiƤcant potential to improve energy eƥciency. For the new headquarter building of the European Central Bank in Frankfurt we developed a concept which would enable the building to be exclusively naturally ventilated and allow us to dispense with mechanical systems completely. We have since developed these concepts further in a research project where we have demonstrated the feasibility of concepts to avoid mechanical ventilation completely in very tall buildings. The beneƤts of these concepts are: increased energy eƥciency in operation, reduced 103

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embodied energy (ventilation system, plant rooms, shafts), lesser risk of Sick Building Syndrome, savings in running costs (energy costs, maintenance and operation) and savings in capital costs (system, plant rooms, shafts). We have just started to work on a research project concerned with the nature of the relationship between diơerent forms of teleworking and total energy eƥciency in society. In recent years the use of new forms of working has unquestionably increased energy consumption. There is a potential however to use these new parameters to generate radically new forms of building and transport systems with the aim of increasing total energy eƥciency. To study this we are not modelling the energy performance of building or city structures but of typical corporation and company structures. There is a huge potential for increasing energy eƥciency by architectural means by developing concepts for usage neutral spatial structures which enable adaptation for varied uses during the lifetime of a building. The days where a new build residential apartment block is by design condemned to remain a residential apartment block, on account of its ƪoor to ƪoor height and its structural, facade and circulation systems, must soon come to an end. Another issue is the degree of utilisation of our building stock. One look at a typical city in the western world quickly reveals that the percentage of time that any particular building is in use, is very very low. If we begin to think about buildings in this way, building design parameters will also radically change. One small example of this is the fact that the 24/7 use of buildings means that concepts employing thermal mass may no longer make much sense. While we are naturally primarily concerned with the issue of increasing energy eƥciency with the aim of stopping global warming, an interesting question poses itself with regard to the seemingly inevitable climate change which will occur and how this will eơect the design of our buildings; in other words, how must we design our buildings to cope with the eơects of impending climate change? In a recent research project we examined the inƪuence of the expected climate change on the heating and cooling demand for buildings in Austria. In the future we will need to look more closely at possibilities for integrated building and transport systems. In a project on the coast of the Adriatic sea we have developed a total energy concept for a carbon neutral development on an peninsula with an area of approx. 100 hectares. In our proposed solution the energy demand of the entire development including all buildings and vehicles is supplied by on-site renewable energy sources. The use of solar and wind energy, rain water, even waste water and garbage are integrated into the more or less closed system. We are 104

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proposing an integrated building and vehicle network; an Energy Grid. An interchange building provides the transformation from the primary conventional system outside the site to a secondary transportation system on the peninsula comprising electrical taxis, in which the batteries are recharged by renewable energy. A combination of centralized plant and decentral building integrated systems supply the Energy Grid with renewable energy. Buildings and vehicles are connected together via the Energy Grid. Both buildings and cars can extract and supply energy to the grid. When using renewable energy sources, energy storage systems are a vital component of the total system in order to match supply and demand and the cars thus partly fulƤl this important function by providing storage capacity. We are also using the topography of the site to store energy by using excess energy produced by solar and wind sources to pump water to the highest point of the peninsula and store it in a large reservoir. This potential energy in the form of water mass can be used, when required, to drive turbines and generate electrical power. This system is also combined with a system for collecting and using rainwater. Sea water is used for cooling purposes. Solar cooling systems employ solar energy to drive absorption chillers.

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Concentrating the urban development in densely built villages means that a large part of the peninsula can be left in its natural condition, the biodiversity can be preserved to a large extent and the transportation demand can be minimized. Solar geometry and wind analysis are used to generate urban morphologies which provide pleasant microclimatic conditions in the external urban spaces. A central issue in my work in research and practice is the relationship between built form and energy eƥciency; summed up in the phrase Form follows Energy. When aspects relating to energy eƥciency are considered right from the start of a design process, new and interesting possibilities for form language and form result. Many built examples show this already. In any case, there is always a relationship between architecture and energy. Whether Form follows Energy or energy follows form; the energy eƥciency of a building is inƪuenced to a large extent by it’s architectural design. All of these aspects will have huge implications for the design of future facade systems. Using case studies and based on the results of recent research work these themes will be explored in my talk.

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Together with his wife Prof. Swantje Kühn, Dipl.-Ing. Oliver Kühn manages the architecture oƥce GKK+ Architekten in Berlin. They have designed many award winning buildings and they desire being general planner of a project to gain better a control over the design. Oliver Kühn claims that the strategy of uniting the diơerent designers under the lead of the architect has often awarded their projects with success.

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The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-107

THE CONSTANT OF CHANGE

Oliver Kühn GKK+ Architekten

Project: Süddeutscher Verlag Building, Munich The acceleration of modern processes suggests that the only constant in life is change. As Albert Einstein said, within these processes, things develop from the primitive through the complicated to the simple. Simple, no simpler!

Architect:

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GKK+Architekten, Berlin Prof. Swantje Kühn and Oliver Kühn Consultants: Landscape Architect: ST raum a LandschaŌsarchitekten, Berlin General Planner: CBP Generalplanung GmbH, Munich Structural Engineers: CBP Tragwerksplanung GmbH, Munich Energy Concept: CBP Technische Ausrüstung GmbH, Munich Facade Planning: R+R Fuchs GmbH, Munich Lightning Planning 1: MS Licht – Michael Schmidt Lichtplanung, Munich Lightning Planning 2: LXon light and airdesign AG, Munich Facts: Total gross Ňoor area: 79.000 m² Start of planning: October 2004 Start of construcƟon: January 2006 CompleƟon: October 2008

Fig. 1 Süddeutscher Verlag Building, Munich Image: Claus Graubner

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While it seems impossible to predict the end result of change, we can still analyze the drivers of change. In a comprehensive study, the foresight and innovation team of OVE Arup in London have identiƤed the so called STEEP categories which categorize those areas of our lives where change is generated. In that study, S stand for Social, T for Technology, E for Environment, E for Economy and P for Politics. The STEEP categories are also applicable when broken down to the issue of facades and the process leading from modular glass and ironware technology to integral, responsive building skins. In most of the developing countries, we are watching a steep increase in populations and the phenomenon of exploding cities. Taking into account the fact that the 160 million buildings in the EU use over 40% of Europe’s energy and generate over 40% of its carbon dioxide emissions, the social issue has a direct link to facade technology and the issue of saving resources and generating renewable energies.

Fig. 2 The glass atrium Image: Claus Graubner

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Technology helps us develop and optimize integral building skins. With the development of new materials as renewable energy sources, and the latest knowledge from nanotechnology for modern coatings and the disaggregation of composites, facades will emerge with a performance and appearance entirely diơerent from what we are used to. Our environment provides us with excellent examples of nature’s principle of achieving the most with the least. By studying bionic principles, we will soon be able to dramatically reduce the number of modular elements down to a system which performs as a service network for buildings, just as our skin does for our body. This process of economizing helps us join forces in our globalized society, to share experiences and develop and produce competence. Large-scale production permits cost eơective solutions worldwide. Smart facade technology will no longer be something “nice to have” for developed countries, but will also be available for developing countries, where most construction activity occurs.

Fig. 3 The glass atrium Image: Claus Graubner

Finally, the political sphere must set clear rules and regulations to sustain the ecological performance of our built environment. It is foreseeable that within the next decade, all buildings will have to themselves generate the energy they consume. The facades as the interface between the inside and the outside will be a key focus of such policy decisions. This means that when we plan facades today, facades themselves are certainly not the only issue. Rather, a holistic understanding of architecture and construction technology embedded in the context 108

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of our local and global social parameters is at issue as well. In order to attain this goal, we must, more strongly than has previously been the case, integrate the disciplines involved into a network, and bundle competences. This therefore requires both new planning structures and the readiness to open planning to factual contexts which have been disregarded to date, i.e., a new objectivity.

Fig. 4 Lounge area Image: Claus Graubner

However, still more is required: the willingness on the part of all involved to once more understand and accept planning and construction as a research and development task. The client too must realize that real innovation requires a willingness to make decisions for which there is no precedent in traditional ways of doing things. The following example, the new Süddeutsche Zeitung highrise building designed by GKK+ Architekten, is particularly suited for describing the aspects Environment and Technology, which means conscious management of energy, but also its technological and social interconnections. With a motivated, decisive and innovative client, it has been possible here to successfully address the energy technology issue holistically in the facade as the interface.

The Süddeutscher Verlag Building in Munich Responsible clients think with consideration and with the long term in view. For them, a well-balanced business and work atmosphere is just as important as a balance of economics and the ecology.

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Hence, the goals set for the new Süddeutscher Verlag Building included not only optimum conditions for an eơective and eƥcient working environment, but also social, cultural-political and ecological goals. The integrated design team Conventional planning structures suggest working alongside one another, a “team of stars.” However, working with one another requires a “star team” – which is a little diơerent. As required for this task, an integrated design team was set up for the Süddeutscher Verlag Building, which was complemented by two members of management who were the authorized decision-makers and who had dealt with all planning issues intensively. This early decision had considerable advantages. There were no losses whatever due to friction; at the same time, in spite of the high pressure of time and costs, something new and better could be developed: a design and performance of a building which constitutes true added value, and has been able to contribute both to the success and to the positive image of the Süddeutscher Verlag. 109

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For this purpose, the actual planning process was preceded by two steps, in which the conventional foundations of that process were analyzed, particularly from a social and energetic point of view. In a Ƥrst step, the standard oƥce functions were complemented by such “soft factors” as a bright representative glass atrium (Ƥgs. 2, 3), an employee restaurant (Ƥg. 5) designed by world famous artist Tobias Rehberger, an integrated art exhibition, a child-care center, and lounge areas (Ƥg. 4) on every ƪoor, so that employees could feel at home, even in the oƥce. At the same time, individual needs were taken into account with such special comfort features as individual control of the oƥce conditions by its users such as climate, maximum natural ventilation and lighting, and openable windows for every oƥce. In a second step, a survey of working hours was taken to determine the times of use to be assumed for the new building. The result was astounding: the extreme variability of work times resulted in operating hours of from 6 a.m. through 2 a.m., or an unbroken twenty hours, even on weekends.

Fig. 5 Employee restaurant designed by arƟst Tobias Rehberger Image: Claus Graubner

Fig. 6 Free Ňow area, food court Image: Claus Graubner

In order to be able to ensure a sustainable energy supply despite this exceptionally high operating period, new paths were taken in the energy concept and in facade technology, on a Macro level, a Meso level and Ƥnally on a Micro level of design.

The Macro-Level

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Energy-opƟmized Ňoor plan First, the ƪoor plan was optimized with respect to the angle of incidence of the sunlight; as a result of this the core area is eccentric. (Ƥg. 7) In this way, open-plan oƥces of great depth could be placed in the east and west, similar oƥces of less depth in the south, and cellular oƥces with very little depth in the north.

Fig. 7 Floorplan with excentric cores

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SimulaƟons On the basis of the new ƪoor plan an the initial information on building use, several computer-aided simulations were run, which on the one hand assessed the primary energy requirement and the humidity over the course of the year, and on the other, the investment and operating costs throughout the entire life cycle of the building. Using the results of the simulation, an energy and facade concept consisting of the following components was then developed:

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• natural ventilation via a double facade • reduction of solar gain by integrated sun-shading in the space between inner and outer facade • an activated concrete core for basic heat and cooling loads • decentralized facade ventilation devices for peak load and mechanical ventilation • back cooling • use of district heat • and geothermal energy via thermally activated foundation piles.

Fig. 8 Climate concept and facade

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The energy concept thus consists of a passive system for the basic loads not accessible to the employees, and an active system that is individually adjustable digital via facade and ventilation control equipment. Seasonal heat shiŌ In the passive system, heating and cooling of the building are carried out via geothermal energy and the activated concrete core. For this purpose, the temperature level of the soil, which is a little above 13°C in winter, is raised to the desired ƪow-pipe temperature via a heat exchanger, or in summer, reduced to that temperature. The heat exchange is carried out via water which is passed in tubes through the drilled piles of the high-rise building up to the storey ceilings and then back again to the drilled piles. That permits heat to be transferred from the building into the soil, or else from the soil into the building, depending on the season.

Fig. 9 The use of geothermal energy

Due to the long operating hours mentioned above of twenty hours, even on weekends, a considerable share of energy savings and production is provided by the seasonal heat shift.

The Meso-Level If optimization at the macro-level is achieved via geothermal energy and concrete activation, energy is saved at the meso-level via the facade. Here, new ground has been broken, both visually and technically.

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The modula / integral double facade The facade which covers all the components of the building has an important function as a metaphor for the work of the Süddeutscher Verlag. Like a sparkling crystal, the information consisting of light, shadow, the surroundings and the clouds is mirrored in its facets which are placed at various angles in relation to one another, so that each observer sees something slightly diơerent from what his or her neighbor sees – as when reading an article, in which the information is the same, but the interpretations diơer from one individual to another. (Ƥg. 10)

Fig. 10 PerspecƟve view on the facade Image: Claus Graubner

Technically, however, the facade consists of perfectly uniform modules which are resolved integrally in themselves. In each module, 7 m high x 5.40 m wide, the four outer plates of the module are inclined toward one another with a climax in the middle, 112

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thus providing the visual attraction of a polished facets. Behind each plate is the sun-shading, and further inside, room high, openable insulation glazing. The frame of each module has air openings for natural ventilation, and decentralized facade ventilation devices at each window bay coupled to heat exchangers reduce the peak loads in the oƥce, and in the air recycling mode, permit natural ventilation, even with the windows closed.

Fig. 11 The facade modules are inclined diīerently to create a faceƩed eīect Image: Claus Graubner

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Fig. 12 Detailed view on integrated decentralized venƟlators Image: Henning Hesse

With individual window ventilation, the decentralized facade ventilators switch themselves oơ automatically, so that energy is not released and “the landscape” cooled or heated. (Ƥg. 12) For monitoring of function and quality control, several modules from the facade were sampled at a scale of 1:1. Using the sample and empirical knowledge, it was possible over the course of several months, together with the executing companies, to realize optimizations in the accessories technology, the coating and the glass quality. Moreover, it also proved possible to concretize the light qualities in Ƥeld tests, which in turn made it possible to dispense with an additional anti-glare shield at the workplace – a decision arrived at by consensus, which was of considerable relevance, too, with regard to the costs. From the sample, information was also gained with regard to the temperatures occurring in the oƥces, and this was incorporated into the energy concept. 113

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Waste heat use Thus, surplus heat is generally used within the building. Cooling is, for instance, required year round, to cool conference rooms or the computer center. The heat generated in the cooling machines is in turn used to support the underƪoor central heating of the central atrium and the concrete-core activation. At the same time, the oƥce exhaust air is collected and used centrally to preheat cold outer air before it is blown into the oƥces. The remaining heat energy requirement is obtained from the very eƥcient municipal district-heat network.

The Micro-Level Several measures for increasing energy eƥciency have also been taken at the micro level. Intelligent building instrumentaƟon and control All building functions controlled by employees are regulated by a “transponder”, a microchip which they carry on their key-chains. This device provides control of access, from the parking garage to the oƥce; of time monitoring, invoicing and switching on and oơ of the lighting; of the rolling out and in of the sun-screens; and of ventilation, heating and cooling, just as needed. Sensor technology in everyday work in the oĸce

A multifunctional deck sail permits the regulation of such additional critical aspects of oƥce routine as acoustics, Ƥre protection, presence detectors and no-glare illumination in an element.

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SpeciƤc comfort values are passed on from the PCs of the employees, which are connected with the building automation via intranet, to the room controllers by means of a bus system. If the employee enters his or her oƥce, the presence detector will turn on the light to the required brightness. Shortly before that, the facade ventilation equipment will already have produced the desired temperature in the room, and the slats of the venetian blinds will have moved from the standard position to the preferred position. Thus, it is no longer possible to forget to switch oơ the light, turn down the heating or roll in the sun shading when one leaves the oƥce – all that saves energy, from the smallest scale to the greatest.

Figs. 13, 14 The oĸce area Image: Claus Graubner

Figs. 15 The conference room Image: Henning Hesse

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Summary The new high-rise building of the Süddeutsche Zeitung sets new standards, both with regard to facade technology and with respect to its energy concept.

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And the two cannot be separated! Only by combining the energy aspects with a facade concept designed to Ƥt it makes it possible for the Süddeutscher Verlag Building to save approx. 80% of the primary energy used, over comparable buildings – at the macro, meso, and micro levels.

Fig. 16 Detailed view on facade modules Image: Claus Graubner

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Prof. Dr.-Ing. Jan Knippers and Dipl.-Ing. Thorsten Helbig are structural designers in Stuttgart.

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They have build together with numerous famous architects in places all over the world. Amongst their projects they have designed a number free-form glazed grid shells. The paper shows the latest developments in this structural concepts and how a tight cooperation between architect and engineer can lead to impressive architectural results.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-117

RECENT DEVELOPMENTS IN THE DESIGN OF GLAZED GRID SHELLS Jan Knippers, Thorsten Helbig

IntroducƟon

Knippers Helbig / ConsulƟng Engineers

Due to Computer Aided Manufacturing (CAM) nearly every 3Dgeometry can be built. Single layer triangulated grid shells are often used as a structural system. Although, many examples can be found where an elegant 3D-shape was not accordingly transferred into a built structure. Irregular grids and rough construction details aơect the structural integrity and the elegance of the architectural idea. Often, the reason is that the architectural design on the one hand, and the technical realization on the other hand, are considered as two diơerent tasks carried out subsequently by diơerent people with diơerent approaches and tools. While architects frequently work with 3D modelling tools, engineers use Ƥnite element analysis software with an interface to CAD applications. Thus, even on a technical level, the communication between the aesthetic and the structural design is often diƥcult. To achieve an optimal solution for a grid shell, a continuous process of engineering from the very Ƥrst architectural idea to the assembly on site is necessary. This process basically consists of the following steps:

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-

Structural optimization of the 3D-shape with regards to the ƪow of forces and the support conditions - Transformation of the shape into a load bearing grid - Structural analysis of the grid - Design of details, especially the nodal points of the grid The meshing of the grid, in particular, is a new design step which requires new tools. All four steps need to be carried out carefully to achieve an optimal solution. Diơerent examples which highlight this consistent process of design are shown below:

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Wesƞield Shopping Centre, London, White City The Ƥrst example shows a free formed grid shell for a shopping mall in London-White City. The roof consists of two parts with a regular span of 24 m and a total surface of 17.000 m2 (Fig. 1). The 8.500 steel members consist of welded hollow box sections with a size of 160 x 65 mm and an average length of 2,30 m. Both parts of the roof are jointless and are supported in a spacing of 12m. The bearings allow for displacements parallel to the roof edges and are Ƥxed perpendicular to this direction.The roof is covered alternatley by insulating glass panes as well as thermal insulated metal sheets, both with a triangular shape.

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Fig. 1 Shopping complex in London White-City

The architects’ (Benoy, London) initial idea for the geometry of the roof was based on the image of concetric waves on a water surface after a stone has fallen in. Our Ƥrst contribution was to optimize this shape from a structural as well as from an aesthetical point of view. One string of members of the triangulated net follows the orientation of the mall, the two others cross it with an angle of 30 degrees. From a structural point of view, the waves act eơectively, when they span perpendicular to the mall like a corrugated sheet. To achieve a smooth surface without any faceting edges the overall geometry and the orientation of the members can not be discussed independently. The ‘waves’ should follow the orientation of the steel members, i.e. span the mall with an angle of 30 degrees. In this case an angle of 60 degrees was chosen for the waves. By doing so, the geometry of the roof combines the structural requirements and aesthetics (Figs 2 and 3).

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Fig. 2 Diīerent orientaƟon of grid members on surface

Fig. 3 Grid for structural analysis and fabricaƟon

The net was generated by projecting a plain triangulated mesh onto the 3D shape. The plain net has a regular grid. Therefore the built structure has varying member lengths according to the position of the respective member in the shell. The grid shown in Fig. 3 was used for the structural analysis. It also served as a basis for the shop drawings and the fabrication.

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An interesting aspect of this project are the innovative tools, which were used for design and manufacturing. A bolted connection was proposed by the contractor (Seele, Gerstofen, Germany, Figs 4 and 5), which connects the members by vertical face plates. Fig. 4 Nodal connector Wesƞield (Seele Gersthofen, Germany)

Fig. 5 Exploded view nodal connector Wesƞield

The hollow box nodes were welded. Each of them has a diơerent geometry and consists of 26 diơerent plates. Each of these plates as well as the bolts are optimized for the loading of the respective connection. The Ƥnal adjustment to the exact geometry was achieved by machining the face plates (Fig. 6). The nodes were delivered in packages of six, so no large storage space was necessary on site. 119

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The nodes were bolted to the straight members on site without any option for adjustment of the geometry. After the assembly, a deviation of 15mm to the reference geometry was measured on a total length of 164m (Figs 7 and 8). The high degree of prefabrication, the accuracy of the bolted connectors, and a shop-made corrosion protection allowed for a rapid installation; regardless of weather conditions.

Fig. 6a Machining of face plates for Įnal accuracy of geometry Fig. 6b Final check of geometry Fig. 6c Steel member with varying plate thicknesses and bolts

The geometric data from the shop drawings were used for the detailed structural analysis of the nodes. A complex automated process was established this way. In doing so, the structural model of the grid served as a database for the shop drawings, which provided the geometric data for the detailed structural analysis of the plates and bolts of the nodes. The results of the latter, i.e. the adapted thicknesses of the plates and the varying diameters of the bolts, were again incorporated in the shop drawings and automatically transferred to the production line. In addition, an assembly drawing for each node was issued.

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Creating and maintaining the persistent structural model, and organising the data exchange, form a new and independent set of planning work. This is preferably executed by the structural designer, who acts as a mediator between the architect’s design intentions and the technical constraints of production and assembly.

Fig. 7 Fastening of bolts on site

Fig. 8 Assembly of roof structure Figs 9a & b Interior view

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The planning of 3D structures, which is consistently based on digital methods, establishes new scopes for structural designers; beyond the classic tasks in statics and construction. The chosen fabrication technology is also of interest from an aesthetical point of view. In contrast to most other comparable structures, no central nodal connector is visible, even though the entire structure is connected by bolts, except from a few heavily loaded welded nodes at the edge (Figs 9a and b). Members and nodes consist of a great many geometrically diơerent steel plates which are Ƥxed by invisible connections. The challenge in engineering was not only the design of elegant structural details, but rather the organisation of a smooth and precise ƪow of data between structural analysis, shop drawings and production.

Retail Centre MyZeil, Palais QuarƟer Frankfurt The handling of complex geometries is highlighted in the second example. Palais Quartier is the name of a large building complex in the heart of Frankfurt, which consists of two high-rise buildings and a 5-storey retail-centre, called MyZeil. The latter was designed by the Italian architect Massimiliano Fuksas from Rome and is covered by a free formed glazed roof of 13.000 m2 (Fig. 10).

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Fig. 10 Retail centre MyZeil

Fig. 11a IniƟal shape of the roof

Fig. 11b Final shape of the roof aŌer opƟmizaƟon

Like a carpet, a grid shell covers the concrete slab levels. Fig. 11a left shows the Ƥrst architectural vision of the geometry, that we received as a ‘Rhino’ Ƥle. The geometry consists of ƪat areas, which are connected by sharply bent edges. The ‘canyon’ in the centre, which is above the shopping mall, is supposed to be column free for the comfort of the pedestrians. In the Ƥrst design step, the 3D shape was optimized in two ways. First, the two horns, which were initially only aesthetic elements, were used as large columns, i.e. as 121

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structural elements. One is supported on the ground level and the other by the facade structure. Thereafter, the sharp edges were smoothed to allow a ƪow of forces which enables shell-behaviour and reduces the bending moments in the steel members (Fig. 11b). By doing so, a column free shopping-mall was achieved. The ƪat zones above the top levels are supported by columns with a regular spacing. At this stage of the design, intense discussion between architects and engineers about geometries and shapes took place via the exchange of ‘Rhino’ Ƥles.

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In the next design step, the 3D-shape had to be transferred into a structural grid. In contrast to the WestƤeld Shopping Centre in London, which was described in the previous chapter, the geometry is much more complex and shows larger curvatures. Therefore the simple projection method used for the structure in London could not be applied in this case. Standardised methods and tools do not exist for this task. Often, automatic mesh generators from FEanalysis- or 3D modelling software are used. However, they usually do not lead to satisfying results. These meshing tools start from the boundaries and connect separately generated zones, which leads to irregular meshes in the centre (Fig. 13a). This is not satisfying from an aesthetical or structural point of view. First, to achieve an orientation of the members, which satisƤes aesthetic as well as structural requirements, ‘lines of orientation’ as well as connection points for the vertical facade were deƤned (Fig. 12). These were used as starting points or as boundary conditions for the mesh generation. Next, the shape was divided in ‘mega-triangles’, which deƤne the position of the 5-member nodes, which are unavoidable for such kind of geometries. Within these ‘mega-triangles’ continuous nets with smaller triangles and 6-member nodes were generated. This procedure is similar to the one used by Buckminster Fuller for his geodetic domes. Then a tool was developed to even the member lengths and vertex angles (relaxation tool). Therefore the boundaries of the mega triangles can not be detected in the Ƥnal grid anymore. At their connecting points special vertices with 5 or 7 members instead of 6 appear. After several intermediate steps the grid in Fig. 13b was achieved, which served as a data-model for structural analysis and the shop drawings as well as for fabrication. The average member length is 2.30 m. The transformation of the data model into a built structure depends very much on the experience of the contractor and the means of fabrication. There is no standardized solution for the nodal points of the grid. In contrast to the roof for the trade fair in Milano, which

Fig. 12 'OrientaƟon lines' for mesh generator

Fig. 13a IniƟal grid of the roof

Fig. 13b Final grid aŌer opƟmizaƟon

Fig. 14 Nodal connector of Frankfurt Hoch Vier (Waagner Biro)

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was also designed by Massimilano Fuksas, the architect wanted an aesthetically unobtrusive detail for the nodal connector. In this case the contractor (Waagner Biro, Vienna, Austria) proposed a welded connection for the node, which is based on the experience that he had gained from the roof over the courtyard of the British museum in London (Fig. 15). The members are welded to a central ‘star’, which is burned out of a thick steel plate. However, due to the complex geometry, about 10% of all nodes are fabricated as a compact steel block. Ladders were prefabricated in the shop and the connected to the completed structure on site (Fig. 16). The node geometry is developed in a way that the centre lines on top of the steel members meet in the node (the same holds for the WestƤeld project in London). The members are welded hollow box sections with an average size of 120x 60 mm. The thicknesses of the plates are adapted to the respective loading conditions.

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Fig. 15 Grid during construcƟon

Fig. 16 Completed structure

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Bao’an InternaƟonal Airport, Shenzen The methods illustrated for the projects in London and Frankfurt, were developed for the static/constructive optimisation of single layer grid shells. With the following example we would like to point out, how geometric methods can be applied to meet intricate requirements; where not only the ƪow of forces matters, but also energy and light. Currently, we are running a parametric generation of the facade panels for the terminal building of the airport Shenzen in China, which was also designed by Massimilano Fuksas.

Fig. 17 Terminal Building Bao'an InternaƟonal Airport, Shenzhen

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The roof structure with a developed surface of 300.000 m² at a total length of 1700 m, consists of a two-layer space framework with spans up to 80 m with installed facade building units on both sides. The geometry of the roof structure changes between one-way curved barrels, and two-way irregular curved dome-shaped areas, at the intersection of the terminal Ƥnger piers. The facade building units are insulated metal panels with glazed openings. Both, the dimensions of the glazing and the inclinations are variable. These parameters are determined as subject to the orientation to the sun, the required visual connections from interior to exterior, and the needs of natural illumination of the building. The geometry of the facade building units allows for these parameters of the transparent openings, and combines them with the freely shaped and complex roof geometry. Based on the surface of the roof, developed by the architects, we began by creating a data model for the space framework. Building on that, the next step was to develop a Rhino-Script, which generates the data for the facade building units depending on the parameters for the transparent openings. 124

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To meet the manufacturing conditions in China, an ‘open’ joint between the panels was designed, which does not only compensate thermal expansion and production tolerances, but also enables us to combine panel geometries in groups. In this way it was possible to reduce the number of geometrically diơerent panels from 60.000 to approximately 3000. Fig. 18 Model facade structure

Fig. 19 Geometry facade panel

Conclusion In all three examples it was very important, that the structural engineer was part of the team from the very early stages of conceptual design up to the detail design and shop drawing phase with the contractor. For such complex tasks a consistent approach is necessary to reach thoroughly high quality for the structural and esthetical aspects of the building.

Project credits WestƤeld, London White City: Client: WestƤeld Shoppingtowns Ltd. Architect: Benoy/ London, Buchanan Group/ London Contractor: Seele GmbH & Co KG, Gersthofen, Germany Fig. 20 Rendering facade panels

Retail Centre MyZeil, Palais Quartier Frankfurt: Client: Bouwfonds MAB Frankfurt HochVier GmbH Architect: Massimilano Fuksas Architetto, Rome / Frankfurt Contractor: Waagner-Biro AG, Vienna, Austria

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Bao’an International Airport, Shenzen: Client: Shenzen Airport Group Co. Ltd. Architect: Massimilano Fuksas Architetto, Rome

Structural Design for all Projects: Knippers Helbig Consulting Engineers, Stuttgart (for the Frankfurt Project in cooperation with Krebs und Kiefer, Darmstadt) Team: Fabian Friz , Florian Kamp, Sven Wörner, Florian Scheible, Markus Gabler

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

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As an architect, facade planner and researcher in the Ƥeld of facades, Dipl.-Ing. Tillmann Klein looks at ways to innovate facade construction. He is leading the facade research Group at the TU Delft and is editor of the book series “The Future Envelope”. The paper is a result of student works from the International Facade Master program at the TU Delft.

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

The Future Envelope 3 – Facades-The Making Of. U. Knaack and T. Klein (Eds.). IOS Press, 2010. © 2010 IOS Press and the Authors. All rights reserved. doi:10.3233/978-1-60750-672-0-127

THE MAKING OF ͳ A SUMMARY

Tillmann Klein TU DelŌ / Facade Research Group

When talking about “the making of”, it is understood that we deal with items that play in the background. They compose what the target readership of this book works with everyday. But in fact, all of these eơorts focus on the Ƥnal product: in our case, architecture. The building envelope contributes signiƤcantly to the architectural design of a building, but unlike the Ƥlm industry facades are no stage sets where the aesthetic impression is the main focus. This makes a big diơerence. Facades have to fulƤl numerous other functions such as protection from the exterior climate.

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The functions call for a certain way of construction. We have load bearing components, insulation layers, sealing components, and components that concentrate on the architectural design. High requirements related to tightness and thermal insulation have generally led to a new way of layered constructions. A good example is the brick wall, which was originally built solidly, and now evolved into cladding that merely covers the actual structure and only simulate compactness. There is nothing basically wrong with layered constructions, but it becomes clear that it has an inƪuence on architectural design. Architecture and construction are intrinsically tied to one another; thus, technological development is of essential importance for architecture. Developments in the Ƥelds of materials, production, and planning tools are numerous; this book presents some of these trends. This chapter summarizes the diơerent contributions, and is organized by topic.

Materials and Technologies Transferring new materials into facade applications is very diƥcult. Materials with new visual qualities can often be easily used for interior design, but applying them to facade design poses much higher challenges. Whereas Ƥre resistance, for

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

example, is a property required for both, materials used in facades must withstand various weather conditions over many years. And material may not loose visual quality while its structural properties must be examined from the ground up. Matthias Michel shows how much developmental work, including setbacks, was necessary to apply acrylic to a project such as the BMW Hourglass. For example, he found out that the strength of the connection of point holders in acrylic relies on the surface Ƥnish of the material much more than the thickness of the material. Here we deal with high engineering. The smallest constructional mistakes can jeopardise a project’s load-bearing capacity. It is obvious that this requires a special project ƪow. Executing companies must be closely accompanied because they do not yet have the necessary experience with the materials.

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The boundaries of the feasible expand continuously. Structural engineer James O´Callaghan is responsible for the design of various Apple stores. He applies structural glass in previously unknown and breathtaking dimensions. This is possible by using autoclaves, usually used for the fabrication of aeroplane wings to laminate the mega glass sheets into a monolithic piece of glass. The transfer of technology, together with excellent engineering and the willingness to take risks made this step possible.

Fig. 1 Roof of the Apple store, New York

Textile envelopes have developed from experimental approaches to technically mature applications. But this technology is still rather new and the market involved remains small. In addition, the variety of technologies in the Ƥeld of foil is still expanding. Functional low-e coatings have been developed and new ƪexible solar cells are available for application, making textile envelopes even more interesting for architectural application. Jan Cremers from Hightex 128

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

Group points out though that this poses a new challenge for the education and consultation of architects until the technology becomes a standard.

New Structural Facade Concepts

Fig. 2 Munich football stadium with texƟle envelope

In order to create a very slender glass facade, Mick Eekhout transferred technology originally used for sailboat masts. The suspended facade structure has internal composite cables. Turning this into a real project, which would withstand the next decades, proved to be a real challenge. With the words of Mick Eekhout : “Trustworthy innovation takes years!” In this special case, the loadbearing cables are integrated within the space of the double glazed units. The downfall of this very thin structure is that exchanging a glass pane, though not likely to happen, would involve demounting the entire facade. Contrary to, for example, the aerospace industry, stakeholders in the building industry typically have rather limited Ƥnancial capacities. High personal risks are involved, which obstructs large scale innovation.

Industry and standardizaƟon

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This book contains papers about high end facade construction with unique boundary-shifting projects. But if we talk about the standard market we can see that the making of facades actually begins long before the architect gets involved. Facades are highly standardized products and what the industry oơers deƤnes what is built. Jeroen Scheepmakers talks about Alcoa´s eơorts as a major system supplier to oơer products of the highest standards with maximum customizability. He refers to the automotive industry and its concept cars that are forerunners for a broad market. The development requires a team of stakeholders from the industry, engineering and architects, and success is not guaranteed. Bert Lieverse, director of the European Facade Association (FAECF) sees a closer cooperation of the facade and building services disciplines. In his view, it is not only about facades contributing to the energy use of the building and to a good user comfort, but also about creating a future market for the facade industry.

Architecture, Design and Engineering Structural engineer Jan Knippers uses the example of glazed grid shells to show how highly complex facade geometries can be realised. Architect, facade planner and structural engineer must work together seamlessly. With the WestƤeld shopping centre in London, the planning process went so far as to structurally dimensioning 129

The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

each element and every node to the particular requirements. All components were pre-manufactured and then welded on-site without the possibility of adjusting tolerances. Thus, the engineered detail disappears and is no longer visible architecturally – oơering possibilities for architectural design. This project is also particularly interesting, because it contradicts traditional construction and detailing approaches, which assume moderate on-site tolerances. Building shifts from the concept of craftsmanship to an approach of industrially pre-manufactured production. Today we have planning tools such as computer software at our disposal that allow virtual geometric presentation and calculation of complex structures. However, we must not forget that high quality engineering cannot be substituted. The actual realisation of the project is a big challenge and requires a courageous attitude of all participants.

The Future “Making of” The contributions in this book show cutting edge examples of what is currently possible. But they also reveal where possible innovative developments will emerge from and what the typical problems are to implementing them in the unique building market.

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On one hand there is architecture demanding new solutions from construction and technology. “How can an idea be realised?“ A good example is the light and transparent glazed grid shells, presented by Jan Knippers. This cooperation of architect and engineer enabled new surprising solutions in creating the desired free-form shapes. On the other hand, there are new materials that, via construction, oơer new possibilities for architecture. The textile industry, for example, is rapidly developing new products that are gratefully adopted by architects.

Fig. 3 InnovaƟon in building envelopes: architecture pull and technology push

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

But there is a third way. Innovation can also emerge from technology or construction itself. Being able to produce bigger glass sheets enabled the impressive construction of the Apple store. The example shows an enhancement of existing possibilities. Also, the designs by the students of the Facade Master Program in Delft oơer new possibilities by rethinking traditionally evolved constructional principles. The implementation in practise is, of course, a separate problem. Completely new concepts, such has the composite facade for the Inholland building, presented by Mick Eekhout, are the most diƥcult. Although theoretically feasible, the realisation of the original design was not possible, because none of the involved parties where able or willing to bear the Ƥnancial risks. As a result the concept had to be changed resulting in a more standard solution. Innovation in the project “Süddeutsche Zeitung” is of a diơerent nature. Here it is not the structural concept that is new, but the role of the building envelope for the climate concept of the building. In order to bring the project to a success, a new, integrated design team was required. The fundamental issue that inhibits new ways of making facades are the risk of injury and damage as well as Ƥnancial risks. Calculation software and testing methods aid in predicting the behaviour of the facades and reducing the risks in practise. Daniel Meyer impressively shows how testing of one-to-one mock-ups is a part of an innovative creation process. Eventually the experience helps raising the standard and becomes a known building practise, as shown with the development of textile enveloping technology.

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What we can learn from the contributions in this book is that making facades is becoming increasingly complex. The speed with which new technologies become available seems to increase. Again, using the association to Ƥlm making from the title of the book, the director must have broad knowledge of the technical aspects of producing a Ƥlm. If a designer wants to leave the basic standard and wants to have full control over the outcome of his work, he needs to cover all the diơerent aspects of the making of – which is only possible by involving specialist right from the start of a project. In terms of the building as a whole, over the past few years, the envelope has developed into a specialised building discipline and will remain an exciting topic of critical signiƤcance for the future development of architecture.

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,

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The Future Envelope 3 : Facades - the Making Of, edited by U. Knaack, and T. Klein, IOS Press, Incorporated, 2010. ProQuest Ebook Central,