Fundamentals of Architectural Lighting [1° ed.] 1138506753, 9781138506756

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The theme of this book is that light is an inseparable part of architectural design, and is intended to provide students of architecture and interior design with a graphic guideline to the fundamental role lighting plays in this process. While simple light sources may be enough to satisfy practical needs, the design process must expand beyond basic illumination. The challenge for architects and designers is the creation of luminous environments offering visual interest and a sense of well-being, while also meeting basic seeing needs. Technological advances provide opportunities for the lighting designer’s creative introduction of light, and the visual and psychological perceptions of the illuminated architectural environment. offers a complete and comprehensive guide to the basics of lighting design, equipping students and practitioners with the tools and ideas they need to master a variety of lighting techniques. The book is extensively illustrated with over 250 illustrations to demonstrate basic principles and procedures. It is an excellent resource for anyone interested in the fundamentals of integrated lighting for architectural interior spaces.

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

is a retired architect and lighting designer with a career focused on the coordination of lighting and architecture With over forty years of experience with his own architectural firm, he also held the position of Director of Lighting for two large architectural firms. He was an Associate Professor of architecture at Kent State University, and an adjunct instructor at Oklahoma State University School of Architecture. His work experience includes graphic design, technical writing and illustration for architectural and lighting-related publications, as well as writing a monthly column for Architectural Lighting magazine.

SAMUEL MILLS

First published 2018 by Routledge 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN and by Routledge 711 Third Avenue, New York, NY 10017 Routledge is an imprint of the Taylor & Francis Group, an informa business © 2018 Samuel M. Mills The right of Samuel M. Mills to be identified as author of this work has been asserted by him in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this book may be reprinted or reproduced or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Publisher’s Note This book has been prepared from camera-ready copy provided by Samuel M. Mills British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book has been requested ISBN: 978-1-138-50675-6 (hbk) ISBN: 978-1-138-50676-3 (pbk) ISBN: 978-1-315-14700-0 (ebk) Typeset in Arial MT Std Light & Myriad Pro by Samuel M. Mills

FUNDAMENTALS OF ARCHITEC TURAL LIGHTING

PREFACE During the past century architectural lighting has been influenced and guided by the field of illumination engineering through its scientific approach to furnishing adequate illumination for our working and casual seeing needs. Architects and interior designers relied on the illuminating engineer for lighting solutions partly due to its inherent complexity and their personal lack of knowledge. However, there has also been a growing interest in the consideration of other design parameters beyond merely providing adequate levels of lighting. As far back as 1938 Professor Stanley McCandless, of Yale University, published an extensive paper on the subject titled “Lighting For Designers” (meaning other than engineers). The following excerpt was extracted from this long, detailed paper because of its relevance to current lighting design practice, and its forward thinking and incisive discussion of the topic, and also appropriately, the theme of this book. Practically all architects seem to agree that at night the lighting makes things fit and even dramatizes the design. There are also examples to indicate that lighting properly used is a great asset and promises to influence design far beyond its purely utilitarian aspects. From one point of view, lighting can be thought of as a structural material which is used in a building to help it serve various functions. Lighting has certain characteristics which determine its use and design like other materials, such as brick, steel, stone, and concrete. It should be designed by the architect as definitely as when he uses these materials. Unfortunately today (1938) it is common practice to treat interior lighting like furniture and decoration; lighting equipment that can be added after the building has been designed. If this point of view persists, lighting practice is bound to continue in the same channel. Difficult as it may be to visualize lighting as a structural element in architectural design, this consideration must eventually, also exist as a conviction in the mind of the designer.

This book is primarily intended to offer students and professionals interested in architectural interior lighting, a basic, graphically oriented, and detailed understanding of the important role lighting plays in architecture and interior design. A further intent is to stimulate the upcoming designer’s imagination and creativity with a presentation of lighting fundamentals to help find and develop new innovative solutions in melding lighting with the architecture, so occupants perceive the installed lighting systems, as an integral part of the interior space.

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FUNDAMENTALS OF ARCHITEC TURAL LIGHTING

CONTENTS V PREFACE IX INTRODUCTION Chapter 1

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

1 INTRODUCTION 2 BASIC MODES OF DISTRIBUTION 3 DOWNWARD DISTRIBUTION

Concentrating & Diffusing Downward Distribution

4 UPWARD DISTRIBUTION

Concentrating & Diffusing Upward Distribution

5 SIDEWARD DISTRIBUTION

Concentrating & Diffusing Sideward Distribution

6 MULTIDIRECTIONAL DISTRIBUTION

Concentrating & Diffusing Multidirectional Distribution 7 PATTERN & SPARKLE

Pattern & Sparkle Distribution Chapter 2

THE LUMINOUS ENVIRONMENT 9 INTRODUCTION 10 SURFACE CHARACTERISTICS

Surface Reflectance & Finishes

12 LUMINOUS ARCHITECTURAL SURFACES

Brightness Intensity Creating Environmental Focus Modifying Spatial Proportions Ambient Luminescence Luminous Ceiling & Luminous Wall

OLED Elements

20 ARCHITECTURAL INTEGRATION

Chapter 3

DESIGN OF THE LUMINOUS ENVIRONMENT

31 INTRODUCTION 32 PRELIMINARY GUIDELINES

General Design Concepts Range of Human Vision

34 THE DESIGN PROCESS

General Design Concepts Step-by-Step Method Lighting Research Subjective Appraisal Semantic Differential Scaling

42 OFFICE & CLASSROOM LIGHTING

General Guidelines

44 RETAIL & DISPLAY LIGHTING

General Guidelines

46 RESTAURANT LIGHTING

General Guidelines

50 HEALTHCARE LIGHTING

General Guidelines

52 MUSEUM & EXHIBIT LIGHTING

General Guidelines

54 RESIDENTIAL LIGHTING

General Guidelines

56 DAYLIGHTING

General Guidelines Chapter 4

LIGHT & COLOR

22 SECONDARY LIGHT SOURCES

59 INTRODUCTION 60 THE ELECTROMAGNETIC SPECTRUM

24 LIGHT & SHADOW

61 PRIMARY COLORS

26 PERCEPTION OF THE LUMINOUS ENVIRONMENT

62 COLOR MIXING

Integration with Form & Surface Utilizing Refected Light Surface Reflectance & Intensity

Creative Use of Light & Shadow Conditioned Association

The Perception of Brightness Controlling Visual Clutter Visual Direction & Virtual Surfaces Visually Prominent & Subordinate Light Sources 29 DISTRIBUTION OF BRIGHTNESS

Horizontal & Vertical Plane Brightness

VI

Electromagnetic Energy Refraction of Light

Additive & Subtractive Colors Descriptive Characteristics Additive & Subtractive Mixing Efficiency of Light Sources White Light from Color Sources The Appearance of Colors

64 SUBJECTIVE CHARACTERISTICS

Color Temperature & Light Levels

FUNDAMENTALS OF ARCHITEC TURAL LIGHTING

CONTENTS

Relative Sensitivity of the Human Eye Perception & Adaptation, Relative Color Attraction Complementary Afterimages Surface Colors & Brightness Contrast Color Perception

67 COLOR OF WHITE LIGHT

Color Temperature Spectral Energy Distribution Color Rendering & Color Association

70 COLOR & CIRCADIAN RHYTHMS

The Circadian Cycle The Range of White Light

72 COLOR FILTERS

Absorption Filters Interference Filters

73 COLOR LIGHT SOURCES

LED Lamps Incandescent Lamps Fluorescent Lamps

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98 100 102

Chapter 5

LIGHTING QUALITY, COMFORT, & CONTROL 77 INTRODUCTION 78 THE RANGE OF HUMAN VISION Photopic, Mesopic, & Scotopic Vision 79 REFLECTED GLARE Specular & Diffuse Surfaces Minimizing Veiling Reflections Transparent Surfaces & Veiling Reflections 82 DIRECT GLARE Glare as a Function of Location, Bare Lamp Glare Acceptable Glare 84 DISCOMFORT & DISABILITY GLARE 85 BRIGHTNESS RELATIONSHIPS Human Perception of Brightness, Luminance Ratios 86 BRIGHTNESS CONTROL & SHIELDING TECHNIQUES 87 CONTROL TECHNIQUES 88 SHIELDING TECHNIQUES Baffles & Louvers Reflected Images

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Brightness Control of Louvers & Baffles Material Transmittance Surface Reflectance Surface Shape & Form Diffusing Elements Louvers, Grilles, & Screens Large Diffusing Elements Louvers, Grilles,& Screens ENERGY MANAGEMENT ASHRAE/IES 90 Energy Reference Standard Lighting Controls & Lighting Control Matrix LIGHT TRANSMISSION Transmitting Characteristics Typical Transmitting Materials LIGHT REFLECTION Reflection Characteristics Typical Reflecting Material LIGHT REFRACTION Refraction Characteristics Lenses and Chromatism The Fresnel Lens Supplemental Reflectors REFLECTOR CONTOURS Basic Reflector Contours Parabolic & Elliptical Section Specular Reflector Light Control Diffuse Reflector Light Control Chapter 6

ILLUMINATION MEASUREMENT & CALCULATION 111 INTRODUCTION 112 UNITS OF MEASUREMENT Lighting Units, Terms, & Definitions Examples of Ever yday Illuminances 114 ILLUMINATION CALCULATION The Lumen Method The Point-by-Point Method The Inverse-Square Law & Cosine Calculation 120 RECOMMENDED LIGHTING LEVELS General Considerations Aspects of Lighting That Affect Recommendations Quanity & Quality of Lighting Levels, Lighting Level General Guidelines Recommended Lighting Levels Tables

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FUNDAMENTALS OF ARCHITEC TURAL LIGHTING

CONTENTS Chapter 7

LIGHT SOURCES & COMPONENTS 125 INTRODUCTION 126 LIGHT SOURCE SELECTION High-Performance Sources Incandescent Watts to Lumens Equivalent Typical Lamp Performance Values 128 LED LAMPS Operating & Electrical Characteristics Physical Characteristics Color and Semiconductor Materials Representative Lamp Types 132 FLUORESCENT LAMPS Operating Characteristics Ballasts & Circuits Representative Lamp Types Lamp & Ballast Wireways 137 HALOGEN LAMPS Operating Characteristics Representative Lamp Types 139 INCANDESCENT LAMPS Operating Characteristics Representative Lamp Types Silverbowl & Tubular Lamps Lampholders 144 METAL HALIDE LAMPS Operating Characteristics Color Characteristics

Representative Lamp Types

147 HIGH-PRESSURE SODIUM LAMPS Operating Characteristics Color Characteristics

Representative Lamp Types 150 DIMMING CONTROL Dimming Basics High-Low Dimming Control Fluorescent Dimming Chapter 8

LIGHTING APPLICATION & DETAILS 153 INTRODUCTION 154 LUMINAIRES Representative Luminaire Layouts 157 WALL LIGHTING Wall Lighting from One Direction Representative Techniques

VIII

With Specular Reflector With Diffuse Reflector Multiple Lamp Wall Lighting, Spot & Flood Lamp Beam Patterns, Par & R Lamp Beam Patterns 164 COVE LIGHTING Lighted Ceiling & Wall Coves Representative Details Surface-Mounted Cove Cove Lighting Placement Ratios 168 COFFER LIGHTING Lighted Ceiling Coffer Simulated Skylight Coffer 170 LIGHTED WALL ELEMENTS Lighted Cornice Lighted Valance Lighted Wall Brackets 174 TRANS -ILLUMINATED ELEMENTS Luminous Walls Luminous Ceiling Luminous Soffit 178 TASK LIGHTING Under- Cabinet Task Lighting 179 TASK-AMBIENT LIGHTING Under/Over Cabinet Lighting Overhead Ambient-Task Uniform System Overhead Task-Ambient Non-Uniform System Overhead Ambient & Local Task System Indirect Ambient & Local Task System 184 LIGHTED RAILINGS General Considerations Chapter 9

20TH-CENTURY ARCHITECTURAL LIGHTING PIONEERS 185 INTRODUCTION Stanley McCandless Abe Feder Sylvan Shemitz Richard Kelly Derek Phillips James Nuckolls Wm. M.C. Lam John Flynn Howard Brandston Jules Horton Raymond Grenald 197 GLOSSARY 205 BIBLIOGRAPHY 207 INDEX

FUNDAMENTALS OF ARCHITEC TURAL LIGHTING

INTRODUCTION Good architectural lighting involves the successful evaluation of our human visual and psychological perception of space, where the lighting designer is somewhat more in control than the architect of our perceived environment. Lighting is a fundamental and visual element of architectural design and is critical to our everyday activities as visually oriented occupants of space – especially architectural space. When electric lighting became the dominant light source in our everyday environment, the selection of techniques and equipment posed a challenge to the creative judgment of the designer, and especially the lighting designer. This new challenge became more complex than the requirement for basic illumination. Although simple light sources will satisfy this need, they did not satisfy the aesthetic and psychological needs of our contemporary life style. The important problem for the lighting designer is not to merely provide basic illumination, but rather to control and modify the light and lighting to establish a more suitable visual environment and a general sense of well being. This is especially true today where a building may be used both day and night without any significant change or restriction of visual activity. The historical solution for interior lighting utilized windows, skylights, and other similar daylighting techniques. Natural light has proven to be valuable where past architectural periods developed their own approach to lighting, reflecting the basic technology of the time. Even with the acknowledged benefits of daylighting, electric lighting has also proven to have an important contribution in this area. The following fundamentals of interior architectural lighting review lighting design techniques, procedures, and details.

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CHAPTER

1

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE In the past architects and interior designers often worked to realize their visions of lighting of an interior space with the help from an illuminating engineer. This often resulted in a more utilitarian approach to the illumination needs of a project with simple techniques and equipment. It was also thought if an architect were to assume a larger role and interest in lighting he would be distracted from his other fundamental architectural responsibilities. Today most architects and interior designers are considerably more familiar with current lighting technology and its application to architecture and interior design within their own practice. They also now have easy access to the expanded area of information and lighting consultants, resulting in more satisfying and appropriate environmental and visual architectural interior lighting solutions. Over the past extended period of time the field of illumination engineering developed many unique tools and techniques available today in the practice of illumination design and calculation. One was identified as the “Basic Modes of Lighting” which demonstrated the fundamental ways light is distributed within an architectural interior space. Currently the design parameters go beyond simple illumination considerations, and incorporate visual, psychological, and physical characteristics of the lighting design and the luminous environment. This chapter will identify and illustrate the basic distribution of light as utilized in interior space. It is intended to be somewhat simplistic and not representative of the wide scope of lighting techniques available to the contemporary designer.

1

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

BASIC MODES OF DISTRIBUTION DIFFERENT PATTERNS OF BRIGHTNESS The methods of distributing light in architectural interior space is an indispensable component of the design process for interior environments. Lighting design requires the ability to visualize how space is to appear with some areas enhanced, and others subdued, in a uniquely coordinated way. The lighting designer must perceive how the patterns of brightness are to be integrated with the physical structure as well as the fulfillment of the occupants’ requirements. Every design requires a different interpretation of the space and the visual elements that define the space, and the solution must, most importantly, reflect the human activities involved. On the other hand, it must be remembered that the casual observer, as well as the occupants of an area, are not fully aware of such variables as illumination levels, contrast ratios, and brightness. In fact, in a well-integrated space, the occupants usually have very little awareness of the lighting, or the means incorporated in generating and controlling the light. The final judgment is typically based on how well it serves the intended use and if the occupants are comfortable and have a sense of well-being. With the current development of energy-efficient light sources and power distribution, light has become a more available and controllable design element. The extent that the distribution of light can be modified and controlled is unlimited, offering a broad palette of design options. While many contemporary lighting needs can be successfully satisfied and executed with the use of natural daylight, it is only minimally covered in this book.

2

CONCENTRATING DOWNWARD

DIFFUSING DOWNWARD

CONCENTRATING UPWARD

DIFFUSING UPWARD

CONCENTRATING SIDEWARD

DIFFUSING SIDEWARD

CONCENTRATING MULTIDIRECTIONAL

DIFFUSING MULTIDIRECTIONAL

PATTERN

SPARKLE

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

DOWNWARD DISTRIBUTION

CONCENTRATING DOWNWARD DISTRIBUTION Luminaires with no upward component and narrow downlighting will de-emphasize the ceiling, and the illumination on horizontal surfaces will be relatively high. Stray light is limited and the other surfaces of the room receive little illumination. The effect is an impression of low ambient illumination with high brightness accents. This distribution of light comes from concentrating downlights, small cell parabolic louvered luminaires. Built-in architectural lighting elements can add vertical surface lighting with a downward distribution – notice the cove (or cornice) lighting of the back wall in the illustration. NOTE: These distributions of light have been traditionally identified as Direct Distribution.

DIFFUSING DOWNWARD DISTRIBUTION Luminaires with only a diffusing downward component of light will have wide-angle light beam patterns, distributing light on the vertical surfaces and increasing the overall sense of brightness in the space. The ceiling will receive very little light and remains somewhat dark, unless there is a low ceiling and a high reflectance floor, reflecting light back to the ceiling. The slightly darker ceiling will make the luminaires appear as higher brightness luminous elements. This effect will vary depending on the room finishes and the inter-reflection in the space.

3

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

UPWARD DISTRIBUTION

CONCENTRATING UPWARD DISTRIBUTION A concentrating upward component of light comes from equipment with internal beam control or a concentrating light source. The illustrated variation in upper wall brightness demonstrates the effect of non-uniform light distribution from equipment mounted in close proximity to the illuminated surface. It’s a technique providing high contrast with visual interest and surface patterns. Variation in the architecture, like spacing of the arches, can also add interesting light patterns. The luminaires would give more uniform lighting effect if mounted farther away from the wall. NOTE: These distributions of light have been traditionally identified as Indirect Distribution.

DIFFUSING UPWARD DISTRIBUTION When diffuse light is directed upward, with a small downward component, the ceiling becomes a visually dominant area. It also becomes a diffuse lighting element through secondary reflection. The upward light may be used to emphasize structural forms or decorative details, while also producing a flat, low-contrast environment from the interreflection of light. This reduces contrast and shadow, while furnishing minimal task illumination, particularly when used with high ceilings. The feature of this technique is in establishing an impression of soft uniform illumination and low ambient brightness.

4

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

SIDEWARD DISTRIBUTION

THE CIT OF

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CONCENTRATING SIDEWARD DISTRIBUTION

TO W N A M

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Concentrating sideward distribution is used in special applications that utilize compact light sources with controlled beam patterns like reflector lamps. If offers the opportunity to develop unique architectural lighting solutions, but requires careful attention to the details, installation parameters, and light source maintenance and replacement. It also offers the opportunity to introduce color, with both saturated and subtle effects, and where appropriate, color mixing and motion. Although very rarely used, this sideward distribution of light in architectural space can challenge the lighting designer ’s creativity.

DIFFUSING SIDEWARD DISTRIBUTION Custom built-in lighting equipment can be utilized to create unique architectural lighting elements. A number of different treatments can be used for the transmitting lens, from diffusing translucent plastic sheet material to perforated metals and three dimensional open louvers and grilles. The internal light sources have been tubular fluorescent lamps because of their shape and relatively cool operating temperature. LED sources would also be appropriate for this application, especially in linear tubes and strips. They furnish the benefits of simple dimming control, color, and significant energy savings.

5

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

MULTIDIRECTIONAL DISTRIBUTION

CONCENTRATING MULTIDIRECTIONAL DISTRIBUTION

This concentrating distribution will create non-uniform brightness patterns from the beam characteristics of the luminaire and light source. When utilizing multidirectional luminaires, any one of the components is usually adequate to relieve extreme contrasts in the space. However, the non-uniform quantity of light reflected from the wall and ceiling surfaces is usually insufficient to wash out shadows. This reduced diffusion of light results in the effect of moderate contrast and concentration. This may be useful when trying to highlight or develop focus on a particular area or feature.

DIFFUSING MULTIDIRECTIONAL DISTRIBUTION

Multidirectional distribution from luminaires, such as diffusing pendant units or suspended direct-indirect fixtures, emit light in several directions. These types of fixtures furnish a relatively efficient distribution of light, and the inter-reflection of light off the room’s ceiling and walls supplements the general distribution and can reduce shadows and contrast. This creates a visually bright and generally uniform luminous environment. The diffusing globe luminaire shown in the illustration demonstrates this type of light distribution in its simplest form with its typical complete 360 degree distribution. NOTE: These distributions are traditionally identified as Direct-Indirect and General Diffusing.

6

DISTRIBUTION OF LIGHT IN ARCHITECTURAL SPACE

PATTERN & SPARKLE

PATTERN & SPARKLE DISTRIBUTION The use of light patterns and sparkle within interior spaces can provide an interesting luminous component in the architectural environment, and provide a focus and festive mood. This can be accomplished with the application of luminous elements and bare light sources in creative ways. LED and OLED light sources can be incorporated for this use due to their small size and long life. Special precautions are needed to avoid the appearance of visually unappealing light patterns, or using overly bright sources that can sometimes also be equally unappealing. The use of small high-intensity light sources can offer the additional visual effect of sparkle and glitter, transforming a pattern of light into a decorative luminous element or special feature. This use of light provides a non-utilitarian source of illumination and a sense of visual interest. However, very little useful illumination is furnished this way. Although, in special cases it can. (see below). Simple patterns can be used in low traffic areas to furnish ambient and circulation lighting.

Kleene

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7

CHAPTER

2

THE LUMINOUS ENVIRONMENT An important goal of interior lighting is to incorporate techniques that furnish a pleasant working and casual luminous environment – similar to the lighting associated with the shade of a tree on a sunny day. The designer needs to be familiar with the practices that establish this pleasant environment, where good lighting is similar to background music, in the creation of a comfortable and appropriate psychological setting, and contributes to the successful design and utilization of architectural interior environments. Interior lighting was once considered as a utilitarian function necessary only to allow the use of a building. We now understand light has qualities other than simple illumination. We’ve experienced the holding power of a spotlight on a stage, or been impressed by the impact of a dramatic sunset. Similarly, lighting of a carnival with colors and sparkle represents gaiety and excitement. We also recognize the difference between a pretty day and a dull, dreary day, is primarily the lighting. Designers are aware of the dynamic quality of light, however they often under estimate its significance. A suitable lighted interior environment is not limited to providing a space where people merely perform a given activity. Rather, it should be where the occupants are encouraged to participate, appreciate the luminous ambience, and enjoy a sense of well-being. Understanding the luminous environment involves the human perception of our spatial orientation through a central (foveal) vision and background (peripheral) vision. Central foveal vision gives us detail and color and provides accurate seeing for the performance of most typical visual tasks, while peripheral vision is responsive to brightness patterns and light intensity. The eye is generally attracted to bright objects and patterns, enabling occupants to interpret interior space by these brightness relationships. Understanding of this by the designer is critical to the successful development of the luminous environment.

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THE LUMINOUS ENVIRONMENT

SURFACE CHARACTERISTICS SURFACE REFLECTANCE & FINISHES The luminous appearance of architectural interior space is a function of surface characteristics and reflectances, as well as the spatial proportions of the space, as illuminated by the incident light. The quality and method of distribution of light will determine the overall definition of the major architectural surfaces and intended brightness patterns – but is dependent on the programed surface finishes and reflectance values, as well as the intensity of the distribution of light in the space.

CONCENTRATED DISTRIBUTION & HIGH REFLECTANCE FINISHES

CONCENTRATED DISTRIBUTION & LOW REFLECTANCE FINISHES

10

The lighting designer’s control of the luminous environment will depend on his ability to understand the relationship between the illumination distribution and interior surfaces, and his understanding of the need for the close coordination of the two components working together. It should also include a clear definition of any form or shape of the surface. The smooth plane of a ceiling or wall surface should be illuminated with a continous wash of light for best results, without any shadows, scallops, or some variation of intensity or color – unless as a specifically intended visual effect, like a strong shaft of light, or a interesting pattern of brightness or even shadows. The contribution of such variations and novel effects can furnish a temporary or permanent spatial stimulant, perhaps for

THE LUMINOUS ENVIRONMENT

SURFACE CHARACTERISTICS a special event or celebration. On the other hand, the incorporation of more meaninful special effects should relate to the intended environmental utilization. The architectural surface reflectances and finishes, and resulting inter-reflectance of light within a space, may influence the effective use and functioning of the space, and especially the resulting occupant appraisal of the lighting system and the environment in general. The overall distribution of light from the lighting equipment will also reinforce or surpress the visual impression of a high or low surface brightness, depending upon whether it will effectively illuminate or.

DIFFUSE DISTRIBUTION & HIGH REFLECTANCE FINISHES

obscure the major architectural surfaces. The size, dimensions, and proportions of a space, along with the reflectance of the architectural surfaces, will determine the extent of any inter-reflections of light that might offer secondary sources of light. If all the room surfaces are light colored, the inter-reflections will tend to fill in any shadows and reduce contrast. If darker colors and finishes are used, it would tend toward the opposite effect. This action is somewhat independent of the light distribution, and the choice of the materials and finishes may reinforce or nullify the intent of the lighting system

DIFFUSE DISTRIBUTION & LOW REFLECTANCE FINISHES

11

THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL SURFACES BRIGHTNESS INTENSITY The subjective response to interior space can be modified by the luminous intensity of the architectural surfaces. Variations in the quantity or intensity of the light will affect the brightness of the surfaces and the inter-reflections, changing the subjective impression of the environment. This is particularly true with a concentrating downlighting system as shown in the illustration on the right. When the lighting level and intensity is set at a lower level with dimming control or lower wattage light sources, the brightness and prominence of the interior surfaces and visual contrast between the adjacent areas with different reflective qualities is greatly reduced, creating a much more relaxed and subdued environment. Increasing the intensity of the lighting in a space increases the inter-reflection and brightnes of the architectural surfaces, creating a higher brightness environment, which in turn, reduces the shadows and contrast, resulting in a more stimulating and visually dominant environment. The creation of a high-intensity environment that will furnish architectural interest, function, and visual comfort, needs the careful coordination of all the important design elements – especially the selection of surface finishes, furnishings, and decorative items. This is especially true when the space is intended to be used with variable levels of lighting along with different occupant needs.

THE LOW BRIGHTNESS LUMINOUS ENVIRONMENT

THE HIGH BRIGHTNESS LUMINOUS ENVIRONMENT

Note: Even though the human eye is ver y adaptable to an extremely wide range of illumimation levels, the minimum visually discernible variation in surface brightness is approximately a ratio of 2 to 1.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL SURFACES CREATING ENVIRONMENTA L FOCUS Modifications to the illumination introduced to an interior space, such as the distribution and intensity of the lighting, affects the subconscious response of the occupants to the environment. This is primarily a direct result of our human visual interpretation and reaction to the lighted architectural surfaces and forms within the space. The illustrations found throughout the book are presented to demonstrate some representative environments illuminated with a few fundamental brightness distributions and patterns of light.

Additional solutions involving the utilization of the distribution and patterns of light are, of course, also possible and somewhat unlimited. The illustrations also suggest a number of typical examples of nontypical lighting solutions for the basic luminous environment through creative composition and treatment of the lighted surfaces. The lighting distribution and brightness patterns within a space can significantly affect the human perception of the space, the environmental focus, and all the associated planned occupant activities.

HIGHLIGHTING CREATES ENVIRONMENTAL FOCUS

Nonuniform lighting can create architectural emphasis when one wall or surface of a room is lighted to a higher lever than the adjacent surfaces, creating a high brightness contrast between the major architectural sufaces, and a visual response, directing attention to the brighter area. Both the lighting intensity directed to this surface and the reflectance of the surface contribute to this brightness contrast and visual focus.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL SURFACES MODIFYING SPATIAL PROPOR TIONS Luminous patterns can be creatively utilized to facilitate or reinforce the programed function or appearance of an interior space. An example might be the use of lighting to create selected architectural and decorative emphasis, exit or directional assistance, access motivation and restriction, and building or occupant oriented activities. The lighting designer can also use methods to subliminally modify the perceived visual proportions of a room or space, such as expanding the apparent width of a narrow room

by specifying highly illuminated, lighter colored, side walls, in contrast to a dark colored end wall, resulting in side walls that are perceived to make the room appear wider. Some of the concepts and techniques presented here are generally of a intuitive nature, and are only partially based on accepted lighting standards and recommended lighting practice. However, most designers understand and use their experience and intuitive judgement this way, realizing there is more than one way to modify the luminous environment.

RECESSED COVE LIGHTING CREATES A SENSE OF SPACIOUSNESS

Vertical surfaces can be modified with different levels of illumination and the degree of reflectance to visually alter the perceived spatial proportions of a room. For example, reversing the brightness patterns from dark side walls and a light end wall, to higher lighting and reflectance values on the side walls, and a much darker wall at the end, creates an increased sense of spaciousness and a visual impression of a wider room.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL SURFACES AMBIENT LUMINESCENCE Cove lighting is very often referred to as indirect lighting because it furnishes a visually soft and diffuse uniform distribution of light. It’s an attractive lighting technique due to it offering comfortable illumination where the light source is concealed from normal viewing angles. There are two cove types, ceiling and wall coves. One directs light down for a wall washing effect, (see previous page) and the other across a ceiling. It may be used as a form of ambient illumination or an aesthetic accent of a decorative or vaulted

ceiling. It can also be useful as background illumination to supplement and complement other lighting installations and special decorative or architectural themes. Cove lighting can be found in both residential and commercial settings. In residential areas, it is often used above kitchen cabinets. Because of its low efficiency, it’s usually suggested to always incorporate high reflectance architectural surfaces and finishes to provide the best lighting performance and overall appearance. (See Chapter 8 for design and installation details)

COVE LIGHTING CREATES SOFT AMBIENT LUMINESCENCE

Cove lighting is an established indirect lighting technique that directs light up toward the ceiling from one or more sides of a room to furnish a soft general diffuse ambient illumination. This illustration shows wall coves directing light upward, while recessed ceiling coves direct light down as a wall washing effect. (see opposite page). This type of built-in lighting is popular because it hides the light sources and creates a soft dramatic effect.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITETURAL ELEMENTS LUMINOUS CEILING Stained glass windows were one of the earliest forms of a luminous architectural element. They added beauty, a soft and colorful lighting to the building’s interior, and told a relevant religious story. Some suggest a full luminous ceiling is simulation of natural diffuse daylighting, and a ideal form of illumination for human activities. This raises questions with regard to currently available lighting techniques and light sources. Today’s large luminous elements function as both architectural features and surfaces, and have visual implications beyond the extent of just the illumination and the distribution of light.

The dominant influence of these elements is significant in the definition of interior space. Their characteristics reinforce the architectural form and detail, and the luminous surfaces become a unifying factor in the design and composition of the interior environment. They may also distract from the casual viewer’s unsightly view of the building’s structura l and mechanical elements. Luminous ceilings became popular in the mid 20th century with the availabilty of the fluorescent lamp and quality plastic diffusing materials, and as an alternative to the common suspended ceiling grid, and recessed luminaires.

FULL LUMINOUS CEILING

The placement of trans-illuminated (or self-luminous) elements as a superimposed surface or form can creatively alter the apparent visual character, form, and proportions of an architectural interior space and environment.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL ELEMENTS

The luminous ceiling’s main attribute has been the uniform, shadow-free, distribution of light However, this should not influence or limit an architect’s or designer’s creative control over the luminous environment – or suggest a specific solution. Beyond the typical luminous ceiling’s uniform distribution there is an interest in the creative variation of distribution and color made possible with use of LED sources. Lighting design can be thought of as a creative endeavor involving the visualization of three-dimensional space that furnishes pleasant visual lighting patterns and ratios, as well as an interesting

composition of the lighted architectural surfaces, in compliance and support of the architectural objectives. Research in this area suggests the visual images and patterns created with this process influences the interpretation of our physical surroundings, as well as our emotional and psychological responses to the resulting interior luminous environment. The illustrations shown on these pages suggest how the use of trans-illuminated ceiling surfaces can enhance and integrate the illumination requirements with the general architectural spatial environment. (See Chapter 8 for application and technical details).

FULL LUMINOUS CEILING

A full luminous ceiling furnishes a distribution of light with soft shadows and uniform intensity, similar to a comfortable exterior environment and appropriately suited for the viewing of surface finishes and details.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL ELEMENTS LUMINOUS WALL A full luminous wall offers a way to illuminate an interior space with a distribution of light that furnishes a unique visual sensation. It creates a fresh feeling of luminous intensity that is not associated with other forms of lighting, partially due to the familiar strong horizontal distribution, without the view. At higher levels it becomes a dominant visual element to attract occupant attention and interaction. At lower levels it will furnish a background for some more subdued activities. Similar to other luminous elements,

the dominant influence is significant in the definition of interior space and form. They can also be utilized as a focal factor and luminous background for plants and silhouetted decorative features. A luminous wall can visually extend an interior space to create an appealing visual element that reinforces occupants’ impression that the space is more expansive than it actually is. Construction techniques, materials, and light sources are described in Chapter 7 & 8, Light Sources and Lighting Application & Details.

FULL LUMINOUS WALL

A full luminous wall furnishes a unique and dramatic distribution of light in a horizontal direction, creating a vibrant, dominant, and expansive visual environment that encourages occupant attention and interaction.

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THE LUMINOUS ENVIRONMENT

LUMINOUS ARCHITECTURAL ELEMENTS

Illuminated surfaces allow occupants to more easily perceive the form and dimensions of interior space. Lighted or, trans-illuminated elements, consist of transmitting and softly diffusing materials installed over an enclosed space. Fluorescent or LED lamps in the space are located to create a uniformly illuminated surface. The newer LED light source technology has made it possible to furnish illumination in the form of thin self-luminous sheets or panels, eliminating the need for the built-in cavity normally associated with typical trans-illuminated elements.

OLE D E LEME NTS Future use of the new Organic LightEmitting Diode (OLED) light sources in such forms as flexible panels, lighted wallpaper, or glass that can be turned off to create a clear view, may also contribute to this method of lighting. The very thin OLED materials could be surface applied, with an appearance similar or equal to built-in elements, especially with the ability to utilize them on curved and irregular architectural surfaces. The introduction of these and similar innovations will significantly add to the lighting designer’s creative imagination and available new tools.

ADMINISTRATOR'S OFFICE 101 VISITOR'S LOUNGE 102 RADIATION PREP 220 LABORATORY 212 CHECK IN AREA

LUMINOUS WALL ELEMENTS

19

THE LUMINOUS ENVIRONMENT

ARCHITECTURAL INTEGRATION INTEGRATION WITH FORM & SURFACE Many lighting techniques use creative design solutions that have an aesthetic significance beyond the normal connotations of engineering design. Some elements of the lighting system become prominent in the visual composition, and exhibit how the architectural concept is partially dependent upon the character of the illumination. These integral lighting elements must be analyzed by architectural standards as well as by the engineering performance. Lighting design standards cannot govern the use of these lighting techniques in architecture, any more than basic rules can be applied to architectural design. Architectural design recognizes and utilizes a great variety of folded, curved, textured and flat surfaces which are possible with contemporary techniques. These surfaces and forms that define the physical limits of a space may constitute the actual building framework, or may be superimposed INTEGRATION WITH ARCHITECTURAL FORM

20

non-structural elements in the space. Often, these elements are conceived as prominent visual elements and the achievement of the design objective can be dramatically reinforced by the effective design of the distribution of light. Integration of the lighting and equipment with the architecture implies a concern for the unique characteristics of the built interior environment. Also, equally important, is the recognition of the important relationship between the programed illumination and architectural design objectives. Successful coordination may involve the major architectural surfaces and forms, or may be only simple built-in elements that visually and physically integrate the lighting effects, sources, and equipment with the architecture. New applications of integrated lighting techniques are possible when utilizing LED light sources. The compact size of these sources allows for the

THE LUMINOUS ENVIRONMENT

ARCHITECTURAL INTEGRATION

installation in small areas of architectural cavities and surfaces without any major interference with structural components. This promotes a new imaginative design element that offers a unique distribution of light with interesting visual patterns, continuous lighted slot elements, and expanded use of color. It falls into a category identified as integrated architectural or luminous elements that are more than vintage built-in lighting techniques, being truly integrated. The illustrations on these two pages suggest a range of techniques that demonstrate how the lighting can be closely integrated, or coordinated, with the architecture, such as, lighting compound architectural surfaces, using similar building forms as lighting elements, reinforcing and highlighting the ceiling grid, creating new luminous creative patterns of light, and integrating the lighting, the ceiling structure, and the HVAC systems with the ceiling plane.

INTEGRATED CEILING & WALL ELEMENTS

INTEGRATED CEILING SOFFIT

21

THE LUMINOUS ENVIRONMENT

SECONDARY LIGHT SOURCES UTI LIZI NG R EFLECTE D LIGHT Most surfaces inclosing an architectural space that reflect light can be considered as secondary sources of light, creating a relationship between the distribution of light from the installed lighting and the action of the architectural surfaces in redirecting the light. In appraising the architectural contribution of a lighting installation, the influence of reflected light must be recognized. Some quantity of light from either source is incident on all major surfaces and the inherent intensity of light reflected from them determines their visual significance in the environment. Light reflected from these elements is generally diffuse and tends to fill-in shadows, reduce contrast, and produce a uniform sense of light and brightness. The utilization of architectural surfaces as secondary light sources is a SECONDARY LIGHT SOURCES

22

THE LUMINOUS ENVIRONMENT

SECONDARY LIGHT SOURCES

simple design tool that can make an important contribution to the integration of light and architecture. Attention to the surface finishes is also an important consideration in interior design, and is particularly important in lighting, where the surfaces function as secondary light sources. They affect the brightness of the elements that define the space, and also determine the significance of these elements in space. Brightness can be defined as the intensity of the illumination that is reflected or transmitted from a surface toward the eye of the observer and is dependent on the relative darkness or lightness of the surface itself. Low reflectance surfaces will absorb much of the light that falls on them, reflecting little back into the room, creating the impression of somberness, while high reflectance surfaces furnish a brighter environment with more diffusion, and a greater degree of visual clarity.

The floor and walls in a room can contribute to the lighting of the space through reflected light. The illustration at the top of the opposite page shows the effect of downlighting within a room with dark vertical surfaces, where the lighter floor and table top reflect some light back on the ceiling, resulting in a high contrast environment with a focus on task oriented activities. The center illustration with lighted high reflectance walls, and lower downlighting, creates a brighter, more uniformly illuminated environment. The bottom illustration shows using multiple light sources and different surface finishes provides a variety of lighted environments, from task lighting and decorative highlighting to occupant and activityspecific lighting solutions. This also shows that successful architectural lighting is dependent upon both proper selection and application of the lighting equipment, and careful consideration of all architectural interior surfaces and finishes.

SURFACE REFLECTANCE & INTENSITY Designers understand the importance of surface finishes as a controllable factor in establishing contrast and visual interest. The brightness of an architectural surface can be altered by adjusting the quantity of incident light, irrespective of the reflectance value of the surface. Careful selection of lighting can transform even very dark surfaces into the brightest image in a visual field. The manipulation of brightness through control of the lighting intensity, rather than the color of finishes, offers another aspect of design and a way of establishing luminous variation.

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THE LUMINOUS ENVIRONMENT

LIGHT & SHADOW CREATIVE USE OF LIGHT & SHADOW Most architectural surfaces and forms may be observed as a relationship between highlighted areas and shadows. Also, when the directional aspects of the lighting changes, the impression of depth and form changes. The perception and appraisal of sculptural form, surface texture, and materials is dependent upon the character and intensity of the applied lighting. A grazing angle will highlight and reinforce surface textures and forms by the generation of highlights and shadows. The relationship between light and shadows on a surface can assist in our visual

perception of blemishes in workmanship. With a more diffused frontal distribution of light on the textured surface the shadows and flaws can be minimized, creating a visual impression of flatness and uniformity. (see lower illustrations). The significance of the use of light to reinforce the natural characteristics of a surface or form is generally well accepted, although , the creative designer can also manipulate and control the lighting to produce a range of impressions of form and patterns that may be independent of an unlighted textured surface, shape, and form.

LIGHT PATTERNS

SHADOW PATTERNS

SURFACE BLEMISHES IN FRONTAL DIFFUSE LIGHT

SURFACE BLEMISHES IN GRAZING LIGHT

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THE LUMINOUS ENVIRONMENT

LIGHT & SHADOW CONDITIONED ASSOCIATION A lighting condition that alters or reverses the usual direction of light will change the normal relationship of light and shadow. The resulting visual impressions may appear to be unnatural, producing a sense of uncertainty, mystery, or even fear. While most situations probably favor a more natural impression, special conditions can be suggested where the sense of mystery would be an asset, such as viewing a Gothic gargoyle or a stage set that involves a dramatic sense of the supernatural. In each of these cases, variations in the lighting, color, and shadow will condition the casual observer’s unconscious interpretation. Our visual appraisal is based not

only on the form of the object, but on the object as modified by light distribution; in addition, our life experience and association are factors in seeing and human vision. Artists, for example, are known to incorporate the contrast between bright yellow highlights (representing bright sunlight) and light blue tints and blue shadows (suggesting daylight) to achieve an impression of the combined natural light. Such visual conditioning effects of light can be a factor to both the artist and lighting designer. Although the significance of this involves further study, the emotional implications can be represented by the two classic illustrations shown below.

NATURAL DOWNLIGHTING

UNNATURAL UPLIGHTING

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THE LUMINOUS ENVIRONMENT

PERCEPTION OF THE LUMINOUS ENVIRONMENT THE PERCEPTIO N OF BR IGHTNESS

CONTROLLING VISUAL CLUTTER Lighting installations that generate confusing visual or spatial cues, or visual clutter, can be generally distracting, and especially when visual tasks are involved and over extended periods of time. It can be considered similar to distracting noise. Even the casual observer might find it visually uncomfortable. Visual performance will decrease with the increase of high-contrast random visual cues, particularly where difficult tasks or safety is involved. Poorly directed high-intensity spotlighting should also be avoided, and the overall design of the luminous environment should be simplified in terms of spatial order, luminaire layout, and brightness patterns. Exceptions may occur for casual activities and general interest where novelty effects are desired as a stimulant to any monotony and boredom.

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90

PERCENT MEASURED BRIGHTNESS

The human perception of our surroundings is not always as we expect it to be based on our life experiences. When viewing high levels of brightness and brightness contrast, our eyes make adjustments by reducing the size of the pupil to lower the intensity of the perceived image. On the other hand, the response to low lighting levels and brightness is the pupil enlarging to compensate for the low levels of light. However, these adjustments are not on an expected one-to-one scientific ratio. Light dimmed to 10% will be perceived as being dimmed to approximately only 32%. And lighting dimmed to 40% is perceived to be at only 60%. (see the chart on the right).

80 70 60 50 40 30 20 10 5 1

0

10

22 32 40 50 60 70 80 PERCENT PERCEIVED BRIGHTNESS

90

IESNA Handbook 9th Ed.

PERCEPTION VERSES MEASURED BRIGHTNESS

THE LUMINOUS ENVIRONMENT

PERCEPTION OF THE LUMINOUS ENVIRONMENT VISUAL DIRECTION & VIRTUAL SURFACES Carefully integrated lighting elements are able to introduce a visual response similar to the effect of spotlighting in attracting and directing attention. The top illustration shows the use of continuous ceiling and base cove lighting to create an impression of direction and spatial perspective. This use of lighting within an architectural environment is similar to other elements of design, such as the concepts of line and pattern. Creatively integrated lighting elements can also be a major factor in design composition and can be utilized to suggest a impression of a virtual surface. For an example, the lower illustration demonstrates how using closely and evenly spaced fixtures of a similar size and brightness can create a strong visual sense and impression of a continuous luminous architectural surface.. CREATION OF A VIRTUAL SURFACE

VISUAL DIRECTION & SPATIAL PERSPECTIVE

27

THE LUMINOUS ENVIRONMENT

PERCEPTION OF THE LUMINOUS ENVIRONMENT VISUALLY PROMINENT LIGHT SOURCES A light source or luminaire may itself become a dominant factor in our visual environment, especially where light transmitting materials are involved. These units then become architectural as well as lighting elements. They are also important in the creation of a successful coordination of the architectural design and the lighting program objectives. This coordination can materially contribute to the successful physiological and visual impression of the interior space. Also, as a supplement to some objects and surfaces illuminated by reflected light, the utilization of individual self-luminous lighting elements and architectural forms can help create a successfully integrated interior environment.

VISUALLY SUBORDINATE LIGHT SOURCES The utilization of indirect and concentrating lighting systems in an interior space will result in a visually subordinate appearance of the installed lighting elements. With the careful use of appropriate shielding and brightness control techniques, these lighting elements direct light toward a specific architectural surface or object, emphasizing these areas with little distracting influence from the installed lighting equipment itself. The incorporation of this type of lighting equipment can be utilized to furnish a visually subordinate illuminated interior space or environment of reflected brightness patterns and areas, resulting in a comfortable space with visual focus placed to reinforce architectural surfaces, and decorative elements.

28

THE LUMINOUS ENVIRONMENT

DISTRIBUTION OF BRIGHTNESS HORIZONTAL PLANE BRIGHTNESS The distribution of brightness within an architectural space can affect the visual perception of the occupants, as well as the area’s intended function. Where brightness contrast affects the general interest and attention of the occupants, the perceived lighting can either emphasize or subdue the visual impression and intended activity. The upper illustration demonstrates the effect of lighting to furnish interest in local activities. The illuminated table tops encourage local activities and interests to become more dominant and the background areas become of somewhat secondary visual importance.

VERTICAL PLANE BRIGHTNESS Environments interpreted through the image of relative distribution of vertical brightness, as in the lower illustration, shifts the perception and emphasis to the peripheral areas, reducing interest in the local areas, and causes local activity to be visually subordinate, as in a theater. It also encourages public activity and a more open atmosphere. However, horizontal illumination will increase nearby activity and movement, encouraging a gregarious environment, and highlight special displays, events, and activities, as in a museum or restaurant. In smaller, or more personal space, it may also encourage a strong perception or feeling of personal privacy.

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CHAPTER

3

DESIGN OF THE LUMINOUS ENVIRONMENT The design of interior lighting incorporates established design techniques utilized by experienced professionals to furnish successful lighting solutions. They have wellestablished tools to assist in the design of quality lighting, but must also use experience and an intuitive sense of what is considered to be good design. The evaluation of good design is very subjective, and is affected by the need to satisfy task performance as well as aesthetic, psychological, and environmental concerns. The pressure to meet quantity needs sometimes overshadows the search for quality illumination and the development of a successful overall aesthetic solution. A common thread is the idea that lighting design is both art and science, and is most successful when it is coordinated with and integrated into the very fabric of the architecture – the underlying theme of this book. Interior lighting was initially an engineering function with emphasis on providing adequate illumination for circulation and the performance of visual tasks – with less attention in the aesthetic aspects. Today, the lighting designers work in-concert with the electrical engineer to furnish energy-efficient lighting designs that also satisfy the overall functional, psychological, and physiological parameters. It also requires visualization of solutions that fulfil specific requirements related to spatial orientation, visual comfort, and especially the integration and coordination with architectural objectives. It’s important to consider this as a learned process requiring appropriate education and/or experience before becoming a successful and qualified lighting designer. The appropriate education for this would be in architecture or interior design. However, some successful lighting designers have backgrounds in stage and theater lighting – which has insight in spatial aesthetics and drama that other disciplines only partially offer.

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DESIGN OF THE LUMINOUS ENVIRONMENT

PRELIMINARY GUIDELINES GENERAL DESIGN CONCEPTS Beyond furnishing basic shelter, a properly designed interior space should encourage and support occupant activities, and provide a comfortable physical, and psychological environment. We can, perhaps, characterize the meaning of comfort to also suggest the reduction of negative influences, such as, too much heat, cold, noise, or humidity, and as it relates to lighting, excessive glare or contrast, visual clutter, and even darkness. The designer must recognize these distractions and strive for a environment that does not promote stress and fatigue, or undesirable ambience. The role of human vision in the design process is of particular importance due to the fundamental contribution it makes to human functions, activities, and the awareness of the environment, including the ability to perform visual tasks, or more critical occupant endeavors, like the sense of physical and visual orientation, perceiving spatial relationships, enjoying a feeling of well-being, and the ability to engage and evaluate interior environments. Also, our visual abilities enable us to interpret movement and change within a space, as well as, brightness patterns, intensity, and visual cues. Our vision is limited to a narrow band of energy of the electromagnetic spectrum. Within this band the eye is most sensitive to the small portion of the visible wavelengths in the yellow-green range, with a reduced sensitivity at the extreme red and blue ends of the visible range. Beyond these areas are the infrared and ultraviolet wavelengths, which are not visible

32

to the human eye. In addition, our night vision is much more sensitive to the blue-green range, with a somewhat reduced overall color vision.

The Range of Human Vision: The design of lighting is a process significantly involving human vision. The participants include both the designer and the occupants of the space, with a goal set on the successful fulfillment of the physical and psychological lighting requirements. Human vision involves a binocular field of view at about 50 degrees upward from a horizontal line of sight, 70 degrees downward, and about 180 degrees horizontally, without any rotation of the eye. (see illustration on the opposite page ) Detailed human vision takes place in the foveal area at the back of the eye and is limited to a small angle parallel to the line of sight. This angle is approximately 2 degrees and gives us sharp vision in an area about the size of a dime when viewed at a typical reading distance. Beyond the area of more precise vision, and within the overall field of view, is a broader area of peripheral vision where detail and color becomes less accurate. A central portion of this area involves a cone of vision that is sometimes identified as the “near surround”, which is approximately 25 - 30 degrees above, below, and to both sides. This cone of vision furnishes a relatively clear image of detail and color. The field of view further out allows less distinct vision of general forms and shapes, and is sensitive to changes in brightness patterns and intensity, which may affect an occupant’s relationship to the activities within the space.

DESIGN OF THE LUMINOUS ENVIRONMENT

PRELIMINARY GUIDELINES

UPPER LIMIT OF THE VISUAL FIELD

50°

LIMIT OF NEAR SURROUND & COLOR DISCRIMINATION

25°

DETAILED FOVEAL VISION LIMIT OF NEAR SURROUND & COLOR DISCRIMINATION

25° 70°

LOWER LIMIT OF THE VISUAL FIELD

RELATIVE SENSITIVITY

80% 60%

DARK ADAPTED VISION (Night)

7500

7000

6500

6000

5500

(Angstroms)

5000

4000

WAVELENGTH

4500

THE RANGE OF HUMAN VISION

LIGHT ADAPTED VISION (Day)

40% 20%

Ultraviolet

Violet

Blue

Green

Yellow

Red

Infrared

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DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS GENERAL DESIGN CONCE PTS . . . continued The visual and physical perception of interior architectural space can be significantly modified through the incorporation of more creative and imaginative lighting. Considering the historical emphasis on task illumination and the current need for environmental concerns and energy conservation, the desire to introduce other aesthetic aspects of lighting design takes on a significantly more important challenge for the architect, interior designer, and lighting designer. Occupants of interior space perceive their environment in shades of brightness patterns and forms within a three-dimensional context. With this as a guide, the aesthetic aspects of lighting design should make a greater attempt to incorporate the elements that may be appropriate to the design goals, such as the composition of perceived brightness patterns, the recognition of any significant forms and surfaces, plus components of good lighting, including, focal points of interest, ease of circulation, adaptability, the provision of visual comfort, and emphasis on a sense of well-being.

THE STEP-BY-STEP METHOD A relatively simple approach to lighting design can be described as a layered composition where each layer takes on its separate and specific contributing role. The layers are generally considered to be ambient lighting, accent lighting, and task lighting. While a considerable portion of the design process is facilitated through experience and intuition,

34

some rely on a step-by-step check list of observations and considerations established over the years – many of these elements are described and illustrated throughout this book. Using this step-by-step method to achieve a visually balanced and appropriate luminous composition is sometimes also referred to as the “Total Concept of Lighting Design.” The following pages will generally outline and further describe the utilization of this method.

Step 1. Visual Composition The first step involves the establishment of the desired appearance of the lighted architectural surfaces, elements, forms and finishes, and set the overall visual composition of the space. The visualized solution should include a pattern of illuminated surfaces, their relationship to the total environment, and how it reinforces and enables the utilization of the space – while also highlighting the important centers of interest. This process is seldom the single responsibility of the architect or lighting designer, and must be carefully coordinated with all the other participating parties involved, such as, the interior designer, owner, and occupants. An additional consideration for this initial step is the consideration of the resulting brightness ratios between all the different interior surfaces, including the walls, the floor, and the ceiling areas. When the brightness ratio is 3 to 1 or less, the visual difference is minimal and hardly noticeable, while a more visible difference

DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS

would be a range of 10 to 1. On the other hand, a somewhat noticeable and dominant range of brightness would be approximately 100 to 1 or more.

Step 2. Architectural Review A lighting designer may sometimes have little input to the preliminary and programmed design of an architectural interior space, other than the general lighting requirements, and have to act within a predetermined set of conditions. However, to furnish a comprehensive design of the visual environment, he must first become familiar with the architectural design concept and physical surroundings, being of particular importance as it relates and impacts other environmental systems and planned activities. And also be aware and have knowledge of space allowances provided for the lighting systems.

Step 3. Special Considerations This step involves the consideration of the lighting and appearance of objects and special features and functions within the space. The lighting techniques and methods chosen that might affect the objects and activities within the space could involve special light beam control, object location, time of day, light and shadow, the type of surface finishes and color of light.

Step 4. Luminaire Selection In addition to the above special considerations, the selection of the luminaires and associated lighting equipment, including the light sources, requires careful attention to the proper light distribution and control to satisfy the programed

illumination objectives, along with any other sound, thermal, or visual characteristics of the selected luminaires. In this sense, the proposed lighting techniques and elements should be very carefully coordinated and integrated with the basic architectural character and detailing. These light source selections for the generation and controlled distribution of luminous flux are generally referred to in the architectural and interior design community as luminaires or lighting fixtures. They are also called luminous elements when describing custom equipment, or sometimes identified as structural lighting.

Step 5. HVAC Systems Coordination Early in the preliminary design phase it is important to confer and coordinate with the engineering consultants with respect to the successful integration of the proposed Heating, Ventilating and Air Conditioning systems. This is especially true with regard to the ceiling plane, where placement of heating, cooling, acoustical and sprinkler equipment may seriously interfere with the proposed and desired lighting layout.

Step 6. Task Illumination The initial consideration involving the design and furnishing of the required task illumination must have a clear understanding of the actual environmental and visual requirements of the programed occupant visual tasks. This must consider the characteristics of the lighting with regard to the distribution, as well as surface reflectances, veiling reflections, and shadows.

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DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS THE STEP-BY-STEP METHOD . . . continued

LIGHTING R ESEARCH

Step 7. Layout and Computer Aided Design

The Contribution of Lighting Research

The determination of the physical layout of luminaires and lighting equipment is typically established by their location in relation to the occupancy requirements, visual tasks, or special lighting effects. The design and layout may be identified as, general lighting, ambient lighting, localized general lighting, local lighting, task oriented lighting, and special luminous elements. Use of lighting design software at this step can be very useful, fun, and rewarding to furnish a clear visual review and design confirmation for all interested parties – especially the owner and future occupants. Additional considerations may include the control of discomfort and disability glare, and possible veiling reflections.

The creative process of lighting design is influenced by the many things we observe and understand about our physical surroundings and emotional responses. We have learned the way we see our environment depends on our activities, past experiences, and not surprisingly the majority of times, almost entirely on lighting.

Conclusions Good lighting should furnish a productive, appropriate, and comfortable environment with a general sense of well-being. The lighting design process has always been elusive, but should involve the composition of brightness patterns within a three-dimensional space, along with a hierarchy of brightness and illuminance from the occupants’ point of view. The developed process must also furnish task illumination and involve a programed lighting design methodology that addresses all the functions of good lighting, such as, providing comfortable and appropriate space utilization, points of interest, a sense of well-being, and energy, psychological, and cost considerations.

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In the early 1970s professor and architect, John E. Flynn, authored an article entitled “Concepts Beyond The IES Framework” where he clearly brought attention to, and carefully identified the limitations of a totally engineering approach to lighting design. He suggested we consider and addopt a more humanistic and emotionally perspective approach to the design process. Professor Flynn’s research had identified visual cues as a potential and useful architectural utilization of lighting techniques similar to stage lighting concepts that would establish a variety of moods and human responses within an architectural interior setting. His recent research offered a new basic understanding of the relationship between different lighting modes and visual patterns, and the resulting subjective human emotional and physical responses. He surprised many practitioners with his ability to describe in human perceptive, emotional, and psychological terms, the intuitive reasoning a designer used to complete a successful lighting project – even though the designer was mostly unaware of his utilization of intuitive motivations.

DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS LIGHTING RESEARCH . . . continued

Subjective Appraisal The psychological and physiological impact of lighting enables us to be both productive and comfortable in the relationship between lighting and the visual perception and the emotional reaction an occupant feels within a space. His research has reinforced the idea that carefully controlled visual patterns of light are somewhat, and possibly more important, than the quest for quantitative illumination to be the guiding rule. The fundamental goal of lighting design should be to satisfy our human needs for appropriate, productive, and visually comfortable lighted architectural interior spaces and environments. Extensive research in the field of lighting and architecture by Professor Flynn promoted the idea that lighting design should take a much broader approach and consider the occupant’s perception of the interior environment as a critical part of the design process. He also felt an encompassing terminology should be used to identify, not just the quantity of light, but the quality of light and visual composition. He suggested it be called Spatial Illumination. He further proposed that good interior lighting, in most cases, should influence our social interaction, motivation, orientation, mood, and a sense of well-being. His research work was approached primarilly from a psychological rather than from that of an architect or interior designer. To accomplish these objectives he outlined a number of different typical interior lighting schemes that could be investigated

for the subjective physiological and psychological perceptions and reactions to the different lighting environments. A list of some specific design goals he researched and validated are listed below. To confirm his proposed approach, Flynn and his fellow researchers devised a series of full-scale experiments to test and carefully explore the perceived psychological effects of the different lighting arrangements. The first experiment took place in an office conference room that had the required illumination systems in place, which included, two levels of lighting, both ceiling downlighting and wall lighting, with direct and diffuse distribution. Twelve groups of eight people were asked to evaluate the six different lighting arrangements illustrated on the next page. The design goals from the previous page and research conclusions are also briefly reviewed on the following pages.

PROPOSED LIGHTING DESIGN GOALS A. . . . . Create Patterns of Light and Shade B. . . . . Create Visual Focal Centers C. . . . . Furnish Spatial Orientation D. . . . . Create Uncluttered Visual Environment E. . . . . Furnish Balanced Luminance Ratios F. . . . . Reduce Uncomfortable Glare Sources G. . . . . Be Stimulating without Overpowering H. . . . . Furnish a Pleasant Environment

37

DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS LIGHTING RESEARCH . . . continued Subjective Appraisal SIMULATED LIGHTING ARRANGEMENTS USED IN THIS STUDY

1. DOWNLIGHTING AT LOW INTENSITY (10 fc)

3. DIFFUSE DOWNLIGHTING AT LOW SETTING (10 fc)

5. DIFFUSE DOWNLIGHTING AT HIGH SETTING (100 fc)

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2. WALL LIGHTING AT ALL FOUR WALLS

4. DIFFUSE DOWNLIGHTING & END WALL LIGHTING (10 fc)

6. A COMBINATION OF 1, 2, and 3

DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS LIGHTING RESEARCH

. . . continued

The methods utilized in the study of the six lighting arrangements shown on the opposite page, used a questionnaire in a format shown in the illustration below. The participants of the research experiment were asked to indicate their perceptive valuation of the arrangements by checking one of seven scales between the listed opposite descriptive values. To furnish a frame of reference, all six arrangements were shown in SEMANTIC DIFFERENTIAL VALUE SCALES

a rapid order for 15 seconds. Then each was shown in a different order for one minute, and asked to complete the form with semantic scaling. In the initial study the participants were not informed they were to evaluate the lighting and tended to judge the room on all of its characteristics. In a later study they were asked to judge the lighting arrangements and analysis of both studies revealed general agreement. The resulting data was also compared with five factors showing a significant difference in impression between two or more of the observed arrangements.

SPATIAL

CLARITY

EVALUTIVE

Factor 1 was a general (Evaluative) impression

Friendly Pleasant like Harmony Satisfying Beautiful Sociable Relaxed Interesting

:__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________:

Hostile Unpleasant Dislike Discord Frustrating Ugly Unsociable Tense Monotonous

Clear Bright Faces Clear Distinct Focused Radiant

:__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________: :__________:_________:_________:_________:

Hazy Dim Faces Obscure Vague Unfocused Dull

Simple :__________:_________:_________:_________: Complex Uncluttered :__________:_________:_________:_________: Cluttered Spacious :__________:_________:_________:_________: Cramped

where arrangements 4 and 6 were generally preferred, and the arrangements 3 and 5 were the least preferred. Factor 2 was an impression of (Perceptual Clarity), or spatial brightness where arrangements 5 and 6 were considered as the brightest while arrangements 1, 2,3 and 4 had less luminous,or brightness energy. Factor 3 considered (Spatial Complexity) or visual

clutter, found little difference between arrangements, and did not significantly affect overall impression. Factor 4 looked at the impression of (Spaciousness) where arrangements 1 and 3 were judged to be less spacious. The lighting of all four walls in arrangements 2 and 6 induced a feeling of greater spaciousness compared to 1 and 3 low-intensity overhead lighting. Factor 5 considered (Formal and Informal) values

that may represent an impression of style or fashion. This did not strongly differentiate between all six of the lighting arrangements shown for this particular room setting. Findings in other room settings found occupants that had a choice, usually selected seating locations that faced noticeably illuminated walls.

39

DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS LIGHTING RESEARCH . . . continued The study found there were three primary perceptual responses to the lighted spaces, described below.

1. Peripheral/Overhead: These two distributions invoked a distinctive perceptual difference between lighting on the vertical surfaces and the overhead downlighting on the central horizontal surfaces.

2. Bright/Dim: This variation also created a perceptual difference on the horizontal and vertical surfaces, and especially at the work plane. 3. Uniform/Nonuniform: These conditions created a varied perception of the overall lighting in the

Pleasantness is reinforced by the use of nonuniform moderate lighting on the work-plane with direct lighting being preferred over diffuse. Wall lighting enhances the sense of pleasantness. Visual Clarity is sensed by high work-plane luminance, especially in a room center, and wall lighting, important in work spaces. Visual clarity

will not be reinforced by flat, uniform lighting.

Relaxing or Tense is reinforced by non-uniform

room and the ability to model and accent objects.

lighting, especially on wall surfaces. Useful in waiting and conference areas, where high-level uniform lighting can produce a tense atmosphere.

VISUAL EXPERIENCE CHARACTERISTICS

OTHER RESEARCH & OBSERVATIONS

It was concluded from the list of values on the questionnaire that some were redundant, with a smaller number found useful and appropriate as representative features of a visual experience. Listed below is an analysis of the perception by the observers through their semantic differential values.

environmental stimuli have produced additional findings and guidelines. Investigations of other rooms with different furniture arrangements and types of activities suggested appraisal of lighting was consistent for most room types and activities, reinforcing that these impressions were somewhat independent of the room setting.

Spaciousness was reinforced by the uniform work-plane lighting, supported with uniform wall lighting. This characteristic is important in corridors, lobbies, and assembly areas. While overhead lighting by itself, especially at the low levels, makes a space feel confining. Public vs Private is reinforced by non-uniform lighting from low levels in the region of the occupant to higher levels in surrounding areas, and wall lighting. This is important when lighting private offices, nightclubs, restaurants, and residences. A public space, by contrast, requires a high central luminance level.

40

Other observations from this and more recent research suggests people generally gravitate toward higher lighted areas, but prefer to view high brightness areas, rather than move into, or sit under them. Other studies were conducted to investigate the “moth effect”. It looked at behavior as a result of visual cueing with respect to seat selection in a restaurant setting. The selected space had high-contrast adjustable lighting arrangements. The subjects, not knowing about the experiment, entered the space, moved to the coffee bar, then selected a seat at one of the tables.

DESIGN OF THE LUMINOUS ENVIRONMENT

THE DESIGN PROCESS

The lighting arrangement for the illustration below left shows the area to the right of the room was lighted with diffuse wall lighting while the remaining space was unlighted, except for wall lighting behind the coffee bar. The subjects entered the room and selected seats in the order shown by the numbers. They preferred to sit in the unlighted area with the first ones selecting seats facing the lighted area as well as the entrance area. The lighting arrangement in the right illustration had wall lighting on the

WA ENTRANCE

L

IG L-L

HTI

NG

COFFEE BAR

WALL-LIGHTING

8

WALL-LIGHTING WALL-LIGHTING

COFFEE BAR

WALL-LIGHTING

WALL-LIGHTING

rear wall and the coffee bar, with the right half of the room screened off with no illumination. The numbers in the right illustration show the subjects again preferred to sit farthest from the lighted area and facing it and the room interior, indicating a lesser preference for facing the entrance area. The results may question the theory of the moth effect. However, it might be concluded that people will generally move toward illuminated spaces, but also choose to face them rather than to move into them.

SEAT SELECTION PATTERNS

Further information is found at the following references. Flynn, J.E., “The psy chology of light”, Electrical Consultant Magazine , 88:12 through 89:7, 1972-73 (Series of 8 articles). Flynn,J.E.,Spencer,T.J.,Martyniuk,O.,and Hendrick,C.,“Interim study of procedures for investigating the effects of light on impression and behavior,” Journal of the IES, vol.3,no.1, October 1973, pp 87- 94. Flynn,J.E.,“Lighting design decisions as intervention in human visual space” (The role of CIE ‘Study Group A’) Paper presented at the Symposium 1974/CIE ‘Study Group A’, Montreal, Canada, Aug 1974.

ENTRANCE

Flynn,J.E., “A study of lighting as a system of spatial cues”, EDRA-6 Workshopon “The Psychological Potential of Illumination,” The Univ. of Kansas, April 1975. Flynn,J.E. ,Spencer,T. J.,M artyniuk,O.,and Hendrick,C., “The influence of spatial light on human judgement,”Compte Rendu,18e Session, P-75-03, CIE Congress,London 1975, pp 39-46. Flynn,J. E.,“ A study of subjective responses to low energy and nonuniform lighting systems,” Lighting Design & Application, Feb 1977, vol.7, no. 2, pp 6-15. Flynn, J. E., Spencer,T. J., “The effects of light source color on user impression and satisfaction,”Journal of the IES, vol.6,no.3.

41

DESIGN OF THE LUMINOUS ENVIRONMENT

OFFICE & CLASSROOM LIGHTING GENERAL GUIDELINES The usual activities performed every day by typical office and classroom occupants tend to be task oriented – in both the private and open office environments and the classroom – with the goal of task understanding and productivity

being important. The lighting system should provide a comfortable visual, physical, and psychological environment that supports and encourages these goals, and meets and sustains the recommended lighting levels for the tasks.

General Lighting Systems for most educational

Pendant Lighting Systems can furnish quality

and office environments are designed to provide uniform general illumination, and typically are recessed linear luminaires in a suspended ceiling. They are an accepted lighting system because the use of a suspended ceiling offers concealment of HVAC ducts, lighting control systems, sprinkler piping, audio-visual and electrical equipment. For both aesthetic and functional reasons it is the logical surface to locate the needed lighting equipment. Also, being an accessible ceiling, it allows for easy upgrading and maintenance of the systems.

lighting in offices and classrooms, with totally direct, totally indirect, or a combination of light distribution. Totally indirect systems work best with a minimum ceiling height of 9 feet. Luminaires with a wide distribution can be mounted as low as 7-1/2 feet above the floor. of bright architectural surfaces in the field of view can result in visual discomfort. Avoiding high brightness contrasts with these surfaces can help reduce this. The recommended reflectance ranges are: ceilings 60-80%, walls 40-60%, and floors 20-35%.

NOTE: For suggested representative general lighting layout of luminaires see Chapter 8, Page 156.

42

DESIGN OF THE LUMINOUS ENVIRONMENT

OFFICE & CLASSROOM LIGHTING

Task-Ambient Lighting for office and classroom environments should take into account the use of computer monitors and portable electronic devices, and the effect of unwanted reflections and shadows. The specification of indirect-type lighting equipment, shielded luminaires, and task-ambient lighting systems can considerably help to resolve the problem – and furnish good visual comfort. Task-ambient lighting is made up of general (ambient) lighting, supplemented with local task lighting, which can be from fixed or portable lamps, furniture integrated elements, or ceiling-mounted luminaires over the task. This design approach can save significant energy when compared with general lighting systems. In a task-ambient design, lighting fixtures might be concentrated over work areas for the task lighting, locating the light sources on either side of the work space, and slightly behind, eliminating shadows and directing light away from the viewer’s eyes. An indirect lighting system can provide low levels of general (ambient) illumination. When compared to a traditional uniform lighting design, the average light level may be lower, and the number of required fixtures may be reduced. It is ideal for visual tasks and saves energy by providing and locating the illumination only where needed. Additional energy savings can be accomplished with the utilization of user-controlled practices, along with occupancy and vacancy sensors. Vacancy sensors are somewhat different than occupancy sensors in the sense that they do not turn the lights on when detecting motion, but twill turn them off when no motion is detected.

TASK-AMBIENT LIGHTING

43

DESIGN OF THE LUMINOUS ENVIRONMENT

RETAIL & DISPLAY LIGHTING GENERAL GUIDELINES Quality lighting for retail store and display applications helps promote successful buying decisions as a result of clear and accurate seeing. As customers enter the store they perceive an impression of the environment which influences the duration of their stay and overall shopping experience. It also creates an impression of the quality of the merchandise and interior design, and a sense of personal comfort. This atmosphere is typically provided by the following three basic lighting components.

Ambient Lighting furnishes a uniform level of general illumination for merchandise appraisal and circulation. It should furnish illumination that reinforces the desired environment and mood of the store or merchandising image. Successful ambient lighting can also furnish an attractive atmosphere where the shopper feels comfortable and at ease, with appropriate color and quality – at lighting levels of 15 to 50 footcandles (160-540 lux). Other contributions to the ambience might include some lighted architectural elements such as coves, cornices, coffers, and decorative pendant and wall fixtures – adding a strong sense of quality. Accent Lighting is utilized to create visual interest in merchandise and emphasis of a display theme. It highlights color, texture, form and graphics, to attract shoppers to a specific item or area. Successful accent lighting uses lighting levels, brightness ratios, and distribution characteristics. As a general rule, the intensity

44

QUALITY RETAIL LIGHTING

should be three to ten times greater than the ambient illumination level. Three-dimensional merchandise might also require directional lighting and diffuse light to soften shadows. Adjustable accent lighting should not be aimed more than 45° above vertical to reduce glare.

Perimeter Lighting and wall lighting draws customers from main aisles into the display areas creating a pleasant shopping environment and reinforces the visual impact of the displays. Lighting of the vertical surfaces strongly influences the shopper’s impression of the environment and furnishes a feeling of visual comfort and area spaciousness. The use of architectural elements such as lighted coves and wall brackets can create better visual adaptation, comfort, and a sense of architectural integration.

DESIGN OF THE LUMINOUS ENVIRONMENT

RETAIL & DISPLAY LIGHTING Design Considerations: The image of a retail store can be influenced by the lighting used to illuminate the interior spaces and merchandise. Well-designed lighting can contribute to the the store image and overall success. The design has to meet a range of requirements that depend on the type of store – identified by three categories; Big-Box, Mid-Market, and High-End. This division also suggests the shopper’s expectation of the luminous environment. Lighting for the Big-Box store needs only safe circulation and good seeing conditions. While at the High-End store, shoppers should feel comfortable in a pleasant atmosphere with an established and appropriate lighted environment. The quality of upscale environments are often associated with the quality of the lighting.

A working knowledge of the basics of light and color is essential for the lighting designer. A special and positive influence can be introduced in selected merchandising areas with the use of warm or cool ambience. In areas where shoppers spend long periods of time using color can subliminally affect their buying attitudes.

Multiple Systems using concentrating light sources can enhance the form and modelling of merchandise. Also, the shopper’s and sales personnel’s appearance is best when viewed under a mix of directional and diffuse lighting. The four illustrations below demonstrate the visually appealing effect of incorporating three different types of distribution, general diffuse lighting, backlighting, and directional highlighting.

Lighting Systems for general illumination and local display lighting should be designed to furnish maximum attention to the merchandise and the overall environmental impression. Extremely bright lighting can distract the shopper’s attention and makes appraisal of the merchandise somewhat more difficult. The primary light sources should be shielded from direct view with brightness controlling devices such as louvers, diffusers, and shields, as part of the equipment. However, the use of special techniques, like prominent small exposed light sources, decorative patterns, and architectural elements, can be incorporated into the lighting.

Color: Proper use of color is an important considerations in retail merchandising that can create focus, ambience, and stimulate sales..

General diffuse illumination Adding background lighting furnishes uniform lighting creates silhouetting with loss without special highlighting. of some special detailing.

Highlighting alone brings out Using all 3 techniques reveals detailing & color but, creates details and locates the object high contrast and shadows. within the surrounding area.

45

DESIGN OF THE LUMINOUS ENVIRONMENT

RESTAURANT LIGHTING GENERAL GUIDELINES The interior design of restaurants encompasses a wide range of environments and themes and presents the lighting designer a significant challenge. There is an unlimited selection of lighting techniques available for the designer to choose from to comply with the basic lighting requirements, reinforce the interior design theme, and enhance the occupants’ dining experience. The impression of the restaurant’s ambience plays an important role for the overall satisfaction and comfort of the customer’s. The lighting should complement the type of service and food served, from a cafeteria, to the elegant atmosphere of an upscale restaurant or club.

Basic Illumination for most restaurant needs can be provided with simple downlights. They offer a glare-free atmosphere with a minimum of bright distractions, and can be spaced to provide uniform illumination, allowing flexible table arrangements. The illustration on the right demonstrates how downlights can furnish more than adequate and uniform illumination in a fast-food environment, and be utilized to add dramatic interest with grazing light on a brick wall. However, care must be taken to not overly use downlighting that might result in high reflected brightness and unflattering shadows on people’s faces. Downlights can be surface mounted, recessed, or suspended depending on the ceiling height and the decorative theme. Dimming control is typically utilized to enable an appropriate lighting level and atmosphere.

46

LIGHTING FOR A FAST-FOOD ENVIRONMENT

Recommended Levels can vary considerably depending upon the type of restaurant, the decorative theme, and environment. It may vary from as low as 3 footcandles for an subdued intimate environment up to 100 footcandles for a fast-food restaurant with adjacent high brightness surroundings. Consideration must also be given to the age of the diner as well. The use of lower lighting levels, which might be acceptable to younger customers, may also contribute to older customers being unable to easily read the menu and appraise their food.

DESIGN OF THE LUMINOUS ENVIRONMENT

RESTAURANT LIGHTING wall lighting and other ceiling-mounted light sources. Used in the restaurant environment, these types of decorative luminaires should be on dimmer control and utilize warm, high color-rendering light sources. Some upscale eating establishments offer a subdued intimate atmosphere to promote a distinctive theme and menu. A subdued environment can also be achieved with control of surface reflectances and rich darker colors, with low to moderate lighting levels especially on ceilings and walls.

Lighting the Table: The distribution of light on

LIGHTING FOR AN UPSCALE ENVIRONMENT

Decorative Lighting techniques using fixtures such as chandeliers and wall units illuminate with a subtle soft ambient distribution when compared to downlighting, and can add a touch of class when used in a more formal and subdued environment. They can add sparkle and if carefully designed, also furnish adequate task lighting. However, they should not be expected to be the primary source of illumination. Chandeliers create a strong focal point and usually do not need to be used in large numbers, especially when supported with

a dining table can be an important design consideration. While most eating establishments furnish more than adequate illumination with general overhead lighting, some special lighting can generate a sense of intimacy and a personal dining experience – especially with tables for two or four in a subdued and fixed location. Where possible, the lighting should focus on the table, not on the diners, and in a way to prevent reflections from silverwear and menus. An established technique to accomplish this is the careful use of ceiling-mounted adjustable narrow-beam spot or flood lamps, aimed at the center of a table with a beam that matches the size of the table. For example an 24-inch diameter illuminated area with a soft or feathered edge would be appropriate on a table for two. With this method, light is reflected off the table (or table cloth) and would softly uplight the diners – making the color of the table cloth or top very important – with blue or green reflected light being particularly unflattering. Continued . . . .

47

DESIGN OF THE LUMINOUS ENVIRONMENT

RESTAURANT LIGHTING Lighting the Table . . . continued A second method uses a decorative fixture suspended low enough over each table to conceal the light source, but not blocking the view across the table. The light source shielding can be opaque or translucent but not overly bright and create glare. In the past, incandescent silverbowl A-line lamps have been successfully incorporated to accomplish this effect. Another method is the use of a real (or electric) candle on the table, usually shielded with various types of decorative candle holders. However, it may not, provide lighting for the visual tasks involved.

Indirect Lighting installations such as lighted coffers, coves, and other built-in elements can be used to furnish a soft and diffuse distribution of light. They can reduce shadows and offer a more flattering appearance of people and surroundings. The use of fluorescent or LED light sources works well in these applications. However, using only indirect lighting can result in an uninteresting environment, challenging the designer to balance the distribution of the lighting for an attractive luminous environment.

Highlighted features such as paintings, photos, plants, and wall murals can add visual interest to a restaurant’s interior decor. A display of photos or paintings can be an important feature of a restaurant’s environment. The lighting of these elements can be accomplished with recessed or surface-mounted adjustable spot or flood lights, individual picture lights, or built-in lighted cornices and wall brackets for large wall murals. Back-lighted and self-luminous wall panels with decorative grillwork, or silhouetted

48

LUMINOUS ELEMENTS AND DECORATIVE GRILLWORK

sculpture and plants can also add visual interest. Another approach is the use of uplighting under art objects, plants, and special features.

Modifying the Lighting is often desirable to adjust the mood and atmosphere for different events or even the time of day. A change from a breakfast and lunch service to a formal dining environment requires flexible lighting and control to accomplish the transition. Using preset dimming controls offers a simple way to change the feel and tone of the luminous environment, and to keep the daily operation consistent. Dimming control is also particularly useful for after dark periods, and it provides an important capability of raising the lighting levels for the routine set-up and cleaning activities.

DESIGN OF THE LUMINOUS ENVIRONMENT

RESTAURANT LIGHTING Sports Bar lighting is usually unique and may not fit the typical description of architectural lighting, however the basic principles of good lighting still apply. The use of multiple large screen TV's and videos requires close attention to the reduction of unwanted distracting glare on the TV screens, while maintaining adequate task illumination. The lighting fixtures used can range from a simple to a more ornate style. The interior design, and overall theme of the restaurant, will play an important role in determining the fixture selection. Typical bar lighting often furnishes lower levels of light with recessed down lights or indirect elements like under bar and cove lighting. Bartenders’ need for illumination can be met with under-cabinet lights.

Private Dining & Meeting Rooms used for both dining and meeting purposes should provide good lighting that serves both functions. This may require adjustable spot or flood lighting for a flexible podium area, along with dimmable general lighting levels for audiovisual presentations, such as fixed or portable movie screens, white boards, and scribble pads.

SPORTS BAR LIGHTING RESTROOM LIGHTING

Service Areas such as food preparation, maintenance and restrooms should receive special attention to ensure cleanliness and safety. Passageways from kitchens to dining areas need to be designed to prevent the spill of high brightness levels into the dining area. Rest room lighting should be visually comfortable and furnish light that is flattering at the vanity and mirror area. The lower illustration shows a luminous soffit over the mirror in a men’s room with wall lighting extending around the room.

49

DESIGN OF THE LUMINOUS ENVIRONMENT

HEALTHCARE LIGHTING GENERAL GUIDELINES Research has established the multiple benefits of light and lighting in the field of healthcare, including a wide range of both medical and psychological benefits, including a general sense of well-being for both patients and staff. Furnishing adequate and comfortable levels of light impacts both human performance and health, and is typically supplied by both daylight and electric sources. Daylight is not inherently superior to artificial lighting, but has benefits for maintaining general health. The increased use of windows in contemporary healthcare facilities has also resulted in improved patient and staff satisfaction. The focus, however, should be on electric sources with their ability to impact the environment, being available day and night, and help perform many important healthcare functions.

and treatment. Studies also suggest that good lighting will impact healthcare with improved performance of simple to complicated visual tasks, as well as reduced depression and sleep problems. It also shows that light can improve the overall enjoyment and satisfaction of the healthcare physical environment, control the body’s circadian rhythms, and even shorten the patient’s length of stay. Some lighting designers have proposed the use of full-spectrum light sources in healthcare settings because they furnish the full wavelength of visible light similar to natural light, with some of the established advantages of natural light. Others counter the color-rendering advantages are not more important than its higher cost and shorter lamp life when compared to other lamp types.

Quality Lighting in the healthcare environment

Lobby Lighting should be comfortable with focus on reception areas. Architectural lighting works well with supplemented task lighting for both medical records and reading materials.

enables more accurate performance of medical procedures, and benefits both the psychological and physiological aspects of medical evaluation RECEPTION AREA LIGHTING

50

DESIGN OF THE LUMINOUS ENVIRONMENT

HEALTHCARE LIGHTING

Exam Rooms in the past presented a somewhat simple lighting challenge. The typical 8x10 and 10x12 room required general illumination over an examination table and a small counter top. Typical lighting for this space was one or two 2x4 fluorescent ceiling fixtures, lamped with four T12 48-in rapid-start lamps. The counter and sink area usually had no task lighting, or some under- cabinet fluorescent lighting. With the current use of portable tablet computers, the requirement for under-cabinet lighting is substantially reduced. Larger hospital exam rooms and emergency facilities would have similar computer stations and the same general illumination requirements. Due to the desire for energy conservation, many of these ceiling fixtures were relamped or replaced with only two or three energy-efficient fluorescent T8 lamps or LED sources. Some designers and medical facilities also opted for the use of full-spectrum light sources for improved color rendition and more accurate medical diagnosis.

Patient Rooms have found that good lighting impacts general healthcare in a positive way. Many facilities have provided a comfortable residential-type warm environment, and some children’s hospitals now offer new colorful fantasy-themed designs allowing kids to escape the typical sterile medical atmosphere. These innovations tend to promote faster healing and a shorter length of stay. Lighting usually consists of a wall luminaire above the head of the bed with patient control and a night light, furnished from a fluorescent or LED wall bracket. Also, a ceiling-mounted light over the bed, for medical examination purposes. Light sources should be in the warm color range of 2800° to 3500° kelvin. Table and floor lamps and small recessed downlights can also be utilized to offer the comfortable feeling of home-away-from-home. Fantasy-themed designs, with control of the intensity and color of light, offers young patients the opportunity to feel more comfortable and in control of their temporary medical environment.

51

DESIGN OF THE LUMINOUS ENVIRONMENT

MUSEUM & EXHIBIT LIGHTING GENERAL GUIDELINES The lighting for museum interior spaces and other similar exhibition and display venues requires special and careful consideration with regard to their non-conventional function and occupant activities. The design typically involves the development of unique lighting solutions that do not fall into the category of time-tested architectural or display lighting techniques. It also requires new approaches and imaginative design techniques, along with a complete understanding of complex electrical, lighting, and control methods. In many, if not most, a further understanding and incorporation of established theatrical lighting systems and techniques is most helpful and necessary.

for museums involves the utilization of a large number of different light sources, including light-emitting diode, incandescent, fluorescent, halogen, decorative, and even neon in some situations, very often integrated with daylighting sources. Most of the solutions require both concealed and exposed light sources integrated with the architecture. The architect and lighting designer can furnish a design that might improve the occupant’s ability to interact with the learning or entertaining aspects of the space, or may simply promote visual comfort and a sense of well-being. The more difficult spaces to provide a successful design solution are the multidisciplined museum and exhibition areas.

Design Considerations: Almost all museum programs and environments require more complex solutions than the tried-and-true track lighting typically used for display and accent lighting. The fundamental lighting challenge

Careful planning and coordination with clients and contractors can insure the final installed project will be accepted by all participants and interested parties. Other considerations with regard to theatrical and stage lighting equipment

52

DESIGN OF THE LUMINOUS ENVIRONMENT

MUSEUM & EXHIBIT LIGHTING

include an understanding and familiarity with such items as floodlights, spotlights with their special beam patterns, focusing, barn doors and shutters. The understanding of the required complicated theatrical control systems is probably beyond the expertise of most lighting designers and calls for the use of theatrical lighting consultants as part of the design team. The use of a design technique know as “layering” of light is an appropriate approach for these applications. It involves a variable number of layers of illumination described with such terms as ambient, architectural, circulation, exhibit, display and highlighting. Even though each layer suggests it serves a specific function they can be connected and integrated – especially with state-of-the-art control techniques – to provide a lighting solution that provides a seamless visitors experience. The ambient layer can be utilized to also serve the necessary functions of service, maintenance, and cleaning.

Luminaire Types: Museum lighting uses a wide range of lighting equipment and light sources. Of the many types used, some might be realistic copies appropriate to the historical period of the exhibit or the general design or educational theme. The wide range would include typical recessed, pendant, surface-mounted, exposed, and hidden luminaires, and might also include architectural elements and self-illuminated graphics and display panels. Suspended or surface track lighting should also have features such as position locking, beam control and shielding to insure a visually comfortable, glarefree environment for visitors and staff personnel.

Light Source Selection: LED, halogen, and fluorescent sources would be the logical choice because of their energy efficiency and color capabilities. However, the critical problem for most museums is the damaging effect light sources have on exhibited items and artifacts. The most vulnerable items are rare historic documents, sensitive textiles, fragile watercolors, printed materials, and organically dyed items. Even some of the merchandise found in gift shops, such as clothing, books, and posters, can be damaged by invisible ultraviolet and infrared light, along with visible light, which can also damage materials. Reflective materials can reflect some light, however, the remaining light entering will cut atomic bonds holding molecules together. More light results in the more damage. Most museums establish limits for light levels to reduce damage. While lighting designers might over-light exhibits, museum personnel may dim the lights to a lower lighting level but the display damage continues. Dimming changes the light energy to the red and infrared wavelengths, will not register on a light meter, and damage continues because the energy level was reduced by only 5% or 10%. So dimming, especially incandescent, does not work. The use of LED sources offers a significant advantage in efficiency, long life, and color choices. For special areas the use of small flexible LED light strips is a solution. They also offer a choice of color temperatures (from 2700K to 5000K) and, are available in a variety of types. Using red, green, and blue sources also adds a wide choice of available colors.

53

DESIGN OF THE LUMINOUS ENVIRONMENT

RESIDENTIAL LIGHTING GENERAL GUIDELINES

The primary goal of residential lighting is to furnish adequate illumination for everyday tasks, and offer a sense of visual comfort and well-being creating spaces that have a warmth and interesting variety of environments. Good lighting will complement the occupants and their lifestyle as well as enhance the interior design and furnishings. The addition of areas of color and shadow also furnish a more pleasing and attractive luminous environment.

Living Areas can be lighted with a combination of ambient and local lighting techniques that furnish general lighting and soft pools of local lighting. This furnishes light for moving about and casual activities such as watching television, conversation, and listening to music. Using portable lamps offers light for visual tasks like housekeeping and reading, while also adding decorative interest. Architectural elements, like a lighted cornice, can furnish some soft general background lighting and visual interest.

Kitchen & Eating Areas are the spaces home owners most often express interest in lighting which should support activities from casual dining, food preparation, and clean up. Using downlights for general and task lighting, along with undercabinet lighting, focuses the light where needed. Downlights should have a wide distribution to light inside wall cabinets, and recessed to minimize glare – located over the front edge of counter tops to reduce shadows of a person at the counter. Under-cabinet lighting should be shielded from view, especially from seated positions. Built-in elements, such as a lighted valance, also adds background illumination and visual interest. Vent hoods have lights for that location. A central fixture can add a decorative touch and added general lighting.

54

LIVING ROOM LIGHTING KITCHEN LIGHTING

DESIGN OF THE LUMINOUS ENVIRONMENT

RESIDENTIAL LIGHTING

Dining Rooms require lighting that is flexible enough to serve a variety of different functions from formal dining to lunches and birthday parties. Chandeliers have traditionally been used as the primary light source and are typically selected to establish a decorative theme. Downlights can also furnish good lighting, with or without a chandelier, adding sparkle to the silverware and table setting. Low-level background lighting from portable lamps or built-in elements can add to the ambience. Pendant fixtures should not be lower than 30 inches above the table so as to not block the view across the table. Adjacent areas can be adequately lighted with downlights, wall sconces, or built-in elements.

DINING ROOM LIGHTING BATHROOM LIGHTING

Bedrooms have also traditionally been illuminated with a central ceiling fixture and some form of bedside lamps. These techniques hold up well over time, but can benefit from the addition of some indirect lighting such as a lighted cove or cornice. In a large, or high-ceiling bedroom, a little elegance can be added with a chandelier and portable floor and table lamps in sitting areas for reading and television viewing. Closets can use simple ceiling mounted fixtures. Bathrooms are also a multi-function space where high levels of uniform general illumination is needed for regular use and cleaning. Lighting for grooming can be provided from downlights over the vanity when using high reflectance counter tops to reflect some light upward. A better solution is wall lights on either side of the mirror to reduce shadows and furnish adequate illumination for applying make-up, shaving, and general personal grooming, mounted low enough to light under the chin. Showers and toilet compartments can be lighted with downlights.

55

DESIGN OF THE LUMINOUS ENVIRONMENT

DAYLIGHTING GENERAL GUIDELINES

Even though the subject matter in this book only minimally covers daylighting, it is recognized as an important part of the overall lighting environment for architectural interior spaces, and a brief review of the subject follows. Daylighting can significantly alter the lighting distribution in most architectural interior environments, and may be the dominant factor in meeting many lighting requirements for daytime activities. In this context, a window for example, can serve two principal functions; to view the outside, and to furnish a source of illumination. However, an appropriate solution for one of these functions does not insure a good solution for the other.

Daylighting Techniques: The ideal solution for the lighting of interior activities is not usually furnished exclusively by natural light. Daylighting offers three basic sources of light, the sun, the sky, and reflected light from the ground and other adjacent surfaces. Generally, daylighting furnishes a diffuse, multi-directional distribution of light that may reinforce, or in special applications replace, the function or characteristics of an electric lighting system. Room Orientation: The location of classrooms and offices, in relation to the available perimeter areas of a building, can furnish the best utilization of available daylight. For the most efficient harvesting of daylight, rooms should be located next to north or south-facing windows, where they can maximize daylighting with low and translucent partitions to allow light to penetrate deep into the space. The utilization of east- and west-facing windows are the most difficult to take advantage of the natural light

56

because of the low sun angles, unless window blinds or draperies, are carefully incorporated.

Daylighting Controls: Automatic daylighting controls can be utilized to balance the electric lighting installation with the available daylight. Separate photocell controls should be placed in both the primary and secondary daylight zones. Luminaires with switchable multiple lamps are used to furnish uniform illumination without having the appearance of burned out lamps. Light Source Color Temperature: Both LED and fluorescent lamps are available in a range of colors of light ranging from warm to cool. The typical range in degrees Kelvin (K), is 3000K, 3500K, 4100K, and 5000K . The 4100K and 5000K color temperatures will more closely match and be compatible with natural daylight. DAYLIGHTING

DESIGN OF THE LUMINOUS ENVIRONMENT

DAYLIGHTING

Of interior room surfaces, the ceiling and walls are the most significant areas to assist daylight performance due to their reflective nature. For maximum daylighting uniformity and penetration, these surfaces should have a diffuse high reflectance finish of approximately 60 to 80% for the ceilings and 30 to 70% for the walls. A higher reflectance for the floor finish is helpful. REPRESENTATIVE DAYLIGHTING PERFORMANCE

12' ROOM HEIGHT

20' ROOM DEPTH (D)

234 211

70% WALL REFLECTANCE 30% WALL REFLECTANCE 134 112

80 62

Exterior Zone

Middle Zone

Interior Zone

REFLECTANCE: CLG - 80%, WALL - 70%, FLOOR - 30% SKY CONTRIBUTION 206

109

68

GND CONTRIBUTION

28

25

22

TOTAL (Footcandles)

234

134

80

REFLECTANCE: CLG - 80%, WALL - 30% FLOOR - 30% SKY CONTRIBUTION 187

93

47

GND CONTRIBUTION

24

19

15

TOTAL (Footcandles) 211

112

62

57

CHAPTER

4

LIGHT & COLOR

The use of colored light in architecture has only a minor historical precedence, such as the use in stained glass windows. However, current practice reveals an increased use of light and color in merchandising and entertainment, and in corporate applications. Utilizing color in lighting design offers a wide choice of psychological and interesting visual effects, ranging from very subtle to the dramatic. Different colors of light can affect our perception of space. Warm light sources, such as incandescent lamps or the sun, offers a feeling of warmth with emphasis on red, yellow, and orange, while cool sources, like some fluorescent lamps and daylight, strengthen blues and greens for a cool environment. Older sources, like high-presure sodium and mercury, significantly distort colors and the perception of the visual environment due to their limited color spectrum. The perceived color of light can also alter our subconscious appraisal of architectural space by creating environments suggestive of other visual experiences, such as the warmth of an early morning sun, or the coolness of an overcast day. This range of color can be furnished by color lamps, white sources with special coatings, or with the wide range of colors available with the use of the LED sources – which also offers the use of precise color mixing and control. The psychological effect of the use of color can be quite powerful, like a late autumn sunset or a successful theater production, while exposure to an overcast sky can be dull and void of a sense of excitement. A clear understanding of the unique characteristics of light and color is fundamental to its successful application in the field of architectural and interior design. This chapter will examine some of the unique technical and environmental aspects of working with light and color as applied to architectural spaces.

59

LIGHT & COLOR

THE ELECTROMAGNETIC SPECTRUM

The Color of Light is generally determined by the relative amounts of luminous energy emitted at each wavelength of the visible spectrum. White light is a mixture of all colors in about equal amounts. When wavelengths of energy are removed or added the color is changed to be tinted or more saturated. Various light sources have different spectral distributions that result in some subtle differences in the color, and color-rendering capabilities.

--

10 7

--

10 8

--

10 9

--

1010 -FREQUENCY (Hz)

Electromagnetic energy is everywhere and exists in many different frequencies of repeating wave patterns. It is identified by categories of frequencies, such as gamma-rays, x-rays, radar, power, radio, etc., or by the specific wavelengths, measured in nanometers (nm) (billionths of a meter). The eye is sensitive to a small portion of the total energy referred to as the visible spectrum, ranging from violet, at about 400nm, to red, at about 700nm. The range is sometimes expanded to 380 and 800nm. However, human vision at these wavelengths is almost zero. Identification of different colors is divided into six monochromatic colors shown in the diagram on the right. The color cyan is also sometimes added between the blue and green.

10 6

1011 --

POWER

-- 1000 m -- 100 m

RADIO & TV

-- 10 m

700 nm

-- 1 m

MICROWAVES

1012 --

RED

-- 10 cm -- 1 cm -- 1 mm

WAVELENGTH

ELECTROMAGNETIC ENERGY

1013 -- INFRA-RED -- 10 4 nm 14 -10 -- 10 3 nm 1015 -- VISIBLE -- 100 nm 1016 -- ULTRAVIOLET -- 10 nm 1017 -X-RAYS -- 1nm 1018 --- 0.1 nm 1019 -- GAMMA-RAYS -- .01 nm

600 nm

ORANGE YELLOW

500 nm

GREEN BLUE VIOLET

400 nm

Red, green, and blue are considered the primary colors because they are fundamental to human vision. Light is perceived as white by humans when the three cone cell types in the retina of the eye are stimulated equally by the red, green, and blue wavelengths. However, the eye is most sensitive to light in the yellow-green region of the spectrum.

REFRACTION OF LIGHT In 1666, at the age of 23, Newton, experimenting with light, found that a narrow beam of sunlight passing through a glass prism would be dispersed to show all the colors in the visible spectrum, from red to violet. This effect was known before, but was thought the glass filtered or tinted the light somehow. Today, we know the colors are different wavelengths of electromagnetic energy measured in “billionths” of a meter (nm).

60

HOLE

WHITE LIGHT

PRISM

RED ORANGE YELLOW GREEN BLUE VIOLET

LIGHT & COLOR

PRIMARY COLORS ADDITIVE PRIMARY COLORS All colors of light can be produced with “additive” color mixing using three colors in the visible spectrum; red, green, and blue. These colors match the sensitivity of the three cone cell types of the eye’s retina and produce the widest range of colors. Light is perceived as white when all three cone types are stimulated equally by these colors of light. They are generally accepted as “primary” colors. Yellow, cyan, and magenta are created by adding primary colors and are considered secondary colors, and “complementary” to their opposite primary color. Yellow is the complementary color to blue, and green is the complementary color to magenta, etc. Any two colors that produce white light when they are added together are called complementary.

GREEN Cyan

Yellow RED

BLUE

Magenta

ADDITIVE PRIMARIES

MAGENTA Blue

Red YELLOW

SUBTRACTIVE PRIMARY COLORS Passing white light through filters that absorb different wavelengths creates secondary colors of yellow, cyan, and magenta. These become primary colors for “subtractive” color mixing. Different combinations of these colors will also produce any color, or will even absorb all of the light.

CYAN

Green

SUBTRACTIVE PRIMARIES

DESCRIPTIVE CHARACTERISTICS

WHITE

SATURATION YELLOW

BRIGHTNESS GREEN

RED

CYAN BLUE

MAGENTA BLACK

HUE

HUE (Color) Hue is the characteristic that indicates whether it is a specific color like red, blue, green, etc. It’s the quality of light that varies with the different wavelengths. SATURATION (Chroma) Saturation refers to the strength or vividness of a color. A color with low saturation is often called “tinted.” BRIGHTNESS (Value) Brightness is the degree of gray-scale lightness or darkness. It is independent of hue and saturation.

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LIGHT & COLOR

COLOR MIXING ADDITIVE MIXING

EFFICIENCY OF LIGHT SOURCES To mix approximately equal quantities of colored light the different efficiencies of the sources must be considered due to the wide variation found in sources. Quantities of light, and not the number of lamps, is a consideration. For example, 1 green fluorescent lamp is approximately equal to 25 red fluorescent lamps. The output can be balanced by using a variable number of lamps, or dimmers, to reduce the output of the more efficient sources.

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50

RE D 10

%

0%

75

RE

D

%

10 7

0%

5%

BL

50% 75%

100% BLUE

50% 75%

100% RED

W L LO YE

ORANGE

WHITE

AQUA

Subtractive mixing starts with white light and removes various colors of light with the use of absorption filters, and also produces all the colors of the spectrum. If equal quantities of the subtractive primary colors of yellow, cyan, and magenta are removed, the result is that all the light is absorbed for the total absence of light.

E GREEN T U R QU EUS 10 OIS 0% E EEN R CH GR G % 5 E % 0 E 0% N 50 10 75 % % 75 BLUE TINT R A RT

AN

SUBTRACTIVE MIXING

S P E C T R A L C O LO R S

CY

Intermediate hues of colored light are obtained by two methods. Both create all colors in the spectrum, but in opposite ways. One creates by adding light and the other by subtracting it. When adding, the 3 primary colors of red, green, and blue are combined equally to produce white light, or unequal quantities to for intermediate colors and tints of colors. The diagram on the right can be used to determine the mixtures for a specific color. For example, cyan is a mixture of 100% blue plus 100% green, or a more blue cyan (Aqua) can be made with a mixture of 100% blue and only 50% green. Color tints are made by mixing colors with white light, or mixing complementary colors unequally, like 100% blue plus 75% yellow to create a blue tint.

U E B LU E

50

%

MAGENTA

ADDITIVE COLOR MIXING DIAGRAM

The color magenta is sometimes thought to be part of the color spectrum, but actually is not. It can be perceived only through contributions from both the short (blue) and the long (red) wavelengths of light. 100% BLUE + 100% GREEN = . . . . . . CYAN 100% BLUE + 50% GREEN = . . . . . . AQUA 100% BLUE + 100% YELLOW = . . . . . WHITE 100% BLUE + 75% YELLOW = . . . . . . CYAN RELATIVE LIGHT OUTPUT OF COLOR LAMPS COLOR INCANDESCENT FLUORESCENT LED WHITE . . . . . . . 00 . . . . . . . . . . . 100 . . . . . . . . 100 GREEN . . . . . . . 25 . . . . . . . . . . . 130 . . . . . . . . 48 YELLOW . . . . . 70 . . . . . . . . . . . 70 . . . . . . . . 172 PINK . . . . . . . . 45 . . . . . . . . . . . 36 . . . . . . . . 126 RED . . . . . . . . 12 . . . . . . . . . . . 5 . . . . . . . . 152 BLUE . . . . . . . . 6 . . . . . . . . . . . 37 . . . . . . . . 34

All values are approximate, especially LED lamps, due to the wide range of voltages and lamp types available.

LIGHT & COLOR

COLOR MIXING WHITE LIGHT FROM COLOR SOURCES Yellow Blue-White

Pink

INCANDESCENT

Amber

Green

Blue

Red

LIGHT EMITTING DIODE (LED)

Yellow

Green

Blue

Red

Mix

Tinted reflector lamps of blue-white and pink can be mixed in approximate equal quantities to create white light. Yellow can be added for color interest. With colors controlled separately, they can furnish a cool or warm atmosphere with relatively little color distortion. Tinted color general service incandescent lamps in colors of blue-white, pink, and yellow can also be used. These combinations of colored sources are particularly interesting when used to light restaurants, display areas, and table settings because of the multi-colored shadows and highlights, with an overall effect of white light. More saturated lamp colors of red, green, blue, and yellow, from PAR and LED sources, can also be combined to produce white light. Its important with these sources to mix the colors in proportion to their relative light output. The use of blue and yellow fluorescent lamps can also be combined to create white light.

CYCLIC CONTROL

Yellow

It’s possible to manually or automatically control color output through dimming equipment that is available for all lamp types. Individually controlled color circuits can create a wide range of tints and hues for programed or cyclic variation.

THE APPEARANCE OF COLORS Special visibility requirements often dictate the color qualities of light. Color matching and inspection for example – or even everyday shopping. Very often an article purchased under one light source will look altogether different when viewed at home under a

different light source. Using full spectrum white light will make merchandise appear as normal as possible. All color materials and samples should be selected under the lighting conditions similar to those to be installed where the materials are to be used.

FLUORESCENT Blue

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LIGHT & COLOR

SUBJECTIVE CHARACTERISTICS

The color of light is a factor in our perception of the quality of a lighted interior space. Some experiments suggest that for different color temperatures of light there is a corresponding maximum and minimum level of light found to be comfortable. At some color temperatures, if the level is too high, colors will seem faded and unnatural, if too low, the environment and colors will appear dim and cold. The diagram on the right gives the character of this quality of lighting levels and color temperature. It also suggests warmer light is more acceptable at lower levels and cooler light at higher levels, and any room lighted to a level of 20 footcandles (215 lux) would be unpleasant with kerosene lamps at about 2000°K, or with daylight sources (at 4500 - 5000 °K). With the warmer kerosene lamps the level would seem too high. The same level with simulated daylight, on the other hand, would make the room appear to be somewhat dark and dingy, while incandescent or warm fluorescent light would be acceptable with a color temperature between 2700°K to 3000°K.

5000

COLORS APPEAR UNNATURAL

500

FOOTCANDLES

COLOR TEMPERATURE & LIGHT LEVELS

COMFORT ZONE

Incandescent and Warm Fluorescent

50

20

Daylight Lamp

Kerosene Lamp

5 COLORS APPEAR DIM OR COLD

0 0

2000

2500 3000 4000 5000 10000

COLOR TEMPERATURE IN DEGREES KELVIN THE AMENITY CURVE Note: Above data is intended to be only approximate. Adapted from the “Amenity Curve” by A. A. Fruithof, Philips Technische Rundschau

RELATIVE SENSITIVITY OF THE HUMAN EYE The human eye is sensitive to all colors of the wavelengths of light, but not equally, and is most sensitive to the yellow-green range of 550nm for bright-adapted daytime vision. It shifts slightly to shorter wavelengths for darkadapted vision – useful in finding the amount of light needed from different color sources to obtain equal brightness. It takes twice as much orange light at 625nm to equal yellow-green light 550nm for them to appear to be equally bright.

64

Night Vision

400nm

Day Vision

500nm

600nm

700nm

RELATIVE SENSITIVITY OF THE HUMAN EYE TO COLOR

LIGHT & COLOR

SUBJECTIVE CHARACTERISTICS PERCEPTION & ADAPTATION

COMPLEMENTARY AFTERIMAGES

Descriptions identifying colors have changed over time, like the color red, called crimson, apple-red, fire engine red, etc., expressing a subjective observation. Studies have suggested the spectral component of light sources has a significant effect on the perception of reflected colors. In general this is true, but the perception of surface colors is quite stable under large variations of spectral distribution. The human eye and brain adapt our perception of color to a large degree to what might be familiar from experience. Entering a room illuminated with blue light, a white shirt that looks to be tinted blue, but appears to be white after a very short period of adaptation. On the other hand, a pink shirt lighted with spectrally limited cool white lamps appears somewhat less colorful than expected, regardless of the adaptation time. Identifying light source colors and the colorrendering capabilities presents a challenge.

When our eyes are adapted to a particular color it causes a temporary change in our perception of other colors. Complementary color after images will occur after viewing a monochromatic colored surface for a concentrated and short period of time, then moving your vision to a white surface. You will see an afterimage of the complementary color to the color you had previously viewed. This results from a fatigue effect of the photo receptors of the eye. The adaptation to a color lowers the sensitivity of a receptor. When a white surface is viewed, the receptor responds less, and the impression is of the complementary color, whose receptors have not been fatigued. In the past surgeons working with highly lighted images – where red was the predominant color – were concerned about the effect of afterimages when they looked at the white clothing of their medical associates. Today, the use of light-green surgical apparel helps to eliminate this afterimage problem.

RELATIVE COLOR ATTRACTION Different colors of light will have different values of attraction, independent of their brightness. The values are variable, but show the colors of red, green, and blue will compete for attention, and have a greater intensity than white light. The chart below shows that red, green, and blue light are considerably less bright than white light, and yellow is only slightly brighter, for equal attraction.

Try This Example Look at the black dot in the center of the red square for about 20 seconds, then shift your view to the black dot in the white area. You will see an image of the square in cyan, the complementary color to red. (Blinking your eyes may also help to make the image appear.)

RELATIVE ATTRACTION OF COLORED LIGHT

COMPLIMENTARY COLOR AFTERIMAGES

RED .......................................................... 333 GREEN ...................................................... 250 BLUE ......................................................... 166 WHITE ....................................................... 100 YELLOW ..................................................... 83

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LIGHT & COLOR

SUBJECTIVE CHARACTERISTICS SURFACE COLOR & BRIGHTNESS CONTRAST The perceived color of a object is the color of light reflected off its surface. This color is dependent on the wavelength of the light and the reflectance of the surface. The color also depends on the perception of the human eye and brain. The incident angle of the light, as well as the viewing angle, is also a factor in the apparent color of a surface. Transparent and semi-transparent materials in typical lighting equipment may also emit light themselves, contributing to the character of the color. Light striking an opaque surface is either reflected, scattered, absorbed, or a combination of these. Rough opaque surfaces do not reflect light spectrally and have their color determined by the wavelengths of light they scatter most and that which is absorbed. A surface that reflects or scatters all wavelengths will appear white, while if it absorbs all, will appear black. Surfaces that will transmit light are usually transparent or translucent, may absorb light of different wavelengths, and appear tinted with a color affected by their absorption and reflection. Objects may generate light rather than reflect it, such as an elevated temperature similar to an incandescent lamp. The color of an object is a result of its surface properties, transmission properties, and emission properties, all of which contribute a mix of wavelengths in the light leaving the surface. Perceived color is further conditioned by the ambient illumination, and by the color of objects nearby. This effect is known as color constancy and is a function of the characteristics of the observing human eye .

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From Wikipedia the free Encyclopedia

Color Perception: In the top illustration the

color and luminance of the two gray squares is identical; the difference in the brightness is due to lateral inhibitory interactions in the eye. In the middle illustration the color circles are exactly the same color, and are in identical gray squares (see the lower illustration). The human eye will perceive the squares as having different levels of reflectance, and interprets the colors as different. This is known as a simultaneous phenomenon that makes colored areas seem clearer when placed on a dark background. These effects are somewhat limited by the color printing process.

LIGHT & COLOR

THE COLOR OF WHITE LIGHT COLOR TEMPERATURE

Blue Northwest Sky

18000 16000 14000

Values in parentheses is the color-rendering index ( CRI). See COLOR RENDERING on pg.69

12000

One Blue, Two Daylight Fluorescent

8000

6000 5000 4500

4000

Sunlight

3500

3000

7500K Fluorescent (92) Uniform Overcast Sky Daylight Fluorescent (76) Clear Mercury (22) 5000K Fluorescent (90) Average Noon Sunlight Coated Mercury (45) Cool White Fluorescent (62-89) 4100K Fluorescent (70-75) Deluxe Mercury (45) Metal Halide (65-70) Compact Metal Halide (80-93) Sunlight 1 Hour After Sunrise 3500K Fluorescent (70-75) White Fluorescent (57-86) Warm White Mercury (52) Tungsten Halogen (99) Low Voltage Incandescent (95) Warm White Fluorescent (52-80) 3000K Fluorescent (70-75) Standard Incandescent (92) Compact Fluorescent (81)

2500

2000

°Kelvin

High Pressure Sodium (22) Sunlight At Sunrise Candle Flame

Neutral Tones

7000

Cool Tones

10000

Warm Tones

Skylight

26000 22000

The apparent color of a blackbody depends upon its temperature. A system using “color temperature” to describe the color of white light refers to the temperature of a blackbody when its visible radiation closely matches the color of the light source, or identifying a light source to appear to be warm or cool. The Kelvin scale identifies the temperature starting at absolute zero (- 459°F) with intervals at 100 degrees. A theoretical blackbody becomes red at 3000K, white at 5000K, blue-white at 8000K, and brilliant blue at 60,000K. However, since the color will not exactly match the blackbody color, the “ correlated color temperature” is expressed in degrees Kelvin (K). The color temperature applies to sources with a continuous spectrum, like incandescent, fluorescent, and LED lamps. It also describes the whiteness for other lamps. The chart gives approximate correlated color temperatures for some more available light sources along with the comparative values associated with natural sunlight and skylight. Blue and white LED sources have a color temperature, others do not, and colors may be specified in a wavelength in nanometers (nm), at peak output. LED sources are not perfectly monochromatic, but have wavelengths over a small region of the spectrum. Some have a cool temperature at full output and a warmer color when dimmed. The peak wavelength of a green LED lamp is 565nm, 1.0 and emits light from 520nm to 610nm. The spectral line 30 nm half width is the width of the curve at 50% intensity 0.5 (0.5 on the Y-axis). This is about 30nm for this lamp, and is a measurement of 0 the monochromatic purity 500 nm 550 nm 600 nm 650nm of this lamp’s spectral color. GREEN LED COLOR SPECTRUM

67

LIGHT & COLOR

THE COLOR OF WHITE LIGHT

Since white light contains this range of wavelengths, it is difficult to measure the relative warmness or coolness of a source. To identify subtle color variations a method is used that compares the color of light with the appearance of a laboratory blackbody radiator. All objects emit light when heated to high temperatures and change color as the heat increases. Heating a blackbody increases internal agitation of its molecules and atoms. It will appear dull red at first, then orange, yellow, white, and finally, blue-white. No materials are truly a blackbody so laboratories utilize exotic metals in special containers, viewed through blackbody simulating sight tubes. This is identified as the “color temperature” measured in degreed Kelvin (K).

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RELATIVE ENERGY

400 nm 500 nm 600 nm 700 nm SPECTURAL DISTRIBUTION FOR A BLUE FLUORESCENT LAMP

RELATIVE ENERGY

A pink lamp has most of its energy in the red range, a blue lamp peaks in the blue-green range. With very little energy at other wavelengths, these lamps are a true source of color, producing no white light. However, if you mix the two it creates a spectrum that is continuous, producing white light that is weak in yellow.

400 nm 500 nm 600 nm 700 nm SPECTURAL DISTRIBUTION FOR NATURAL SUNLIGHT AT NOON

400 nm 500 nm 600 nm 700 nm SPECTURAL DISTRIBUTION FOR A PINK FLUORESCENT LAMP

RELATIVE ENERGY

Electric light sources contain different amounts of energy in wavelengths that make up the visible light spectrum from violet through red. This variation affects the appearance of light in terms of warmness or coolness, with white light a mixture of all colors in approximate equal amounts. Spectral energy distribution curves for typical white light sources show this variation in energy at different wavelengths. The spectral curves on the right shows the distribution for sunlight at noon and for blue and pink fluorescent lamps.

RELATIVE ENERGY

SPECTRAL ENERGY DISTRIBUTION

400 nm 500 nm 600 nm 700 nm SPECTURAL DISTRIBUTION FOR PINK & BLUE FLUORESCENT

LIGHT & COLOR

THE COLOR OF WHITE LIGHT COLOR RENDERING

COLOR ASSOCIATION

An important characteristic of light sources is their ability to render colors accurately. An established Color Rendering Index (CRI) is used to compare spectral energy of the source with a full spectrum reference source (like daylight). With a maximum value of 100 for full-spectrum light, the index numbers are always less than 100, and typically range between 20 and 80.

Human preferences for color may be the single most discussed design consideration. However, color reactions are universally associated with some very specific moods. For example, reds, oranges, and yellow, are generally accepted as stimulating, while colors blue and violet are considered less so. Green is also accepted as refreshing and cool, but in a light source it’s found to be unnatural and somewhat macabre.

CRI values are complicated and far from perfect, suggesting caution be exercised using them. The CRI metric is known to be a relatively poor index of the user’s impression of the colorrendering ability of a source. It’s obvious that a 5000K fluorescent lamp with a CRI of 85 will render colors better than a 2100K high-pressure sodium lamp with a CRI of 22. Also, a 3000K and 4100K fluorescent lamp, with identical CRIs will make most colors appear to be different. In a search for a better method a new metric that more accurately evaluates the color quality has been suggested by the IESNA. It is entitled the TM-30-15 Method For Evaluating Light Source Color Rendition. It’s based on comparisons of color as rendered by a given light source and a reference illuminant at a same correlated color temperature, and utilizes 99 color evaluation samples and two features provided by the Fidelity Index (Rf ) (closeness to a reference point) and the Gamut Index (Rg ) (increase or decrease in chroma). It provides equations for calculating values for light sources and systems intended for general illumination, is complicated, and will need some more refinement for future use by the general lighting design community.

Good color rendition is also often associated with subjective impressions and what seems familiar, such as the appearance of objects under incandescent lighting. Even though it is deficient in the blue range of wavelengths, it’s generally accepted as normal through decades of use. Where the appearance of people is important, there is a strong preference for white light sources that are rich in red, and indications that people prefer warm light in areas where lower lighting levels are involved, and cool light where there are higher levels of light. People generally agree warm colors appear to advance, while cool colors tend to recede. Subtle changes in the color of light can also alter the mood of a space, like the pinks and purples of a sunset, and the restful qualities of a cathedral where the light is tinted by stained glass windows. People may experience the psychological effects of light and color without realizing that they do. The selection of light source color must be based on previous experience, education, training, and intuition. Use of a metric for color temperature and rendition can be a useful comparative guideline.

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LIGHT & COLOR

COLOR & CIRCADIAN RHYTHMS CIRCADIAN RHYTHMS

MIDNIGHT 2:00

4:00

COLOR TEMPERATURES AFFECTING THE CIRCADIAN WAKE-SLEEP CYCLE

70

6:00

8:00

10:00 NOON

5000 K AM

Sta

r ts

st C Fa oor ste din s B t R ati an est eac on d M He tio Hig usc art E n Tim h le ffi e Hig est B Strencienc he loo gth y st d Me Body Press u lat on Temp re in .

Bo dy R is Te ei mp n . Me B l lat oo d Hig onin P re h S s Hig est tops sur e h A Tes ler tost tne ero ss ne

est Lo w

De

ep est

Sle

ep

THE CIRCADIAN CYCLE

wake-sleep cycle, while exposure later in the day can disrupt the cycle. Also, the prolonged exposure to light has a greater effect than shorter exposure. These characteristics of light are affected by intensity, duration, and the color of the light. Studies have shown that light in the cool range (5000K) will suppress the secretion of melatonin, improving alertness, while warm light (3000K) will increase melatonin and promote the sleep cycle. Some healthcare facilities and nursing homes have installed lighting systems that automatically control the color of the lighting based on the time of day. This has resulted in far fewer resident falls and sleep issues. In still another application of this process, there are computer programs which automatically control a computer’s monitor color; changing to a warm wavelength toward the end of the day helps to promote the sleep cycle.

Be

Human behavior is modified by a timing process of our brains identified as circadian rhythms. They are controlled by light entering our eyes, effecting the release of melatonin that regulates our biological processes and timing of our daily behavior, like the wake-sleep cycle. Melatonin levels start to increase toward the end of the day and stay at a high level during the night, decreasing in the morning. They will vary individually and may be longer or shorter than 24 hours, with most people having longer rhythms. Due to this, they must be reset repeatedly to be coordinated with nature’s cycle, and light entering the photoreceptors of our eyes is a strong factor that influences this variation. The effects of this process are not completely understood, and studies show that exposure of light to our eyes after wakening in the morning helps support the normal

2:00 3500 K

4:00

6:00 3000 K PM

8:00

10:00 MIDNIGHT

LIGHT & COLOR

COLOR & CIRCADIAN RHYTHMS THE RANGE OF WHITE LIGHT Subtle changes in the color of light can somewhat modify the human subconscious appraisal of the environment by suggesting the pinks and yellows of a sunset creates an overall warm impression, while the lighting of an overcast day may produce an opposite impression of a cool or cold environment. Each of these natural lighting conditions are both a result of the perceived general range of “white” light, although each is deficient in areas of the visible electromagnetic spectrum. These color deficiencies, in turn, affects the perception of surface colors, graying some colors while increasing the relative vividness of others. We associate a warm atmosphere with hues of yellow through orange and red, to red-purple. Warm light sources (like the sun or an incandescent lamp) tend to create an impression of warmth by emphasizing these hues, while cool sources (skylight and 6500K sources) emphasize the cool colors of blue-purple through blue and blue-green. A new characterization of the exposure of light on the human eye that can regulate or disrupt our circadian rhythms has been suggested by lighting research professionals. A lot has been learned about how light acts as a stimulant to human circadian systems. Therefore, adopting a circadian stimulus as a new metric for the design of lighting in architectural space would add an important new tool for the lighting designer and the field of architectural and interior design.

SUNRISE

MIDDAY

OVERCAST

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LIGHT & COLOR

COLOR FILTERS ABSORPTION FILTERS Colored light can be created by using color filters with a white light source. They work by absorbing unwanted colors and transmitting other wavelengths. Saturation increases as absorption becomes more general and selective. The absorbed energy is converted to heat, so equipment using color filters will operate at higher temperatures than those not using filters.

Colored Glass Glass filters may be smooth, prismatic, or stippled. They are highly stable and widely used. Moulded roundels are available in many sizes, and colors, such as; red, green, blue, amber, and other special colors like pink, medium blue, straw, etc. The approximate transmission values for the typical basic colors are: Blue 3-5%, Red 8-17%, Green 10-17% and Amber 30-50%.

Gelatines

Gelatine filters are available in a variety of colors, plus frosts and variegated sheets. Deeper saturation is obtained by using more than one thickness. Gelatines tend to be a temporary choice since they fade and shrink from the heat.

INTERFERENCE FILTERS Interference filters consist of a film coating applied to glass, which reflect rather than absorb unwanted wavelengths. The number of coatings and the thickness of the film will determine the transmission. Because the untransmitted wavelengths are reflected rather than absorbed, they remain relatively cool. They are called “dichroic” (two-colored) because they transmit one color and reflect the complementary color.

72

Colored Plastic Colored and tinted plastic sleeves and panels can be used with fluorescent sources because the lamps emit very little heat, creating less fading and disintegration of the plastic. They may be used with some colored LED sources.

Split-Glass

Separate strips of glass mounted in a metal frame or rim produce filters that have a much lighter weight than moulded glass types and offers a much wider selection of available colors. WHITE LIGHT REFLECTED COLOR FILM COATING TRANSMITTED COLOR

Light Source: The spectral makeup of the light source must also be considered. If the desired wavelengths are not present the filter is ineffective. A green lamp with a red filter produces no light. Dimming: Dimmed incandescent lamps change their color. With this reduction in blue and green, the color produced by the filter may be affected.

LIGHT & COLOR

COLOR LIGHT SOURCES LED LAMPS 2-1/4" 57mm

C7

Lamps available in many different bulb types and shapes, colors, and voltages, some with color changing capabilities. Bulb shown is C7 typical Christmas decoration lamp with a candelabra base.

7/8" 22.4 mm

A19

4-1/4" 113 mm

LED 3 WATT 24V 180 LUMENS 50000 HR LIFE

2-3/8" 60 mm

G19 2-3/8" 60.3 mm

Can be used as a single color of Red, Green, Blue and White or in 12 other colors from four primary colors of Red, Green, Blue, and White. Remote control is available for multiple color changes.

LED 1 WATT 120V E26 BASE 50000 HR LIFE Replaces less efficient incandescent type color sign lamps. Lamps able to s h i f t a n d c h a n g e b e t w e e n s e v e n different colors while lighted. For both indoor and outdoor usage.

LED 1.5 WATT 12V 1000 LUMENS 50000 HR LIFE

2" 50.8 mm

RED

4-3/4" 120.6 mm

5-5/16" (134.9 mm)

MR16

PAR30 PAR38 LEDs are made in a number of shapes and sizes. The most common is the 5 mm cylindrical ones shown above on the left, and single modules or multi-chip arrays shown above on the right. The 5 mm type is primarily used as indicator lights because their output is too small for other lighting applications. Common ones are the domed and flat top types. The single or multi-chip, types are used in architectural applications. (see Chapter 7 Light Sources & Components)

LED 1 WATT 120V E12 BASE 50000 HR LIFE

4-5/8" 117.5 mm

LED lamps are more efficient, brighter, and offer lower energy usage than other sources. Color LEDs have been used in traffic signals, and electronics because of their long life. Some have a color-mixing feature to emit a range of colors by changing the proportions of light generated in each primary color. They are manufactured from semiconducting material with impurities to create a p-n junction. Current flows from the p-side, or anode, to the n-side, or cathode, but does not flow in the reverse direction. Electrons and holes flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon. Early red ones were made with gallium arsenide. Different materials have enabled devices with shorter wavelengths, emitting light with a variety of colors.

GREEN

BLUE

YELLOW

WHITE

LED PAR LAMPS 1-12 WATTS 50000 HR LIFE Par 30 & 38 types available in single colors of Red, Green, Blue, and Yellow. Also with color changing capabilities.

LED FLEXIBLE STRIP LIGHT 50000 HR LIFE Frosted flexible PVC strip light with variable lamp spacing in primar y and other colors. Typically 12 volts DC.

LED LINEAR TUBE & STRIP 50000 HR LIFE T5 & T8 tubular and flat strip lamps have different beam spreads with a choice of diode spacing, color combinations and control options.

73

LIGHT & COLOR

COLOR LIGHT SOURCES

PAR & R Lamps: Stained glass, dyed plastic or dichroic coatings produce a specific color by selectively transmitting only the desired wavelengths of light, with almost no energy absorption. Other wavelengths are reflected back into the lamp, resulting in richer and clearer colors that are more intense than those produced by ordinary color lamps. The clear coatings minimize interference with transmission necessary for the lamp’s specific light beam patterns.

74

A19 2-3/8" 60.3 mm

CLEAR RED CLEAR YELLOW CLEAR BLUE CLEAR GREEN

A19 LAMPS 25 WATTS 120V 2500 HR LIFE RED YELLOW BLUE GREEN ORANGE

CLEAR RED CLEAR YELLOW CLEAR BLUE GREEN

A21 LAMPS 60 WATTS 120V 1000 HR LIFE

A21

RED GREEN BLUE SOFT PINK

2-5/8" 66.7 mm

PAR38

5-5/16" 134.9 mm

PAR 38 LAMPS 85/150 WATTS 120V 2000 HR LIFE RED GREEN BLUE YELLOW AMBER

DICHROIC RED DICHROIC GREEN DICHROIC BLUE DICHROIC YELLOW DICHROIC AMBER

4-3/4" 120.6 mm

R30 LAMPS 75 WATTS 120V 2000 HR LIFE

R30

5-3/8" 136.5 mm

high purity of colored light. Their cost is higher and have a limited selection. They provide a high brightness from exposed filaments for sparkle and beam control.

44.5 mm

3-3/4" 95.3 mm

RED PINK GREEN BLUE YELLOW AMBER

R40 LAMPS 150 WATTS 120V 2000 HR LIFE 6-11/16" 169.9 mm

Clear Bulbs: Clear glass bulbs provide a

1-3/4"

4-1/4" 112.7 mm

There are three types of white pigment that can be added to color coatings for diffusion of the light. Outside Spray Coated bulbs are suitable for indoor use or locations where the bulb is not exposed to the weather. Inside-Coated bulbs are uncoated outside, are easily cleaned, and not subject to the weather or dirt, and offer improved performance. Enamelled finishes provide a permanent finish because the color pigments are fused to the glass bulb.

S14

RED YELLOW BLUE GREEN

4-7/8" 111.1 mm

Incandescent color lamps are available in both saturated and tinted colors achieved through absorption blocking the unwanted energy, transmitting only specific colors, resulting in a reduction in source efficiency.

3-1/2" 89 mm

S14 LAMPS 11 WATTS 130V 3000 HR LIFE

INCANDESCENT LAMPS

R40 5" (127 mm)

RED PINK BLUE & BLUE-WHITE DAYLIGHT BLUE YELLOW AMBER

LIGHT & COLOR

COLOR LIGHT SOURCES FLUORESCENT LAMPS Fluorescent lamps produce color by the type of internal phosphor. Lamps appear white with the color showing only when the lamp is lighted. However, some lamps require an additional filtering to absorb the mercurylines that would

otherwise de-saturate the color. In these cases a filter coating is applied inside the bulb for deep blue, red, and gold lamps. Color can also be furnished using colored plastic sleeves that fit over the lamp, available in a range of colors.

T12

T8

T5

T5 LAMPS 5/8" x 22" (558.8 mm) 28 WATTS 120V 20000 HR LIFE

T5 LAMPS 5/8" x 46" (1168 mm) 54 WATTS 120V 20000 HR LIFE

RED BLUE GREEN

RED GREEN BLUE

1540 Lumens 600 Lumens 3000 Lumens

T8 LAMPS 1" x 36" (914.4 mm) 25 WATTS 120V 20000 HR LIFE RED Colored Plastic Sleeve BLUE Colored Plastic Sleeve GREEN Colored Plastic Sleeve

3800 Lumens 7590 Lumens 1650 Lumens

T8 LAMPS 1" x 48" (1219 mm) 32 WATTS 120V 20000 HR LIFE RED Colored Plastic Sleeve BLUE Colored Plastic Sleeve GREEN Colored Plastic Sleeve

T12 LAMPS 1-1/2" x 24" (609.6 mm) 20 WATTS 120V 9000 HR LIFE T12 LAMPS 1-1/2" x 48" (1219 mm) 32 WATTS 120V 20000 HR LIFE BLUE 450 Lumens BLUE 450 Lumens GREEN 1575 Lumens GREEN 1575 Lumens NOTE: Color plastic sleeves are available in many different colors for T5, T8, & T12 lamps from 24" through 96" lengths. COMPACT LAMPS 11, 13, 15 & 23 WATT 8000 HR LIFE FLUORESCENT VS INCANDESCENT LAMPS Fluorescent lamps have a considerable advantage PINK RED over incandescent lamps in terms of efficiency, BLUE especially in the blue and green wavelengths. The GREEN advantage is approximately 3 to 1 for yellow, 15 to 1 YELLOW for blue, and 50 to 1 for green. (red is approx ORANGE imately equal). They also have a much longer life. APPROXIMATE RELATIVE OUTPUT for colors generated by On the other hand, fluorescent lamps are generally internal phosphor coatings, not by colored plastic sleeves. larger in size, lower in brightness, and best suited for broad-beam distribution. For directional control Cool White .......................................................... 100% Pink .............................................................. 45% and sparkle, the relative small size of and higher Red ................................................................. 6% brightness of incandescent and LED sources are Blue .............................................................. 45% usually an advantage. They also offer a wider range Green .......................................................... 160% of colors and filters that can be more easily applied.

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CHAPTER

5

LIGHTING QUALITY, COMFORT, & CONTROL Although light is a prerequisite for human vision, excessive contrast and uncontrolled brightness is often distracting and annoying. For this reason the negative aspects of glare and brightness, along with the other more positive lighting considerations, must be identified and controlled during the planning and development of successful lighting solutions. In some extreme cases, glare can seriously affect human vision by reducing or destroying the observer’s ability to accurately appraise a task, an object, or a space. Driving west in afternoon sun, or viewing the extreme brightness of new snow on a sunny day, are familiar experiences that clearly demonstrate the negative aspects of glare. Glare is often misinterpreted as too much light when, actually, it is the simple consequence of excessive light within a normal field of view. The relative effect of high and low beam lighting from an approaching automobile’s headlights at night demonstrates that glare is a function of directional control as well as the relative intensity. It also demonstrates that glare can be present and just as annoying and distracting within an extremely low lighting environment. Closely associated with the basic problem of seeing, is an understanding of the visually disabling factors that may interfere with normal everyday work and casual activities. Therefore, the overall quality and sense of well-being of a luminous interior environment, is dependent on control of the human and design characteristics that might result in any negative impressions, visual difficulties, or reduced energy efficiency.

77

LIGHTING QUALIT Y, COMFORT, & CONTROL

THE RANGE OF HUMAN VISION PHOTOPIC, MESOPIC, & SCOTOPIC VISION

78

Sunshine

3,000,000 300,000 30,000 3,000

Upper Limits of Vision Fresh Snow on a Clear Day

Photopic

Incandescent Lamp at 2700K

Fluorescent Lamp Surface of the Moon

30

3

Overcast Sky White Paper under Reading Light 15 Minutes after Sunset Snow in Full Moonlight

0.3 0.03 0.003 0.0003

White Paper in Moonlight Fairly Bright Moon Moonless Clear Night Sky Snow in Starlight Grass in Starlight

0.00003 0.000003

Mesopic

300

Threshold of Vision

Scotopic

When the eye moves it re-adjusts by adjusting the iris, regulating the size of the pupil. Initial dark adaptation takes place in approximately four seconds of profound and uninterrupted darkness. Full adaptation through adjustments in the retina are mostly complete in 30 minutes. Hence, a dynamic contrast ratio of about a million to one is possible. Full adaptation is depends on good blood flow, and is hampered by vasoconstrictors like alcohol or tobacco. The eye is similar to lenses in optical instruments such as cameras. The pupil is about 4 mm in diameter, ranging from 2 mm in a brightly lit place to 8 mm in the dark. The dark value decreases slowly as we grow older, to sometimes not more than 5-6 mm.

900.000,000

LIGHT LEVELS IN CANDELAS PER SQUARE METER (Cd/m2 )

The human eye can see a range of light intensity of about a million to one. The eye adjusts to different lighting conditions and varies its mode of vision as the lighting levels change. We have all experienced the difference between daytime and night vision. The photoreceptors of light in the eye (rods and cones), have similar sensitivity to light while rods produce a larger response and operate in three different modes: photopic, mesopic, and scotopic vision. Photopic vision occurs at high light levels with high visual acuity, low light sensitivity, and color perception. Scotopic vision occurs in very low light levels with resulting low visual acuity, high light sensitivity, and no color vision. Mesopic vision is a mixed mode with performance based on whether objects lie in the central or peripheral visual zone and shifts toward scotopic vision as light levels decline toward the low threshold of human vision. The contrast ratio of the eye is around 100:1.

LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTED GLARE Visual comfort and the control of glare involves the entire luminous environment, including light sources and architectural surfaces. This also considers the inherent quality of the entire lighting system itself. Reflected glare can be defined as excessive uncontrolled brightness in the direct or indirect human field of view.

However, there can be little analysis of a lighting solution without careful appraisal of the physical characteristics of the surfaces involved. Light itself is inconsequential until it strikes a surface or object. The ability of surfaces to alter refected light is a unique characteristic that should be considered for the successful control of glare.

SPECULAR SURFACES

Specular surfaces reflection is usually the mirror image of the light source itself. The significance of a specular material is determined by the position of the observer and the reflected image he sees. Even though the reflected images would be somewhat less bright than the source itself, they can be annoying. This makes specular surfaces valuable as reflecting contours in luminaires for controlling the re-direction of light. But the utilization of polished or specular materials for most typical architectural surfaces introduces problems which must be considered during the design of lighting. The illustration shows a situation in which the polished vertical surfaces reveal reflections of the luminaires. DIFFUSE SURFACES

Diffuse surfaces will not show reflected images with highlights and bright streaks, but can be equally distracting and annoying in a more general way, due to being uniformly bright from all angles of view, and present a considerable larger area of glare. On the other hand, diffuse reflecting characteristics can be desirable for major architectural surfaces where brightness uniformity is the design objective. Diffuse surfaces can be successfully incorporated in some types of luminous lighting elements.

SPECULAR SURFACE GLARE DIFFUSE SURFACE GLARE

79

LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTED GLARE MINIMIZING VEILING REFLECTIONS Architectural surfaces reflect light generally in a diffuse or specular manner. The reflected light on a diffuse surface produces brightness which is dependent on the intensity of the lighting. The brightness of a specular surface is related to the brightness of the source itself due to the mirror-like nature of the surface, and the visual image on the glossy surface will obscure the detail of that surface. When attempting to reduce the disabling effect of veiling reflections, the first approach is to locate the lighting equipment and the bright surfaces out of the reflected view. This involves regarding the subject area as if it were a mirror, so that all the luminous sources, including the lighting equipment and any architectural surfaces and windows, are located outside of the reflected field of view. This can complicate the location and placement of lighting equipment. The designer must also recognize the reflecting characteristics of the architectural surfaces and materials and alter them or make changes to reduce the chances of producing veiling reflections, utilizing reduced specularity and low gloss or matte finishes. Some materials may have a significant specular characteristics, such as, glass, marble, high gloss paints, and clear finishes. When such polished surfaces cannot be avoided, the surface again must be analyzed as a mirror, be shielded, or not located in the reflected field of view. The illustrations show how veiling reflections on vertical and horizontal surfaces can be reduced by locating the light sources and equipment outside the concealment zones, which are also identified as the reflected field of view.

80

THE CONCEALMENT ZONE

To minimize unwanted effects of reflected images on specular architectural surfaces or objects, locate light sources and other bright areas in the concealment zones (or outside of the reflected field of view). THE REFLECTED FIELD OF VIEW

LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTED GLARE

REFLECTED GLARE & TRANSPARENT SURFACES

VEILING REFLECTIONS

TRANSPARENT SURFACES Reflected images of lighting fixtures can create a visual barrier on glass partitions, windows, and doors, for example, when a view is required through the glass to another area for visual communication or to enjoy an exterior view. This is particularly true at night when a large portion of the light that strikes the glass is reflected, the surface acting as a partial mirror. To create an impression of transparency the area on the other side of the glass must be equal or higher in brightness than the viewing side. The illustration demonstrates this condition where the view of the exterior landscape and porch area is partially obstructed by the reflected images of the ceiling lights. It becomes an important design consideration to recognize this effect when locating the lighting equipment. VEILING REFLECTIONS Reflected glare is the basic cause of veiling reflections, especially on specular surfaces – or the interference of normal visual perception by an uncomfortably bright light source or reflected image. It is the reflection of incident light that partially or totally obscures the details on a surface by reducing or masking contrast and detail. The illustration demonstrates how the lighting equipment location and direction of its distribution can increase or reduce reflected glare, with an example of veiling reflections on a glossy magazine page. We know that veiling reflections in some critical seeing situations can cause disability glare that substantially reduces the ability to perform a particular visual task, or may create a serious hazard and safety concern.

81

LIGHTING QUALIT Y, COMFORT, & CONTROL

DIRECT GLARE

3426 cd/m2

(cd/m2 = candelas/sq.meter)

2569 cd/m2 90° 45° 30° 15°

1559 cd/m2 856 cd/m2

0°

582 cd/m2

BRIGHTNESS LIMITS FOR VISUAL COMFORT

The above average brightness limits apply in areas where there are general lighting systems and involve significant visual tasks. The term brightness refers to the subjective visual sensation of light.

FLUORESCENT

INCANDESCENT

COMPACT FLUORESCENT

LIGHT-EMITTI NG DIODE

5

150

190 450

RELATIVE BARE LAMP BRIGHTNESS For approximate equal total light output

82

GLARE AS A FUNCTION OF LOCATION The effect of glare depends primarily upon the location and proximity of the brightness element in the normal field of view. The illustration on the left identifies permissible levels of brightness for different angles of view, and the lower levels of brightness as the source approaches the normal line of sight. The values shown could be higher provided the surface reflectances in the space are higher, reducing distracting contrasts and permitting higher brightness. They also explain why brightness levels found acceptable for ceiling fixtures, or a full luminous ceiling, are excessive and uncomfortable for wall mounted lighting elements, or a luminous wall. Surfaces having a uniform brightness at all angles, like a luminous wall, should not have an average luminance higher than 856 candelas per sq. m. BARE LAMP GLARE Bare lamp glare, or uncontrolled brightness from an exposed light source, is a form of direct glare that is considered unsatisfactory for most lighting applications, except in the case of specialized pattern and sparkle effects, where lower wattage light sources are used. The illustration shows why for a given quantity of emitted light, an incandescent, high-intensity discharge, or LED light source, will be brighter than a fluorescent lamp due to the much smaller surface area – the more concentrated sources having a higher average brightness. Even though the brightness from a fluorescent source is lower, there is a need for careful brightness control in occupied areas. With the development of significantly higher output light sources, brightness control is a necessary consideration.

LIGHTING QUALIT Y, COMFORT, & CONTROL

DIRECT GLARE

ACCEPTABLE GLARE AS SPARKLE

ACCEPTABLE GLARE Glare is an undesirable lighting experience within our luminous environment, but sparkle as a form of glare, is usually not undesirable. The important difference is in the relationship between brightness intensity and the area of brightness, and the field of view. If large areas of excessive brightness are uncomfortable and distracting, then relatively small areas of similar (or higher) intensity may be points of sparkle that add to our emotional excitement and casual visual interest. This aspect of the design of our lighted environment is important, particularly because the presence of sparkle creates the visual attribute similar to a comfortable and stimulating sunny day, rather than a dull, overcast day. The visual implications of sparkle, along with patterns of sparkle, in the indoor environment can make a contribution to our sense of fun and excitement, and sometimes as a lighting designer, the icing on the cake. In some situations, exposure to sparkle as lowintensity light sources – such as Christmas lighting – creates emotional excitement and gaiety. Although this branch of lighting design might produce a festive, or even carnival-like atmosphere, more subtle detail and careful planning is usually necessary for serious architectural applications. The illustrations on the left are examples of the use of sparkle and glitter to accentuate the architectural forms that define the structural characteristics of the space. It further demonstrates that some forms of sparkle furnish a secondary benefit of glare. An additional form of sparkle is the perforated shielding elements used on the pendant lights.

83

LIGHTING QUALIT Y, COMFORT, & CONTROL

ACCEPTABLE BRIGHTNESS LEVELS (Cd/m 2 )

DISCOMFORT & DISABILITY GLARE

6860

3430

1720

0

20

30

40

50

AGE IN YEARS

60

DISCOMFORT GLARE Glare results from bright areas such as large ceiling fixtures, windows, and reflections from specular surfaces. These are typical sources of discomfort glare. It can be described as a source of light that shines on the retina of the human eye and reduces contrast of the viewed image. Although this glare may be objectionable, it usually does not seriously interfere with a visual task. The angle between the line of sight and the glare source determines the degree of visual discomfort (see pg. 82 “Glare as a Function of Location”). Lighting levels are usually adjusted for age, since the average pupil size for older people is smaller, reducing light input, and the lens becomes less transparent. The illustration shows a relationship between discomfort glare and age. This varies if the source or background lighting is changed.

AGE AND ACCEPTABLE BRIGHTNESS DISABILITY GLARE

DISABILITY GLARE Disability glare occurs when a bright light source is located near the object being viewed, causing degradation of the visual task – due to the extreme high contrast of brightness with our central vision. In comparison to discomfort glare, it seriously interferes with performance of visual tasks. This can be illustrated with the example of driving at night with oncoming headlights reducing the ability to see. This is also prolonged because the eye takes time to re-adapt to the ambient light level. Another example is why stars cannot be seen in the daytime. Yet, when the sun sets, the contrast between the stars and the dark surrounding sky is reduced, allowing the stars to be seen easily.

84

LIGHTING QUALIT Y, COMFORT, & CONTROL

BRIGHTNESS RELATIONSHIPS HUMAN PERCEPTION OF BRIGHTNESS The human eye does not perceive brightness in a simple linear way. An object with twice the brightness as another does not appear twice as bright, even though the minimum discernible variation of brightness is about a 2 to 1 ratio. Brightness of a surface is typically measured in luminance, where the subjective impression of it depends on the relationship between surfaces and objects and their surroundings. Reading by a window on a sunny day can be very uncomfortable. Also, equally uncomfortable is reading something highly illuminated in the dark.

LUMINANCE RATIOS Optimum visual comfort is achieved when a task is only slightly brighter than the immediate surroundings. Studies suggest a ratio of 1 to 1/3 between the task brightness and adjacent areas. With a diffuse lighting, and a task of white paper (60 - 6 5 % reflectance) the work top should be in the range of 20 - 3 0%. The ceiling brightness should be within a range of 2/3 to 3 times the task brightness. Some situations allow the ceiling to not exceed 10 times the task brightness. Partitions and walls in the visual field are also found to be comfortable within a range of 1/6 to 1/3 the task brightness. The floor brightness typically falls in the range of 1/10 to 1/3. However, a ratio of up to 100 to 1 between the brightest and darkest surfaces in a room can be acceptable, especially for accents of light and color, if the relative area of these are small. Although research suggests a reduction of contrast in the working environment, it can be useful for means of circulation and attention.

With visual tasks, brightness relationships in the normal field of view should be controlled to allow the eye to adapt to the surrounding environment. This will reduce the shock of excessive contrast and the need for continual re-adaptation. Research and experience, has shown the importance of achieving this condition of control of the lighting of ceilings and walls in an interior environment. For comfortable seeing, especially over a long time period, brightness of surfaces around a visual task should not differ appreciably from the brightness of the task itself.

High brightness contrast could be a valuable design attribute in environments that involve more casual activities with less critical visual needs, if the changing adaptation levels do not become a major factor of distraction and fatigue. COMFORTABLE LUMINANCE RATIOS

2/3-3

1/6 -1/3

1

1/3

1/10 -1/3

85

LIGHTING QUALIT Y, COMFORT, & CONTROL

BRIGHTNESS CONTROL & SHIELDING TECHNIQUES CONTROL TECHNIQUES Excessive brightness can alter the ability of the eye to see accurately and discern fine detail. The experience of driving toward a bright afternoon sunset, or shielding your eyes from the glare of the sun on snow, are typical examples. This level of glare produces intensities that will impair visual acuity. A lesser form of glare might come from an unshielded fluorescent lamp or an extra bright lighting fixture, but this would be considered moderately uncomfortable. When evaluating acceptable levels of brightness there is a relationship between brightness intensity and the area of brightness. While a small area of brightness may be tolerable, a larger area of the same brightness may be viewed as uncomfortable. Large area luminous elements, such as luminous ceilings and walls, require attention to the problem of brightness control. Larger luminous elements take up a relatively larger portion of the normal field of view, therefore requiring even more control of the brightness with lower limits of the intensity. On the other hand, smaller areas of brightness can be modified by a number of accepted control methods. Sources that might exhibit moderate discomfort in a low brightness environment may be acceptable located in higher brightness areas because of the relative reduced contrast, and the eye tends to adapt itself to the higher brightness background. Brightness causing glare can be controlled by a number of techniques, like the reduction of the light output, shielding by louvers or baffles, and variation of the surrounding surfaces brightness.

86

EXCESSIVE UNCONTROLED BRIGHTNESS

CONTROL WITH LOWER LIGHT OUTPUT

CONTROL WITH SHIELDING

CONTROL OF SURROUNDING FINISHES

LIGHTING QUALIT Y, COMFOR T, & CONTROL

CONTROL TECHNIQUES CONTROL TECHNIQUES

Limit Light Directed Toward the Eye The instinctive reaction to direct glare is the utilization of some form of shielding to improve visibility and visual comfort. This suggests using devices integrated with the lighting equipment or system. Another approach is the control of the direction, similar to the effect produced by switching to low-beam automobile headlights. This shows how a variation in the direction of light can have a subtle effect on visual comfort. The technique uses reflecting contours and refracting lenses that limit the distribution of light and reduces undesirable light rays emitted directly toward the viewer.

The Use of Shielding Devices

The use of louvers or baffles to screen light from view often results in less efficient utilization of the lighting system. Some light will be absorbed, with other parts being reflected or transmitted. Specular parabolic louvers shown in the top illustration will direct light downward away from the view. In spite of the low efficiency, these techniques can considerably help discomfort glare.

LIMIT LIGHT DIRECTED TOWARD THE EYE INCREASE THE AREA OF BRIGHTNESS

Increase the Area of Brightness Where accurate beam control is not required, diffuse transmitting materials may be utilized. This distributes light over a considerably larger area, increasing the area of brightness to where it may fall within the limits of visual comfort. If the illumination is increased, the diffusing material may again reach a level of excessive brightness. If this is inadequate for control, other means like louvers and shielding may be required to provide acceptable visual comfort.

87

LIGHTING QUALIT Y, COMFORT, & CONTROL

SHIELDING TECHNIQUES BAFFLES & LOUVERS Many types of lighting installations utilize louvers and baffles to screen light directed toward the eye to control glare, increase visual comfort, and limit viewing of the mechanics of the lighting system. This may also be justified from the point of supporting architectural detailing and aesthetics, and is effective in a specified zone called the “Shielding Angle,”or the maximum angle the eye can be raised above a horizontal line of sight without seeing light sources through the shielding system.

SHIELDING ANGLE

provide shielding of light sources in only one direction, perpendicular to the axis of the baffles. However, the use of baffles around the perimeter of luminaires or other light sources provides shielding from all directions.

BAFFLES

Louvers utilize a series of baffles or shielding

LOUVERS

elements arranged in a symmetrical geometric pattern to furnish good shielding in more than one direction. Louvers are typically made of plastic, metal, or wood, and furnish brightness control if providing at least 45 degrees of shielding. However, the open cell type may exposes the light sources when viewed at angles along the axis of the louver blades.

REFLECTED IMAGES Although a light source is concealed within a specified zone, it is still directly exposed to the horizontal work surfaces below. This is an inherent disadvantage where glossy pages, and reflective work tops are involved. In such cases, the mirrored image of the light source can become a distracting source of reflected glare and be the generation of veiling reflections.

88

Add transmitting material to increase light diffusion Reduce work surface gloss Locate the fixtures outside the reflected field of view

LIGHTING QUALIT Y, COMFORT, & CONTROL

SHIELDING TECHNIQUES BRIGHTNESS CONTROL OF LOUVERS & BAFFLES The perceived brightness of baffles and louvers is determined by the light intensity directed on their surfaces, and reflected toward the eye due to the reflectance value of the surfaces. Control

MATERIAL TRANSMITTANCE The apparent brightness of louver and baffle systems can be controlled and modified by the selection of the transmitting characteristics of the shielding material used. These shielding materials could be translucent white, colored, or prismatic glass or plastic, perforated metal, etc.

of this intensity to achieve a low reflected or transmitted brightness of the system elements, may be desirable to insure an appropriate visual comfort level, or an architectural design goal.

LOW TRANSMITTING MATERIAL

SURFACE REFLECTANCE Control of louver and baffle brightness made from opaque materials can be accomplished by the modification of reflectance characteristics of the shielding surfaces. High reflectance surfaces like etched metals, finished wood, and painted surfaces result in bright-appearing baffles. Low brightness systems would utilize low reflectance finishes, such as, dark metal, wood, or paint. SURFACE SHAPE & FORM The shape of a louver or baffle can control its apparent brightness. Use of a parabolic baffle or louver can be especially effective because light hitting the vertical surface reflects down at angles equal to or less than the shielding angle. Viewed at angles beyond the shielding angle, they will have significantly lower brightness. The actual brightness depends on the degree of specularity, with fully specular finishes having the lowest brightness, and satin finishes furnishing a slightly lower brightness.

HIGH TRANSMITTING MATERIAL

HIGH REFLECTANCE MATERIAL

SHIELDING ANGLE

LOW REFLECTANCE MATERIAL

PARABOLIC DARK CONTOUR BAFFLE

89

LIGHTING QUALIT Y, COMFORT, & CONTROL

SHIELDING TECHNIQUES DIFFUSING PANELS & ELEMENTS The intensity and brightness of bare light sources can be controlled with covers or lenses that diffuse and soften the light. A variety of materials available are shown here as typical examples of the diffusers used in luminaires and suspended ceiling applications. have good diffusing characteristics with reasonable transmittance at 40 - 6 0 %. Plastics with high reflectance and low absorption qualities help inter-reflection within the fixture cavity to re-transmitt the light. A white finish in the cavity also improves overall efficiency. Lamp spacing of 1½ times the height of the lamps above the diffuser helps achieve good brightness uniformity.

DIFFUSING PANEL

FORMED PANEL

Formed Panels with different concentric designs and surface patterns, help diffusion characteristics, provide support of the larger sizes, and are useful in with hiding lamp images in shallow fixture cavities.

Corrugated Panels of flexible white plastic obscure

CORRUGATED PANEL

brightness variations if lamps are perpendicular to corrugations, need edge support in that direction, but are self supporting if lamps are parallel to corrugations.

Prismatic Panels molded from clear plastics have a higher transmission value than other materials, but have less inter-reflectance in the fixture cavity. Their transmission efficiency is about 70 - 8 0%. They have three-dimensional surface highlights helping light distribution, permiting small increase in lamp spacing.

PRISMATIC PANEL

LED Flat Panels in a frame have multiple lamps on the inside horizontal edge of two or more sides next to a layer of clear plastic that inter-reflects light horizontally through the panel. A white opaque layer on top reflects light downward, with a translucent white layer on the bottom that is a diffusing element.

90

LED FLAT PANEL

LIGHTING QUALIT Y, COMFORT, & CONTROL

SHIELDING TECHNIQUES LARGE DIFFUSING ELEMENTS

PYRAMID PANEL

Large trans-illuminated elements can function as both prominent architectural and decorative light sources – for both horizontal and vertical uses. They often utilize systems for brightness control and concealment of light sources involving different types of diffusing panels. The examples shown below are some representative available materials.

Dichroic Glass can transmit different colors of

ONE-LAMP INDIRECT PANEL

light that change with certain lighting conditions. It consists of a translucent glass containing ultra-thin applied layers of different metals (such as gold or silver) dispersed in the glass so it transmits one color and reflects a different color. There are more than 45 color dichroic coatings available.

DICHROIC GLASS MEDIA

PRISMATIC DIFFUSING MEDIA

DECORATIVE DIFFUSING MEDIA

SKYSCAPE PANEL

PLAIN DIFFUSING MEDIA

OPTICAL BAND PANEL

WOOD FRAME PANEL

91

LIGHTING QUALIT Y, COMFORT, & CONTROL

SHIELDING TECHNIQUES LOUVERS, GRILLES, & SCREENS Louvers and grilles provide good shielding of direct glare and concealment of light sources and components. The open cell configuration has the added advantage of allowing unfiltered light distribution, furnishing better, color and contrast, and enhancing the general appearance of occupants, furnishing, and merchandise. This also allows air to circulate between the room environment and the fixture or ceiling cavity, contributing to a more efficient dissipation of heat, increasing lamp and ballast longevity.

Small Cell Louvers made of a translucent white plastic provide a luminous appearance similar to white diffusing materials, while allowing a direct passage of light and air. They can be used where brightness control is not critical and are sometimes identified as eggcrate louvers. The open cell tends to also minimize the collection of dirt and dust on the louvers.

SQUARE CELL

PARABOLIC CELL

CIRCULAR CELL

Large Cell Louvers with larger open cell areas may require the addition of a diffusing membrane layer on top to provide adequate diffusion and brightness control, while also concealing light sources and other components. Parabolic Louvers offer excellent brightness control with a slightly darker appearance when made of an accurate parabolic louver shape and high reflectance finishes. This combination offers excellent shielding of light sources and reflects maximum light out of the line of sight. Most available types of louvers and grilles are made of acrylic or polystyrene plastic, aluminum or wood with cell sizes ranging from 3/8" to 2".

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SINE WAVE CELL

HEXAGONAL CELL

LIGHTING QUALIT Y, COMFORT, & CONTROL

SHIELDING TECHNIQUES GRILLES & SCREENS These shielding device will reduce the average brightness in direct proportion to the percent of their open area, and are the most effective for brightness and glare control when viewed from an oblique angle – where they function more as a louver or baffle. The examples shown here are representative of the many types and materials available for these lighting applications. They can be used as decorative illuminated horizontal and vertical elements. Ones with a larger cell sizes are usually used in combination with

a translucent white diffusing material located on top or behind that will provide some diffusion and light source concealment. The prominence of vertical surfaces in the visual field becomes an important consideration in the design of luminous vertical elements. This is especially important when the diffuser is plain white without any decorative opaque screening or patterns to soften the light, and the lamps are placed relatively close together to insure the brightness uniformity of the illuminated surface.

PERFORATED METAL

PLASTIC GRILLES

BAMBOO CIRCLES

SHOJI SCREEN

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LIGHTING QUALIT Y, COMFORT, & CONTROL

ENERGY MANAGEMENT ASHRAE/IES 90 ENERGY REFERENCE STANDARD The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) along with the Illuminating Engineering Society (IES) recommends the minimum requirements for energy-efficient design of most buildings, except low-rise residential buildings in their national energy reference standard. The original standard, ASHRAE 90, was published in 1975 with a number of revised editions published since. In 1999 the standard was put on continuous revision, based on changes in energy technology, allowing it to be updated many times in a year. The standard was renamed ASHRAE 90.1 in 2001, and has since been updated in 2004, 2007, 2010, 2013, and 2016 to reflect newer energy technologies. It provides the minimum energy requirements for design and construction of new buildings and systems, new portions of buildings and systems, new systems in existing buildings, and complete information and data for determining compliance with these requirements. It has become the accepted standard reference for architects, engineers, and other professionals involved in the design of buildings and building systems – such as lighting. There is a new 2016 version available; however, the U.S. Department of Energy has recognized the 2013) version of the reference as the national energy reference standard. This requires all states to adopt a commercial building energy code at least as stringent as the 2013 standard within two years, or justify why they cannot comply. By September 2016 nine states had complied with the previous ruling based on the 2010 version. Eighteen of

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the states have also incorporated energy codes to be at least as stringent as the 2007 version. The new (ASHRAE/IES 90.1-2016) version has added a number of energy-savings measures as a result of requested input by professionals and industries involved in efficiency energy design of buildings and building systems – including the Illuminating Engineering Society (IES). It contains 125 addenda published since the 2013 standard. The 2013 standard currently serves as the accepted commercial building reference standard for state building energy codes. The 2016 version is the 10th edition published since the original standard was first published in 1975 during the United States energy crisis. The significant technical changes as they relate to lighting are 1,) Modified control requirements making the application of lighting controls easier for increased energy savings; 2,) Modification of the interior lighting power densities that reflect the efficiency gains from LED technology; 3,) Added the minimum requirements for lighting in dwelling units to set limits on light source efficacy; and 4,) Lighting Power Density gives LPD allowances for most building types and specific space types using either the Building Area or the Space-by-Space Method, along with the Minimum Requirements in Watts / Square.Ft. There are two paths for designers to comply:

1: Prescriptive path: All components of the building meet the min. standards specified by ASHRAE 90.1. 2: Performance path: The design is demonstrated (by building energy simulation) to use less energy than a baseline building built to ASHRAE 90.1 specifications.

LIGHTING QUALIT Y, COMFORT, & CONTROL

ENERGY MANAGEMENT LIGHTING CONTROLS Management of lighting energy usage utilizes a number of different lighting control techniques. Some mandatory requirements include a variety of lighting controls identified in the established “ASHRAE/IES 90.1, Energy Reference Standard.” In addition, there is the “International Energy Conservation Code” (IECC) which recognizes ASHRAE/IES 90.1 as an alternate standard with some similar requirements. Also, many states have their own energy management codes. All these different energy standards, however, have some significant differences in the details, but both versions of the ASHRAE and IECC energy codes, are common in the sense that they are growing more complicated and strict, especially as they apply to lighting energy controls.

Testing: An independent party must test the lighting controls to document the installation and maintenance of installed controls. They must be verified to the owner with appropriate documentation. Testing is required for occupancy, time-based, and daylight controls. The testing contractor furnishes the owner documentation verifying that all the installed controls satisfy the established acceptance criteria. The owner must receive the documentation verifying the lighting and control systems at the conclusion of any project, giving the opportunity to understand them. This includes drawings and maintenance manuals, the written sequence of operations, and recommended schedule for inspecting and recalibrating controls. The lighting designer should understand that most energy control codes are becoming more restrictive and detailed.

Occupancy Sensors are utilized in an wide range of interior spaces like offices, classrooms and assembly rooms. They are required to have a maximum OFF time delay of 20 min. by the 90.1 code or 30 min. by IECC. They must be manual-ON or auto-ON to less than 50% of the supplied power. The IECC code also requires that occupancy sensors that can reduce the lighting power by at least 50% in certain spaces and applications. Time-Based Controls are required, or are allowed where occupancy sensors are not required. The control system must be programmable to address control for any weekends and holiday situations. Space Controls are required where time-based controls are used. These allow override of the schedule for up to 2 hours and must be capable of light reduction. Dedicated controls are required for special uses like guest rooms and accent lighting. Automatic Sensors for indoor lighting turn off the lighting when not in use. Other controls to accomplish this are time-based. Some building controls require the general lighting in certain applications to reduce automatically by at least 50% when the space or room will not be in use. Note: The lighting controls identified above are from both the 90.1-2013 and IECC-2015 Energy Reference Standard codes. This information is intended to be of a general nature. For more information consult the latest versions of all applicable energy codes and any from the local governing codes or authority having jurisdiction. Wireless Controls consist of two devices that make up wireless light control: the transmitter and a receiver. They are used to control light sources with simple on-off, dimming, or other control functions. The transmitter sends a radio signal to a receiver (light switch) to control a light source when the light switch is pressed. The receiver interprets the signal and initiates the desired operation of the source. The transmitter is the part that is actually wireless, eliminating the need to run wires to the switch. This will work within about a 150 foot radius from the transmitter. There are other centralized functions that are possible also, such as building data analysis, total energy monitoring, and scheduling.

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LIGHTING QUALIT Y, COMFORT, & CONTROL

ENERGY MANAGEMENT LIGHTING CONTROL MATRIX Operation of the Lighting Controls

MANUAL CONTROL ON MANUAL CONTROL OFF KEY MANUAL SWITCH DIMMING CONTROL ZONE CONTROL SW OVERRIDE SWITCH TIME CLOCK SW ON TIME CLOCK SW OFF OCCUPANCY SENSOR WIRING DIAG. SYMBOL

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ML

RA

Rm#

identified in a Lighting Control Matrix for a typical private office, or conference room, could be described and specified as follows below.

Rm#

MR

BR

RM. CAL

HANI

MEC

RO O M AG E

S

S TO R

RO O M

OM

REST

BREA

K RO

ING R

M.

S

RM. NCE

CON CR

MEET

CE OFFI

OO

FERE

S

Cd#

OPEN

IDOR

CORR

BLE

OFFI

FFIC

CE

E

When an occupant enters a room or space the lights can turn on using a manual switch or dimmer-switch, and be able to adjust the level to his personal choice or requirements. This may also be activated by a vacancy sensing control. If the lights are turned off and on again, they will automatically adjust to the previous occupant’s setting. A vacancy sensor may also be effective in the entire room for even minor body motion, turning the lights off after 15 minutes of the space being unoccupied. Also, not in the matrix below, a photosensor might raise or lower the light level automatically to take advantage of available daylight for additional energy savings.

DOU

ATE O

N AR

PRIV

PTIO

RECE

MAIN

LOBB Y

EA

Lighting systems and controls offers lighting designers, as well as occupants and owners, an opportunity to design a user-oriented and adaptable lighting – with significant energy conservation as an additional bonus. Today’s energy management of interior lighting may, however, involve a number of different control techniques. To clearly identify the design of these systems the designer may utilize a written narrative in the form of a graphic matrix to furnish a detailed description of the desired control parameters. The illustration below is a generic example where the columns represent room or space types, and the rows the specific control techniques. It offers all participants a common guide to the desired lighting control, and energy-saving strategies for individual identified interior rooms, area or user function.

M&W Rm# MECH

LIGHTING QUALIT Y, COMFORT, & CONTROL

ENERGY MANAGEMENT ENERGY AUDITS Energy management and conservation reduces the need for energy provided for commercial and residential lighting, and the associated energy services that are furnishing the electric power. The reduced demand for energy also directly impacts the need for new and expanded power generation facilities – and the added benefit of improved environmental quality. These savings can be achieved either by using energy more efficiently (using less energy through the use of automatic lighting controls) or by reducing the amount of services used (specifying more efficient light sources). Energy conservation is also part of the concept of lowering energy costs, and the prevention of future resource depletion. Use of a periodic energy audit is an effective way to improve energy conservation in most commercial buildings and homes. An energy audit is a professional inspection and analysis of the energy usage and conservation, usually for a specified period of time, in a building or a system to reduce the amount of energy used in the building without affecting the quality or extent of the energy usage. This is done by trained professionals and can be part of some of the available national programs. In addition, recent development of smartphone and tablet applications will enable business owners and homeowners to complete relatively simple and complex energy audit and analysis on their own. A description according to Wikipeda follows: An energy audit is an inspection, survey and analysis of energy flows, for energy conservation in a building, process or system to reduce the amount of energy input into the the system without negatively affecting the output. In

commercial and industrial real estate, an energy audit is the first step in identifying opportunities to reduce energy expense and carbon footprints When the object of study is an occupied building then reducing energy consumption while maintaining or improving human comfort, health and safety are of primary concern. Beyond simply identifying the sources of energy use, an energy audit seeks to prioritize the energy uses according to the greatest to least cost effective opportunities for energy savings. There are 4 levels of analysis:

Level 0 – Benchmarking: This first analysis consists in a preliminary Whole Building Energy Use analysis based on analysis of the historic utility use and costs and the comparison of the performances of the similar buildings. This benchmarking of the studied installation allows determining if any further analysis is required; Level I – Walk-through audit: Preliminary analysis made to assess building energy efficiency to identify not only simple and low-cost improvements but also a list of energy conservation measures (ECMs, or energy conservation opportunities, ECOs) to orient the future detailed audit. This inspection is based on visual verifications, study of installed equipment and operating data and detailed analysis of recorded energy consumption that is collected during the benchmarking phase; Level II – Detailed/General energy audit: Based on the results of the pre-audit, this type of energy audit consists in energy use survey in order to provide a comprehensive analysis of the studied installation, a more detailed analysis of the facility, a breakdown of the energy use and a first quantitative evaluation of the ECOs/ECMs selected to correct the defects or improve the existing installation. This level of analysis can involve advanced on-site measurements and sophisticated computer-based simulation tools that are used to evaluate precisely the selected energy retrofits; Level III – Investment-Grade audit: Detailed Analysis of Capital-Intensive Modifications focusing on potential costly ECOs requiring rigorous engineering study.

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LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT TRANSMISSION TRANSMITTING CHARACTERISTICS The transmission of light passing through various materials is affected by two things, the amount of

absorption and reflection in the material, and the degree of light reflection at the material surface. .

Direct Transmission refers to passing light through a transparent material with virtually no diffusion, and some reflection dependent upon the angle of entry. Transparent materials, such as, glass and plastic are utilized for cover lenses to protect equipment from weather or to alter the color with very little alteration of the distribution. Spread Transmission emits light at wider angles because of surface configurations on at least one side of the material. This type of spread transmission provides a degree of light source concealment and brightness control, where the complete brightness uniformity or diffusion is not required and a degree of sparkle and brilliance may be desirable characteristics. will effectively scatter the light in all directions and destroy all the directional characteristics of a light beam. The materials used to accomplish even distribution and the appearance of uniform brightness are glass or plastic with microscopic white particles embedded within or applied to either surface.

Mixed Transmission is a result of materials such as opalescent glass which permits direct transmission of selected wavelengths of light, while other wavelengths are diffused. A white light source would be visible through most

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opalescent glass and appear as a subtle pink image because the pink wavelengths are directly transmitted, with all of the surrounding area appearing white because all of the other colors of light, or wavelengths, are being diffused.

LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT TRANSMISSION TYPICAL TRANSMITTING MATERIALS CLEAR GLASS AND PLASTIC

Thickness .10 -.375in 2.54-9.53mm Transmission 8 0 - 94% Reflection 08 - 10% Absorption 02 - 10% Characteristics HIGH TRANSMISSION

SATIN OR ETCHED GLASS AND PLASTIC

Thickness .08 -.250in 2.0-6.35mm Transmission 6 3 - 88% Reflection 06 - 20% Absorption 03 - 17% Characteristics HIGH TRANSMISSION

NO DIFFUSION

TRANSPARENT COLOR GLASS AND PLASTIC

Thickness .10 -.375in 2.54-9.53mm Transmission (below) Blue 0 3 - 05% Red 08 - 17% Green 10 - 17% Amber 30 - 50% Characteristics POOR TO GOOD TRANSMISSION NO DIFFUSION LAMINATED SANDWICH GLASS

Thickness .21 -.320in 5.33-8.13mm Transmission 8 9 % for Clear Reflection 08 - 10% Absorption 02 - 10% Characteristics SHATTER PROOF, CLEAR, WHITE & COLORS AVAILABLE FOR PLASTIC INSERT CONFIGURED GLASS AND PLASTIC

Thickness .10 -.375in 2.54-9.53mm Transmission 5 7 - 94% Reflection 07 - 24% Absorption 03 - 21% Characteristics HIGH TRANSMISSION, FAIR TO GOOD DIFFUSION, MANY DIFFERENT PLASTICS & CONFIGURATIONS

POOR DIFFUSION

SOLID OPAL GLASS

Thickness .08 -.312in 2.0-7.92mm Transmission 1 2 - 40% Reflection 40 - 78% Absorption 04 - 31% Characteristics FAIR TRANSMISSION EXCELLENT DIFFUSION WHITE APPEARANCE

OPALESCENT & ALABASTER GLASS

Thickness .08 -.20in 2.0-5.0mm Transmission 5 5 - 88% Reflection 15 - 30% Absorption 02 - 15% Characteristics GOOD TRANSMISSION FAIR DIFFUSION SELECTIVE TRANSMISSION PLASTICS: ACRYLIC, STYRENE, & RESIN

Prismatic Clear & White Patterns Smooth Clear & White Clear Cracked Ice Pattern Smooth & Patterned Translucent White Smooth Frosted Clear & White Available in Custom Colors (Acr ylics are non-yellowing)

NOTE: This information is presented as average representative values for the wide range of similar materials available.

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LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT REFLECTION REFLECTION CHARACTERISTICS Materials and surfaces that are able to reflect light can make a noticeable contribution to the illumination of an interior space as usable secondary light sources. Therefore, the surface from a smooth, polished surface will alter the direction of light without changing its basic form. The angle of reflection will be equal to the angle of incidence. Since they are mirrors, their appearance depends on their brightness in the field of view, whether dark or light, based on the observer’s position.

characteristics and resultant action of reflecting and redirecting light incident to their surface become a significant design consideration in the choice and design of architectural finishes.

ANGLE OF INCIDENCE ANGLE OF REFLECTION

from irregular surfaces, like corrugated, hammered, brushed, or naturally textured, will partially disperse and spread the reflected light. However, the greatest intensity of light is also reflected at an angle similar to the angle of incidence for specular materials. These materials will, therefore appear with dominant highlights or streaks on a diffuse background. from a roughened or matte surface will not have directional mirror qualities of the incident light, with light reflected in all directions and high intensity viewed normal to the surface. The surfaces will appear the same when viewed from all directions, a desirable characteristic for major architectural surfaces.

involves the combination of the two effects, specular and diffusing reflection. The obvious examples of this are glossy paints, porcelain enamel, some textiles, and other finishes

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with a smooth specular finish – like a transparent coating over a matte base. While being essentially diffuse, with 5 to 15 % of light reflected specularly, this might give undesirable highlights and images.

LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT REFLECTION TYPICAL REFLECTING MATERIALS POLISHED ALUMINUM

WHITE PORCELAIN ENAMEL

Reflection: 60 - 70%

Reflection: 60 - 83% White

Characteristics; Light weight and available in many gauges. Can be worked and easily shaped and polished. Chemical etching can provide varying degrees of spread reflection.

Characteristics; A powdered glass fused to a substrate by firing at a high temperature. The powder melts and hardens to a smooth, durable vitreous coating on metal, glass or ceramic.

COATED ALUMINUM

WHITE FLASHED OPAL GLASS

Reflection: 75 - 95%

Reflection: 40 - 80%

Characteristics; Features a hard anodized or highly reflective oxide coating to enhance and/or protect a polished aluminum surface. Available in clear and color finishes.

Characteristics; Consists of a clear glass base with a thin white flashed layer. It is resistant to water, acids, alkalis, and salt. More often used as a transmitting material.

CHROMIUM PLATING

MARBLE & GRANITE

Reflection: 85 - 95%

Reflection: 30 - 70% 20 - 25%

Characteristics; Chrome plating is more reflective and more mirror like than other finishes. It is usually applied to steel, but also to other materials like aluminum, brass, copper, plastic, and stainless steel.

Characteristics; Marble and granite have a crystalline structure and can be polished to specular finish, are available in a wide range of colors and patterns. Used as a common stone for architectural applications.

STAINLESS STEEL

Reflection: 50 - 60% Characteristics; Stainless steel is strong and durable, can be shaped and formed and offers excellent resistance to corrosion. It has semi-specular and slightly diffuse finish.

WOOD

Light Oak Dark Oak Light Birch Mahogany Walnut

Reflection 25 - 35% 10 - 15% 35 - 50% 6 - 12% 5 - 10%

NOTE: This information is presented as average representative values for the wide range of similar materials available.

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LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT REFRACTION REFRACTION CHARACTERISTICS Refraction is bending of light as it passes from one medium through another, such as air through water, due to the different speed of light in the transmitting mediums. Materials, like glass and plastic, are used for the control of light in

Displacement occurs when clear materials with two parallel surfaces have refraction (displacement) at each face canceling each other, not changing the light direction. If the opposite surface is not parallel, the refraction alters the direction. In the illustration angles A and B are similar, but the light direction is different than the original.

Transparency in materials of uniform thickness does not alter the direction of light passing through – useful for protective cover plates of glass and plastic when the beam control is achieved by other means, like reflectors or PAR and R lamps. When light strikes glass perpendicularly, about 3 to 4 % is reflected at the first surface and 3 to 4 % at the second surface. Another 2 to 8 % is absorbed, and 85 to 90 % is transmitted. As the angle deviates from perpendicular, the reflection increases. At about 85 degrees nearly all is reflected.

Prismatic Control by a prism (a transparent material bounded in part by two non-parallel faces) has refracting characteristics that causes a beam of light passing through one face to be emitted in a different direction. Transparent materials with multiple small prisms provides a greater degree of accuracy and beam control.

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lighting equipment, by refracting light in this same way. If materials are shaped and formed into lens elements, they become valuable for controlling the direction and distribution of light in both interior and exterior architectural space. LIGHT RAY

LIGHT RAY

A

A B

B

LIGHT RAY 3 - 4% REFLECTED 2 - 8% ABSORBED 3 - 4% REFLECTED 85 - 90% TRANSMITTED

LIGHT RAY 85°

LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT REFRACTION

occurs when light strikes a transmitting material at an angle, where part of the light is transmitted and part is reflected internally. At specific angles of entry, none of the light is transmitted through the material, but

is totally reflected internally. Using this principle of refraction, efficient reflectors can be designed entirely made of prisms, with the contour and prisms configured to produce the desired appropriate redirection and distribution of light.

Angle of Incidence is the angle between a ray of light entering a medium and a line normal to the surface. Light passing through one transparent medium to another changes speed, and bends. (like a half submerged stick in water appears bent at the entry point). The extent the stick appears to bend depends on the angle of incidence, and refractive indexes of the mediums. The angle between the light and normal line, as it enters a medium, is the angle of refraction.

The Critical Angle

is where total internal reflection occurs. Light bends toward the normal when it enters a medium of greater refractive index, and away from the normal when entering a medium of lower index. The critical angle in glass is approximately 35° to 45° and is the relationship between the Index of Refraction of the two materials Most available clear glasses and plastics have an index between 1.5 and 1.6.

This illustration shows a ray of light entering a clear prism with a vertex of 90° will be internally reflected in a 180° direction. Also, the various wavelengths of white light entering a prism are dispersed at different refractive angles into all colors (wavelengths) present in the original light.

NORMAL LIGHT RAY

ANGLE OF INCIDENCE

SURFACE

ANGLE OF REFRACTION

LIGHT RAY IOR AIR = 1.0 IOR GLASS = 1.5

NORMAL ANGLE OF INCIDENCE CRITICAL ANGLE

(Index Of Refraction)

ANGLE OF REFRACTION

WHITE LIGHT

TOTAL INTERNAL REFLECTION

RED ORANGE YELLOW GREEN BLUE VIOLET

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LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT REFRACTION LENSES Lenses are made up from two or more refracting surfaces that consitute a lens system with a common axis. A simple form of lens is made

Converging lenses (also called convex lenses) are considerably thicker at the middle than at the edges, with the focal point located on the central axis. The refraction of light causes parallel rays of light to converge to a focus at the focal point.

from transparent materials having two opposite faces, either or both of them are curved. Two common types are; converging and diverging.

FOCAL LENGTH

DOUBLE-CONVEX LENS

Diverging Lenses (also called concave lenses) are considerably thinner at the middle than at the edges, with the focal point located on the central axis. The refraction of light causes parallel rays to spread out in a diverging pattern.

DOUBLE-CONCAVE LENS

Built-up Lenses are identfied, considered, and analyzed as a built-up system of prisms that are combined to reduce the size of portions of the convex lens, for a reduction in weight and cost while also providing the same optical control.

PLANO-CONVEX LENS

Cromatism is a term used where extremely precise light control is required and optical dispersion in the lens produces a color fringe in the beam, and the blue wavelengths have a shorter focus than red. This dispersion is corrected with a two-piece (achromatic) lens.The greater refraction in the crown glass lens is balanced by the increased divergence of the light in the flint glass. This lens combination brings all the wavelengths to the same focus.

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WHITE LIGHT

FOCUS FOR BLUE WAVELENGTHS FOCUS FOR RED WAVELENGTHS

CROWN GLASS

FLINT GLASS FOCUS FOR ALL WAVELENGTHS

LIGHTING QUALIT Y, COMFORT, & CONTROL

LIGHT REFRACTION THE FRESNEL LENS Because refraction takes place at surfaces of a material, part of this transmitting material can be removed without affecting the optical control. The fresnel lens uses this and consists of a convex lens with sections of the glass removed. This produces a thinner and light weight lens.

Lamp Position

The position of a light source will change the control characteristics of the lamp-refractor combination. The diagrams shown on the right demonstrates the different asymmetric and spread distributions that are produced when the light source is located at points that are different than the primary focus of the lens.

Note: The refraction and reflection of light shown here assumes a point source of light. The nearest approach to this is an incandescent filament in a clear glass bulb. Major variations in beam control occurs with diffuse bulb finishes. In these cases, the bulb itself is the effective light source not the filament, resulting in more diffuse light distribution. However, lightly frosted bulbs or lenses will help reduce striations in the beam distribution as a result of irregular lamp glass and filament construction.

SOURCE AT FOCUS

SOURCE AHEAD OF FOCUS

SOURCE OFFSET FROM FOCUS

SUPPLEMENTAL REFLECTORS

Control of light by a lens may be improved with a reflector for beam control and fixture efficiency. This is par ticularly helpful where precise light beam control is required.

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LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTOR CONTOURS BASIC REFLECTOR CONTOURS The basic reflector contours are mathematically predictable shapes, including the parabola, the ellipse, and the semi-circle. The reflecting action

send light rays starting at the focal point of a parabolic shape and reflect them in a direction parallel to the axis of the reflector–producing a light beam of essentially parallel rays useful for spot and flood lighting, especially where a concentrated beam of light with a limited beam spread of light is required.

send light rays starting at the focal point of the elliptical shape and reflect them through the second, or opposite, focus producing a generally divergent beam of light. This distribution is useful in lighting equipment where a beam of controlled divergence is being projected through a small aperture to create a unique inconspicuous light source.

send light rays starting at at the focal point of a circular shape and reflect them back through the same focus point creating a widely divergent beam of light. The circular section is a special form of the ellipse, where both foci are coincident. This contour is for individual or combination reflectors that redistribute light otherwise misdirected or trapped.

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of these is understood. The simplicity of their shapes make them particularly convenient and useful. The most basic contours are shown below.

SOURCE AT THE FOCUS

SOURCE AHEAD OF FOCUS

SOURCE BEHIND FOCUS

SOURCE AT THE FOCUS

SOURCE AHEAD OF FOCUS

SOURCE BEHIND FOCUS

SOURCE AT THE FOCUS

SOURCE AHEAD OF FOCUS

SOURCE BEHIND FOCUS

LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTOR CONTOURS PARABOLIC SECTION 5

4

3

HEIGHT (H)

4 3 2 1

2

1

1

2

3

4

5

AXIS OF SYMMETRY FOCUS

LENGTH OF ARC = W [1+8/3 (H/W)2] WIDTH OF OPENING (W)

A parabolic section has a single axis of reflective symmetry, which passes through its focus. A light source at its focus directs all light parallel to the axis of symmetry.

A parabola can best be described as the intersection of a cone with a plane parallel to the cone’s side

ELLIPTICAL SECTION If a light source is placed at one ASYMMETRIC focus of an elliptic mirror, all DISTRIBUTION FOCUS light rays on the plane of the ellipse are reflected to the second focus. Since no other smooth curve has such a property, it can be used as an alternative definition of an ellipse. If the B2/A (typ) ellipse is rotated along its major axis to produce CIRCLE OF RADIUS A DETERMINES HEIGHT an ellipsoidal mirror this CIRCLE OF RADIUS B DETERMINES MAX. WIDTH property will hold for all the rays out of the source. Alternatively, a cylindrical FOCUS mirror with elliptical crosssection can be used to focus An ellipse can light from linear fluorescent lamps be described as the along a line of the paper, like mirrors intersection of cone with a used in some types of document scanners. plane angle other than horizontal

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LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTOR CONTOURS SPECULAR REFLECTOR LIGHT CONTROL While specular reflectors furnish precise control of the reflected light, stray light outside of the controlled beam may have an effect on the desired distribution and contribute to unwanted glare. This light emerges directly from the light source beyond the control of the reflector and suggests that additional control techniques and

may be used to restrict the beam spread within a reflector as shown in the illustration. This method most effectively uses variable spaced louvers. The louvers intercept the stray light and control the beam through absorption, with louvers usually finished matte black. In some situations it may be necessary to restrict the stray light in only one direction. This method is useful in special installations where it is desirable to eliminate the stray light in the direction of the viewer. The stray light in the other direction may be useful as fill light to soften precise beams and reduce shadows.

used in a small circular or spherical shape, positioned in front of the light source, intercepts the stray light and redirects it back toward the primary reflector. Since this light is redirected through the focal point it produces a more efficient utilization of the emitted light. The reflector should be of a small size, to avoid obstructing the primary beam. This method is also most effective with the use of clear light sources and sources of a compact or small size, such as LED lamps.

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restrictions may be required to shield or redirect this stray light. Two generalized methods of controlling this are illustrated below with representative reflector contours. However, keep in mind that these techniques are also applicable to special built-in and customdesigned architectural lighting elements.

LIGHTING QUALIT Y, COMFORT, & CONTROL

REFLECTOR CONTOURS DIFFUSE REFLECTOR LIGHT CONTROL Reflection of light from a diffuse surface is in multiple directions and generally spherical in shape. The angle of reflection is independent of the angle of incidence. The typical reflecting action associated with different diffuse contours is therefore substantially subdued and the shape of the reflector has little or no effect on the

resulting direction and distribution of light. Because diffuse reflection disperses light in many directions, the beam is broad and relatively uniform in intensity. Also due to the lack of directional control the projected distance is relatively small. Diffuse reflectors are useful in the generation of a uniform brightness level.

for brightness and lamp concealment works with open louvers and diffusing plastic or glass, and they effect little change in the diffuse beam. Whether from reflection or transmission, the distribution of light is essentially the same. Since the contour does not affect the distribution, the proportions and size of the diffuse reflector can depend primarily on the objectives of the architectural objectives. As a general rule, the lighting housing should incorporate a minimum surface area, or cross section, to reduce unnecessary absorption of the light within the element. characteristics of a reflector affects the directional distribution of reflected light and the appraisal of the general surface brightness. This has little bearing on the overall efficiency of the reflection, and the reflectivity of diffuse surfaces may be higher than specular finishes. The reflection efficiency is dependent on the material. In this sense, proper design of diffuse reflectors provides a highly efficient utilization of light where uniform illumination and soft distribution is desired.

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ILLUMINATION MEASUREMENT & CALCULATION

FOOTCANDLES

6

FOOTCANDLES

FULL LUMINOUS CEILING

Minimum lighting may be sufficient for seeing tasks involving large objects and contrasts. This is true in many of our everyday circumstances, such as the reading of a newspaper headline in a dimly-lighted room. However, when careful reading of some smaller print is attempted with the similar illumination, it becomes apparent that such lighting conditions are inadequate, especially when the more difficult tasks are required in our living and working situations. To improve the visibility of a task, a person might subconsciously move a book closer to a light source or window. Improvement in seeing small detail may be made by using a flashlight or other similar device to increase the lighting on the specific area involved. These experiences show an instinctive reaction to light intensities, and indicate that insufficient lighting levels can be uncomfortable. Studies show that by making an extra effort it’s possible to improve performance. However, any increase in accuracy is achieved with considerable strain and consequent fatigue.

FULL LUMINOUS WALL

LIGHTED WALL BRACKETS

Light, as perceived in the practice of lighting design and illumination engineering, is that part of the electromagnetic spectrum which can be seen by the human eye. The performance of many everyday activities requires only the simple distribution of light, along with the provision of minimum lighting levels. However, lighting has architectural implications that go beyond simple illumination and utility, such as, the furnishing of visual environments that may be controlled and programed in accordance to the difficulty and requirements of a wide range of visual tasks.

FOOTCANDLES

CHAPTER

111

ILLUMINATION MEASUREMENT & CALCULATION

UNITS OF MEASUREMENT LIGHTING UNITS, TERMS, & DEFINITIONS The established fields of science and engineering utilize standardized units of measurement with two different systems, the English system and the metric system. The English system grew out of making measurements and naming familiar items from human anatomy, like the foot or arm. Some capacities and volumes were measured with such items as bottles, cups, and pails. Obviously, this created discrepancies between different utensils and individuals, and a better set of standards were developed to ensure the measurements and descriptions were more accurately represented. The metric system was accepted for use in the United States in the 19 th century, but was never completely established as the official system. A third system was developed and identified as the Systeme International (SI) where definitions and measurements are accepted internationally. The three common units of measurement are mass in kilograms, length in meters, the time in seconds, and for lighting terms, a measure of luminous intensity is in candelas (formerly called candlepower). Light is generated from radiant luminous energy capable of exciting the retina of the human eye, producing sight. The visible wavelengths of the electromagnetic spectrum extend from about 380 to 770 nanometers. (see Chapter 4, pg. 60 ) Special terminology and the use of both systems tend to complicate the measurement of light. In the past the reference standard was a spermaceti wax candle of special specifications. Today the standard is more scientific, but some of the terms are carried over from the earlier simple measurement concepts.

112

1 METER RADIUS (r)

SURFACE OF THE SPHERE

1 FT. RADIUS (r)

1 STERADIAN SOLID ANGLE

1 CANDELA (12.57 lm)

1 SQ. FT. (R2)

ILLUMINATION 1 fc (10.76 lx) (1 lumen/sq.ft.)

1 SQ. M. (R2) ILLUMINATION 1 lx (.0926 fc) (1 lumen/sq.m.)

TOTAL SURFACE AREA OF A SPHERE IS EQUAL TO (4 π r2) If r = 1 ft. The Total Area Is (4 x 3.1416 x1) = 12.57 sq.ft. If r = 1 m. The Total Area Is (4 x 3.1416 x1) = 12.57 sq.m.

MEASUREMENT OF ILLUMINATION

Candela (Cd) (Candlepower) is a measure of the light intensity, or the energy emitted by a light source, measured in lumens. A common candle emits a luminous intensity of approximately one candela (12.57 lumens).

Lumen (lm) is a unit of luminous flux of one candela emitted uniformly in a solid angle of one steradian (1 cd/1 sr = 1 lm). A lumen is a measurement of the total energy of a light source emitted in all directions. A sphere has a solid angle from the center of 4π steradians, so a source emitting in all directions has a total luminous flux of 1 cd x 4 π sr = 12.57 lumens.

Steradian (Sr) is a solid angle extended from the center of a unit sphere of a radius (r) to the sphere’s surface with an area of (r²), or 1/4π.

ILLUMINATION MEASUREMENT & CALCULATION

UNITS OF MEASUREMENT Lux (lx) is a metric unit of measurement of the illuminance (E) on the inner surface of a sphere with a radius of 1 meter, falling on an area of 1 sq. meter, with a light source at the center of the sphere of 1 candela. (1 lux = 0.0926 fc).

Lumen Method (or Zonal Cavity Method) is a simplified method to calculate average lighting level in a room. It uses cavity ratios of upper, middle, and lower volumes of a space to find horizontal illuminance and number of luminaires.

Footcandle (fc) is an English measurement

Light Loss Factor (LLF) or the Maintenance

of the illuminance (E) on the inner surface of a sphere with a radius of 1 foot, falling on an area of sq. foot, with a light source at the center of the sphere of 1 candela. (1 fc = 10.76 lux).

Illuminance (E) is the amount of luminous flux (energy) incident on a unit area of a surface or object, measured in Lux or Footcandles. A light meter measures lumens per a unit area falling on a given surface. A lux equals 1 lumen per sq. meter of illuminated surface area, and a footcandle equals 1 lumen incident per sq. foot.

Luminance (L) is the brightness, or amount of reflected light off a surface or object, measured in footlamberts. While illuminance (see above) follows the inverse-square law, where lighting levels drops at a rate of E/d2 ( for example to 1/4 at twice the distance from a source, see pg. 119). luminance does not follow this law, it does not depend on the distance. Being closer or farther doesn’t change the perceived brightness, it changes only with the reflectivity of the surface.

Footlambert (fL) is the luminance emitted or reflecting from a surface equal to 1 lumen per sq. foot. A perfectly reflecting surface receiving 1 footcandle has a luminance of 1 footlambert. A footlambert equals 1/π candela per square foot, or 3.4262591 candelas per square meter.

Factor (MF), is a combination of the Lamp Lumen Depreciation (lamp performance over its life), the Luminaire and Room Surface Dirt Depreciation, and Ballast Factor (BF) (ballast efficiency). LLF values are found in the IESNA Lighting Handbook and some luminaire specifications. is a measure of the amount of light reaching the work plane. Factors reducing efficiency are the type of light distribution from fixtures, the room surface reflectances, and room size and proportions. is the effectiveness of a light source to convert electrical energy to visible light, expressed in lumens per watt, or the quotient of total luminous flux by the total radiant flux.

Work Plane is the horizontal level where visual tasks are typically performed and illumination levels measured. Typically, this is 30, 36, or 48 inches above the floor, or the floor itself. EXAMPLES OF EVERYDAY ILLUMINANCES A Bright Sunny Day .......... 100,000 Lux.............. 10,000 Fc Full Daylight ...................... 10,000 Lux.................. 1000 Fc Overcast Day ..................... 1000 Lux ...................... 100 Fc 200-1000 Lux.......... 20-100 Fc Twilight .............................. 10 Lux ............................ 1.0 Fc Street Lighting ................. 0.25 Lux ..................... 0.025 Fc Full Moonlight .................. 0.1 Lux ......................... 0.01 Fc Starlight ........................... 0.001 Lux ...............0.0001 Fc

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ILLUMINATION MEASUREMENT & CALCULATION

ILLUMINATION CALCULATION THE LUMEN METHOD Design of many types of lighting systems for architectural interior space can be quickly and easily accomplished with a number of software programs. However, being familiar with basic methods of calculation is an important knowledge base for lighting designers. One wellestablished procedure not requiring the use of a computer is called the Lumen or Zonal Cavity Method. A lumen (lm) is a unit of luminous flux emitted uniformly in a solid angle or in all directions, measured in lux or footcandles. 1 lux of illumination is produced when 1 lumen of luminous flux is incident on 1 square meter, or a footcandle when 1 lumen of luminous flux is incident on 1 square foot. (For more definitions and terms see Pages 112, 113 and the Glossary). The Lumen Method is an accepted procedure of calculating average uniform light levels within a space. Its basic features include taking into consideration inter-reflectance within a room or space with a uniform ceiling height

and rectangular or non-rectangular floor plan. The method divides a room or space into three 3-dimensional volumes or cavities; the ceiling cavity, the room cavity, and the floor cavity. It calculates average illumination levels on a work plane located at specified distances above the floor, usually 30, 36, or 48 inches, or the floor itself. (see the illustration below). The cavities are used to find values called “cavity ratios”, which are used to determine effective, or average, reflectance of the cavity surfaces, and the overall efficiency of the lighting system, identified as the Coefficient of Utilization (Cu). It can also calculate the needed number of luminaires required to furnish a specified level of illumination. Although it calculates average illumination, in most situations the lighting levels are higher in the center of a room and drop off near the walls. The Lumen Method incorporates four fundamental steps which are identified and described on the following pages.

CEILING CAVITY

hcc (HGT.OF CEILING CAVITY)

ROOM CAVITY

hrc (HGT.OF ROOM CAVITY)

FLOOR CAVITY

hfc (HGT.OF FLOOR CAVITY)

WORK PLANE TYPICALLY 30, 36, 48 INCHES ABOVE THE FLOOR

114

ILLUMINATION MEASUREMENT & CALCULATION

ILLUMINATION CALCULATION

Step 1: DETERMINE THE CAVITY RATIOS

Step 1: DETERMINE THE CAVITY RATIOS

Ceiling Cavity Ratio (CCR) = 5 x hcc x (L+ W) / (L x W) Room Cavity Ratio (CCR) = 5 x hrc x (L+ W) / (L x W) Floor Cavity Ratio (CCR) = 5 x hfc x (L+ W) / (L x W) FOR NON-RECTANGULAR ROOMS C. R. = 2.5 x Cavity Hgt. x Cavity Perimeter / (L x W) Step 2: FIND EFFECTIVE CAVITY REFLECTANCES (ρ)* Using the Cavity Ratios and existing reflectances, find the Effective Cavity Reflectances (ρcc & ρfc) for ceiling and floor cavities using Table A (next pg.) If luminaires are recessed or surface mounted, or work plane is the floor, the ceiling cavity ratios are zero and equal to existing surface reflectances.

Ceiling Cavity Ratio (CCR) = 5 x 0 x (24+ 28) / 672 = 0 Room Cavity Ratio (CCR) = 5 x 7.5 x (24+ 28) / 672 = 3 Floor Cavity Ratio (CCR) = 5 x 2.5 x (24+ 28) / 672 = 1

Step 3: FIND THE COEFFICIENT OF UTILIZATION

Using effective reflectance values ρcc, ρfc, ρw, and Room Cavity Ratio, find the Coefficient of Utilization for the selected luminaire from the manufacturer’s published Cu tables. The Light Loss Factor (LLF) will need to be determined, which often is also furnished by the luminaire manufacturer. The floor reflectance ρfc is typically set at 20% in the manufacturer’s Cu tables. If the floor reflectance is other than 20% , the Cu will need to be adjusted using the Multiplying Table B shown on the following page. *(ρ=lower case letter rho, the 17th letter of the modern Greek alphabet)

Step 2: FIND EFFECTIVE CAVITY REFLECTANCES

Using Table A (on the next page), and the actual ceiling and wall reflectances (80% & 50% ), the Effective Ceiling and Floor Cavity Reflectances were determined to be ρcc = 66% and ρw = 30% Step 3: FIND THE COEFFICIENT OF UTILIZATION

Using the Effective Ceiling and Floor Cavity Reflectances values of ρcc and ρw from step 2, and the Room Cavity Ratio of 3, it’s found that the Coefficient of Utilization from manufacturer’s Cu Table C can be interpolated between 0.65 and 0.68, or Cu = 0.67. Because the floor reflectance is more than 20% , the Cu value will need adjusting by using the Multiplying Table B. The adjusted Cu value is = 0.67 x 1.054 = 0.71 Step 4: FIND NO. OF LUMINAIRES & ILLUMINANCE

No. of Luminaires = (50 x 672) / (0.71 x 0.9 x 4280) No. of Luminaires = (33,600) / (2735) = 12.28 Luminaires Maint. Illuminance = (51,360 x 0.71 x 0.9) / 672 = 48.8 fc 28’ 8’

Step 4: FIND NO. LUMINAIRES & ILLUMINANCE

No. of Luminaires = (lx or fc x Area) / (Cu x LLF x tot. lumens.) Maint. Illuminance = (tot. lumens x Cu x LLF) / Area (ft ² or m²)

6’

EXAMPLE CALCULATION

Find the number of luminaires to light a classroom to a maintained lighting level of 50 footcandles (500 lux) using the Lumen Method. The room is 24 ft. by 32 ft., with a ceiling height of 10 ft. and a work plane at 2.5 ft. The reflectance of the ceiling is 80% , walls 50%, and the floor is 30% . The luminaires selected are 35 watt, LED 2 ft. X 4 ft. single-lamp, furnishing 4289 lumens.

24’

LUMINAIRE SPACING SELECTED FOR UNIFORMITY

115

ILLUMINATION MEASUREMENT & CALCULATION

ILLUMINATION CALCULATION THE LUMEN METHOD . . . continued TABLE A. EFFECTIVE CEILING OR FLOOR CAVITY REFLECTANCES (%)

EXIST. REFLECTANCE CEILING OR FLOOR

90 %

80 %

70 %

CEILING OR FLOOR CAVITY RATIO

WALL REFLECTANCE 90%70%50%30% 8 0 % 7 0 % 5 0 % 3 0 % 70%50%30%

50 %

30 %

10 %

70%50%30% 80 % 70 % 50 % 30 %

50%30%10%

0.0 0.1 0.2 0.3 0.4 0.5

90 90 89 89 88 88

90 89 88 87 86 85

90 88 88 85 83 81

90 87 87 83 81 78

80 79 79 78 78 77

80 79 78 77 76 75

80 78 77 75 74 73

80 78 76 74 72 70

70 69 68 68 67 66

70 69 67 66 65 64

70 68 66 64 63 61

50 59 49 49 48 48

50 49 48 47 46 46

50 48 48 46 45 44

30 30 30 30 39 29

30 30 29 29 29 28

30 29 29 28 27 27

30 29 28 27 26 25

10 10 10 10 11 11

10 10 10 10 10 9 10 9 10 9 10 9

0.6 0.7 0.8 0.9 1.0

88 88 87 87 86

84 83 82 81 80

80 78 77 76 74

76 74 73 71 69

77 76 75 75 74

75 74 73 72 71

71 70 69 68 66

68 66 65 63 61

65 65 64 63 63

62 61 60 59 58

59 58 56 55 53

47 47 47 46 46

45 44 43 43 42

43 42 41 40 39

29 29 29 29 29

28 28 27 27 27

26 26 25 25 24

25 24 23 22 22

11 10 11 10 11 10 11 9 11 9

9 8 8 8 8

1.1 1.2 1.3 1.4 1.5

86 86 85 85 85

79 78 78 77 76

73 72 70 69 68

67 65 64 62 61

74 73 73 72 72

71 70 69 68 68

65 64 63 62 61

60 58 57 55 54

62 61 61 60 59

57 56 55 54 53

52 50 49 48 47

46 45 45 45 44

41 41 40 40 39

38 37 36 35 34

29 29 29 28 28

26 26 26 26 25

24 23 23 22 22

21 20 20 19 18

11 12 12 12 12

9 9 9 9 9

8 7 7 7 7

1.6 1.7 1.8 1.9 2.0

85 84 84 84 83

75 74 73 73 72

66 65 64 63 62

59 58 56 55 53

71 71 70 70 69

67 66 65 65 64

60 59 58 57 56

53 52 50 49 48

59 58 57 57 56

52 51 50 49 48

45 44 43 42 41

44 44 43 43 43

39 38 37 37 37

33 32 32 31 30

28 28 28 28 28

25 25 25 25 24

21 21 21 20 20

18 17 17 16 16

12 12 12 12 12

9 9 9 9 9

7 7 6 6 6

2.1 2.2 2.3 2.4 2.5

83 83 83 82 82

71 70 69 68 68

61 60 59 58 57

52 51 50 48 47

69 68 68 67 67

63 63 62 61 61

55 54 53 52 51

47 45 44 43 42

56 55 54 54 53

47 46 46 45 44

40 39 38 37 36

43 42 42 42 41

36 36 35 35 34

29 29 28 27 27

28 28 28 28 27

24 24 24 24 23

20 19 19 19 18

16 15 15 14 14

13 13 13 13 13

9 9 9 9 9

6 6 6 6 6

2.6 2.7 2.8 2.9 3.0

82 82 81 81 81

67 66 66 65 64

56 55 54 53 52

46 45 44 43 42

66 66 66 65 65

60 60 59 58 58

50 49 48 48 47

41 40 39 38 38

53 52 52 51 51

43 43 42 41 40

35 34 33 33 32

41 41 41 40 40

34 33 33 33 32

26 26 25 25 24

27 27 27 27 27

23 23 23 23 22

18 18 18 17 17

13 13 13 12 12

13 13 13 13 13

9 9 9 9 8

5 5 5 5 5

3.1 3.2 3.3 3.4 3.5

80 80 80 80 79

64 63 62 62 61

51 50 49 48 48

41 40 39 38 37

64 64 64 63 63

57 57 56 56 55

46 45 44 44 43

37 36 35 34 33

50 50 49 49 48

40 39 39 38 38

31 30 30 29 29

40 40 39 39 39

32 31 31 31 30

24 23 23 22 22

27 27 27 27 26

22 22 22 22 22

17 16 16 16 16

12 11 11 11 11

13 13 13 13 13

8 8 8 8 8

5 5 5 5 5

3.6 3.7 3.8 3.9 4.0

79 79 79 78 78

60 60 59 59 58

47 46 45 45 44

36 35 35 34 33

62 62 62 61 61

54 54 53 53 52

42 42 41 40 40

33 32 31 30 30

48 48 47 47 46

37 37 36 36 35

28 27 27 26 26

39 38 38 38 38

30 30 29 29 29

21 21 21 20 20

26 26 26 26 26

21 21 21 21 21

15 15 15 15 15

10 10 10 10 9

13 13 13 13 13

8 8 8 8 8

5 4 4 4 4

4.1 4.2 4.3 4.4 4.5

78 78 78 77 77

57 57 56 56 55

43 43 42 41 41

32 32 31 30 30

60 60 60 59 59

52 51 51 51 50

39 39 38 38 37

29 29 28 28 27

46 46 45 45 45

35 34 34 34 33

25 25 25 24 24

37 37 37 37 37

28 28 28 27 27

20 19 19 19 19

26 26 26 26 25

21 20 20 20 20

14 14 14 14 14

9 9 9 8 8

13 13 13 13 14

8 8 8 8 8

4 4 4 4 4

4.6 4.7 4.8 4.9 5.0

77 77 76 76 76

55 54 54 53 53

40 40 39 38 38

29 29 28 28 27

59 58 58 58 57

50 49 49 49 48

37 36 36 35 35

26 26 25 25 25

44 44 44 44 43

33 33 32 32 32

24 23 23 23 22

36 36 36 36 36

27 26 26 26 26

18 18 18 18 17

25 25 25 25 25

20 20 19 19 19

14 13 13 13 13

8 8 8 7 7

14 14 14 14 14

8 8 8 8 8

4 4 4 4 4

Adapted from the IESNA Lighting Handbook

116

ILLUMINATION MEASUREMENT & CALCULATION

ILLUMINATION CALCULATION

TABLE B: MULTIPLYING FACTORS FOR OTHER THAN 20% EFFECTIVE FLOOR CAVITY REFLECTANCE pcc 80% 70% 50% 30% 10% pw 70% 50 % 30% 10% 70% 50% 30% 10% 50% 30% 10% 50% 30% 10% 50% 30% 10% ROOM CAVITY RATIO

FOR 30% EFFECTIVE FLOOR CAVITY REFLECTANCE (20% = 1.00)

1 2 3 4 5 6 7 8 9 10

1.095 1.082 1.075 1.068 1.079 1.066 1.055 1.047 1.070 1.054 1.042 1.033 1.062 1.045 1.033 1.024 1.056 1.038 1.026 1.018 1.052 1.033 1.021 1.013 1.047 1.029 1.018 1.011 1.044 1.026 1.015 1.009 1.040 1.024 1.014 1.007 1.037 1.022 1.012 1.006

1.077 1.070 1.064 1.059 1.068 1.057 1.048 1.039 1.061 1.048 1.037 1.028 1.055 1.040 1.029 1.021 1.050 1.034 1.024 1.015 1.047 1.030 1.020 1.012 1.043 1.026 1.017 1.009 1.040 1.024 1.015 1.007 1.037 1.022 1.014 1.006 1.034 1.020 1.012 1.005

1.049 1.044 1.040 1.041 1.033 1.027 1.034 1.027 1.020 1.030 1.022 1.015 1.027 1.018 1.012 1.024 1.015 1.009 1.022 1.013 1.007 1.020 1.012 1.006 1.019 1.011 1.005 1.017 1.010 1.004

1.028 1.026 1.023 1.026 1.021 1.017 1.024 1.017 1.012 1.022 1.015 1.010 1.020 1.013 1.008 1.019 1.012 1.006 1.018 1.010 1.005 1.017 1.009 1.004 1.016 1.009 1.004 1.015 1.009 1.003

1.012 1.010 1.008 1.013 1.010 1.006 1.014 1.009 1.0 05 1.014 1.009 1.004 1.014 1.009 1.004 1.014 1.008 1.003 1.014 1.008 1.003 1.013 1.007 1.003 1.013 1.007 1.002 1.013 1.007 1.002

ROOM CAVITY RATIO

FOR 10% EFFECTIVE FLOOR CAVITY REFLECTANCE (20% = 1.00)

1 2 3 4 5 6 7 8 9 10

0.923 0.929 0.935 0.040 0.931 0.942 0.950 0.958 0.939 0.951 0.961 0.969 0.944 0.958 0.969 0.978 0.949 0.964 0.976 0.983 0.953 0.969 0.980 0.986 0.957 0.973 0.983 0.991 0.960 0.976 0.986 0.993 0.963 0.978 0.987 0.994 0.065 0.080 0.988 0.995

0.933 0.939 0.943 0.948 0.940 0.949 0.957 0.963 0.945 0.957 0.966 0.973 0.950 0.963 0.973 0.980 0.954 0.968 0.978 0.985 0.958 0.972 0.982 0.989 0.961 0.975 0.985 0.991 0.963 0.977 0.987 0.993 0.965 0.979 0.989 0.994 1.067 1.081 1.990 1.995

cc

0.956 0.960 0.963 0.962 0.968 0.974 0.967 0.975 0.981 0.972 0.980 0.986 0.975 0.983 0.989 0.977 0.985 0.992 0.979 0.987 0.994 0.981 0.988 0.995 0.983 0.990 0.996 0.984 0.991 0.997

0.973 0.976 0.979 0.976 0.980 0.985 0.978 0.983 0.988 0.980 0.986 0.991 0.981 0.988 0.993 0.982 0.989 0.995 0.983 0.990 0.996 0.984 0.991 0.997 0.985 0.992 0.998 0.986 0.993 0.098

w

0.981 0.991 0.993 0.988 0.991 0.995 0.988 0.992 0.996 0.987 0.992 0.996 0.987 0.992 0.997 0.987 0.993 0.997 0.987 0.993 0.998 0.987 0.994 0.998 0.988 0.994 0.999 0.988 0.994 0.999

Adapted from the IESNA Lighting Handbook

TABLE C. REPRESENTATIVE COEFFICIENTS OF UTILIZATION FOR 35 W 2 X 4 LED RECESSED LUMINAIRE pcc 80% 70% 50% 30% 10% pw 50% 30% 10% 50% 30% 10% 50% 30% 10% 50% 30% 10% 50% 30% 10

ROOM CAVITY RATIO

pfc 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

20% 0.99 0.98 0.89 0.77 0.68 0.61 0.54 0.49 0.45 0.41 0.38

0.99 0.97 0.82 0.69 0.59 0.51 0.45 0.40 0.36 0.33 0.30

20% 0.99 0.95 0.75 0.62 0.52 0.44 0.38 0.34 0.30 0.30 0.24

0.98 0.97 0.87 0.75 0.67 0.67 0.53 0,48 0.44 0.40 0.37

0.98 0.95 0.80 0.68 0.58 0.58 0.45 0.40 0.36 0.32 0.30

20% 0.98 0.93 0.74 0.61 0.52 0.52 0.38 0.34 0.30 0.27 0.24

0.96 0.95 0.83 0.73 0.64 0.64 0.52 0.47 0.43 0,39 0.36

0.96 0.93 0,78 0.65 0.57 0.50 0.44 0.39 0.35 0.32 0.29

20% 0.96 0.90 0.73 0.60 0.51 0.44 0.38 0.33 0.30 0.27 0.24

0.94 0.92 0.80 0.70 0.62 0.55 0.50 0.45 0.41 0.38 0.35

0.94 0.89 0.75 0.64 0.55 0.48 0.43 0.38 0.36 0.31 0.29

20% 0.94 0.87 0.71 0.59 0.50 0.43 0.38 0.33 0.30 0.27 0.24

0.92 0.89 0.77 0.67 0,60 0.53 0.48 0.44 0.40 0.37 0.34

0.92 0.86 0.73 0.62 0.54 0.47 0.42 0.38 0.34 0.31 0.28

0.92 0.84 0.69 0.58 0.49 0.49 0.37 0.33 0.26 0.26 0.24

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ILLUMINATION MEASUREMENT & CALCULATION

ILLUMINATION CALCULATION THE POINT-BY-POINT METHOD

EXAMPLE CALCULATION

The point-by-point method of illumination calculation will accurately calculate lighting levels delivered to specific points on a work plane or on vertical surfaces. It utilizes two separate lighting components, the direct and the reflected component. The direct component comes straight from a light source, while the reflected component arrives indirectly off the room surfaces. The reflected component is considerably more complicated to calculate, very often makes only a negligible difference, and is beyond the scope of this book. This page concerns the direct component only.

STEP 1. DETERMINE ANGLES OF INCIDENCE

(For Luminaire 1). . . . . COS A = h / d 1 (For Luminaire 2). . . . . COS = 0 ° (For Luminaire 3). . . . . COS B = h / d 3 With actual dimensions you would be able find angles A and B from a cosine table similar to one shown below.

STEP 2. DETERMINE THE DIRECTIONAL CANDELAS Find the candelas at angle A from a representative manufacturer’s candlepower distribution curve that shows the light emitted from the luminaire or lamp. The candlepower curve at 90° the left shows half of the total light directed down500 ward. The straight lines represent the distribution 1000 angles, while the circular 1500 lines show the intensity. 45° In this example at angle 2000 A (45°) the candlepower 25° is approximately 1250 Cd. 5° 15°

The use of computer software programs can insure both components are accurately calculated to produce the desired illumination levels. However, a basic understanding of the process should be an important part of the designer’s vocabulary. While the point-bypoint method is an accurate way to compare lighting levels at specific points and patterns of light on walls, the easier lumen method offers the comparison of average illuminance.

1

A

d1

light is not calculated in this example.

118

ILLUMINANCE @ P = E1 + E2 + E3 = E (Fc or Lux)

2

3

h

d3

A NOTE:

STEP 3. CALCULATE COMBINED ILLUMINANCE (Illuminance1). . E 1 = Candelas 1/ d12 x cos A (Illuminance2). . E2 = Candelas 2 / h 2 (Illuminance3). . E3 = Candelas 3 /d3 2 x cos B

B

P

cos A = h/d1 cos B = h/d3 I = Directional Candelas E = Illuminance (Fc or Lux) E1(Fc) = I(Cd)/d12(ft) x cos A E2(Fc) = I(Cd)/h2(ft) E3(Fc) = I(Cd)/d32(ft) x cos B (Fc x 10.76 = Lux)

COS 0.996 0.985 0.966 0.939 0.906 0.866 0.809 0.766 0.707 0.643 0.574 0.500 0.423 0.342 0.259 0.174 0.087

ANGLE = 05 ° = 10 ° = 15 ° = 20 ° = 25 ° = 30 ° = 35 ° = 40 ° = 45 ° = 50 ° = 55 ° = 60 ° = 65 ° = 70 ° = 75 ° = 80 ° = 90 °

ILLUMINATION MEASUREMENT & CALCULATION

ILLUMINATION CALCULATION INVERSE-SQUARE LAW & COSINE CALCULATION

THE INVERSE-SQUARE LAW 3f d3= d2= d1=

t

2ft

as much. Moving out to a three-foot distance the area increases to nine square feet (3 2 = 9) and the illuminance is 1/9. This is the inverse relationship between the initial illuminance and the square of the distance from the source. The illustration on the lower right demonstrates how the cosine of the angle of incidence is used to calculate levels of illuminance when the light is directed at an angle. The light at point P has two vector components, one is horizontal and one is vertical. The measurement of illuminance on a horizontal surface only considers the effect of the vertical component. The cosine of angle A is used to calculate this value. This fractional value of the cosine represents the amount the illuminance is reducing the initial energy of the beam. The cosine of the angle B, then, may also be used to calculate the vertical illuminance.

USING THE COSINE CALCULATION A = Angle of Incidence I = Candelas (Cd) Cos A = v/d Horiz. Component (h) Cos B = h/d

B

1ft

d A

1 CANDELA (I)

E = I/d12 E = I/d22 E = I/d32

Vert. Component (v)

The point-by-point method of calculation gives the illuminance at an exact point rather than an average value. This is visualized by placing a light meter at the point of interest and reading the illuminance. This illuminance can also be predicted by the point-by-point method. The use of this method is based on the principle of the inverse-square law which demonstrates the illuminance (E) in footcandles or lux is equal to the luminance intensity of the source in candelas (Cd) divided by the distance from the source squared (d2), or (E=Cd/d2). This is shown below where the light source has a luminous intensity of one candela, furnishing one lumen over one square foot at a distance of one foot from the source. When the distance is doubled to 2 feet, the area increases to 4 sq. ft. (or 2 2 = 4) and the illuminance becomes 1/4

P HORIZONTAL ILLUMINANCE Ep = I/d2 x cos A

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RECOMMENDED LIGHTING LEVELS GENERAL CONSIDERATIONS Recommended lighting levels are intended to establish an adequate amount of luminous flux directed on a work plane or object to enable the easy and comfortable performance of identified specific visual tasks. They are measured in lux or footcandles, where 1 footcandle equals 10.76 lux. Common visual activities require a range of 500 to 1000 lux, with more detailed visual tasks needing 1500 to 2000 lux. Information on the following pages gives a range of recommended illuminances for specific and general tasks, from casual, less intense activities, to the more prolonged and more difficult visual tasks.

There is a long history of recommended lighting levels with a wide range of suggested values. The first ones were in the form of lighting codes issued in 1924. The Illuminating Engineering Society has published the latest recommended values in the 10th edition of their IES Lighting Handbook. They have been developed over the years through a procedure that includes new categories for determining recommendations like; target conditions, adaptation, technology, environmental constraints, energy efficiency, minimum, average, and maximum levels, and age (less than 25, 25 - 6 5, greater than 65 years).

ASPECTS OF LIGHTING THAT AFFECT RECOMMENDATIONS & ACCOUNT FOR ENERGY & AGE Decreased Allocation of Energy Devoted to Lighting: This has increased the amount of information and effort needed to adequately allocate lighting to locations and times when it is required. New Technology: Has produced new sources, tasks, and delivery of information, altering objects and spaces and the equipment to light them. Extending the role of designers and clients to respond to the tightened requirements, take advantage of new technology, and accommodate environmental concerns, requires flexibility in recommendations and information necessary to use that flexibility.

Extending the Role of Designers & Their Clients: This role to respond to tightened requirements, effectively take advantage of the new technology, and accommodate the environmental concerns, requires not only flexibility in the recommendations but also with regard to the information that will be necessary to implement the flexibility. Accounting for Energy: The need to account for energy has three aspects that help recommendations respond to the demands of reduced energy. 1.) The step size of the illuminances values of recommendations has been made

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small. 2.) Guidance is provided to help use the recomended illuminances in the form of a gauge. Average, minimum, and maximum are possible gauges, indicating a way to interpret illuminances when applied over areas or when minimum or maximum values are necessary. 3.) Many outdoor activity levels vary considerably with the location and time of the activities. Accounting for Age: Accounting where age reduces the transmittance of the lens and intraocular media of the eye reducing light reaching the retina. To account for this where at least half of the observers are at least 65 years old, then the recommended levels should be doubled. Accounting for Adaptation: Where the spectral response of the visual system changes with the state of adaptation. Past suggestions are based on the assumption the state of adaptation is only photopic to mesopic luminances. (see pg. 78 for photopic/mesopic information) Future Recommendations: Unless the IES’s role as the principle source of information and recommendations is successfully challenged, it will be the primary source of guidance embodied in these recommendations.

ILLUMINATION MEASUREMENT & CALCULATION

RECOMMENDED LIGHTING LEVELS QUANTITY & QUALITY OF LIGHTING LEVELS The importance of the distinction between the quantity and quality of lighting has been discussed over most of the last century. At times quantity has been considered separate from other important aspects of lighting with emphasis on providing adequate illumination for circulation and the performance of visual tasks – with less attention in the aesthetic aspects such as, color, visual comfort, and the psychological and physiological considerations. Nevertheless, since the quantity of light is an integrated aspect of the luminous environment it should be considered equally important. Foot candles and lux are units of measurement

used to identify lighting levels by lighting designers. One lux equals 0.0929 footcandles, or one footcandle equals 10.76 lux. However, since it is difficult to measure illuminance more accurately than ±10% most designers agree a 1 to 10 ratio is sufficiently accurate – where 10 footcandles approximately equals 100 lux. The tables of recommended lighting levels shown on the following pages give some general levels and some more specific recommendations. However, some individual situations and local requirements may require further modification of the levels. For more information refer to the latest edition of the IESNA Lighting Handbook.

LIGHTING LEVEL GENERAL GUIDELINES TASK CHARACTERISTICS Non-work related, casual occupation and circulation, relatively large scale tasks and dark adapted surroundings

RANGE OF ILLUMINANCES* LUX

FOOTCANDLES

20- 50-10 0

2- 5- 10

Work related with occasional moderate scale and size tasks, like a bank lobby,, auditorium, warehouse, and home areas

100- 150-20 0

10- 1 5- 20

Easy to normal office work, study library,, classrooms, some social activities with large size, high- contrast visual tasks

200- 300-50 0

20- 3 0- 50

Detail office work, supermarket, drafting, mechanical work, and sport activities with small size and low- contrast tasks

500- 750- 1 000

50- 75- 100

Prolonged very small size, low-contrast, extra cognitive and life-sustaining tasks in the fields of research and healthcare.

3000- 1000- 2 0000

300- 100- 20 00

* Levels are Min, Avg, Max, maintained after light sources operated 100 hours. The information on these pages has been adapted from the 10th Edition of the Lighting Handbook with permission from the Illminating Engineering Society of North America.

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RECOMMENDED LIGHTING LEVELS AREA / ACTIVITY

LUX

FOOTCANDLES

Auditoriums Assembly .................. 100-150-200 Social Activities .......... 50-75-100 Automotive Showroom .................... 500-750-1000 Service Area .............. 500-750-1000 Banks Lobby............................ 100-150-200 Teller Station ................. 500-750-1000 ATM Area ...................... 200-300-500 Barber/Beauty Shop..... 500-750-1000 Computer Station Ambient Lighting

White Screen Background.. 250-500-750 Dark Screen Background .. 200-300-500

10-15-20 5-7.5-10 50-75-100 50-75-100 10-15-20 50-75-100 20-30-50 50-75-100

25-50-75 20-30-50 50-75-100

Reference & Reading ..... 500-750-1000 Conference Rooms 20-30-50 General ......................... 200-300-500 50-75-100 Reading ........................ 500-750-1000 Drafting 50-75-100 Tracing Paper,Mylar...... 500-750-1000 Educational 20-30-50 Corridors ..................... 200-300-500 50-75-100 Classrooms .................. 500-750-1000 Auditoriums (see above) Laboratories .................. 1000-1500-2000 100-150-200 50-75-100 Study Hall ..................... 500-750-1000 Gymnasiums 50-75-100 High School ............... 500-750-1000 College ...................... 1000-1500-2000 100-150-200 Elevators 10-15-20 Passenger & Freight ..... 100-150-200 Food Ser vice 50-75-100 Kitchen ......................... 500-750-1000 10-15-20 Dining ........................... 100-150-200 25-50-75 Cashier, Cleaning ......... 250-500-750 Foundries 50-75-100 General Core Making ... 500-750-1000 Inspection .................... 1000-1500-2000 100-150-200 Graphic Design 50-75-100 Layout, Art Work .......... 500-750-1000

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AREA / ACTIVITY

LUX

FOOTCANDLES

Healthcare Anesthetizing................ 500-750-1000 Autopsy General .................... 500-750-1000 Exam Table ............... 000-3000-5000 Corridors Nursing,Day ............. 100-150-200 Nursing, Night .......... 50-75-100 Operating Rms,Labs.. 500-750-1000 Critical Care Areas General ..................... 100-150-200 Examination .............. 500-750-1000 Surgical .................... 5000-7500-10000 Dialysis Area ................ 1000-1500-2000 EKG .............................. 100-150-200 Emergency, Waiting ...... 100-150-200 Examination Room ....... 500-750-1000 Eye Surgery .................. 1000-1500-2000 Laboratories ................. 1000-1500-2000 Locker Rooms .............. 100-150-200 Medical Records .......... 500-750-1000 Nurseries General .................... 100-150-200 Observation ............. 500-750-1000 Nursing Stations General .................... 200-300-500 Desk ........................ 500-750-1000 Obstetrics Labor Rooms ........... 500-750-1000 Birthing Rooms ....... 1000-1500-2000 Delivery Area ........... 2000-3000-5000 Recovery Area .......... 500-750-1000 Patient Rooms General .................... 50-75-100 Examination ............. 500-750-1000 Reading .................... 200-300-500 Toilets ...................... 200-300-500 Pharmacy General .................... 500-750-1000 Consulting Area ....... 200-300-500 Night Light ............... 20-30-50

50-75-100 50-75-100 200-300-500 10-15-20 5-7.5-10 50-75-100 10-15-20 50-75-100 500-750-1000 100-150-200 10-15-20 10-15-20 50-75-100 100-150-200 100-150-200 10-15-20 50-75-100 10-15-20 50-75-100 20-30-50 50-75-100 50-75-100 100-150-200 200-300-500 50-75-100 5-7.5-10 50-75-100 20-30-50 20-30-50 50-75-100 20-30-50 2-3-5

ILLUMINATION MEASUREMENT & CALCULATION

RECOMMENDED LIGHTING LEVELS AREA / ACTIVITY LUX

FOOTCANDLES

Healthcare ...continued Physical Therapy Gymnasium ........... 200-300-500 20-30-50 Treatment Area ....... 500-750-1000 50-75-100 Radiology General, Waiting..... 200-300-500 20-30-50 Treatment Area ....... 500-750-1000 50-75-100 Solarium General .................. 100-150-200 10-15-20 Reading.................. 200-300-500 20-30-50 Stairways ............... 100-150-200 10-15-20 Surgical Areas Operating Rm.......... 1000-1500-2000 100-150-200 Scrub Room............ 500-750-1000 50-75-100 Holding Area .......... 500-750-1000 50-75-100 Waiting Area .......... 200-300-500 20-30-50 Hotels Rooms ................ 200-300-500 20-30-50 Bathrooms ............... 200-300-500 20-30-50 Lobby ...................... 100-150-200 10-15-20 Front Desk ............... 500-750-1000 50-75-100 Corridors, Stairs ...... 200-300-500 20-30-50 Elevators .................. 100-150-200 10-15-20 Laundries Washing, Drying ...... 200-300-500 20-30-50 Ironing, Folding ....... 500-750-1000 50-75-100 Libraries Book Stacks ............. 200-300-500 20-30-50 Cataloging, Repair ... 500-750-1000 50-75-100 Reading Area ............ 200-300-500 20-30-50 Check Out Desk ....... 500-750-1000 50-75-100 Locker Rooms ........ 200-300-500 20-30-50 Restrooms ................ 200-300-500 20-30-50 Machine Shops Simple BenchWork .. 200-300-500 20-30-50 Medium Bench Work 500-750-1000 50-75-100 Precision Work .........2000-3000-5000 200-300-500 Materials Handling Loading Areas .......... 200-300-500 20-30-50 Stock Picking ............ 500-750-1000 50-75-100 Packing, Wrapping .... 500-750-1000 50-75-100

AREA / ACTIVITIES Offices Accounting ................... Conference ................... Audio-Visual ................ General & Priv. Offices.. Corridors ...................... Reception, Lobbies ....... Mail Room ................... Restrooms .................... Lunch, Break Areas ...... Print Shops Composing Room ........ Press Area .................... Color Inspection .......... Proof Reading .............. Reading Offset Printing .............. Ink Jet, Laser Printing...... Impact Printing ............ Poor Copies ................. Keyboards .................... Ballpoint Pen Writing.... Soft Pencil Writing ....... Hard Pencil Writing ...... Retail General Ambient ........... Self-Service Areas ....... Circulation ................... Stock Rooms ................ Grocery General ........... Grocery Circulation....... Accent Lighting ............ Warehouse & Storage Large Items & Labels...... Med. Items & Labels...... Small Items & Labels...... Cold Storage ................ Inactive ......................... Woodworking Rough Work ................. Fine Work/Finishing .....

LUX

FOOTCANDLES

500-750-1000 500-750-1000 200-300-500 500-750-1000 100-150-200 100-150-200 500-750-1000 200-300-500 200-300-500 500-750-1000 500-750-1000 1000-1500-2000 1000-1500-2000 200-300-500 200-300-500 500-750-1000 500-750-1000 200-300-500 200-300-500 500-750-1000 100-150-200 500-750-1000 1000-1500-2000 200-300-500 200-300-500 500-750-1000 200-300-500 2000-3000-5000

50-75-100 50-75-100 20-30-50 50-75-100 10-15-20 10-15-20 50-75-100 20-30-50 20-30-50 50-75-100 50-75-100 100-150-200 100-150-200 20-30-50 20-30-50 50-75-100 50-75-100 20-30-50 20-30-50 50-75-100 10-15-20 50-75-100 100-150-200 20-30-50 20-30-50 50-75-100 20-30-50 200-300-500

100-150-200 200-300-500 500-750-1000 200-300-500 100-150-200

10-15-20 20-30-50 50-75-100 20-30-50 10-15-20

200-300-500 500-750-1000

20-30-50 50-75-100

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CHAPTER

7

LIGHT SOURCES & COMPONENTS Contemporary light sources require some form of electrical power, while it wasn’t that long ago that candles and whale oil lamps furnished all our lighting needs – even though a form of electricity was discovered as far back as 600 BC. Greek philosopher and mathematician Thales, noticed that when a piece of amber was rubbed with a cloth, it would attract, and then repel small objects brought near it. This phenomenon remained lost for two thousand years until Dr. William Gilbert (Queen Elizabeth’s physician) repeated the experiment in the year 1600 with amber rubbed with a cloth and called it “electrica” after the Greek word for amber. By January of 1879, Thomas Edison had his first incandescent electric lamp. It worked by passing electricity through a thin platinum filament in a glass vacuum bulb, but the lamp only burned for a few short hours. Edison then tested thousands of other materials for the filament. He even thought about using tungsten, the material used for light bulb filaments now, but was unable to work with it due to the limited tools available to him. He began testing materials including carbonized filaments of many natural materials, like boxwood, hickory, cedar, flax, and bamboo. Before he finished he had tested up to six thousand different vegetables, and ransacked the world for the most suitable material. Some time later Edison finally decided to try carbonized cotton thread as a filament, and when voltage was applied to the completed bulb, it began to radiate a soft orange glow. However, about fifteen hours later, the cotton filament burned out. Further experimentation produced filaments that could burn longer and longer with each test. A US Patent number 223,898 was given to Edison’s electric lamp.

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LIGHT SOURCES & COMPONENTS

LIGHT SOURCE SELECTION HIGH-PERFORMANCE SOURCES High-performance light sources offer the ability to meet existing lighting and energy codes. The sources available include a variety of energyefficient lamps and systems such as, LED, T5 fluorescent, halogen, and ceramic metal halide. Used with electronic components and controls they can easily achieve ASHRAE’s suggested existing and future Lighting Power Densities.

Light-Emitting Diodes (LED) are solid-state semi-conductor devices that produce a range of both white and saturated colors of light. In addition, they offer significant energy efficiency. Lamp efficacy of common LED sources can range from 50 to 300 lumens per watt with a wide range of lamp configurations available. Their small size, color temperature, and color mixing capabilities offers a wide choice of types and sizes suitable for many of the traditional lighting applications – and fortunately, are also especially suitable for use in built-in custom architectural elements and details. LED lamp light output is rated in lumens rather than watts, like incandescent lamps, and sometimes has the equivalent incandescent wattage shown on the packaging to assist in the new user’s confusing transittion to LED light sources. (see below). INCANDESCENT WATTS TO LUMENS EQUIVALENT INCAND. WATTS 40 . . . . . . . . . . 60 . . . . . . . . . . 75 . . . . . . . . . . 100 . . . . . . . . . 150 . . . . . . . . .

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. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

LUMENS . . . . . . . . . . 450-500 . . . . . . . . . . 800-900 . . . . . . . . . . . . 1100 . . . . . . . . . . . . . 1600 . . . . . . . . . . . . . 2000

Organic light-emitting diodes (OLED) are light-emitting diodes in which a thin film of an organic compound emits light in response to electric current – they present a future promise as an efficient, thin, and flexible light source.

Linear Fluorescent lamps called high-output, have a efficacy of a minimum of 90 mean lumens per watt (MLPW) and a CRI of 82 or higher. Mean lumens is the light output at 40% of the lamp's rated life. CRI is a measurement of a lamp’s ability to accurately show colors on a scale of 0 to 100, with lamps needing a CRI of 80 or more for accurate color perception. High performance is achieved by increasing output while keeping the same input as a standard lamp or reducing the wattage while keeping the light output similar to a standard lamp. The light output will also vary by the color temperature. High output T5 lamps offer at least 90 MLPW with any available ballast. When used in optimally designed luminaires, they offer high efficiency even operating on dimming ballasts.

High-Performance Ballasts for fluorescent lamps offer energy savings utilizing a combined lamp and ballast system. High output versions will have a ballast factor (BF) of 1.15 or greater, and when operated with a two-lamp ballast can furnish a much higher efficiency and light output.

Program Start Ballasts are used on lamps frequently switched on and off more than five times a day, extending lamp life. Instant start T8.

LIGHT SOURCES & COMPONENTS

LIGHT SOURCE SELECTION

ballasts give greater energy savings and lower cost, however, when controlled with occupancy sensors or daylight switching systems, they reduce lamp life. They are used to achieve recommended Lighting Power Densities with T5 and T5HO (High-Output) lamps because their lumens per watt compare to high output T8 s. When evaluating the lamp and ballast as a system, high-performance T8 perform better than T5HO. T5 s have a higher brightness and should not be used as exposed lamps.

Compact Fluorescent lamps are generally considered as a high-efficiency source, used for a variety of general lighting installations. They are defined as high-performance if having a lamp efficacy of 55 or more lumens per watt, based on mean lumens divided by lamp watts, and a CRI of 82 or greater. Electronic ballasts should be used with all compact lamps, but are less efficient than linear fluorescent lamps, and not adaptable to beam-controlled accent lighting.

Ceramic Metal Halide lamps have an efficacy of 50 or more mean lumens per watt and a CRI of 81 or greater when operated on electronic ballasts to obtain an energy-efficient operation. However, their high efficacy is offset by their high rate of lumen depreciation, requiring a warm-up and re-strike time of as much as one minute if turned off during operation, requiring a supplemental source during the re-strike time.

Halogen lamps are an incandescent-type lamp that is filled with a small amount of gas, usually

iodine or bromine gas to a high internal pressure to maximize lamp efficacy. The gas creates a cycle which redeposits evaporated tungsten back onto the filament, increasing lamp life and the clarity of the glass bulb. Halogen IR lamps have a lamp efficacy of 20+ lumens per watt using a thin film on the inside of the bulb redirecting energy to the filament, increasing light output. Even though ceramic metal halide lamps are more efficient there are instances where the use of CMH lamps is not practical due to cost considerations. Halogen PAR30IR and PAR38IR lamps are suggested also, because they are especially adaptable for typical accent and track lighting applications. TYPICAL LAMP PERFORMANCE CHARACTERISTICS LAMP TYPE

LUMENS PER WATT RATED LIFE (hrs)

Edison’s First Lamp Incandescent Halogen Compact Fluorescent Fluorescent Metal Halide High Pressure Sodium Light-Emitting-Diode

1.4 05 - 25 15 - 40 25 - 80 75 - 100 65 - 120 80 - 140 30 - 200

? 750-2000 2000-6000 9000-20,000 5000-36,000 10,000-20,000 10,000-40,000 12,000-50,000

ASHRAE‘s Advanced Energy Design Guide series gives extensive, detailed energy management and design recommendations for different building types to achieve a 30% and 50% energy saving. To incorporate up-to-date and detailed energysaving design recommendations, a periodic download and review of all current ASHRAE Advanced Design Guides is highly recommended.

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LED LAMPS

1-5 mm (0.04-0.20 in)

DIFFUSER LENS

CATHODE LEAD

LED ARRAY

PLASTIC OR EPOXY LENS

GOLD CONNECTING WIRES DRIVER ELECTRONICS

SILICONE ENCAPSULENT SEMICONDUCTOR CHIP/DIE HEAT SINK

SINGLE LAMP MODULE

Characteristics

Light-Emitting Diodes have been around and in use for a number of years in areas of automotive and aviation indicator lights, and traffic signals. White LEDs, however, were not available until the end of the 20th century when a new method was found to convert blue LEDs into white light. LEDs primary advantages are high lumens per watt and a long life, surpassing incandescent by thousands of hours. They are also very durable.

Operating Characteristics LED lamps give off light by the process known as electroluminescence, where semiconducting materials emit light when electrical current is passed through them. A semiconductor is a special diode material that has a varying ability to conduct electricity. When two different materials are bonded together a diode is created, which is a semiconductor device with two connections that conducts electricity in only one direction. If electricity is passed through a

128

HEAT SINK MEDIUM SCREW BASE

MULTIPLE LED LAMP

diode the atoms are excited to a high energy level and shed electrons from one material to the other in the semiconductor chip, releasing energy as photons (basic units of light) at the junction of the two semiconductor materials. Semiconductors are made by bombarding materials like germanium or silicon with atoms of phosphorus or boron. This is called doping and converts the materials into semiconductors, changing their electrical conducting properties, creating two different types of semiconductors in the same crystal material. Undoped materials will have all their atoms perfectly bonded to their neighbors, with no free electrons available (the negative charged particles) to conduct electricity. In doped materials, the added impurities change the electrical balance by creating free electrons or areas called electron holes. The boundary between the two semiconductor materials is identified as the (p-n) junction.

LIGHT SOURCES & COMPONENTS

LED LAMPS Electrical Characteristics: A result of doping semiconductor materials is one layer creates electron holes (where electrons would be), giving it a positive charge (p-type), and the other layer would have extra electrons, giving it a negative charge (n-type). LEDs require a electronic device, called a driver, that converts AC power into low-voltage DC power, and maintains a constant current. An LED diode has the n-type material bonded to the p-type material, with electrodes on each end. When the negative electrical circuit is connected to the n-type material and the positive side to p-type layer, current flows from the p-type layer to the n-type layer, but will not flow in reverse. The free electrons in the n-type material are repelled by the negative electrode and drawn to the positive electrode. The holes in the p-type material layer move the other direction. When the holes and electrons meet at the p-n junction, the electrons release energy as they move from a high-energy orbit of the atom to a lower orbit, releasing their energy in the form of photons of light. RELEASED PHOTONS OF LIGHT

p TYPE SEMICONDUCTOR MATERIAL WITH NO NEG. CHARGED ELECTRONS

p-n JUNCTION (BAND GAP) n TYPE SEMICONDUCTOR MATERIAL WITH NEG. CHARGED ELECTRONS

LIGHT GENERATION FROM A LIGHT-EMITTING DIODE The p-n junction is where the photons of light are generated and materials are bonded together called the band gap (energy in a solid where no electron activity can exist with difference in volts between the n-type and p-type material ) or energy needed to free electrons to move to a lower orbit. Materials with large band gaps are insulators, those with small band gaps are semiconductors.

Physical Characteristics: There are 3 common types of LED lamps; miniature, mid-range, and high-powered. The mid-range and high-power ones are most suitable for architectural use. Single LEDs are very small, typically less than 1mm. Most products are multiple lamp arrays to simulate many existing conventional light sources – identified as a Chip-on-Board (COB), packaged together as one lighting module. They incorporate LED chips mounted on a substrate or printed circuit board, have an advantage of thermal resistance, larger cooling area, better lighting effect, and high light efficacy. The number of LEDs that can be mounted on a 10 x 10mm base can range from 9 to over 300. CONNECTING WIRES PRINTED CIRCUIT BOARD

1± mm ENCAPSULATION

LED CHIP OR DIE

INDIVIDUAL CHIP USED IN A MULTIPLE LED ARRAY

After the materials are doped, they are cut into individual wafers and those with different electrical characteristics are bonded to create the diode. The light generated at the diode is in a small space (a point source), where heat cannot be easily dissipated, and requires heatsinking. The chips are encapsulated and covered with a clear or colored molded plastic shell (or lens), with a domed top and a reflective base, making mounting chips easier, and protecting the small and fragile wiring. Because adjacent points of light are perpendicular, directing light within a small concentrated area, the curved shell diffuses and redirects the light into a wider distribution, somewhat reducing the concentration. continued . . .

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LIGHT SOURCES & COMPONENTS

LED LAMPS Color Characteristics: The color of light from LED sources can be intense and saturated. Some consider it to be overly bright and a major source of glare. However, the saturated colors and the availability of an extensive range of colors, accounts for its wide acceptance as a versatile source of color in the field of lighting. The actual color of LED light depends entirely on band gap energy of different types of materials utilized forming the p-n junction (see below). COLOR

SEMICONDUCTOR MATERIAL

Blue UV Diode with Yellow Phosphor GaAs: Gallium Arsenide INFRARED AlGaAs: Aluminium Gallium Arsenide AlGaAs: Aluminium Gallium Arsenide GaAsP: Gallium Arsenide Phosphide AlGainP: Alum. Gallium Indium Phosphide RED GaP: Gallium(lll) Phosphide GaAsP :Gallium Arsenide Phosphide AlGainP: Alum. Gallium indium Phosphide ORANGE GaP: Gallium(lll) Phosphide GaAsP: Gallium Arsenide Phosphide AlGainP: Alum. Gallium Indium Phosphide GaP: Gallium(lll) Phosphide YELLOW InGaN: Indium Gallium Nitride GaN: Gallium(lll) Nitride GaP: Gallium(lll) Phosphide AlGainP: Alum. Gallium Indium Phosphide GREEN AlGaP: Alum. Gallium Phosphide ZnSe: Zinc Selenide BLUE InGaN: Indium Gallium Nitride VIOLET InGaN: Indium Gallium Nitride Dual Blue & Red LEDs PURPLE Blue LED with Red Phosphor or White LED with Purple Enclosure AlN:Aluminium Gallium Nitride ULTRAAlGaP:Aluminium Nitride VIOLET BN:Boron Nitride Diamond WHITE

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Different materials can have band gap energies that correspond to a variety of lightwavelengths, such as near-infrared light, near- ultraviolet and and a wide range of visible light. High-intensity white light can be made in two different ways. 1.) three individual LEDs that emit the primary colors of red, green, and blue (RGB), that are mixed to form white light. 2.) is a phosphor coating used to convert light from a blue or ultraviolet LED to white light, similar to a fluorescent lamp. White LEDs are available in typical ranges of warm and cool color temperatures. The ability of light to render the color accurately is very subjective. The Color Rendering Index (CRI) is used to measure this. It’s a method adopted and used by the lighting industry to measure the colorrendering quality of a light source. However, its ability to accurately evaluate the light from LEDs has been discovered to be considerably deficient. End of Life Considerations: LED light sources fail in many ways, the LED itself, the driver, the wiring, or optical and thermal components. Most components are expected to fail at about the same time, but a common symptom is the gradual reduction of light caused by the clouding of the clear encapsulant. Degradation of the phosphor on phosphor-coated white lamps is another mode of early failure. Useful life is considered to be approximately 50,000 hours, or when the lumen output drops to about 70%. Some LED assemblies are not easily serviceable because of their integrated construction, while many modular units that isolate the components eliminate this replacement problem. In some situations, due to the extended lamp life, the driver may fail before the LED. Life is also affected by the surrounding temperatures. Used in climates where it gets very hot, results in low output or even failure. Otherwise, light output will increase somewhat at lower temperatures.

LIGHT SOURCES & COMPONENTS

LED LAMPS REPRESENTATIVE LAMP TYPES LED lamps are available in a wide range of shapes and sizes with many that simulate conventional sources with modifications for the small chip size, different electrical requirements, and heat dissipation. Modules are available in both linear and area configurations suitable for architecturally integrated lighting elements. Regularly spaced LEDs, on linear strips or area modules, furnish an even and diffuse light distribution when properly located away from translucent coverings and architectural surfaces.

These LED characteristics offer an economical alternative to existing linear fluorescent sources. Low-power and high-efficacy LEDs in a regular layout also eliminates the need for heat sinking for some applications. LED modules are available with integrated driver and dimming circuits to simplify electrical installation and furnish digitally enabled luminaires. Usually low voltage, they are available for direct AC power operation in a range of colors and in warm or cool colors of white light from 3000K to 5000K.

See page 141 for a complete description of lamp shapes, sizes, and names

MR16 PAR16 PAR20 R20 GU10 Medium Medium Medium

R20 Medium

PAR20 Medium

PAR38 Medium

PAR30 Medium

PAR30 Medium

CA11 A19 A19 Candela Medium Medium

PAR38 Medium

BR30 Medium

G19 Medium

G25 Medium

BR30 Medium

G25Slim Medium

BR30 Slim Corn Bulb Medium Medium

Modular Linear Strips 9 Chip Array

Single Modules

Tubular (T8) Linear Lamps

Thin Flexible Strips

G4 Miniature

NOTE: LED lamps operate on low voltage or 120 to 277 volts. Some lamps have integrated drivers, others require external drivers, most are dimmable. Lamps shown are only representative of the wide range of currently available lamps and future types and configurations. HISTORICAL NOTE: In 1962 Nick Holonyak Jr. of General Electric invented the first visible-spectrum LED in the form of a red diode.

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LIGHT SOURCES & COMPONENTS

FLUORESCENT LAMPS

BULB FILLED WITH ARGON GAS AND MERCURY VAPOR

BASE

PHOSPHOR COATING ON INSIDE OF BULB

Characteristics

Light generated by a fluorescent lamp is from a gas-discharge action that consists of a flow of electrons emitted by the cathodes located at each end of the glass tube. There is a small bit of mercury plus an inert gas, typically argon, in the tube and kept under low pressure. The inside of the glass tube has a phosphor coating and two electrodes, one at each end. When electrical current flows through the electrodes electrons move through the gas from one end of the tube to the other. This energy excites the mercury atoms within the glass tube and causes them to give off radiation. The major portion of this radiation is in the invisible short-wave ultraviolet range, and the phosphors that coat the inside of the glass bulb convert this energy into visible light. The color of the light and other operating characteristics can be controlled by using different combinations of phosphors.

Operating Characteristics Fluorescent lamps operate on a principal of a hot-cathode. There are two types of cathodes, hot and cold. The cold-cathode method is found in light sources like neon lamps. The

132

CATHODE

hot-cathode is a coiled tungsten filament impregnated with electron-emissive materials. The operating temperatures are about 950°C for hot-cathode and 150°C for cold-cathode. With fluorescent lamps at this temperature electrons are emitted with a small wattage loss at each cathode. The voltage drop at the cathodes for cold-cathode lamps is higher than hot-cathode. This results in higher wattage loss, more heat, and lower lamp efficiency. These small diameter lamps are used for signs and other bent shapes and offer instant starting. Light from fluorescent sources are emitted at the perimeter of the bulb, and the entire tube becomes the light source. Because light is generated over the entire bulb the average brightness is low when compared to other light sources like incandescent. This low brightness may be desirable, however, it may also furnish an overcast, or flat, luminous environment. The brightness of an incandescent or compact fluorescent lamp may be 30 to 40 times brighter than a fluorescent lamp, while an LED lamp may be 60 to 80 times, or more, brighter.

LIGHT SOURCES & COMPONENTS

FLUORESCENT LAMPS Light from fluorescent lamps is produced by an electronic method, in contrast to the less efficient electric heating process used in the incandescent lamp. The fluorescent lamp is

about three to four times more efficient in luminous efficacy than filament-type lamps. This also results in a significant longer average operating lamp life than incandescent lamps.

Electrical Operation: Fluorescent lamps are known as negative resistance devices where the electrical resistance drops as more current goes through them. If connected to a constant-voltage power supply lamps will self-destruct. To prevent this, they must be connected to a ballast to regulate the current flow.

There is also the question of leaving a lamp on or turning it off and on. Electronic ballasts use a large startup current, but for only a fraction of a second, using a small amount of current when compared with the on time. Turning the lamps on and off frequently does reduce a lamp’s life a little. However, leaving them on all the time also reduces a lamp’s life. The on and off option reduces total hours, but extends life because they operate only when needed.

Rated & Average Output: The rated lumen output is based on a seasoned lamp measured at 100 hours of life. Initial output will be slightly higher, but will drop quickly. Average output over the life of the lamp will be about 85% of the rated output. This output loss is due in part to the evaporation of electron-emissive material from the hot cathodes, resulting in some blackening at the ends of the bulb. There is also some decay of the interior phosphor. Relative Light Output: Some of the preferred colors and color rendering qualities require the use of special phosphors that generate added energy at a specific wavelength. These phosphors are often less efficient, resulting in some efficiency and light loss.

Lamp Life: The filament-type cathode at the ends of a fluorescent lamp is coated with an electron-emissive material. When the lamp is on, this material is used up, and the lamp fails. Since this happens mostly during lamp start up, the lamp life is, in part, related to the number of starts. Ballasts also contribute to lamp life, being heavily dependent on operating temperature. For each 10°C temperature rise above the optimum temperature of 25°C, the life is halved. A compact fluorescent lamp with an integral ballast used base-up will result in hotter electronics, which can reduce lamp life. The lamp phosphor efficiency can drop over time and cause half brightness.

Operating Temperature: Fluorescent lamps are sensitive to bulb wall temperature. Efficiency and output drop if the lamp is operated above or below optimum. Low temperatures condense the mercury vapor on the bulb, reducing the ultraviolet radiation. Lamp Flicker: Where current is reduced to zero with each half-cycle of AC current, a variation in the light magnitude occurs, which some people perceive as flicker. Even a stroboscopic effect can be noticed, where something spinning at just the right speed may appear stationary or perhaps, spinning in reverse. The use of two-lamp lead-lag ballasts will minimize by using a split-phase operation. The use of electronic ballasts will eliminate the light flicker. Color Rendering Index (CRI): A measure of how

well colors can be perceived using light from a source, in comparison to light from a reference source such as daylight or a blackbody of the same color temperature. An incandescent lamp has a CRI rating of 100. Fluorescent lamps achieve CRIs in a range of anywhere from 50 to 99. Fluorescent lamps with low CRI have phosphors that emit too little red, light making colors appear less pink, and somewhat unnatural when compared to incandescent lighting. Colored objects will also appear to be muted.

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LIGHT SOURCES & COMPONENTS

FLUORESCENT LAMPS BALLASTS & CIRCUITS When a fluorescent lamp starts, the current in the arc will increase very rapidly, causing the lamp to become inoperative, unless there is a device in the circuit to limit the surge of current

with a constant-voltage. This is the primary function of the ballast, which is designed to exactly match all of the electrical operating requirements of each lamp type and size.

Electronic Ballasts incorporate a design that

Magnetic Ballasts are an older type of ballast,

uses advanced electronics to precisely regulate the current flowing through the electrical circuit. Since they use a higher cycle rate, there is less flicker or humming noise from an electronic ballast. Different lamps require specific ballasts designed to maintain the voltage and current.

which regulates the current by use of magnetic inductor circuits. They modulate the current at a low cycle rate, which can cause a noticeable flicker. They may also vibrate at a low frequency – the source of audible humming people would associate with fluorescent lamps.

Pre-Heat Circuits require heating before the lamp will start. When the starter switch opens, electrons given off by the heated electrodes strike an arc through the gas-filled lamp – with the assistance of the voltage surge supplied by the ballast – and the lamp lights. A simple choke circuit works with shorter lamp lengths, but a step-up transformer is needed with longer lamps.

Rapid-Start Circuits use low voltage cathodes that are pre-heated by the windings (H) in the ballast, eliminating the need for starters. Then the autotransformer furnishes a low current discharge through the lamp. As the cathodes heat up, current builds to full output in seconds. Having the cathodes continuously heated also enables the lamps to be dimmed or flashed.

AC POWER

CHOKE

STEP-UP TRANS CAPACITOR STARTER LAMP

CAPACITOR AC POWER

HEATER PRIMARY SECONDARY HEATER

LAMP

Instant-Start & Electronic Circuits use a high initial voltage for starting, eliminating the need for starters or pre-heating. Electronic ballasts use a solid-state circuitry and a power frequency of 20,000 Hz or higher in place of the standard 50 - 60 Hz, offering increased output, less weight, and no flicker. The higher initial cost will be compensated for by the energy reduction.

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AC POWER

STEP-UP TRANS

CHOKE

LAMP LAMP TWO-LAMP LEAD-LAG CIRCUIT

LIGHT SOURCES & COMPONENTS

FLUORESCENT LAMPS REPRESENTATIVE LAMP TYPES PRE-HEAT & RAPID START

SLIMLINE & HIGH OUTPUT

T5 MINIATURE BIPIN (5/8" DIAMETER)

T5 SINGLE PIN (5/8" DIAMETER)

T8 MEDIUM BIPIN (1" DIAMETER)

T8 & T12 SINGLE PIN (1" & 1-1/2" DIAMETER)

T12 MEDIUM BIPIN (1-1/2" DIAMETER)

T12 RECESSED DBL CONTACT (1-1/2" DIAMETER)

ABOVE LAMPS AVAILABLE IN TYPICAL SIZES OF 18" 24" 36" 48" 60" 72" 96" WITH 7000 TO 24000 HOUR LAMP LIFE. AVERAGE RATED LIGHT OUTPUT FOR THE POPULAR 32 WATT 48 INCH LAMP RANGES FROM 2850 TO 2950 LUMENS.

22-1/2" 6.5", 5.5", 8.1"

T9 CIRCLINE

4 PIN COMPACT

3-5/8"

22-1/2"

6"

8.25",12", 16"

1-5/8"

T8 & T12 U-SHAPE

COMPACT PLUG-IN

4 PIN 2 PIN 2 PIN 4 PIN SINGLE DOUBLE DOUBLE TRIPLE

4 PIN DOUBLE HIGH OUTPUT

COMPACT SELF-BALLASTED

DOUBLE MED BASE

TRIPLE MED BASE

SPRIAL SPRIAL A-LINE MED BASE

PAR20 FL PAR30 FLOOD

PAR38 FLOOD

A-LINE MED BASE

CANDLE GLOBE MED BASE MED BASE

PAR40 FLOOD

POST

LOTUS

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LIGHT SOURCES & COMPONENTS

FLUORESCENT LAMPS LAMP & BALLAST WIREWAYS SINGLE-LAMP CHANNELS 4-3/16"

3-1/8"

1-7/8"

SIDE-MOUNT CHANNEL

2-3/4" 1-7/8"

1-7/8"

1-7/8" 2-1/8"

1-5/8" 2-1/8"

2-3/4"

2-3/4"

1-7/8" 2-1/8"

2-3/4"

WIRING CHANNELS ARE GENERALLY WHITE BAKED ENAMEL FINISH. LAMPS SHOWN ARE T8 (1") AND T12 (1-1/2") UNLESS OTHERWISE NOTED.

MULTIPLE-LAMP CHANNELS 9-1/2"

4-7/8"

3 LAMP CHANNEL

1-7/8" 2-7/8"

2-3/4"

4-1/8" 1-7/8" 2-7/8"

1-7/8" 1-7/8"

4" - 5-3/8"

7-5/8"

THE REFLECTORS ARE TYPICALLY WHITE BAKED ENAMEL, SPECULAR AND ETCHED ALUMINUM FINISH

2-3/8"

6-1/2" 5-3/16"

3-1/2" - 5-1/2"

4-3/4"

4"- 5"

REMOTE BALLAST WIREWAYS

FOR T5-T6-T8 LAMPS

6 -1 /1 -2

2-5/8"

1- 1 /2

1-3/4"

2-1/4" 2-1/4"

1-1/8" 7/8"

1-7/8"7/8"

1-7/8"

1-7/8" 1"

2-3/4"

1-3/8"

1-1/4"

1-3/4"

1-3/8"

2-1/4"

136

4" - 6-1/4"

4"

2-7/8"

2-3/8"

ACCESSORY REFLECTORS

LIGHT SOURCES & COMPONENTS

HALOGEN LAMPS

FILAMENT IN GAS-FILLED QUARTZ BULB

FILAMENT IN GAS-FILLED QUARTZ BULB OUTER BULB 2-PIN BASE MEDIUM BASE

PAR LAMP

FILAMENT OUTER BULB GAS-FILLED QUARTZ BULB LEAD-IN WIRES MEDIUM BASE

MR LAMP

Characteristics Halogen lamps are incandescent lamps filled with a small amount of gas, such as iodine, at a high internal pressure that maximizes lamp efficacy. The action of the tungsten filament and the internal gas creates a cycle which redeposits evaporated tungsten back onto the filament, increasing lamp life and the clarity of the glass bulb. Because of this, halogen lamps can be operated at much higher temperature producing light with an increased luminous efficacy and color temperature. Halogen IR lamps have an high efficacy of 20 plus lumens per watt by using a reflective thin film on the inside of the bulb to redirect thermal energy back through the filament, resulting in even more light output.

Operating Characteristics Incandescent lamps are inefficient due to the process of radiating light, and a large amount of infrared heat – more heat than light. Lamp life and output is reduced over time because the tungsten in the filament evaporates and deposits on the inner bulb surface, the thinner filament breaks, and the lamp burns out. The tungsten filament is encased inside a small

BI-PIN LAMP

A LAMP

quartz bulb. An ordinary glass bulb would melt from the heat of the filament. The gas inside the small strong quartz bulb is a halogen gas which combines with tungsten as it evaporates and redeposits on the filament allowing the filament to last longer and run hotter with more light. There is a lot of heat generated and the quartz envelope and outer bulb gets very hot.

Operating Temperatures

The operating temperator supports the selfcleaning cycle of the lamps. The filament tube temperatures should never go below 482°F (250°C). Hot spots on the bulb wall itself may go up to 1230°F (700°C). Due to the heat fixture design should allow for the dissipation of heat. Halogen lamps used in extremely confined fixtures may require extra ventilation to ensure the tungsten redepositing cycle and prevent any fixture damage. Good practice recommends a test of the lamp in the expected operating environment early in the design to guarantee safe and useful performance. Smaller lamps permits use in compact systems. Extra care must be taken in the selection of materials . . . Continued next page

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LIGHT SOURCES & COMPONENTS

HALOGEN LAMPS for lampholders, reflectors, and lamp housings because the bulb wall temperature may be greater than the kindling temperature of many materials. Lamp base temperatures should not exceed 662°F (350°C) because, above that, lead wires may deteriorate and the base cement will loosen, causing a premature lamp failure.

amounts of ultraviolet energy are required. Ultraviolet radiation can cause skin and eye irritation under extended exposure. However, light passing through ordinary glass, such as the outer bulb, gives adequate protection. For example, the glass lens of the halogen PAR lamp would provide more than adequate protection.

Spectral Distribution of halogen lamps is

Caution: Both the outer glass bulb and internal filament tube of halogen lamps operate at high temperatures and could unexpectedly shatter. If the outer bulb breaks, particles of extremely hot glass could discharge into surrounding areas, creating a serious risk of personal injury or fire.

made up of both visible and infrared radiant energy. This energy originates from a relatively small light source. About 90% of the energy is in the infrared range. Some lamps can be utilized for special applications where small

REPRESENTATIVE LAMP TYPES Incandescent light bulb shapes and sizes are identified with a letter and a number. The letter gives the shape and the number the maximum diameter of the bulb in eighths of an inch. For

BT19 Medium

A19 Medium

PAR16 Medium

R20 PAR20 Medium Medium

QUARTZ T3 Recessed SC

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BT14.5 Medium

PAR30 Medium

QUARTZ T3 Recessed SC

G25 Medium

PAR30L Medium

QUARTZ T3 Recessed SC

example, an A19 lamp is 19/8 (2-3/8) inches in diameter. The different incandescent lamp base sizes are Candela, Intermediate, Medium, Mogul, screw type, and Side Pin and Bayonet.

T10 Medium

G16.5 Medium

BR30 Medium

PAR36 Screw Term.

QUARTZ T4 DC Bayonet

G16.5 Candela

PAR38 Medium

QUARTZ T4 2-Pin

B10 Medium

B10 Candela

PAR56 Mog End Prong

MR11 2-Pin

MR16 2-Pin

LIGHT SOURCES & COMPONENTS

INCANDESCENT LAMPS

EFFECTIVE LIGHT SOURCE

EFFECTIVE LIGHT SOURCE

FILAMENT GAS-FILLED BULB LEAD-IN WIRES LAMP BASE

CLEAR LAMP

INSIDE-FROSTED LAMP

Characteristics Incandescent lamps offer a simple option in a light source. Since no current regulation is needed and only a lamp holder is needed for its operation, it is simply “a hot wire in a bottle.” The hot wire is a coil of tungsten wire heated to incandescence by passing an electric current through it, and the bottle is a sealed glass bulb. Its efficiency is inherently low, at 1/3 of a fluorescent source and 1/10, or less, of LED sources. However, efficiency is not the sole factor in a lighting system, and the advantages of control and simplified installation can make up for low efficiency. Despite these shortcomings, they have a record of versatility and wide use. Diffuse sources have the bulb other than clear glass to inside-frosted or coated, resulting in the distribution of light being modified. The filament point source is subordinated and the surface of the bulb becomes the effective light source. Light acid treatment to the inside of the bulb produces the inside-frosted lamp which tends to soften the sharp shadows associated with clear

COATED LAMP

lamps. Another method is the use of a fine white coat of silica deposited on the inside of the bulb, producing relatively good light diffusion, with approximately the same light output as the inside frosted lamp. An enameled coating on the inside or outside of the bulb is another way to diffuse the filament with equally good light output and diffusion. The enamel coatings are generally used only for color light sources.

Clear Lamps Clear sources with a soft image of the filament emitts a spherical distribution generating light in all directions. The exposed filament from low wattage sources makes the clear lamp useful where a sparkle or twinkle effect is desirable.

Operating Characteristics An incandescent light source’s efficiency will generally increase in the higher wattage lamps. This characteristic is due primarily to the gas inside the bulb. For lamps that are of essentially the same type of construction, design, and voltage class, the heat losses from the filament are primarily due to the internal gas conduction . . . Continued next page

139

LIGHT SOURCES & COMPONENTS

INCANDESCENT LAMPS being relatively constant. Therefore, the percentage of efficiency loss is less for higher wattage lamps and these lamps generally perform more efficiently. As an example, a 500 watt lamp would be approximately twice as efficient (in lumens per watt) than that of a 50 watt lamp.

Lamp Life

Unusual operating conditions such as vibration will cause early failure, the normal cause of failure is evaporation of the tungsten filament. Where lamps are subjected to usual shock and vibration special rough service lamps are used with slightly lower efficiency of 90%. The rate of evaporation of the filament is dependent on the operating temperature. Increasing the current to the filament will increase the temperature and the light output – while vaporizing the tungsten faster and shorting lamp life. If the current is reduced by dimming or the lamp design, the temperature is reduced proportionally, the lamp life is extended, however, with lower light output.

Light Output Maintenance Output over their life due to evaporation of the tungsten filament averages about 85% of initial output. Blacking inside of the bulb from the evaporation is an obvious visual indicator of the end of life. This is the evaporated tungsten re-condensing on the cooler bulb wall. There are techniques used to reduce this effect. One is the use of wire mesh collector grids attached to the lead-in wires to attract and hold the tungsten particles. Another is using of a trace of iodine gas in the bulb to intercept the evaporated particles and re-deposit it on the hot filament.

140

Under-Voltage Operation

Operating lamps at a reduced voltage, like a dimmer, results in a significantly longer life and reduced light output. Where the cost of the lamp replacement is high because of inaccessible locations the use of dimming can extend the lamp life and reduce the re-lamping cost. A 5% voltage reduction can almost double lamp life with a 10% lower output. Another option is to operate 130 volt lamps on a 120 volt circuit.

Over-Voltage Operation

With some uses an increase in light output can be gained for short periods, such as recreational and sports facilities, by operating the lamps at approximately 10% over voltage. This would furnish an increase in light output of about 25% to 35%. The trade-off however, is the lamp life would also decrease by approximately 50%.

Beam Control

Incandescent lamps used as point sources in specular reflectors or with prismatic elements should be clear type lamps for precise beam control and maximum light output. Insidefrosted and coated bulbs can be used in diffuse reflectors or custom-in elements where the maximum light diffusion is generally desirable.

Lamp Flicker

Alternating current used to power incandescent lamps, drops to zero twice each cycle of the sine wave distribution. The filament temperature fluctuates with each change of current, creating a visual flicker. However, there is no noticeable flicker on standard 60 cycle operation. The frequency of the alternating current has no effect on lamp life except for very low wattage lamps.

LIGHT SOURCES & COMPONENTS

INCANDESCENT LAMPS REPRESENTATIVE LAMP TYPES Incandescent light bulb shapes and sizes are identified with a letter and a number. The letter gives the shape and the number the maximum diameter of the bulb in eighths of an inch. For

A19 Medium

B13 Medium

PS25 Medium

PAR38 Medium

B10 Candela

CA8 C7 Candela Candela

ER30 Medium

R40 Medium

example, an A19 bulb is 19/8 (2-3/8) inches in diameter. The different incandescent lamp base sizes are Candela, Intermediate, Medium, Mogul, screw type, and Side Pin and Bayonet.

CA9 Medium

CA10 Candela

BR40 Medium

F15 Medium

PAR46 Med Side Pin

G25 Medium

PAR56 Mog End Prong R52 Mogul

T5 Candela S14 S11 Medium Candela

T10 Medium

T8 Disc

P25 Medium

PAR20 Medium

PAR30 Medium

R14 SC Bay

R20 Medium

A-Line light bulbs are the most familiar lamps, particularly in the incandescent type. This is the shape most people think of when picturing a light bulb. B&C - Candle Shape bulbs look like a candle flame for decorative use in chandeliers, indicators, and night lights. F-Flame Shape bulbs are like C bulbs except the glass bulb is blown or etched to look like a flickering flame. S-Sign Lamps bulbs are typically found in exposed lamp signs for both indoor and outdoor use. T-Tubular Shape bulbs have a compact tubular shape for use in showcases, appliances, and exit lights . PS- Pear Shape bulbs are similar to A line, except they have a larger diameter and a longer neck, which causes the bulb to appear more like a pear. G-Globe Shape bulbs are used for decorative applications, such as bathrooms, theaters, and hotels. lamps uses the reflector bulge in the bulb neck to redirect light lost in the neck and reflect it to increase total light output. lamps use the elliptical reflector to increase output by redirecting light that has been lost at the sides of the light bulb. lamps use an aluminized parabolic reflector to accurately control light from a narrow spot to a wide flood.

141

LIGHT SOURCES & COMPONENTS

INCANDESCENT LAMPS SILVER BOWL LAMPS Some incandescent bulb types are designed for special, or limited application, such as, the silver bowl A-line lamp that has a reflective silver coating on the outside of the bulb to produce an internal reflection action. The silver

coating is applied to the bowl of the lamp – both as a brightness control hiding the bright filament, and to alter the internal distribution of light – providing part of the function usually performed by a light fixture.

CLEAR OR FROSTED UPPER BULB AREA OPAQUE SILVER COATING ON OUTSIDE OF THE BULB

Integral reflectors like the silver bowl coating reduces total light output, even though the useful light may be distributed more efficiently. The loss is due primarily to absorption by the reflector itself.

Maintenance: While this integral reflector silver bowl lamp has about the same efficiency as a clear lamp in an external reflector, there is a definite maintenance advantage to the interior sealed surface of the silver bowl reflector.

TUBULAR LAMPS Tubular incandescent lamps are useful where a small linear source is needed and space is limited. A clear glass version with a visible filament can be used with a linear reflector for precise beam control. Lumiline lamps were CLEAR T8 BULB

FROSTED T10 BULB

CLEAR T10 REFLECTOR BULB

142

used in place of linear fluorescent lamps (before LED lamps) because they do not require space for ballasts and starting aids. Tubular showcase lamps are also useful in display cases and areas with a shallow depth and trough reflectors

F that are used in showcase lamps require some additional support because of their length. Since these supports also conduct some heat away from the filament, there is a relative reduction in lamp efficiency. utilize an internal circular reflector that provides a degree of directional control. They are useful when a spread beam is required. The spring contact lamp bases allow the bulb to be rotated to direct the light.

LIGHT SOURCES & COMPONENTS

INCANDESCENT LAMPS LAMPHOLDERS

KEYLESS

PULL CHAIN

TURN KNOB

KEYLESS

KEYLESS

PORCELAIN SHELL MEDIUM BASE

INTERMEDIATE

KEYLESS METAL CAP

PENDANT

FEMALE BUSHING

KEYLESS VENTILATED

KEYLESS 2-PIECE

CENTER

PULL

TURN KNOB

PULL CHAIN

KEYLESS SIGN TYPE

KEYLESS PONY CLEAT

PORCELAIN SHELL MOGUL BASE

KEYLESS KEYLESS CLEAT TYPE SCR. RING

KEYLESS SIGN TYPE

CANDELABRA BASE

KEYLESS

ANGLE PAN SOCKET W/ SCREW TERMINALS

KEYLESS CLEAT TYPE

KEYLESS SIGN TYPE

INTERMEDIATE BASE

3 SOCKET FIXTURE TYPE

MEDIUM BASE FIXTURE LAMPHOLDERS

SCREW TERMINAL KEYLESS METAL COVER

KEYLESS CLEAT TYPE

KEYLESS SCREW RING

KEYLESS SIGN TYPE

MEDIUM BASE

WIRE LEAD KEYLESS POCELAIN COVER

PULL CHAIN KEYLESS METAL COVER

MEDIUM BASE LAMPHOLDERS FOR OUTLET BOX

143

LIGHT SOURCES & COMPONENTS

METAL HALIDE LAMPS

SPRING DOME SUPPORT SUPPORT FRAME QUARTZ OR CERAMIC ARC TUBE WITH TUNGSTEN ELECTRODES GETTER / ABSORBS EXCESS HYDROGEN TEMPERATED GLASS OUTER BULB LAMP BASE

QUARTZ METAL HALIDE LAMP

Characteristics Metal Halide (MH) lamps belong to a family of high intensity discharge (HID) lamps that generate light from an electric arc in small discharge tube. They offer pure white light, have high efficacy, long life, and good color rendering. Their compact light source allows for excellent optical control. These characteristics make them popular for commercial applications such as retail stores, where both low operating cost and good light quality are important. Because of their long life, metal halide lamps are desirable for use in buildings with high ceilings, such as, warehouses and other high-bay and low-bay industrial types, and particularly where their use is for extended hours. They are also popular for use in stadiums and sports lighting applications.

Lamp Types There are two types of metal halide lamps that are based on the arc tube characteristics and the starting mode. The pressurized arc tube is made of quartz glass or ceramic, and the starting mode is either probe-start or pulse-start. In addition to the types of operating and starting

144

CERAMIC METAL HALIDE LAMP

modes, they also are available with a choice of standard or high output. The different bulb configuration ranges from the standard elliptical and bulge shape, to tubular, single-ended and PAR shapes. The lamps also come in a variety of wattages from 35 up to 2000 watts. Most manufacturers offer lamps typically in sizes of 175, 200, 250, 300, 320, 350, 360, and 400 watts.

Operating Characteristics Metal halide lamps use mercury vapor in the arc tube to generate a clear white light, and other metal salts, such as fluorine, chlorine, and iodine. Halide is a chemical compound of halogen combined with electropositive metal elements which readily form negative ions. Earlier metal halide lamps operate with a Probe-Start starting circuit where a ballast supplies a starting voltage through a gas mixture in the arc tube, ionized the gas, allowing current to flow to start the lamp. The ballast controls operating and starting currents. There are three electrodes in the arc tube of a probe-start lamp – a starting probe and two

LIGHT SOURCES & COMPONENTS

METAL HALIDE LAMPS operating electrodes. The lamp starts with a discharge across a gap between the starting electrode and operating electrode. Electrons cross the arc tube to the opposite electrode to start the lamp. A bi-metal switch removes the starting electrode from the circuit after startup.

Pulse-Start L amps are the other type of MH lamp. The pulse-start uses a high-voltage ignitor that works along with a ballast to start the lamp using high-voltage pulses. The end of the arc tube is smaller, resulting in less heat loss and higher efficiency. The ignitor also reduces the tungsten evaporation from the electrodes by heating them up faster during startup. The warm-up time is also reduced. Probe-start lamps may take up to 10 to 20 minutes to re-start, while pulse-start lamps re-start within 2 to 8 minutes, because of the furnished high-voltage pulses. The pulse-start lamps were designed to improve lamp life and to furnish both an energy efficiency comparable to high-pressure sodium lamps, along with the good color-rendering characteristics of MH lamps. They also provide faster cold starting at very low temperatures – as low as minus 40°F. After a lamp starts the temperature and pressure in the arc tube increase, allowing current to pass through and vaporizing materials in the arc and emitting light. Tungsten evaporates from the electrodes and deposits on the arc tube wall, blackening it. However, the electrode is treated with radioactive thorium, reducing this process. The outer bulb, made of borosilicate glass, blocks ultraviolet radiation. Some lamps have a phosphor coating inside of the outer bulb that diffuses the light and alters the lamp’s color characteristics.

Self-Ballasted Lamps are available as a replacement for metal halide lamps, as well as, the self-ballasted mercury-vapor lamps. These lamps have a tubular halogen lamp connected in series with an arc tube to regulate the current in the arc tube, and is connected directly to a power supply, not requiring an external ballast. Lamp Arc Tubes are manufactured from either fused quartz or a ceramic material. Traditional MH lamps were made from quartz with later lamps turning to the use of a ceramic material. Arc tubes constructed of ceramic have higher arc tube temperatures, resulting in higher light output in lumens (a measure of the total amount of visible light emitted from a source per watt), along with bright white light, better color rendition, and stability of the color properties. Color Characteristics: MH lamps generate white light in a range of color temperatures from 3200° to 5200° Kelvin, with a color rendering index (CRI) of 65 to 70, but can be as high as 90. They are superior in color performance to most high-pressure sodium (HPS) and mercury vapor lamps that have lower values. The whiter light also provides better peripheral visibility at low lighting levels than HPS lamps. However, variations in color among the same type of MH lamps can be greater than color variations for linear fluorescent lamps of the same color temperature. The variations are particularly noticeable during the first 100 hours of use. Using lamps from the same manufacturer and of the same wattage can minimize this variation. Operating them in the same position (like, base-up or base down) will reduce variation. As lamps age they will also exhibit color shifts.

145

LIGHT SOURCES & COMPONENTS

METAL HALIDE LAMPS Warm-up and Restrike Time: Metal halide

Burning Position: The operating position of

lamps do not achieve their full output right after starting and require up to 15 minutes to reach 90% of their full light output, calle the warm-up time. After being on for a period of time and then turned off, they will not restart until the arc tube has time to cool down, called the restrike time. The restrike time for probe-start lamps can take 15 minutes or longer, but restrike times for pulse-start lamps are typically considerably shorter, being more than two times as fast.

metal halide lamps creates a difference in the color shift and variation of the color of the light output, and may also influence the life of the lamp. Although some lamps perform well when installed base-down, best results typically result when installed in a base-up position, reducing the color variation and maximized lamp life. To determine the best operating position, as well as the lumen output for lamps in different burning positions, the lamp maker should be consulted.

REPRESENTATIVE LAMP TYPES Most light source lamps are identified with a letter and number, giving the shape and the maximum diameter measured in eighths of an

inch. For example, an ED17 bulb is 17/8 or (2-1/8) inches in diameter. The typical lamp base sizes are Medium, Mogul, BiPin, and G.

T6.7 Dbl.Ended MR16 GX10

PAR20 Medium

PAR30L Medium

PAR38 Medium

ED17 Medium

BD17 Medium

T4 GU6.5

T4.5 BiPin

T6 G12

EX39 Socket Standard E39 Mogul EX39 Base with Mogul Base extended ctr. contact

T15 Mogul

146

ED18 Mogul

ED23.5 Mogul

ED28 Mogul

ED37 EX39 Mogul

BT37 Mogul

BT56 Mogul

LIGHT SOURCES & COMPONENTS

HIGH-PRESSURE SODIUM LAMPS

SUPPORT FRAME OUTER VACUUM BULB TRANLUCENT ALUMINUM OXIDE CERAMIC ARC TUBE TUNGSTEN ELECTRODES LEAD-IN CONNECTIONS LAMP BASE

HIGH-PRESSURE SODIUM LAMPS

Characteristics

High-Pressure Sodium (HPS) lamps are a highintensity discharge light sources that produce a very efficient, warm, yellow-to-orange color of light. They have been widely used in outdoor applications such as area lighting, street and security lighting. The lamp consists of an arc tube supported by a wire frame inside an outer vacuum bulb, made of a translucent aluminum oxide. The arc tube made of an oxide ceramic material is resistant to the corrosive effects of the sodium and extremely high chemical activity and pressure taking place in the arc tube. The electrically excited state of sodium in the tube produces the light and the high pressure is responsible for the high efficiency (lumens per watt). Mercury added in the arc tube acts as a color buffer, plus a small amount of xenon added in the arc tube to help the starting sequence.

Operating Characteristics HPS lamps are gas-discharge lamps that use sodium in an excited state to produce the light.

The light is made of atomic emission lines of mercury and sodium, but is dominated by the sodium emission. HPS lamps have different physical, electrical, and photometric characteristics from other high-intensity discharge light sources. There are two types of lamps; low pressure and high pressure. Low-pressure sodium lamps are less efficient, and their monochromatic yellow light limits many applications. High-pressure lamps have a wider color spectrum of light, but also have reduced color-rendering capabilities. High-pressure lamps are powered with an AC voltage, along with a ballast to supply constant current, rather than a constant voltage, furnishing a stable operation. Sodium and mercury vapor is needed to draw an arc to start the lamp, which is generated from an amalgam (mixture) of metallic sodium and mercury. The higher the temperature of the amalgam, determined by the lamp’s power, the higher the mercury and sodium vapor pressures in the lamp. As the temperature and pressure rise, nominal power is reached. The desired operating state . . . Continued next page

147

LIGHT SOURCES & COMPONENTS

HIGH -PRESSURE SODIUM LAMPS is when it operates with liquid amalgam in the arc tube, causing a slow loss of amalgam over time, which has less effect on the lamp’s operation than a fully evaporated amalgam. This increases the lamp’s life in excess of 20,000 hours. They also require a long narrow arc tube to obtain maximum efficiency, and very high voltages are needed for proper lamp ignition.

Color Characteristics: HPS lamps furnish a yellowish-orange light, with an approximate color temperature of 2,000° Kelvin. Sodium is the primary source of light from the lamp because of the high sodium pressures in the arc tube. The typical color-rendering index is very low, at 20 - 3 0 CRI. The lamps are often used for indoor plant growth because of their reddish light, which may trigger a greater flowering response in selected plants, and their relative high efficiency of 80 to 140 lumens per watt. Although the color-rendering capabilities of high-pressure sodium lamps are limited, they can be particularly effective on some special architectural surfaces and finishes that fall in the general warm range of colors – creating a distinctive appearance. The warm-up period to reach full brightness is three to four minutes. During this time there may be several changes in the color of the light, starting with a bluish-white color, then replaced with a partial monochromatic yellow, then changing to the final characteristic bright golden-white light.

Ballast Operation: HPS lamps are the most efficient type of the high-intensity discharge family of lamps. Ballasts have to furnish the usual ballasting functions, including sufficient open circuit voltage to maintain the voltage in series with an inductive type ballast to supply a

148

starting voltage and a constant current. The ballast is inductive, rather than resistive, to minimize resistive losses. Since a lamp goes out at each AC zero-current point, the inductive ballast provides re-ignition with a voltage spike at the zero-current point. The ballast also works to limit the current when high power is required from the lamp. HPS ballasts have three primary, elements: a transformer, a capacitor, and an igniter. The igniter provides a high-energy spark to start breaking down the gas so it will conduct electricity. The transformer provides the proper voltage, and the capacitor does ripple suppression, so the 60 cycle in the power is minimized. The buzz sometimes coming from a lamp is a 60 cycle hum, indicating the capacitor is going bad. Some ballasts will detect cycling and stop trying to start the lamp after a few cycles. Due to the repeated ignitions ballast life is shortened.

Lamp Life: High-pressure sodium lamps are made with an excess of sodium, in the form of an amalgam with mercury. The lamps will exhibit an on and off cycling when they approach the end of life – caused by a loss of sodium in the arc tube. Sodium is highly reactive and is easily lost by reacting with the aluminum oxide arc tube. Although these lamps can be started at a low voltage, as they heat up the internal gas pressure rises, and a higher voltage is needed to maintain the arc. As a lamp gets older the required voltage exceeds the voltage output from the ballast. At this point, the arc fails, and the lamp burns out. Eventually, the lamp cools down and the gas pressure in the arc tube is reduced, allowing the ballast to strike the arc again. The lamp starts once more for a while and then cycles out again. However, before the end of their rated life, lamps have a very favorable average rated life of 24,000 hours.

LIGHT SOURCES & COMPONENTS

HIGH-PRESSURE SODIUM LAMPS

REPRESENTATIVE LAMP TYPES

ED17 Medium

BD17 Medium

ED23.5 Mogul

ED28 Mogul

BT28 Mogul

ET23.5 Mogul

ED18 Mogul

T15 Mogul

E18 Mogul

E25 Mogul

BT37 Mogul

ED37 Mogul

149

LIGHT SOURCES & COMPONENTS

DIMMING CONTROL DIMMING BASICS Control of the lighting intensity within the architectural environment offers the designer a significant tool to manipulate the lighting levels for basic seeing needs and the environmental and comfort requirements. This may be for the lighting design objectives or to improve overall energy utilization and efficiency. Dimming is recognized by many certification agencies as a valid means of energy reduction, while also offering occupants the convience of individually controlling their illumination requirements. Many dimmers use some form of silicon controlled rectifiers (SCR) instead of the older variable rheostats, potentiometers, auto transformers, magnetic

INCANDESCENT, CFL, & LED LAMPS This group of lamps can be dimmed using a silicon controlled rectifier dimmer that provides an infinite dimming range by supplying a variable amount of current to the lamps.

HIGH-LOW DIMMING

High-low dimming can be obtained by adjusting the AC voltage cycle with a silicon rectifier, not a controlled rectifier. The type of silicon rectifier used will determine the amount of dimming.

amplifiers, and electronic tube dimmers. They allow a controlled amount of current to pass during both the positive and negative half cycles of the AC current. It uses a gating allowing a flow of current at full voltage, but for only a portion of the time, giving the same effect as reducing the voltage. Control is obtained with a small, variable, DC voltage applied to the gate of the silicon rectifier, offering a very small size with high efficiency, and noiseless operation. Basic dimmer circuits are illustrated below as simplified wiring diagrams and descriptions. These probably do not represent current dimming technology but are intended as a general introduction to basic dimming technology. 2 WIRES

+

AC

-

DIMMER 2 WIRES

+

AC

-

HI OFF LO

FLUORESCENT LAMP DIMMING Fluorescent lamp dimming is achieved with control of the current in the secondary of the special dimming ballast. To reliably operate lamps at low levels, some power must be applied to the lamp filaments (that usually turn off after startup) while the current flowing through the bulb is reduced.

150

3 WIRES

+

DIMMING BALLAST

AC

-

DIMMER

FLUORESCENT LAMP

LIGHT SOURCES & COMPONENTS

DIMMING CONTROL

are fully dimmable with the advantage of maintaining their efficiency at low levels. They use a driver to convert AC power to low-voltage DC power at 12 to 48 volts. A transformer is required to convert the 110V-240 volt AC to the required DC voltage. Resistive dimming is a way of dimming incandescent lamps and works by reducing the voltage to the bulb and is not considered energy efficient. Because LEDs require a fixed voltage, these dimmers cannot be used with them and will damage the transformer, cause the lamps to flicker instead of dim, and will slowly damage the LEDs. Dimming LED light sources works by reducing the current rather than reducing the voltage.

DC Dimming is a widely used method of dimming LEDs and involves the use of a driver and a 0 to 10 volt system, where 10 would be full brightness and 0 would be off. With this method, changes in voltage supplied to the driver signals the driver to adjust the current and results in the variable control of the light output. Even though it requires separate low voltage wiring it is a popular method and is compatible with other energy saving systems.

method applies full DC voltage for a very short period of time, as much as thousands of times per second. The eye does not perceive the flicker of the on-off cycle, and detects it as a continuous light, but it appears dimmer due to the short periods of being turned off. It is capable of dimming from full brightness to zero. To produce the appropriate frequency and pulse width, a LED drive circuitry requires a programmable timer control. Some early PWM dimming circuits use a simple timer with a variable resistor for simple circuits. However, the use of more advanced microcontrollers will offer better opportunities for this PWM dimming method. TRANSISTOR RESISTOR 1

0-10 V

LED R2

R3

SIMPLE DIMMING CIRCUIT

OUTPUT

Dimming Light-Emitting Diodes: LED amps

Pulse Width Modulation (PWM): This

VARIABLE

Current technology offers two basic options, dimming down to 20 percent and dimming down to 1 percent. Many systems dim only to 20 percent as a cost-effective method and because human perception of light levels below 20 percent is less aware of the actual measured levels. New technology and increasing interest in energy efficiency will offer new options for the 1 percent systems over 20 percent systems.

This dimming circuit uses a 0-10Volt AC control voltage input to drive a single 1-watt white LED when connected to 12-15V DC power supply.

NOTE: A transistor is a miniature electronic component that has different functions, either a switch, an amplifier or a rectifier. As a switch a small electric current can switch or control (amplify) a larger current. It can also perform as a rectifier, converting an alternating current (AC) into direct current (DC) by restricting the flow of electricity to only one direction.

151

CHAPTER

8

LIGHTING APPLICATION & DETAILS The process of designing and creating appropriate and successful architectural interior environments requires education, training, and experience, along with, creativity, dedication, and an understanding of three-dimensional space. The process of constructing these spaces involves the assembly of many components and the research and manipulation of numerous materials and systems. Because of this, the designer’s ideas are realized through the creative coordination of these physical variables. It is the theme of this book to assist the designer in choosing the appropriate elements and sources associated with good architectural lighting practice. This chapter presents a wide range of applications and details that involve the nuts-and-bolts of architectural lighting, including some traditional lighting elements that represent the mainstream concept of lighting design, along with some special, or custom, applications of light and lighting that do not fit into the traditional concept of interior lighting design. These special applications make an attempt to integrate, and coordinate the lighting into the fabric of the architecture, rather than be merely applied or suspended from its surfaces and forms. The compilation of lighting systems and custom elements that follow is a result of many years of experiment and unique application on the part of lighting designers and represents only a basic, and perhaps simplistic, attempt to integrate the lighting with the architecture – in the hope of motivating current and future lighting designers in the creation of more fully coordinated and integrated architectural lighting solutions, elements, and innovative systems.

153

LIGHTING APPLICATION & DETAILS

LUMINAIRES The word luminaire (which is just another word to describe a light fixture), was thought to be first used in the year 1921, and was most likely derived from the word luminaries, identified as “any objects or bodies that give off light.” The Editors of Encyclopaedia Britannica give the meaning as “Complete lighting unit, consisting of one or more lamps (bulbs or tubes that emit light), along with the socket and other parts that hold the lamp in place and protect it, wiring that connects the lamp to a power source, and a reflector that helps direct and distribute the

RECESSED WALL LTG

light. Luminaires also include both types of portable and ceiling and wall-mounted fixtures.” Another description from the (CIE) Commission International de l’Eclairag, which is the French International Commission on Illumination, says that a luminaire is an “apparatus which distributes, filters, or transforms light transmitted from one or more lamps and which includes, except the lamps themselves, all the parts necessary for supporting, fixing and protecting the lamps and, where necessary, circuit auxiliaries, with the means to connect them to the electrical supply.”

RECESSED UP & DOWN PENDANT SURFACE TROFFER PENDANT DOWNLIGHT DOWNLIGHT

SURFACE TROFFER

SURFACE RECESSED HALF-GLOBE DOWNLIGHT

CONVENTIONAL

RECESSED CLG COVE

RECESSED COFFER

LED SLOT LIGHT

RECESSED WALL COVE

LED SLOT LIGHT

ARCHITECTURAL

154

RECESSED BASE COVE

LIGHTING APPLICATION & DETAILS

LUMINAIRES

CORNICE, BRACKET COVE OR VALANCE

FLOATING CLG. ELEMENT

CORRIDOR CLG. BRACKET

UNDER AND OVER CABINET

CUSTOM-BUILT

WALL UP & DOWN

TRACK LIGHTS

SURFACE GLOBE

PENDANT SHADE

PENDANT CHANDELIER

PENDANT BARE LAMP

WALL SCONCE

DECORATIVE

LUMINOUS WALL

LUMINOUS CEILING

LUMINOUS DISPLAY

LUMINOUS ELEMENTS

155

LIGHTING APPLICATION & DETAILS

LUMINAIRES REPRESENTATIVE LUMINAIRE LAYOUTS Ceiling-mounted lighting equipment of a variety of luminaire types, such as surface mounted, recessed, or suspended, may be arranged to

Uniform Distribution is used in many applications

where it is desirable to provide relatively uniform illumination over the entire space or room. This approach also helps facilitate space planning and allows periodic relocation of the work surfaces.

S

1/2 to 1/3 S

LINEAR LAYOUT

REGULAR LAYOUT

Non-Uniform Distribution is typically used where work areas are permanently located (private offices, retail areas, labs, etc.) and can furnish task illumination where needed, with the other areas lighted for casual activities. This has the potential for a reduction in operating costs. In rooms with a

156

To prevent variations in lighting levels, luminaire spacing should not exceed a maximum spacing to fixture height ratio suggested for each fixture type, which is usually shown with the fixture manufacturer’ s coefficient of utilization tables.

S

1/2 to 1/3 S

CUSTOM SHAPES

fulfil the general or task lighting requirements for either uniform or non-uniform distribution of illumination over the horizontal work plane.

IRREGULAR LAYOUT

RANDOM LAYOUT

GRID LAYOUT

non-uniform layout of fixtures, attention must be given to the effect of lighting on wall surfaces. It may be necessary to modify the room finishes and reflectances to conform to the design goals, or to add wall lighting to achieve the suggested brightness ratios, and furnish a comfortable visual environment.

FIXTURE GROUPINGS

PRIVATE OFFICE

LIGHTING APPLICATION & DETAILS

WALL LIGHTING WALL LIGHTING PLACEMENT RATIO

D = 1/4H

Note: The lighting techniques shown here are approximate recommendations for the choice and placement of lighting equipment intended for the illumination of vertical surfaces such as walls, whiteboards, tack boards, murals, draperies, etc.

Placement Ratio: For relative uniform illumination when utilizing broad-beam lighting systems, a placement ratio of 1 to 4 is recommended for the distance from the wall (D) to the height of the vertical surface (H). The brightness at the bottom of the surface will be about 1/10 the brightness at the top, producing an impression of uniformity. When precise reflector or lens control is used, visual uniformity can be achieved with lighting equipment that is located closer to the surface.

H

Surface Finishes: To minimize reflections from the lighted surfaces a diffuse, or matte, finish can be incorporated. When polished surfaces are involved the light source can be located outside the reflected field of view (see Chapter 5, pg. 82) Surface texture and low sculpture relief can be emphasized with grazing lighting that is located closer to the surface than the suggested 1 to 4 ratio. When the lighting is directed only from the top the distribution uniformity can be slightly improved by specifying a floor that has a high reflectance finish. REPRESENTATIVE TECHNIQUES

INCAND. STRIP WITH LOUVER SHIELDING

GROUP OF INDIVIDUAL SHIELDED LUMINAIRES

FLUORESCENT OR LED STRIP W/REFLECTORS

PLASTERED-IN LED RECESSED ADJUSTABLE RECESSED STRIP LED CONTINUOUS STRIP

157

LIGHTING APPLICAION & DETAILS

WALL LIGHTING WITH SPECULAR REFLECTOR

INITIAL FOOTCANDLES IN CTR. OF 1 FT. SQ. D = 36"

W

CONTINUOUS LAMPS

H = 60"

SOURCE . . . TUBULAR FLUORESCENT OR LED OUTPUT . . . . . . . . . . 700 LUMENS PER FOOT REFLECTOR . . . . . . . PARABOLIC SPECULAR WITH WIDTH W EQUAL TO 4 X BULB DIAMETER AIMING POINT . . . . . DOWN 4/5 FROM TOP

Aiming Point: The indicated aiming point is located down 4 feet from the lamp axis, (or 0.8 x the wall height). The uniformity of the light distribution could be improved with a lower aiming point, but the effective utilization of the light would be somewhat reduced.

158

52

52

52

52

57

57

57

57

57

57

65

65

65

65

65

65

57

57

57

57

57

57

43

43

43

43

43

43

68

68

81

81

68

68

67

67

68

68

67

67

68

68

68

68

68

68

49

49

49

49

49

49

34

34

34

34

34

34

D = 12"

Wall Height: These charts can be used to estimate the illuminance of any wall height by using the D/H ratio. The new footcandle values can be calculated with the use of the following equation: New Footcandles = Chart fc X 5/New H . Vertical spacing of the grid will then be the new wall height divided by 5.

52

D = 24"

Note: The illuminance values shown here are approximate and represent the general distribution characteristics. They can vary with different lamp types, especially those with a different (CCT) Correlated Color Temperature. The values will vary in direct proportion with any difference in the lumens per foot output, and approximately double with an arrangement of two rows of lamps.

52

108

108 128 128 108 108

74

74

82

82

74

74

49

49

52

52

49

49

29

29

29

29

29

29

19

19

19

19

19

19

D = 8"

140 140 166 166 140 140 61

61

78

78

61

61

40

40

43

43

40

40

24

24

24

24

24

24

14

14

14

14

14

14

LIGHTING APPLICATION & DETAILS

WALL LIGHTING WITH DIFFUSE REFLECTOR

INITIAL FOOTCANDLES IN CTR. OF 1 FT. SQ. D = 36"

CONTINUOUS LAMPS

H = 60"

SOURCE . . . TUBULAR FLUORESCENT OR LED OUTPUT. . . . . . . . . . 700 LUMENS PER FOOT REFLECTOR . . . . . 70% MATTE WHITE FINISH

are for the initial lamp lumen output (at 100 hours of lamp life) Since these values will be reduced over time due to lamp depreciation and accumulation of dirt, use of a maintenance factor of 70% to 85% will be more realistic.

67

64

64

58

58

58

58

58

58

44

44

44

44

44

44

30

30

30

30

30

30

20

20

20

20

20

20

71

71

71

71

71

71

45

45

45

45

45

45

22

22

22

22

22

22

13

13

13

13

13

13

D = 12"

these two pages represent the direct illumination (illuminance) in vertical footcandles. The actual brightness in footlamberts will depend upon the reflectance of the illuminated surface.

Maintained Values: These values

67

112 112 118 118 112 112

will vary proportionally with any variation in the lumens per foot output, and are approximately 185% when two rows of lamps are used. The values are approximate and representative of the general distribution characteristics.

Light reflected from nearby adjacent and parallel surfaces will typically improve the brightness uniformity over the surface.

64

D = 24"

Note: The illuminance values shown

Brightness: The charts shown on

64

191

191 220 220 191 191

70

70

72

72

70

70

32

32

32

32

32

32

16

16

16

16

16

16

9

9

9

9

9

9

D = 8"

224 224 286 286 224 224 45

45

46

46

45

45

15

15

16

16

15

15

8

8

8

8

8

8

4

4

4

4

4

4

159

LIGHTING APPLICATION & DETAILS

WALL LIGHTING MULTIPLE LAMP WALL LIGHTING

1'-6"

2'- 0"

12"

12"

10'- 0"

6"

17

7

40

11

41

31

73

49

95

71

69

82

17 WATT PAR38 LED

49

62

25° BEAM SPREAD

33

42

18

28

ILLUMINANCE IN VERTICAL FOOTCANDLES

1'-6"

2'- 0"

12"

12"

10'- 0"

6"

10

4

23

6

25

18

43

29

56

42

41

48

75 WATT PAR38 HAL

31

39

25° BEAM SPREAD

22

28

16

20

ILLUMINANCE IN VERTICAL FOOTCANDLES

BRIGHTNESS These charts show the direct illumination in footcandles (FC). Actual brightness will depend on the reflectance factor (RF) of the surface and be measured in footlamberts (FL). The actual brightness will be: FC x RF = FL. These charts also indicate initial illumination. Because these values will be reduced over time due to the accumulation of dirt and the gradual deterioration of the lamp lumen output, the use of a maintenance factor of approximately 75 - 8 5% will result in a more realistic value for long-term illumination levels.

160

LIGHTING APPLICATION & DETAILS

WALL LIGHTING SPOT & FLOOD LAMP BEAM PATTERNS D = 5'- 0"

ILLUMINANCE IN VERTICAL FOOTCANDLES

45°

H = 10'- 0"

24

75 WATT R30

8 4

SPOT LAMP

D = 5'- 0"

H = 10'- 0"

45°

75 WATT R30

11 6 3

FLOOD LAMP

D = 5'- 0"

50 WATT R20 FLOOD LAMP

H = 10'- 0"

45° 7 2

4

NOTE: THE CENTRAL WHITE FOOTCANDLE CIRCLE WITH A 50% MAX. CANDLE POWER OUTER EDGE IS THE APPROXIMATE PERCEIVED BEAM PATTERN.

161

LIGHTING APPLICATION & DETAILS

WALL LIGHTING PAR & R LAMP BEAM PATTERNS These illumination charts represent average beam patterns and illumination levels for a variety of typical light sources. The illuminance values are in vertical footcandles (which is the horizontal

vector of the beam) and initial rather than maintained values. Actual brightness on the lighted surface would depend on the surface reflectance. To convert to lux multiply by 10.76.

7 WATT PAR20 LED 23 º 50 WATT PAR20 HAL 25º 13 WATT PAR30 LED 25º

D = 5'- 0"

ILLUMINANCE IN VERTICAL FOOTCANDLES

H = 10'

41 27

2

60

8

4

38 13

1.9'

2.0'

30

43

6

122 75 23

2.0'

6" A 26°

3'- 0" 13 2

88

18

3

2

37

5

5

9

2.6'

2.6'

2.6'

24

35

70

6" A 37° 4'- 0" 14

10 2

5

2 2.9'

28

5

4 2.9'

10

2.9'

NOTE: THE CENTRAL WHITE FOOTCANDLE CIRCLE WITH A 50% MAX. CANDLE POWER OUTER EDGE IS THE APPROXIMATE PERCEIVED BEAM PATTERN.

162

LIGHTING APPLICATION & DETAILS

WALL LIGHTING

Footcandle values represent an average of different lamp manufacturers, intended primarily for a relative comparison. For different distances (D) use the multipliers shown at the right. 100 WATT PAR38 HAL 25º

D = 5'- 0"

D = Dx2.0 multiply footcandles by ............. 0.25 D = Dx1.5 multiply footcandles by ............. 0.45 D = Dx0.5 multiply footcandles by ............. 4.00 100 WATT PAR38 HAL 10º 75 WATT ER30 INC 40º

ILLUMINANCE IN VERTICAL FOOTCANDLES

H = 10'

200 175 146 96

47

1200

2

39

5

22

2.2'

0.9'

3.8'

144

967

34

6" A 26°

3'- 0" 92 56

19

6

2

15

40 2.6'

1.0'

4.0'

115

832

26

6" A 37° 4'- 0" 12

52

5

42

10 2 2.8'

1.1'

4.2'

163

LIGHTING APPLICATION & DETAILS

COVE LIGHTING LIGHTED CEILING & WALL COVES

LOUVERED CEILING COVE

OPEN WALL COVE

Lighted coves are designed to furnish a soft wash of light over an architectural surface to create a luminous emphasis within the space, typically on a wall or ceiling surface. They may also contribute to the general room illumination. Ceiling coves can be utilized over a single wall or on perimeter walls to create a floating ceiling effect. The definition of a lighted cove is that a ceiling cove lights the wall and the floor, while a wall cove will light only the ceiling.

It is important to locate the light source so that there are no visible gaps or shadows in the linear line of light – unless a scalloped lighting effect is desired. Louvers or baffles may be utilized, to shield the light source, when the cove will be viewed lengthwise. In some cases the recessed opening in the ceiling allows the distribution of heating and cooling outlets from the cove, and the venting of unwanted heat generated by the lighting and components.

Design Considerations: The proportions

Light Source Selection: Tubular lamps

and size of the lighting aperture is usually determined by the scale of the space, or the desired lighting effect, while also furnishing a good distribution of light and visual shielding of the light source. For ceiling coves the depth of the opening above the ceiling is established by the space available above the ceiling and the type of light source and components to be used.

have been used as the traditional light source with recommended energy-efficient T8 and T5 fluorescent and LED sources. The LED’s offer significant advantages in efficiency, long life, color choices, and dimming capabilities. Both lamp types are available in a choice of color temperatures (from 2700K to 5000K) and are also manufactured in wide range of lengths.

164

LIGHTING APPLICATION & DETAILS

COVE LIGHTING REPRESENTATIVE DETAILS HVAC DUCT ACOUST. TILE CLG. LED OR FLUOR LAMPS 1-5/8" METAL STUDS 5/8" GYPSUM BOARD

5/8" GYP. BOARD 1-5/8" MET. STUDS LED LAMP STRIP FLAT WHITE FINISH 3/4" HARDWOOD TRIM PLASTIC LOUVERS

5"

WD. CROWN MOLDING

OPEN LIGHTED WALL COVE / CORNICE

6"- 10"

LOUVERED LIGHTED CEILING COVE

1-5/8" MET STUDS MET WIREWAY WITH CONTINUOUS FLUOR OR LED LAMPS 5/8" GYP BOARD

7"

ACOUST. TILE CLG. 3/4" WOOD TRIM

5"

LED OR FLUOR LAMPS FLAT WHITE FINISH 1-5/8" METAL STUDS 5/8" GYPSUM BOARD 3-1/2" METAL STUDS

4"

OPEN LIGHTED CEILING COVE

LIGHTED WALL COVE

1-5/8" METAL STUDS FLUOR OR LED LAMPS WITH ADJ AIMING FLUOR. BALLAST OR LED DRIVER MODULAR UNITS OF DIFFERENT LENGTHS

6"

ACOUST. TILE CLG.

OFF-THE-SHELF LIGHTED CEILING COVE

5/8" GYP BOARD 1-5/8" MET STUDS LED LAMP STRIP 2-1/2" MET STUDS RUBBER COVE BASE

6"

LIGHTED BASE COVE

165

LIGHTING APPLICATION & DETAILS

COVE LIGHTING SURFACE-MOUNTED LIGHTED COVES Lighted coves can best be utilized in rooms with high ceilings where they direct the light toward the ceiling, furnishing an upward and horizontal component of light across the surface of the ceiling – resulting in a lighting effect of a soft and diffuse uniform general illumination. They can be useful as background illumination to supplement other lighting in the space. Due to the low efficiency of cove lighting, the use of high reflectance architectural surfaces provides the best performance and overall appearance.

Design Considerations: The distance, or the width out from the wall, is traditionally in the range 5 to 12 inches, but will vary considerably depending on the design, which should also furnish a good spread of light and visual shielding of the light source. The location below the ceiling should be as far as possible to allow even distribution of light on the ceiling (see the opposite page). The design of the shielding element should be appropriate to the decorative or architectural theme. It’s also important to locate the light source so the visible gaps or shadows in the line of light are minimized.

SURFACE-MOUNTED LIGHTED COVE

2" 12" MIN. TO CEILING 1/2" MET. BRACKETS FOR LONG LENGTHS MET. WIREWAY WITH FLUORESCENT BALLAST 3/4" WD. FACEBOARD W/ LIGHT-TIGHT JOINT

Light Source Selection: Continuous tubular lamps have been used as the traditional light source with recommended energy-efficient T8 and T5 fluorescent and LED lamps. LED sources will have significant advantages in efficiency, long life, color choices, and dimming capabilities. Both fluorescent and tubular LED lamps are available in a choice of color temperatures (from 2700K to 5000K) and available in a variety of different lengths.

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FLUORESCENT STRIP SPACED FROM WOOD BLOCKING TO REDUCE BALLAST HEAT WOOD OR PVC MOLDINGS WITH LIGHT-TIGHT JOINT WOOD OR PVC MOLDING

4" MIN

LIGHTING APPLICATION & DETAILS

COVE LIGHTING COVE LIGHTING PLACEMENT RATIOS

HARDWOOD TRIM CONTINUOUS LEDLAMPS ON METAL WIREWAY

H = 1/4 S

S = CEILING SPAN TO BE LIGHTED

WHEN LIGHTING IS FROM ONE SIDE ONLY, UNIFORMITY IS IMPROVED WHEN THE FAR WALL HAS A HIGH REFLECTANCE FINISH.

S H = 1/6 S

The ratios of 1:4 and 1:6 are appropriate for lighting a ceiling with a broad beam light source. When using precise beam control, the source can be placed nearer to the ceiling. However, best results are achieved when the beam is aimed to light the far two-thirds of the ceiling surface. If lighting from one side, the uniformity is improved when the far wall has a high reflectance. The 1:6 ratio is also applicable with cove lighting. As a general rule the ceiling should have a high reflectance matte finish to create uniformity and minimize specular reflections. The shielding should conceal the light source at an occupant viewing angle, and not interfere with the light distribution. The accepted average standing eye height is approximately 66 to 72 inches above the floor.

LIGHTING FROM TWO SIDES INCREASES UNIFORMITY. THE 1:6 RATIO ALSO APPLIES FOR LIGHTING DIRECTED FROM 4 SIDES.

WOOD BLOCKING 1/2" GYPSUM BOARD

1/2" MET. BRACKETS WHEN NEEDED FOR LONG RUNS LED MODULAR LIGHT STRIP 3/4" HARDWOOD WITH LIGHT-TIGHT JOINTS

GOOD SHIELDING WITH EXCESSIVE B E A M C U T- O F F

GOOD SHIELDING WITH CORRECT B E A M C U T- O F F

SHIELDING CONSIDERATIONS

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LIGHTING APPLICATION & DETAILS

COFFER LIGHTING LIGHTED CEILING COFFER An archite ctural coffer is a reces sed cavity in the ceiling, open at the bottom, and in a typical square or rectangular shape, although, other shapes are also used. Lighted ceiling coffers highlight the recessed cavity and create a luminous element with architectural appeal, as well as a light source. If repeated across a ceiling they focus attention on the illuminated threedimensional surface. The light has an upward and horizontal component across the surface of the cavity resulting in a soft and diffuse uniform general illumination. Coffers are particularly useful as background lighting to supplement and complement other forms of lighting in an area.

Light Source Selection: Small T8 and T5 lamps are often used with rectangular coffer shapes with both fluorescent and LED sources. LED sources will offer an advantage in efficiency, long life, and dimming control. For irregular shapes, using flexible LED light strips is suggested. Both fluorescent and LED lamps are available in a choice of color temperatures, and available in almost any length. Using red, green, and blue (RGB) colors, adds a variable and wide choice of available and mixed colors.

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LIGHTED COFFER

D

MIN.1/6 D

Design Considerations: Concealment of the light source is similar to that for lighted coves, however, it will also vary considerably depending on the type of lighting equipment utilized and size of the coffer. The configuration of the shielding element, beyond the mere concealment of the source, may be determined by proportions of the space or the architectural theme, and the planned function of the space.

MOLDINGS CAN ADD INTERESTING HIGHLIGHTS

WHITE (OR COLOR) MAT FINISH LIGHTED WALL NICHES HAVE SIMILAR DESIGN ELEMENTS

GLASS OR PLASTIC CLEAR SHELVING

SECTION THROUGH CEILING COFFER & WALL NICHE

LIGHTING APPLICATION & DETAILS

COFFER LIGHTING SIMULATED SKYLIGHT COFFER Special cove or coffer lighting installations can be used to simulate daylighting elements if attention is paid to the scale. They can take on a special luminous characteristic when utilized in interior space. This is most apparent when reflected off architectural surfaces creating a soft, indirect quality of lighting. However, attempting to duplicate this effect with electric light sources presents a special challenge to the designer.

Design Considerations: This type of coffer

Light Source Selection: T8 and T5 tubular lamps can be specified with energy-efficient fluorescent and LED sources. The use of LED sources offers a significant advantage in efficiency, long life, color choices, and dimming capabilities. Using the small continuous modular LED light strips also offers the most flexibility and choice of light output. Both lamp types are available in a choice of color temperatures (from 2700K to 5000K) with the higher temperatures best simulating natural light. Using red, green and blue (RGB), in either sources, can add interesting color mixing.

SKYLIGHT COFFER

PAINT INSIDE FLAT WHITE CONTINUOUS LED LAMPS ON MET. WIREWAY

6" MINIMUM

(or large cove) requires sufficient space above the ceiling for proper installation and depends on high reflectance ceiling and wall finishes. As a general rule, these surfaces should have a flat or satin finish for proper diffusion of light. The need for concealment of the light source is similar to that for any indirect lighting feature. The design of the shielding element, beyond mere concealment of the source, may be determined by the proportions of the space, the architectural theme, and function of the space.

WOOD OR METAL FRAMING OPTIONAL DIFFUSING GLASS OR PLASTIC IN ALUM. OR WOOD FRAME 6"

12 " TO 24"

SECTION THROUGH SKYLIGHT COFFER

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LIGHTING APPLICATION & DETAILS

LIGHTED WALL ELEMENTS LIGHTED CORNICE Lighted cornices direct all their light downward to highlight the wall below, such as, textured surfaces like stone or brick, decorative wall coverings, and paintings. They are also useful over draperies where space above a window does not permit valance lighting. They can also furnish lighting for reading and visual tasks near the wall and background lighting in the form of comfortable indirect ambient illumination.

Design Considerations:

Similar to a lighted wall bracket or valance, the height of the cornice element is usually in the range 6 to 9 inches, and molding profile may be determined by decorative characteristics of the space – while also furnishing a good spread of light. The faceboard can be made of typical molding shapes of wood, MDF or PVC. If draperies are used, the light source should be located farther out from the wall and 2 to 3 inches in front of the draperies. If the cornice will be viewed lengthwise the use of diffusing lens or louvers is recommended to provide shielding of the light source. Also, care should be taken to prevent light leaks at the ceiling by using blocking, or caulking inside or decorative trim outside.

LIGHTED CORNICE

CROWN MOLDING WIREWAY WITH BALLAST OR DRIVER FLUOR. OR LED LAMPS OPTIONAL CEILING TYPE DRAPERY TRACK

Light Source Selection:

Energy-efficient T8 and T5 fluorescent or LED lamps can be used for efficiency, long life, and color choices. Both lamps types are available in a choice of color temperatures (from 2700K to 5000K) and also available in a wide range of lengths from 12" up to 60". The lower illustration on the right suggests using evenly spaced small flood lamps to create a decorative scalloped lighting effect on the wall.

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METAL WIREWAY WITH EVENLY SPACED LAMPHOLDERS 3/4" WOOD FACEBOARD SMALL FLOOD LAMPS CONTINUOUS LOUVER

3"

LIGHTING APPLICATION & DETAILS

LIGHTED WALL ELEMENTS LIGHTED VALANCE Lighted valances are intended for use over draperies, furnishing both an upward and downward light distribution to provide general room illumination along with lighted emphasis of the draperies. They can have a closed top, like a lighted cornice, or a lighted wall bracket. They are traditionally fabricated as a custom-made, built-in element, or as a ready-made luminaire.

Design Considerations: The size of the shielding element is usually in the range 4 to 10 inches in height and may be determined by the proportions and decorative characteristics of the draperies and the space, while also furnishing a good spread of light and visual shielding of the light source. Locating the light source too close to the ceiling may result in uncomfortable high ceiling brightness. They should not be closer than 10 inches from the ceiling. If needed to be installed closer to the ceiling than 10 inches, use a closed top of opaque or low transmitting diffusing material to reduce the light on the ceiling. To provide room for the draperies, the light source should be located farther out from the wall and at least 3 inches in front of the draperies and a minimum of 2 inches behind the faceboard. With long runs support the shielding board with 1/2 inch metal brackets mounted at intervals of 36 to 48 inches.The best lighting effect is achieved by hanging draperies at the very top of the pleats so they hang flat.

Light Source Selection: Linear fluorescent lamps have been the traditional light source with recommendations similar to those for the lighted cornice illustrated on the previous page.

LIGHTED VALANCE 10" MIN. TO CEILING

2"

MET. WIREWAY W/ FLUOR. BALLAST ON NON- COMBUSTIBLE BLOCKING 3/4" WD. FACEBOARD CEILING TYPE DRAPERY TRACK

3" 6" MIN

1/2” MET. BRACKETS AT 36 TO 48 INCHES O.C. LED LAMPS ATTACHED TO MET. WIREWAY 3/4" WD. FACEBOARD PAINT INSIDE MAT WHITE METAL WIREWAY WITH LED DRIVER CLG. TYPE DRAPERY TRACK

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LIGHTING APPLICATION & DETAILS

LIGHTED WALL ELEMENTS LIGHTED WALL BRACKETS Lighted wall brackets furnish both an upward and downward distribution of light providing general room illumination along with decorative emphasis on wall hangings and lighting for specific visual tasks. They are typically used on walls without doors or windows and are located up high or lower on a wall – over a work area, or continuously wall-to-wall. This type of lighting equipment is available as off-the-shelf lighting fixtures or as custom-made elements. They are similar to a lighted valance, but offer a variety of different lighting patterns and applications.

Design Considerations: The size of the shielding element is usually in the range 4 to 10 inches in height and may be determined by the proportions and decorative characteristics of the space, while also furnishing a good spread of light and visual shielding of the light source. Locating the light source too close to the wall or ceiling may result in uncomfortable high wall brightness depending on the reflectance values of the wall or ceiling. The height location on the wall should be determined by the intended visual task, and to furnish good visual comfort. With long continuous runs the shielding board can be supported with 1/2 inch metal brackets mounted at intervals of about 48 inches. When installed closer to the ceiling than 10 inches, a closed top may be used of opaque material to reduce the brightness on the ceiling. If a bracket is viewed lengthwise (as in a hallway) a bottom louver or diffuser can provide a shielded, visually comfortable, view of the light source and a somewhat more attractive appearance.

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LIGHTED HIGH WALL BRACKET

Light Source Selection: Traditionally, linear fluorescent lamps have been used as the preferred light source in lighted wall brackets. Recommended lamp type is the energy-efficient T8 (1"diam.) l amp – or in a smaller special application T5 (5/8" diam.) lamp. These lamps, being tubular, radiate light with a 360 degree distribution, furnishing a relative equal spread of light in both the upward and downward direction. Tubular T8 LED sources can also be used with some significant advantages in efficiency, long life, color choices, and built-in dimming capabilities. Both fluorescent and tubular LED lamps are available in a choice of colors temperatures (from 2700K to 5000K) and also available in a variety of different lengths.

LIGHTING APPLICATION & DETAILS

LIGHTED WALL ELEMENTS

10" MIN. TO CLG. SHIELDING ANGLE TUBULAR LED LIGHT STRIP 3/4" WOOD FACEBOARD

4" to 6"

PLASTIC OR METAL LOUVER

CUSTOM HIGH WALL BRACKET ALUMINUM HOUSING IN MODULAR LENGTHS

LED LAMPS AND DRIVER ALUMINUM REFLECTORS OPTIONAL DIFFUSER OR LENS

OFF-THE-SHELF HIGH WALL BRACKET TRANSLUCENT WHITE GLASS OR PLASTIC DIFFUSER 3/4" WOOD FACEBOARD LED LAMPS ATTACHED TO METAL WIREWAY WITH LED DRIVER

4" to 6"

CUSTOM LOW WALL BRACKET 4"

FROSTED ACRYLIC TOP & BOTTOM DIFFUSERS ALUMINUM HOUSING IN MODULAR LENGTHS TUBULAR LED OR FLUORESCENT LAMPS

OFF-THE-SHELF LOW WALL BRACKET

LIGHTED LOW WALL BRACKET

Mounting Height: The mounting height of lighted brackets should be determined by both seated and standing eye height of the occupants. This helps identify any glare from the source. Reduction of Shadows: For an uninterrupted line of light, use fluorescent wireways with removable ends that allow the lampholders to be mounted back-to-back, or modular linear LED lamps that plug together for a continuous line of light. Spacing of faceboard end returns should not be more than 6" beyond the light source. Fluorescent ballasts transmit significant heat through metal wireways which should be installed on non-combustible materials or spaced with 1/4" metal spacers or washers.

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LIGHTING APPLICATION & DETAILS

TRANS-ILLUMINATED ELEMENTS LUMINOUS WALL PANELS The creation of individual trans-illuminated wall panels can utilize the cavities of typical frame construction in the design of large or small luminous elements. The general rules with regard to cavity finishes, lamp types, and diffuser materials apply here also. The brightness of the diffusing material should be limited to somewhat lower levels than usually associated with full luminous walls and ceilings to eliminate the effect of highcontrast visual glare. Individual wall cavities can be combined to form large area luminous elements or smaller individual panels or creative arrangements of elements.

Luminous LED Panels can simplify the application of luminous wall panels. They are made in two types, the back-lit and the edge-lit. The back-lit panels use multiple evenly spaced lamps located behind the diffusing material to produce a uniformly lighted panel. This requires a typical panel thickness of about 30 mm (1¼"). Edge-lit panels are thinner due to placement of the lamps around the sides of the panel in an aluminum frame edge-lighting the panel. The distance between each lamp can be adjusted to give different light intensities and uniformity. The resulting slim profile makes them ideal for architectural lighting applications, along with drop-in panels for suspended ceilings. Both types are made in a range of color temperatures, and larger edge-lit types may have uniformity problems due to the extended distance the light has to travel through the diffusing panel.

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LUMINOUS WALL PANEL

2X4 STUD WALL @ 24" O.C.

OPTIONAL GRILLE LED OR FLUOR LIGHT STRIPS

DIFFUSER FINISH CAVITY FLAT WHITE

TRANS-ILLUMINATED PANEL

2X4 STUD WALL @ 24" O.C.

BACK-LIT LED PANEL WITH REMOTE DRIVER LOCATION

LED ILLUMINATED PANELS

EDGE-LIT LED PANEL W/ REAR ATTACHED DRIVER HOUSING

LIGHTING APPLICATION & DETAILS

TRANS-ILLUMINATED ELEMENTS LUMINOUS WALL Trans-illuminated wall elements may function as prominent architectural features with visual implications beyond the extent of of just the light distribution. The visual dominance of these lighted elements is significant in the definition of interior space and form. Their attracting characteristics can reinforce architectural form and detail, becoming a unifying factor in the design of the interior environment. They are made up of large area transmitting materials located in front of a system of lamps installed behind the transmitting diffusing material.

Design Considerations: Design flexibility can be achieved through the placement of the elements within the space, the use of color sources, and particularly, through the choice of the diffusing materials and possible decorative grills or louvers. Added flexibility can be achieved with the use of sliding transmitting panels, similar to sliding door units, offering access to the lamps for easy maintenance of the cavity. The cavity, similar to luminous ceilings, should be free of obstructions and finished in a high reflectance matte white color. Interesting light patterns and color effects can be achieved on the diffusing material by locating the lamps at the top and bottom of the cavity with color fluorescent and reflector LED lamps. Aim reflector lamps at 2/3 of the height of the cavity.

FULL LUMINOUS WALL

BLOCK AND SEAL AT THE REAR OF THE FRAMEWORK TO PREVENT LIGHT LEAKS

FINISH CAVITY AREA WITH HIGH REFLECTANCE MAT OR LOW GLOSS WHITE PAINT TRANSLUCENT DIFFUSER IN SLIDING OR HINGED PANEL FOR EASY ACCESS & MAINTENANCE ARRANGE FLUORESCENT OR TUBULAR LED LAMPS IN VERT. OR HORIZ. ROWS SPACE LAMPS FOR EVEN BRIGHTNESS AS SHOWN ON THE NEXT PAGE (176)

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LIGHTING APPLICATION & DETAILS

TRANS-ILLUMINATED ELEMENTS LUMINOUS CEILING Trans-illuminated ceilings are made of transmitting materials suspended below a system of lamps. The suspended grid becomes the finished ceiling plane and the system furnishes a luminous architectural element, providing uniform and diffuse general lighting. The diffuser framework can also be suspended below the structural ceiling, away from the side walls, to create the effect of a floating luminous ceiling.

FULL LUMINOUS ELEMENT

Design Considerations: The transmitting material serves to conceal the light sources and transmit a diffused source of light. The cavity, where possible, should be free of obstructions, like structural beams and pipes, finished in a high reflectance flat white color, and have lamps located below, and at right angles, to any obstructions.

Light Source Selection: Tubular LED or fluorescent lamps, in continuous runs, are used as the light source. Energyefficient T8 fluorescent lamps have been the typical source. However, LED sources can be used with advantages in efficiency, long life, color choices and dimming, especially edge-lit LED panel lamps. Lamps of the same color should be used to prevent color variations in the transmitting material. Both fluorescent and LED lamps are available in a wide choice of color temperatures (ranging from 2700K to 5000K). When using lamps of different lengths, the output per foot should be similar to achieve a uniform appearance.

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S/2

S = 1½ D

D

SPACING FOR UNIFORM

FL AT WHITE CAVITY FINISH

DIFFUSER BRIGHTNESS

FLOATING LUMINOUS ELEMENT

OPEN TUBULAR METAL FRAMEWORK

S/2

S = 1½ D

TUBULAR LED LIGHT STRIPS

D DROP-IN EDGE-LIT LED PANEL

LIGHTING APPLICATION & DETAILS

TRANS-ILLUMINATED ELEMENTS LUMINOUS SOFFIT Luminous, or lighted, soffits are useful over task areas and for personal grooming. Over task areas they can furnish high-level illumination on the work, with a minimum spread of light in other directions. For personal grooming, they provide light directly on a person’s face and head, and with light-colored counter tops, reflect light the under areas of the face and chin.

Design Considerations: Lighted soffits for personal grooming should be at least 36 to 48 inches wide to insure adequate illumination on the sides of the face and head. Full spectrum light sources should also be incorporated to compliment skin tones. A minimum depth of 12 inches from the wall, and down from an 8 foot ceiling is typical for two rows of lamps. Increasing the distance out from the wall to 18 inches offers the opportunity to use three rows of lamps and about a 50 % increase in the light output. Over work areas an increase in lighting can be gained with polished metal reflectors on the light strips, with open louvers or clear configurated plastic diffuser, rather than white.

Light Source Selection:

Similar to other trans-illuminated elements, the use of tubular LED or fluorescent lamps will result in the best light distribution and energy efficiency. Warm color sources are best when used for vanity and personal grooming areas, with color temperatures from 2700K to 3500K. Use lamps of the same color temperature to prevent visible color variations in the transmitting material. Separate low-wattage sources with individual switching can furnish comfortable night lighting feature.

8.27

LUMINOUS SOFFIT

T8 TUBULAR LED OR FLUOR. LAMPS 8"-12" FROM 8 FT CLG. FINISH CAVITY FLAT WHITE

12" - 18"

WHITE LOUVERS OR DIFFUSING PLASTIC

REPRESENTATIVE DETAILS

T8 LED LAMPS 8"-12" FROM 8 FT CLG.

18" - 24"

FINISH CAVITY FLAT WHITE WHITE DIFFUSING PLASTIC

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LIGHTING APPLICATION & DETAILS

TASK LIGHTING UNDER-CABINET TASK LIGHTING Many open office furniture systems have wall cabinets that create shadows on the work surface, reducing task illumination from the overhead lighting. Some have under-cabinet lighting to overcome this problem. The correct location and shielding of this light source can impact the successful performance of a task. The light source may be located in a position that produces annoying reflected glare – called veiling reflections – that can mask the visual task, especially on glossy surfaces and materials. The glare problem usually results from the position of the light source, relative to the viewer’s eyes. Many times there is no shielding on the front of the light source, directing light straight into the viewer’s eyes. The illustration at the lower right shows how a light source located near the wall will create a reflected image closer to the wall and further away from the task area, usually located at the front of the desk or counter top.

Design Considerations: The use of shielding to block the direct horizontal component of light, and diffusing materials to spread the light can help in reducing the visual discomfort. Undercabinet lighting can create an uncomfortable environment when dark-finished cabinets are contrasted with wall and work surfaces. These conditions, even for short periods, can cause eye fatigue due to the eyes continuously readjusting to different levels of brightness. To minimize this condition use a slightly lower wall reflectance and lighter cabinet finishes, along with ambient illumination that is sufficient to adequately light the cabinet vertical surfaces.

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UNDER-CABINET TASK LIGHTING

AMBIENT LIGHTING CONTRIBUTION

LIGHTER CABINET FINISHES REDUCES CONTRASTS THE LAMP POSITION DETERMINES THE LOCATION OF REFLECTED IMAGE TYPICAL LOCATION OF THE VISUAL TASK ON THE WORK SURFACE

LIGHTING APPLICATION & DETAILS

TASK-AMBIENT LIGHTING UNDER/OVER-CABINET LIGHTING Manufacturers of lighting equipment and office furniture systems offer a number of luminaires and innovative under-cabinet task lighting solutions that offer a reduction of glare and veiling reflections. Light directed sideway, away from the viewer’s eyes, reduces glare and veiling reflections by furnishing illumination in a direction 90 degrees to the task. In addition to the direction of the light, the use of special louvers and lenses further reduces the source of unwanted glare. In most cases, this involves locating the light sources on either side of the task area. A few of the luminaire types designed for this task lighting application are shown below. UNDER / OVER-CABINET TASK-AMBIENT LIGHTING

4" 12½"

Multiple lamp LED fixtures with remote drivers can be used to furnish adequate and comfortable task lighting.

12" to 15"

FLUORESCENT OR LED TUBULAR LIGHT STRIPS

PAINT CAVITY FLAT WHITE

LED strip lights in various modular lengths that can be plugged together for ease of installation.

2" 12½"

3/4" HARDWOOD TRIM

5"

Twin units with compact fluorescent or LED lamps with louvers and reflectors that will direct the light sideways.

36"

3/4" HARDWOOD PLYWOOD (TYP)

1/2" CELL ALUMINUM LOUVERS WITH 30° ANGLED BLADES

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LIGHTING APPLICATION & DETAILS

TASK-AMBIENT LIGHTING

OVERHEAD AMBIENT-TASK UNIFORM SYSTEM

Advantages: This uniform pattern of ceiling mounted luminaires furnishes both ambient and task illumination for both work areas and general circulation. It has the advantage of allowing furniture arrangement without the need to change the lighting, resulting in the efficient distribution of illumination throughout the space. Only general, or average, information regarding the visual tasks to be performed in the space is required to design the lighting system. Also, because the luminaires are not located in the occupied space, it permitts more

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effective control of the heat from the lighting system when using fluorescent lamps. This transfer of heat from the luminaires also improves the lighting efficiency and permits recovery of excessive heat. Disadvantages: The required lighting level for the entire space is established on the basis of the tasks needing the highest degree of illumination, and the distribution characteristics of the direct lighting system can result in annoying shadows and reflected glare. Most importantly, the entire area is lighted when only one work station is in use.

LIGHTING APPLICATION & DETAILS

TASK-AMBIENT LIGHTING

OVERHEAD TASK-AMBIENT NON-UNIFORM SYSTEM

Advantages: This non-uniform pattern of luminaires also furnishes ambient and task illumination, with emphasis on task lighting. It can furnish quality illumination for specific identified visual tasks and local control can provide for optimum energy utilization. Personal control of lighting levels has been shown to improve worker satisfaction and performance. The installed cost of the lighting is minimized, and with the luminaires located above the occupied space, there is more control of the heat from fluorescent lighting. With the use

of a flexible wiring system and power plug connections, luminaires can be easily relocated when a change in occupancy is required.

Disadvantages: The random, non-uniform appearance of the luminaires located in the ceiling could be visually unappealing, and if the luminaires are not properly located may result in annoying shadows, reflected glare, and veiling reflections. This system may also require substantial additional initial and future expense for the provision of local control and possible relocation costs over the life of the system.

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LIGHTING APPLICATION & DETAILS

TASK-AMBIENT LIGHTING

OVERHEAD AMBIENT & LOCAL TASK SYSTEM

Advantages: This system furnishes ambient lighting with overhead luminaires and task lighting with equipment located near the task, and local control at each work area. Local control allowing lights to be turned off when not in use, and fewer ceiling luminaires, results in significantly lower power densities. Lighting levels are established by the tasks to be performed, with the direct distribution of light resulting in excellent energy efficiency. The furniture-integrated lighting elements can be relocated along with work station furniture.

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Disadvantages: The cost of installation is significantly higher due to the individual wiring requirements and the special task lighting equipment. The furniture-mounted task lighting may use less efficient light sources and result in unwanted glare and veiling reflections if incorrectly located. Because the task lighting fixtures are located in the occupied space there is no opportunity to control the heat generated by the light sources. Replacement of the furniture-integrated lighting types when needed can result in a considerable recurring expense.

LIGHTING APPLICATION & DETAILS

TASK-AMBIENT LIGHTING

INDIRECT AMBIENT & LOCAL TASK SYSTEM

Advantages: This system furnishes ambient lighting from luminaires that direct the light to the ceiling from the furniture-integrated light sources, while the task lighting is provided by equipment located near the task. Local control allows lights to be turned off when not in use. No ceiling luminaires results in lower power densities. The lighting levels are established by the tasks performed, with the direct distribution of light resulting in excellent energy efficiency. When needed, the furniture-integrated lighting can be relocated along with work stations.

Disadvantages: Installation costs are higher due to the individual requirements of the task lighting equipment. The furniture-mounted task lighting sometimes uses less efficient light sources and may result in unwanted glare and veiling reflections if incorrectly located or relocated. Because the task lighting fixtures are located in the occupied space there is no opportunity to control the heat generated by the light sources. Replacement of the furnitureintegrated lighting equipment can be a recurring high expense over the life of the equipment.

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LIGHTING APPLICATION & DETAILS

LIGHTED RAILINGS General Considerations: Lighting built into low partitions and railings used in open spaces and circulation areas can offer efficient and interesting ambient illumination. This special and unique type of architecturally integrated lighting can furnish a pleasant luminous environment when compared to other types of typical lighting fixtures, and also be particularly useful with walkways and bridges where there is not a ceiling directly above. With railings located at the edge of balconies or elevated walkways, care must be used in locating the light source so they are not seen from below. An exception may be using of low wattage or color sources partially exposed in a theatrical manner. Handrails located next to stairways can

function as safety barriers and handholds. Their height above stair nosings can range from 30 to 34 inches. Guardrails, on the other hand, are usually used as safety barriers at edges of horizontal walkways, bridges, and balconies, at 36 to 42 inches above the floor and normally would not require a separate handhold railing.

Light Source Selection: Proper lamp selection is important to the successful performance and appearance of a lighted railing. In the past 36 and 48 inch fluorescent lamps were used between the posts. LED light sources, on the other hand, offer more options with regard to available lengths and widths, choices of light output, dimming control, color selection and mixing, and execellent energy efficiency.

HANDRAIL 30"- 34"

GUARDRAIL 36"- 42"

OPTIONAL HANDRAIL WOOD TRIM LED OR FLUORESCENT LIGHT STRIPS BETWEEN POSTS SIGHT LINE FOR SHIELDING LAMPS FROM BELOW 4X6 WOOD POSTS 52" O.C. FOR 4' FLUORESCENT STRIPS 1/2" TEMPERED GLASS OR HORIZONTAL METAL CABLES FINISH FLOOR LINE

LIGHTED WOOD & GLASS RAILING

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WOOD TRIM CONTINUOUS LED STRIP LIGHTS

EXTRUDED ALUMINUM RAILING

FULL WIDTH PARTITION ENDS AND CORNERS

CONTINUOUS LED STRIP LIGHTS OR EXPOSED DECORATIVE LAMPS BETWEEN POSTS

METAL STUDS & GYPSUM BOARD PARTITION

EXTRUDED ALUMINUM POSTS

FINISH FLOOR LINE

PAVEMENT LINE

LIGHTED PARTITION GUARDRAIL

LIGHTED ALUMINUM RAILING

CHAPTER

9

20TH- CENTURY ARCHITECTURAL LIGHTING PIONEERS

The history of architectural lighting allows us to understand what is generally accepted as “good” lighting. The criteria cannot be measured in lumens or watts, but in the effectiveness of the coordination of the architectural objectives, including both environmental and functional considerations. It offers the opportunity for the creation of pleasant and productive spaces. The

current practice of lighting design is involved in the understanding that architecture and lighting are inseparable and dependent on each other. What follows is a review of the history and design philosophy of some of the best and well known lighting design professionals. They are shown in chronological order based on their birth date. A few are not acknowledged due to limited space.

Stanley McCandless (1897-67)

Abraham Feder (1908 - 9 7) was an architectural and theatrical lighting designer, practicing in New York City from 1930s until the early 1990s. He was born in Milwaukee, Wisc. and studied architecture at the Carnegie Institute, but left after his second year. Feder worked briefly for the Goodman Theatre in Chicago before moving to New York City in 1930, where he established a reputation as an innovative designer in major theatrical productions. After World War II, he opened his own lighting design business in New York City and became one of the most prominent architectural lighting designers. His projects from “Lighting by Feder” included the Rockefeller RCA Building, the United Nations, and the main altar of St. Patrick’s Cathedral. He has been accused of using light as if it were a building material like wood,brick, and stone.

An architect, lighting designer, and author who inspired many lighting designers with his teachings. He was considered the father of modern lighting design and was a man with ideas about stage lighting that would change the field forever. He created a method of lighting the stage that is still in use today. He graduated from the University of Wisconsin in Madison in 1920 before receiving a Master of Arts degree in architecture from Harvard in 1923. After college, McCandless worked for some time as an architect before becoming a lighting consultant. McCandless designed the lights for the Center Theater, part of New York’s Radio City. He and George Pierce Baker created Yale’s School of Drama in 1925 offering the first class in stage lighting in 1926. While at Yale, he published many books on stage lighting. The method in his texts is still widely used today. It creates light that appears as natural and gives four elements needed to light a stage: intensity, color, distribution, and control. In 1938 he published an extensive paper on the subject titled “Lighting for Designers” (see the Preface).

He is a founder of the lighting design profession in the U.S. and wrote and lectured on it widely. He was appointed the first president of the International Association of Lighting Designers (IALD) and named a Fellow of the Illuminating Engineering Society of North America (IESNA).

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THE CONTRIBUTORS Richard Kelly (1910 - 77) An architectural lighting designer and pioneer of the practice, and dean to the American lighting designers . He started his practice as a lighting designer in the 1930s and 40s when almost no one made a living that way. His vast credits include many of the most important buildings of the 20th century – working with architects that would make up a substantial Who’s Who list in architecture. Kelly was always interested in architecture, seeing himself as a consulting architect rather than only a lighting consultant. He missed his high school commencement to come to New York to see a stage play and stayed on. To support himself, he had a job designing light fixtures. He entered Columbia College in the Fall and studied math, physics, and English literature. Then, two years after his graduation he opened his own office and was in the business of designing lighting, and selling lighting fixtures. World War ll forced his office to close, and a medical condition kept him out of the military, so he went back to school to study architecture at Yale. After Yale he reopened his office, no longer selling fixtures, but working as an professional lighting consultant. One of Richard Kelly’s first significant works was the renowned Glass House by Philip Johnson in New Canaan. The challenge for transparent architecture, which was gaining popularity with the rise of the International Style, was the clear glass itself, which at night turns into a mirror, reflecting the interior lighting. By minimizing the interior lighting and illuminating

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the surrounding lawn and trees, Kelly restored the continuity and flow from the daytime into the night. He also illuminated some of the 20thcentury’s most iconic buildings. His design strategy was surprisingly simple and successful. Lighting for architecture has been and still often is dominated by an engineering viewpoint, resigned to determining sufficient illuminance levels for a safe and efficient working environment. With a background in stage lighting, Kelly introduced a scenographic perspective for architectural lighting. His point of view might look self-evident to today’s architecture but it became somewhat revolutionary for his time. In the 50s, he defined a vocabulary for lighting terminology and created the terms (ambient luminescence, focal glow and play of brilliants) to describe particular effects of lighting design. His career saw him lecture at Yale and Princeton He dedicated his professional career to the advancement of lighting design and education, and encouraged a close partnership between light and architecture. As a designer and educator, he shared his philosophy of lighting with the emerging new generation of lighting designers. He earned the respect of some of the more important architects of the time working with Philip Johnson, Eero Saarinen, Mies van de Rohe, Louis Kahn and others. The collaboration resulted in some of the best-known examples of successful integration of light and architecture, including: Mies’s Seagram Building, Saarinen’s General Motors Technical Center, Johnson’s Glass House, and Kahn’s Kimbell Art Museum, where with his collaborator Edison Price, created the cycloid vault and curved reflector of perforated aluminum that directs reflected and diffuse natural light into the museum.

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THE CONTRIBUTORS (1938-87) J James was a true pioneer and a early contributor in the area of lighting education. He was one of the first visionaries to advocate that lighting should be recognized as a profession along with with architecture and interior design. He focused his career on the advancement and understanding of the importance of lighting education, especially as it related to architecture. He had a unique understanding of the art and science of light and lighting that guided him in his quest for appropriate illumination training and college-level courses. His popular lectures encouraged students and young professionals that lighting design and teaching was an interesting and exciting profession to consider as a lifetime pursuit. He wrote extensively with many articles in lighting and architectural publications and was author of the formative textbook Interior Lighting for Environmental Designers in 1976. It was an illustrated book on the practice of architectural lighting and interior space emphasizing the aesthetic as well as the scientific values inherent to lighting design. Jim was also an early pioneer in the use of computer technologies before most professionals understood their future impact on architectural and interior lighting design.

As a practicing lighting designer his projects received peer recognition and acclaim, while his greatest accomplishments were in the area of lighting education. He was fortunate to be in the New York area during the 1970s and 1980s when interior design education was changing and expanding and the Parsons School of

Design offered an innovative environmental undergraduate program that differed from existing programs. Dedication to a cause by itself may not easily effect change in educational programs. However, Jim had the talent and charisma to bring about change. At Parsons in 1970 he started an undergraduate program in lighting design and by 1984 expanded it to be the first school to offer a Masters degree in lighting design. The graduates were prepared for careers as architectural lighting designers.

He was active in the IES and instrumental in the creation of the International Association of Lighting Designers (IALD). After his untimely death in 1987 a fund was started to help college-level programs interested in light in architecture. The “Nuckolls Fund For Lighting Education” goal was to provide financial support for lighting education. Each year the Fund solicits proposals from colleges and universities for innovative ideas that will modivate and inspire students with knowledge about light in architecture. The Fund awarded grants since 1989 and funds four annual student awards. The $20,000 Nuckolls Fund Grant is given to assist in the development of a new or expanded course in lighting in an established lighting program. The $20,000 Lesley Wheel Introductory Lighting Program Grant is given to assist in developing a lighting course at a college-level that has minimal or no lighting courses. The $10,000 Edison Price Fellowship Grant enables a lighting educator to enhance his or her own education in order to improve their teaching ability. The $5,000 Jonas Bellovin Scholar Achievement Award is for a student demonstrating outstanding performance in an established lighting program.

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THE CONTRIBUTORS (1930 - 8 0) Born in Cincinnati, Ohio, John earned a bachelors degree in architecture from the University of Michigan in 1953. After serving in Korea as a lieutenant in the Army from 1953 to 1955, he started his professional career in lighting and architecture with the General Electric Company at its Nela Park Lighting Laboratories in Cleveland, Ohio. His work there was involved in the relationship between lighting, heating, and air conditioning. This investigation resulted in a paper he collaborated on and was presented at the 1959 IES Technical Conference in San Francisco titled “Integrated Lighting and Air Conditioning.” Another paper on the subject was presented at the 1963 CIE (International Commission on Illumination) meeting in Vienna. During the period from 1959 to 1963 John’s work was involved in the planning of lighting for the 1964 - 6 5 New York World’s Fair, where he developed lighting concepts for interiors and exteriors of many of the spectacular buildings of the Fair. This was also where he began to develop his ideas about the use of lighting to create subjective reactions in people. He created the concept of “Public and Private Space” determined by lighting. This was also the time he developed interest in the psychological and motivational influences of lighting. Also, while working full time at his job at Nela Park he passed the exam to become a licensed architect and also co-authored the book Architectural Lighting Graphics published in 1962 – which predated word processing, press-type, and computer graphics. In 1973 he co-authored a

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second book titled Architectural Interior Systems that presented the concept of integrating lighting, heating, air conditioning, and acoustical systems. In 1964 John left General Electric for private practice and in the ensuing years completed an impressive list of professional accomplishments. He was a member of the faculties of Michigan, Columbia, Yale, Pennsylvania, Kent State, and Penn State Universities. In 1965 he was given the Arnold Brunner Scholarship Award from the New York Architectural League and also the Technical Achievement Award from the Cleveland Engineering Council. This was followed by being made a Fellow of the Illuminating Engineering Society (IES) in 1973. That same year he wrote an article titled “Concepts Beyond the IES Framework,” in which he suggested that our long-range survival as professionals and as an industry depends upon a better sense of human response in our lighting practices. He suggested there is considerable evidence that light and lighting makes an identifiable contribution to our quality of life, and the value of this contribution should also be considered with other items in the accounting of human environmental factors and building budgets. The technical papers published on this research should be required reading for students and practitioners of lighting design. He started his most important research work at Kent State University in 1967 and continued it at Penn State until his unfortunate and untimely death in 1980. It involved research on the effects of lighting on human judgment, attitudes, and behavior. It was important for many reasons, but primarily due to it including input from environmental and behavioral scientists and employment a new research methodology not

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THE CONTRIBUTORS traditionally associated with accepted lighting research identified as multidimensional scaling and semantic differentials. He was called upon to lecture on his work, which was found to be unexpectedly of interest to his audiences. The International Commission on Illumination (CIE) asked him to chair their Technical Committee on Visual Environment. At that time the Committee was planning to merge with the Study Group and were altering their work to be more in line with his new concepts. It was not easy to obtain a chairmanship in CIE’s technical committees, but he had no peer in this area where there was much competition among nations. He also exhibited leadership in the technical committee structure of the IES as well as his service as a Director. Also, when John’s friend and associate at General Electric, Will S. Fisher, was President of IES he let it be known how fortunate that John had been elected as the Senior Vice President of the Society, because he relied on his counsel and advice during a time when the Society had to deal with a number of important matters. They involved changes in the basis for the IES recommended lighting levels, as well as work with ASHRAE on Standard 90, contacts with the National Bureau of Standards on lighting industry issues, and relationships with societies such as ASHRAE, IEEE, and AIA. Another issue that became particularly trying for the IES, was the Federal Trade Commission’s decision to establish rules for organizations involved in preparing national standards. There was considerable emotion and invective aimed at the IES’s position on these national standards by some misguided detractors. By this time John had assumed the presidency of the IES and had to prepare a statement outlining

the Society’s position on the standards to the Federal Trade Commission. There was also a public hearing where he proved to be an eloquent spokesman with his calm, factual manner of pointing out the errors of those that criticised the Society. His rebuttal of the IES detractors caused one to say that he would not be a witness because his testimony was shown to be full of errors. His performance in defending the IES’s position and establishing it as the proper spokesman and authority in the field of illumination was greatly appreciated by all of the members and staff of the Society. He earlier had identified his research work as being somewhat outside of the IES framework, but looked for and expected future IES leadership in this area. This came true however after his term in office and his premature death, and without his leadership, it became somewhat overlooked at first, but has since then influenced current thinking and the future direction of the Society. I first met John when we were both starting our professional careers in lighting with the General Electric Company at its Nela Park Research and Engineering Laboratories. A new friendship developed fairly early due to our similar backgrounds, and as novice architects in a company staffed primarily with illumination engineers. Our obvious common interest in architectural lighting, as distinguished from illumination engineering, labelle d us as accomplices and advocates of an untested proposition that footcandles were not the only significant measure of lighting design.

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THE CONTRIBUTORS (1919-07) was a native of Warsaw, Poland and was trained as a structural engineer at Polytechnic Institute in Warsaw. In 1947 he came to United States to obtain a Masters degree at Columbia University. Even with his advanced degree in engineering he was drawn to art, music, language, and literature. His years at Columbia University connected him to an interesting circle of friends. One of the most significant people he met there was, Abe Feder, another pioneer in lighting, who introduced Jules to the world of architectural lighting. He apprenticed under Abe for several years and eventually left to start a lighting department with the engineering firm of Syska & Hennessey. After working a number of years on projects such as Madison Square Garden he was asked to design some lighting for the 1964 World’s Fair. With several large-scale lighting projects completed, he opened his own lighting design firm from his own living-room studio in 1969. Soon after, in 1970, he opened a lighting design studio on New York City’s Park Avenue South with the commission of a large project for the Dallas Fort Worth International Airport – along with the architectural firm of HOK. For the airport project, he overcame the then underrecognized phenomenon of glare by lining roadways with special luminaires that spread light away from the eyes of drivers. Inside the terminal, he alternated colored lighting to create a wayfinding system for the airport travellers. This led to a number of additional relationships with major architectural firms with international

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projects where his fluency in Polish, German, Russian, French, and Italian served him well. He was the innovator of the 2x2 lensed fixture used widely in offices in the 1970s. Having learned that the sign industry had developed a new u-shaped fluorescent lamp for compact signage, he saw an opportunity and went on to design a fixture with a prismatic lens to shield the light source. The fixture was used in a large New York office lighting project to the satisfaction of both the building owner and the architect. Jules Horton could naturally boast of his many accomplishments in his career, and could tell stories of his survival in a Russian labor camp during World War II in the Arkhangelsk Islands. When discussing his innovations in lighting design, he checked his enormous ego and became unaware of the impact his visions had on today’s contemporary architecture. Horton expressed concern about the wasteful practice of placing a ceiling fixture every 25 square feet throughout a building, making everything the same, with no accent, direction, or motivation. He was one of the first to suggest the use of task-ambient lighting to reduce energy usage. In every project, he felt the most important question was determining the client’s true needs. After retiring in the early 90s, he stayed quietly at home exploring his passion for music, art, and literature. His travels were curtailed due to arthritis, from knee injuries during the war. For those who knew Jules, this was a terrible thing for someone who loved to travel. A few small strokes confined him to a wheelchair from 2001 and on February 23, 2007 Jules Horton died at his home at age 87. He was a member of an exclusive circle of designers who established architectural lighting as an accepted profession.

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THE CONTRIBUTORS (1925 -0 7) was a lighting designer born in New Haven, CT. He served in the U.S. Navy during World War II and then completed his education at the University of Pennsylvania and the Wharton School of Design. His work with higher education continued throughout his life. Shemitz was known for his passion for lighting and mentoring of lighting professionals and students alike. He was a visiting lecturer at several major schools of architecture including Yale, Princeton, and the University of Pennsylvania. He was a leader in the generation of designers that established architectural lighting as a professional discipline. Shemitz founded his own firm – Sylvan R. Shemitz Associates in 1963 in New Haven where he worked on such signature projects as the lighting of the Jefferson Memorial in Washington, DC, and the facade lighting for Grand Central Terminal in New York City. In the 1980s Shemitz worked with architect Helmut Jahn on the United Airlines Terminal at Chicago’s O’Hare Airport, creating daylighting and nighttime illumination that was coordinated and integral with the architecture. The resulting glowing glass-shed was a modern interpretation of a grand European rail station and became a landmark of the future of transportation terminal design. He was the inventor of over 30 patents for major innovations in asymmetric lighting under the company’s elliptipar brand, which was featured in the addition for the Nelson-Atkins Museum of Art in Kansas City. He also invented and was a strong proponent of task-ambient office lighting.

Shemitz felt good lighting makes a finished building look and function as the architect intended, at all hours of the day and night. Good lighting contributes to the mood, to the desired attitude toward the form and space, and to the effective functioning of the space. He also has suggested that the lighting consultants’s relationship should be with the architect where interaction is vital during the architectural design phase. The lighting designer must also offer suggestions at an appropriate time when they can be acted upon. Also, don’t consider standards that confuse quantity of light with quality of light and avoid fads in lighting. He had rules for the practicing lighting designer : Define the Problem The most difficult part of getting the right answer, is to ask the right question. Go Back to Basics To bring fresh thinking to each project, look at every job as a new problem. Present Alternatives When working with an architect, present reasonable alternatives with their pros and cons rather than a single solution. Consider Custom Design It’s a mistaken idea that custom equipment is more expensive. With quantity you may get it at no increase in cost. Budget for Now and Later Establish a budget that is concerned with more than the initial cost. Pay Attention to Documents Final results depend on professionalism. Take extra effort in creating good drawings and specifications. Get Totally Involved Your best work is always done when you are totally involved in the project. Have Fun Believe your work should be fulfilling and fun. There is an annual Shemitz student scholarship, along with the IES, awarded to one student who demonstrates creativity, vision, and knowledge in the field of architectural lighting.

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THE CONTRIBUTORS Derek Phillips (1923-13) Born in England, Derek spent his early childhood in India where his father worked for the Imperial Bank of India. At the age of five he was returned back to England to St Dunstan’s Prep School in Worthing and then at 13 to Haileybury College in Hertfordshire. On his 19th birthday in February 1942 he was called up to report to HMS St Vincent in Gosport where he served in the Fleet Air Arm of the Royal Navy during World War II. Posted to Trinidad for training after only two months, Derek and his best friend Tommy Morrison went up with an inexperienced pilot who lost control of the plane. They had to bail out and Derek was sadly the only one to survive. Posted back to the UK in 1943 he took up training to become part of the Navy’s first Night Fighting Squadron. It was at this time through discussions with his Pilot Lt. Dennis Thornley, a qualified architect and close friend, that he was influenced to study architecture. Through his many dialogues with Dennis, Derek contemplated his future after the Navy and he thought a career in architecture would combine both art, which he already enjoyed, and science, which he felt he would like to know more about. He took the opportunity to request an early educational release from the Navy and enrolled to study architecture at the University of Liverpool. While at Liverpool Derek met Diana Hesketh and they married in 1952. They had five children Starkie, Adam, Rebecca, Jemima, and Amelia. Sadly, Starkie died in 2002, and Derek’s wife Diana died early in 2013, before Derek’s death.

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Derek gained First Class Honours in Architecture at Liverpool and was then encouraged to apply for a Commonwealth Fund Fellowship which he was granted to study Daylighting and Architecture at Massachusetts Institute of Technology. When arriving at MIT he discussed his aspiration to study the daylighting of cities with Dean Anderson, who told him that they did not know anything about daylighting, so he started a research program on artificial lighting, which is where his career as a lighting consultant really emanated from. Derek met Frank Lloyd Wright and Le Corbusier and both these great architects discussed the importance of light in their work. This further excited and encouraged Derek to focus his future career in the field of lighting. When returning from MIT in 1954 positions in architecture were restricted, so Derek took the opportunity to work with lighting manufacturer, British Thompson Houston (BTH) Company, where he spent four years. Toward the end of his time with BTH he was asked to design the lighting for the British Exhibition in the Tivoli Gardens, Copenhagen, but was restricted to only using BTH products which he found unacceptable. He proceeded to set up his own practice in 1958, “Derek Phillips Associates,” and practiced as both an architect and lighting consultant. This soon became known as “dpa Lighting Consultants” and the practice focused on lighting design. Derek was a pioneer as a professional lighting consultant, a discipline fully divorced from the commercial influences of selling and supplying lighting equipment. He believed passionately in providing the best advice possible for his

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THE CONTRIBUTORS clients and the practice motto was “Not to be satisfied with the best you can do but to do the best that can be done.” Derek had made great friends with American lighting designer Howard Brandston, who influenced his work a lot. Derek collaborated with Howard on projects in Europe and the Middle East in the early days of the practice and they remained friends throughout his life. Derek gave his time freely to lecture and help educate young designers, other professionals, and anyone who was interested and passionate about light in all forms. Following his 1964 publication Lighting in Architectural Design, he wrote another book Lighting, for the British Design Council demonstrating the principles and planning of home lighting which was published in 1966. He believed education to be extremely important and participated with many institutions and their activities. He delivered the inaugural Waldram Lecture in 1990 and titled it “City Lights,” the daylighting influence of his time at MIT was resonating on throughout his career. He was Chairman of Hertfordshire Association of Architects, a RIBA Council Member, and President of the Illuminating Engineering Society and Vice President of the International Association of Lighting Designers (IALD), which made Derek a Fellow in 2001, receiving the highest honour of a Lifetime Achievement Award in 2009. Derek was also hardworking and industrious. When work was slow in the UK economy in the early 1980’s, rather than just wait for things to get better he set up an office in Hong Kong where the practice thrived working on important projects in the territory and mainland China. Projects

included refurbishing the Mandarin Oriental Hotel that he had originally worked on in the 1960’s, the Academy for Performing Arts, and the Macau Ferry Terminal as well as many others. Derek retired in 1993 but his passion for lighting did not cease. He was the author of four books on the subject as well as his autobiography, and attended numerous industry events. His other passions continued also, for example, sailing, his dogs and most importantly his family. Derek’s friendly personality and generosity of time for anyone who was interested in lighting was a great gift that we can all learn from. Derek is survived by four of his children Adam, Rebecca, Jemima, and Amelia, along with 12 grandchildren and at least one great-grandchild. Derek’s good friend Howard Brandston had this to say about Derek upon his death. “Derek Phillips was a true renaissance man, a pioneer in establishing lighting design as a profession. The long list and variety of works to his credit give testimony to his talents. The quality of his work was an inspiration. Derek was the consummate professional, a most modest gentleman. I had the good fortune of being a friend and occasional collaborator. It is hard to single out an example to illustrate the depth of his creativity, but I would suggest his book, Lighting Historic Buildings. His appreciation and understanding of heritage work brings into focus a far better way to consider the work we do today. It gives an insightful look at how people lived and created in years long past. It makes one wonder and inspires a thoughtful focus on the work we are producing. Thank you Derek. You will always be remembered.”

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THE CONTRIBUTORS Wm. M.C. Lam (1924 -12) was born and raised in Hawaii. After serving three years in the Army Air Force as a B-25 co-pilot, he earned a degree in architecture from MIT in 1949. Not long after, he designed a lamp for use in his own home, people admired it and asked where they could obtain one, and the rest is lighting history. Lam founded Lam Inc. in 1951 to manufacture glare-free floor lamps and other products and won a number of “Good Design Awards” from the Museum of Modern Art. However, after eight years of manufacturing he returned to his first true interest, architecture, founding the firm William Lam Associates. The firm specialized as consultants in the coordination of lighting and architecture and urban design. For the next 40 years Lam won acclaim for notable projects and played a prominent roll in the architectural lighting field as a theoretician, designer, and effective critic of the Illuminating Engineering Society. His primary effort was to redirect the practice of lighting design away from the quantitative effort to a more environmental and architecturally integrated approach. The long-running battle with the IES began in the early 1960s and ended during the energy crisis of the '70s. “Quality not quantity” was Lam’s battle cry. He related that at the time, the IES arbitrarily set high lighting levels and ignored good design. He wanted the emphasis on quality, judgment, and common sense rather than engineering and footcandles. This was typical of his design philosophy where the emphasis was placed on thought that

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“Lighting is about design and not engineering.” As a result, light levels once recommended by the IES were reconsidered and lighting design evolved into what is current practice today. Before his return to architecture, the Lam light diffusers were among the first products made from fiberglass reinforced plastic. The desire to retire from manufacturing of lamps and return to architecture led to a shift to design and manufacturing of prefabricated unique built-in lighting systems and elements for buildings. Bill Lam felt a good environment resulted less from light levels and brightness ratios than from careful design and understanding of where the light is coming from. An environment is most pleasant when illuminated from surfaces like architectural walls and ceilings, rather then from typical obtrusive-apparing fixtures, which requires careful integration of the structure and electrical and mechanical systems. His efforts to integrate lighting with architecture is based on the conviction that lighting is part of the architecture and results from the integration of all design elements. This is what he has taught in his lectures at universities including Harvard and MIT and in his writings. “What’s important is designing from the inside, creating spaces for people to live and work in.” Lam’s book Perception and Lighting as Formgivers for Architecture has become a definitive references for many students of architecture. Yet, Lam’s influence went far beyond his students to also reach clients, government officials, and the many people he has worked with on a number of various projects. He stressed the need for all to work as part of an interdisciplinary design team where all members cooperate and work together.

20TH-CENTURY ARCHITECTURAL LIGHTING PIONEERS

THE CONTRIBUTORS Howard Brandston grew up acting or designing theatre productions since his kindergarten years. The theatre contributed to shaping his vision for lighting and a lifetime of contributions to the worlds of lighting and design. Howard Brandston’s first job fresh out of college was with Stanley McCandless – the godfather of lighting at that time. In 1965, he founded his own lighting design consulting firm that became the New York City-based Brandston Partnership Inc. During Mr. Brandston’s tenure, the firm completed over 2,500 projects in 60 countries, including the relighting of the Statue of Liberty and the Petronas Towers in Malaysia. Mr. Brandston is one of only four individuals to have received every major award given by the Illuminating Engineering Society (IES) in its over one hundred year history. In 1999, he received the IES Medal, the Society’s highest honor, and was appointed the Society’s first leader of Design and Application – he also served as the IES president. Other notable awards include the Institute Honors in 1999 from The American Institute of Architects (AIA) for his many contributions to architecture, and being designated an Honorary Fellow of the Chartered Institution of Building Services Engineers and the Society of Light and Lighting, an honor limited to 25 living persons. Mr. Brandston also received the IALD Lifetime Achievement Award from the International Association of Lighting Designers and is the sole lighting designer in the Interior Design Hall of Fame. In 2014, he received the

United States Institute of Theater Technology Distinguished Achievement in Lighting Award. In his 60-year career, Howard Brandston has received more than one 100 design awards. His most cherished award is a Honorary Doctor of Fine Arts from Brooklyn College in 2016. During the 70’s energy crisis, he was selected to represent the IES on the Federal Architectural Engineering Energy Commission. His contribution was the mathematical equation used to set the upper power limit for lighting for our first energy code. He was also appointed to NY State’s first Energy Advisory Council. Howard has defended the incandescent light bulb, opposing its defacto ban. In 2008, he testified before the US Senate to withhold funding for the Energy Independence and Security Act of 2007. Howard’s passion is education. For more than 50 years, he has been an Adjunct Professor, guest lecturer and visiting professor at multiple universities around the world. In 1981, he founded the Workshop for Teachers of Lighting, an IES continuing program to educate teachers. He also founded the Ad Hoc Committee of Lighting Funding Research Organizations which led to the establishment of the Lighting Research Center at RPI. Howard funds in perpetuity the Brandston Grant, an international design competition administered by the IES. He is a former holder of the Feltman Chair in lighting at Cooper Union, and established the Brooklyn College Howard M. Brandston Award in Lighting. Working in the spirit of project collaboration is the hallmark of Mr. Brandston’s work. Collaborations with many artists to bring light to their works include Roy Lichtenstein, Maya Lin, Alexander Calder, Isamu Naguchi, and others.

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THE CONTRIBUTORS Raymond Grenald is one of the living legends of the lighting design profession. He is a founder and past president of the IALD, and has chaired the IES national committee on museum and art lighting. Long active in professional education, he has served as a faculty member or visiting lecturer at more than a dozen major universities, including Harvard University, the University of Pennsylvania, Yale University, and the University of Southern California, and has been a board member of the Lighting Research Institute. He is a Fellow of the AIA, IALD, and IES, and a living legend of the lighting design profession. A long-time observer of people’s cultural habits, Grenald’s conversations are packed with recollections of the places he’s visited and the spaces he’s experienced and designed. His considerable body of work was adjudged to significantly contribute to a better public awareness and appreciation of lighting design’s contribution. Born in Louisville, KY., Grenald inherited design and technical influences. “My uncle was an architect and engineer in Europe,” notes Grenald of his Swedish heritage, “and my father was an artist.” Early aptitude tests indicated that Grenald could achieve success in technology and/or artistic pursuits. But before he could begin his professional studies, World War II broke out and he was a drafted into the U.S. Army, assigned to the Air Force as a research engineer on experimental aircraft. He remained in the military, and was then posted to Korea as an Army combat engineer. When a plane he was in crashed in Korea, he suffered severe back injuries that

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confined him to a military hospital for a year. Following his discharge, he relocated to Washington state, and enrolled in Washington State University. Grenald earned a B.S. in Engineering with a specialty in aeronautical engineering. He decided that he had to unlearn how an engineer thinks. To accomplish this goal he went back to WSU and successfully completed the Bachelor of Architectural Engineering program. His interests also tended toward psychology, physiology, and “human geography.” He decided to forego aeronautical engineering and stick with architecture, hoping that it would provide a design basis for pursuing these topics. He had been hearing that Philadelphia was undergoing a major urban redevelopment program and left the Northwest and headed East . It turned out to be an advantageous move. He started his own architectural practice that he operated for 14 years. Lighting for his projects was carried out by electrical engineers, designing lighting by the numbers. He decided to take on the responsibility for the lighting for his architectural work. He began to win awards for his lighting. In 1968, he founded his own architectural lighting firm. Lee Waldron, whose background was in theatre and television lighting, joined Grenald in 1976. In that same year he was finishing the four-yearlong relighting of the Carlsbad Caverns for the National Park Service in Carlsbad, New Mexico, and it remains his favorite job. He feels light is magic and architecture is the art of expressing and enclosing space, but light is the medium by which it is perceived – using light as architecture. He believes that with the availability of new technologies in lighting, there will always be new solutions, but the basic principles of light and lighting will always remain the same.

GLOSSARY

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FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY

A

A Lamp General service incandescent lamp with medium base. AC (Alternating Current) Current that flows in one direction and then alternates its flow in the opposite direction. Accent Lighting Directional lighting to emphasize objects, draw attention to display items or highlight, dramatize, and focus attention on architectural features. Adaptation Process where human eyes adjust to a change in light level.

ALA

(The American Lighting Association) The trade organization of the residential lighting industry in the U.S., Canada and the Caribbean, with members that are lighting manufacturers, showrooms, sales representatives, designers and other industry associates who promote lighting in the home.

Alzak

A trade name for a method of anodizing, generic term for brightened, anodized aluminum, a brushed nickel appearance as a bright, shiny coating.

Ambient Lighting

General illumination in an area, not including task lighting, accent lighting, special lighting effects, and may, or may not, include daylight.

Ambient Temperature

The surrounding temperature within an environment.

American National Standards Institute (ANSI)

A consensus-based organization which coordinates voluntary standards for the physical, electrical, and performannce characteristics of lamps, ballasts, luminaires, and other lighting and electrical equipment.

Ammperage (Amps.)

Standard unit of measurement of electrical current equal to wattage divided by voltage. Amps (I) = Watts (P) / Volts (V)

Angstrom

Measurement of wavelengths (0.0000000001 m)

Anode

The “positive” terminal of an electrical device.

Anodized

Durable finish consisting of thin, near transparent coating of aluminum oxide on the surface of an aluminum reflector.

ANSI Ballast Type

Ballast type used to operate lamp in accordance with ANSI standard.

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ANSI Codes

Three-letter codes by the American National Standards Institute to provide the assu ring mechanical and electrical interchangeability among similarly coded lamps from various manufacturers . Antique Finish A finish that simulates aging, often accompanied with dark pigment paint wiped across a metal part. Application Refers to specific parameters and usage of light sources as applied to a lighting design or layout for a general or specific application. Arc General term for high-intensity electrical discharge between two electrodes in gaseous medium, along with generation of heat and the emission of light. Arc Lamp A light source containing an arc (see above). Also called a discharge lamp, or an arc discharge lamp. Arc Length The distance between the electrode tips in high-intensity discharge lamps: which represents the physical length of the electrical discharge. Auto Rest Shutdown Circuit A circuit that senses end of life and automatically shuts off power to lamp(s). Ballast resets with a new lamp, and turns on the lamp. Some circuits require power to be interrupted before a new lamp will light.

B

An opaque element used to control the distribution of light at certain angles . Base or Socket A receptacle (socket) connected to electrical supply. The end of a lamp that fits into the socket. There are many types used in lamps, screw bases being the most common for incandescent and HID lamps, with bipin common for fluorescent and some LED lamps. Bayonet A bulb base using keyways instead of threads to connect the lamp to the base or socket. The bulb is locked in place by pushing it down and turning it clockwise. Beam Angle or Spread The angular dimension of the cone of light from reflector lamps (R and PAR types) encompassing the central part

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY of the beam out to the angle where the intensity is 50% of maximum. The beam angle called “beam spread” is often part of the ordering code for the reflectorized lamps. Beam Lumens Total lumens within the beam angle. Beveled Glass Clear glass with edges cut at an angle to add depth and a special effect. Binning Process by which LEDs are sorted in order to maintain proper color consistency between individual LEDs. Bi-Pin Base with 2 metal pins for electrical contact, typical for fluorescent lamps. Has 2 prong contacts which connect to the luminaire. There are medium and miniature types. Black Light A term referring to a light source emitting mostly near ultraviolet (UV) – (320-400 nm) and little visible light. Blackbody A hot body with an incandescent surface at a certain temperature used as a standard for comparison. A black surface is the best radiator possible. A tungsten filament will emit slightly less radiation than a blackbody at the same temperature. Bollard Short post light, for grounds and outdoor walkway lighting. BR Lamp Bulged Reflector R lamp producing a soft-edged beam less precise and narrower than PAR lamps. Brightness Refers to technical terms used for describing luminance . Bulb A way of referring to a lamp, particularly the outer glass bulb. Bulb Size The maximum diameter of a bulb expressed in 1/8s of an i nch. A T4 tubular lamp would be 4 eighths of an inch, or 1/2 inch.

C Candela (Cd) The measure of luminous intensity in a given direction. From a time when a standard candle of fixed size and composition was defined as producing one candela in every direction. Candlepower Term for luminous intensity; currently referred to as candela. Candlepower Curve Photometric curve giving fixture or lamp energy at various viewing angles. Used to calculate coefficients of utilization.

Canopy Part covering an outlet box, or fixture attachment point. Cathode The “negative” terminal of an electrical device. Cavity Ratio Ratio of wall area to the horizontal area of the room, ceiling, or floor cavity. Center Beam Candlepower (CBCP) The luminous intensity in the center of a beam, in candelas . Centigrade (C) Celsius temperature scale where 0°C = 32°F. Ceramic Metal Halide (CMH) Metal halide lamp using ceramic for arc tube instead of quartz, giving better color rendering and improved lumen maintenance. Circuit Breaker Electrical panel protecting device, disrupting the circuit if overloaded. Percent of lumens emitted by a lamp that eventually reaches the work plane. Used in zonal cavity illumination calculations. Cold-Cathode A fluorescent technology sometimes confused with neon. It differs from fluorescent or hot-cathode with a higher voltage supplied to the cathodes so they do not require independent heating to create a discharge. Color Rendering Index (CRI) An international system rating a lamp’s ability to render objects’ colors (color rendition). The higher the CRI (based on a 0-100 scale) the richer colors appear. CRI ratings may be compared, but a numerical comparison is only valid if the lamps are close in color temperature. Color Temperature [Correlated Color Temperature] (CCT) A number for the amount of “yellowness” or “blueness” of white light in degrees Kelvin. Yellowish (warm) sources, like incandescent, have lower temperatures of 2700–3000K. Blueish-white and daylight (cool) sources have higher temperatures of 4100 – 6000K. Also, the absolute tempperature of a black body whose chromaticity most nearlt resembles that of the light source. Compact Fluorescent Lamp (CFL) Fluorescent lamps that are single-ended and have smaller diameter tubes bent to form a compact shape, some with integral ballasts and medium or candelabra screw bases for replacement of incandescent lamps. They are 75% more efficient and generate 75% less heat than incandescen lamps.

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FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY

Contrast The ratio of the luminance of an object to that of its immediate background. The angle of incidence is the angle between the normal to the surface and the direction of the indident light. Controller A device that controls the output of color-changing and tunable white lighting fixtures with software for lighting design and hardware components for sending data to fixtures. Cool White (CW) A lamp’s color temperature of approximately 4100 K. Cove Lighting Lighting using sources shielded by a ledge or cove, while distributing light on the wall or on the ceiling. The critical viewing angle beyond which a source can no longer be seen because of an obstruction (such as a baffle or louver). The angle, measured up from nadir, between the vertical axis and the first line of sight at which the source is not available.

D

Daylight Harvesting Lighting for buildings using daylight to reduce energy. A reflector (or filter) that reflects one region of the spectrum while allowing the other regions to pass through.

100 % of the emitted light in the general direction of the surface or object to be illuminated, usually in a downward direction. Downlight A luminaire that directs light downward and can be recessed sur face mounted, or suspended.

E Effectiveness of light sources to convert energy to light, in lumens per watt – not to be confused with efficiency. The light emitted by a luminaire divided by the light emitted by the light sou rce, expressed as a percentage. Electrical Discharge Lamp Lamp producing light by an electric current flowing through a gas, such as fluorescent and high-intensity discharge lamps. Electromagnetic Ballast (Magnetic Ballast) A ballast used with discharge lamps that consists primarily of transformer-like copper windings on a steel or iron core. Electromagnetic Spectrum Range of radiant energy described by the wavelengths, including visible light, ultraviolet, infrared, x rays, gamma-rats, radio and TV, microwaves, and power.

A lens or material that shields a light source, used to redirect and scatter the light distribution or decrease the luminosity by increasing the surface area. Dimmer, Dimming Control A device used to control the intensity of light emitted by a luminaire by controlling the voltage or current to available to it, reducing the wattage, saving energy and changing the effects. Diodes

The light emitted by a luminaire divided by the light emitted by the light source expressed as a percentage. Electrical Discharge Lamp Lamp producing light by an electric current flowing through a gas, such as fluorescent and high-intensity discharge lamps. Electromagnetic Ballast (Magnetic Ballast) A ballast used with discharge lamps that consists primarily of transformer-like copper windings on a steel or iron core. Electromagnetic Spectrum Range of radiant energy described by the wavelengths, including visible light, ultraviolet, infrared, x rays, gamma-rats, radio and TV, microwaves, and power. Electronic Ballast A ballast using solid-state electronics operating fluorescent lamps a 25–35 khz. The benefits are increased efficacy, lower losses, and smaller size compared to magnetic ballasts.

Direct Lighting Lighting that involves luminaires that distribute 90 to

A lamp with a built-in elliptically reflecting surface that produces a focal point in front of the lamp while reducing light absorption inside some luminaires.

A light source that emits light from a broad surface with a distribution characterized as dispersed light that tends to soften shadows and is perceived as less dramatic in contrast with a point source.

A semiconductor device with two terminals, typically allowing the flow of current in one direction only.

200

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY ELV-type Dimmer An electronic low voltage dimmer used to dim LED lighting fixtures with electronic transformers. Energy Star A U.S. government program created in 1992 in an attempt to reduce energy consumption and green-house gases. The volunteer program has grown into a worldwide effort promoting energy efficient products. Energy Policy Act (EPACT) Comprehensive 1992 energy legislation passed by the U. S. Congress that includes lamp labeling and minimum energy-efficacy (lumens/watt) requirements for many incandescent and fluorescent lamps.

General Lighting Lighting designed to provide a substantially uniformed illuminance throughout an area. Glare Overly bright luminance within the field of view, sufficient to cause discomfort, and loss of visual performance.

F

H

Fiber Optics Thin and flexible glass or plastic fibers that transmit light throughout their length by total internal reflection. Filament Wire inside incandescent lamps producing light when heated by electric current, usually made of tungsten. Filter A device for changing the magnitude or spectral composition of light by transmission, absorption, or reflection. Fixture Common name for complete luminaire containing one or more lamps and lampholders, reflectors, lenses, etc. Flood Spread Beam pattern of a reflector lamp, with light over a wide beam angle (2 0 – 60 deg.), with Narrow to Wide Flood designations. Floodlight A luminaire designed to control light in a broad beam with less precision than a spotlight. Fluorescent Lamp Lamp using electric discharge through inert gas and lowpressure mercury, producing ultraviolet (UV) energy generated by the discharge into light. Flux Measurement of light intensity produced by a luminaire. the rate of flow of light per unit of time expressed in lumens per sq.meter. Footcandle (fc or ft-c) Measurement of light on a surface, or the illuminance on a one-foot square surface with an evenly distributed flux of one lumen. One fc equals one lumen per sq. ft., one foot distance from the light source.

Footlambert A measurement of brightness of any surface emitting or reflecting light at a rate of one lumen per sq. ft. Fovea Area of the retina for central vision, composed of cones.

G

Halogen Lamp An incandescent lamp with a filament surrounded by halogen gases allowing operation at higher temperatures and efficicies, prolonging lamp life with crisp white light.

Hertz Designation of frequency in cycles per second. High-Intensity Discharge Lamp (HID) Family of lamps that produces light from an electric arc through a gas, and operate at a relatively high pressure. High Power Factor Ballast with power factor corrected to 90% or more using of a capacitor. High-Pressure Sodium Lamp (HPS) A high-intensity discharge lamps that produces light by electrical discharge through sodium vapor operating at relatively high pressures and temperatures.

I IALD

International Association of Lighting Designers IESNA (IES) Illuminating Engineering Society of North America Illuminance Term describing the amount of light illuminating a surface, defined as luminous flux incident to a surface measured per perpendicular to the illuminated plane per unit area. Expressed as lumens per square foot and measured in footcandles, or as lumens per square meter, measured in lux. Illumination The act of illuminating or lighting a space or object.

2 01

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY Imperial System Measurement system first defined by British Weights & Measures Act of 1824, still used by the U.S.A, Canada, U.K. and countries formerly part of the British Empire, although all having adapted the Metric System. Incandescent Lamp technology that passes current through a filament, typically tungsten, heating it to a point of emitting light, or incandescence. Lamps characterized by a warm light but short life and inefficiency. Indirect Lighting Lighting a space by directing the light from a source towards the ceiling or wall from an inconspicuous light source. Infared Invisible radiation that heats objects it strikes (780 to 100,000 nanometers). Input Voltage Power supply voltage required for proper operation of fluorescent, transformers, HID ballast or LED drivers. Inverse-Square Law The calculation method where illumination will vary directly in a given direction of a point source of light and inversely as the square of the distance from that source. It is used to calculate light levels at a point.

K Kelvin Unit of measurement for color temperature of a light source, ranging from warm white in the 2700K – 3000K range; cool white (4100K) and natural daylight (6000K). Having zero degrees at minus 272 degrees Celsius. Kilowatt (kW) The measure of electrical power equal to 1000 watts. Kilowatt Hour (kWh) The standard measure of electrical energy and the typical billing unit used by electrical utilities for electricity use. A 100-watt lamp operated for 10 hours consumes 1000 watt-hours, or one kilowatt-hour.

L Lamp An electrically energized source of light, commonly called a bulb or tube. The complete light source package, including the inner parts as well as the outer bulb or tube. Lamp Life (or Rated Lamp Life) For most types, rated lamp life is the length of time

202

of a large sample between first use and the point when 50% of the lamps has depreciated. Lamp Lumen Depreciation (LLD) Ratio of mean light output of a lamp throughout its life to its initial rating. Laser Light amplification by stimulated emission of radiation. Produces a monochromatic, coherent beam of light. LDD Luminaire dirt depreciation. LED A Light-Emitting Diode or a semi-conductor device that emits light when an electric current passes through it. LED Chip The light-producing semiconductor that may be incorporated into an LED. LED Driver An electronic device with a circuit that converts input power into an appropriate current source for the LED, protects LEDs from voltage fluctuations, over voltages, and vol tage spikes. LED Module A single LED device or group of self-contained LED devices designed either to function on their own or to a compatible LED fixture. Lens A transparent or semi-transparent glass or synthetic element , which controls the distribution or transmission of light by redirecting individual rays. Louver An assembly of baffles to shield glare from normal viewing angles, assembled in a geometric array, parallel wlith the main path of light, designed to have minimum impact on light output. . Low-Pressure Sodium Lamp Discharge lamp producing light by passage of current through sodium gas under low pressure and very high efficiency and very low color rendering. Low Voltage Used in areas requiring protection from higher voltages, or for lamp sources requiring a reduced or highly controlled current from a transformer to reduce the voltage for the lamp. Lumen Is a unit of measurement that decribes how much light is directed to a certain area. The amount of light falling on 1 square foot surface, 1 foot away from a 1-candlepower (1-candela) source.

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY Lumen Depreciation The decrease of lumen output over time, caused by bulb wall blackening, phosphor exhaustion, filament depreciation and other factors. Luminaire (Fixture) A complete lighting unit consisting of a lamp(s), ballast, transformer, or driver as required together with the parts designed to distribute the light, position and protect the the lamps, and connect them to the power supply. Luminance A measure of “surface brightness” when an observer is looking in the direction of the surface. It is measured in candelas per square meter (or per square foot). Lux (lx) International unit of illuminance equal to 1 lumen per square meter (10.76 lux equals 1 Footcandle).

M

Maintenance Factor Ratio of maintained to initial light levels. Mercury Lamp High-intensity discharge lamp operating at a relatively high pressure and temperature. The light is produced by radiation from excited mercury vapor. Metal Halide Lamp Lamp using an arc in a capsule filled with several rare earth metal salts (metal halides), and mercury vapor. Utilized f or its balance of HID efficiency, lamp life with broad spectrum white light, considered a HID source . Mounting Height (MH) Distance from fixture bottom to the floor or work plane.

N Nanometers (nm) A metric unit equal to one billionth of a meter and the common unit for wavelengths of light in the visible spectrum. The wavelengths of light describe color characteristics of a light. Nanotechnology The study and development of manipulating matter, devices, and other structures on an atomic and moleclar scale, to allow functional items to be extremely small, from 1 to 100 nanometers in size. National Electric Code (NEC) A national electrical installation code to reduce the risk of fire, developed by the National Fire Protection Association.

Near Ultraviolet From about 320 to 380 nanometers (Black Light) .

O Organic Light-Emitting Diodes (OLED) Are thin films of organic molecules in a crystalline phase, or a flexible polymer that create light with an application of electricity.

P Parabolic Louvers Louvers with vertical elements that have parabolic shape, and produce low brightness at normal viewing angles. PAR Lamp Parabolic Aluminized Reflector lamps with halogen, incandescent, or LED light source, rely on internal reflector Pendant Luminaire suspended from a ceiling canopy, or track. Photocell A light-sensing system component that controls lighting fixtures and equipment in response to detected light levels. Photometry (Photometrics) The measurement of a fixture’s or lamp’s optics including luminance, luminous flux, luminous intensity, and spectral distribution of visible light. Preheat Circuit for fluorescent lamps using a momentary contact switch starter. Photopic Vision Vision entirely by the cones on the retina, capable of discerning colors due to the three types of cone receptors associated with the three primary colors. Point-by-Point Method Lighting calculations used to determine light levels at particular points. Polorization Light control method that causes light waves to oscillate in only one plane. Point Source A lamp or luminaire that can emit light from a point, creating crisp light patterns and shadows. Projector A luminaire with precise beam of even intensity using a parabolic or ellipsoidal reflector and lenses. Used for spotlighting and projecting images through a filter.

R

Rapid Start Fluorescent circuit where ballast provides preheating current.

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FUNDAMENTALS OF ARCHITECTURAL LIGHTING

GLOSSARY Rated Lamp Life The mean value of estimated or usable life, determined by a lamp manufacturer or a testing laboratory.

Spot Luminaire or lamp with a concentrated beam of light, around 10 degrees or less, as opposed to a wide flood of light.

The ratio of light reflected by a surface to the total amount of radiation incident on the surface.

T

Device redirecting flux from a source by reflection. Light source with built-in reflecting surface. R, PAR and MR . Refraction Light control method where light rays are bent by passing through a prism. Retina A light sensitive membrane lining of the inner surface of the eye, composed of rods and cones. Room Cavity Ratio (RCR) Proportions of a space determined from its length, width, and height. RCR = 5H (L + W) / (L x W)

S Self-Ballasted Lamps A discharge lamp with integral ballast allowing lamp to be directly connected tom a socket providing line voltage. Semiconductor A material having electrical conductivity between a conductor and an insulator, the foundation of modern electronics. Solid-State Lighting Lighting with light-emitting diodes (LEDs), organic (OLEDs), or polymer (PLEDs) as light sources. Light emitted by electroluminescence, crerating light with reduced heat generation or energy dissipation. Lighted trans-illuminated architectural element directing light in a downward direction, similar to a wide lighted cornice. Spacing To Mounting Height Ratio (S/MH) Ratio of fixture spacing to mounting height above work plane. Spectral Power Distribution (SPD) Visual profile of the color characteristics of a given light source. An SPD represents the radiant power of a source emitted per wavelength or range of wavelengths in the visible portion of the electromagnetic spectrum. Specular A highly reflective surface similar to a mirror. Reflection from a smooth, shiny surface.

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Task Lighting Lighting directed to a specific s urface, object or process to provide illumination for visual tasks. Task-Ambient Lighting Lighting systems providing both localized lighting for a seeing task and general illumination. Track Lighting Lighting using fixtures that plug into a power strip. Translucent Characteristic of material or surface with partial or diffuse transmission of light. Transmittance The proportion of light directed through a medium to the amount arriving. Transparent Characteristic of material with transmission of light without significant diffusion.

U Ultraviolet Radiation (UV) Area of electromagnetic spectrum between x-rays and visible light from 100 nm to 400 nm.

V Valance / Wall Bracket draperies or walls, plus general room illumination. Visual Comfort Probability (VCP) Method of forecasting percent of people visually comfortable in a specific lighting application.

W Wattage Electrical power equal to voltage times amperage. The rate of energy consumption when measured in watts. Wavelength Characteristic of where radiant energy occurs on the electromagnetic spectrum in angstroms or nanometers (nm). Work Plane Horizontal surface where a visual task is per formed, at 30 inches above the floor if not otherwise indicated.

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

BIBLIOGRAPHY

BOOKS J.Flynn / S.Mills, Architectural Lighting Graphics, Reinhold, New York, 1962 J.Flynn / A.Segil, Architectural Interior Systems, Reinhold, New York, 1970 IES, Lighting Handbook , 9th & 10th editions, New York, 2011 J.Kraehenbuehl, Electric Illumination, John Wiley & Sons, New York, 1951 J.Murdoch, Illumination Engineering, Macmillan Publishing, New York, 1985 D.Phillips, Lighting in Architectural Design , Mc Graw-Hill, New York,1963 ASHRAE 90.1, 2016

PERIODICALS AIA, Architect Architectural Lighting Architectural Record IES, Lighting Design & Application Industry Technical Publications

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INDEX

207

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

INDEX

A Absorption Filters, 72 Accent Lighting, 44 Acceptable Glare, 83 Additive and Subtractive Colors Mixing, 62 Additive and Subtractive Primary Colors, 61 Age and Acceptable Brightness Levels, 84 Ambient Lighting, 44, 180-183 Ambient Luminescence, 15 Angle of Incidence in Light Refraction, 103 Appearance of Light Colors, 63 Architectural Integration, 20, 21 Architectural Lighting Pioneers, 185-195 ASHRE/IES 90 Energy Standard, 94 Aspects of Lighting that Affect Recommendations, 120 Average Noon Sunlight, 67

B

Baffles and Louvers, 88 Bare Lamp Glare, 82 Basic Modes of Distribution, 2 Basic Reflector Contours, 106 Bathroom Lighting, 55 Bedroom Lighting, 55 Blackbody, 68 Blue Northwest Sky, 67 Brandston, Howard, 195 Brightness Control of Louvers and Baffles, 89 Brightness Control Techniques, 86 Brightness Intensity, 12 Brightness Limits For Visual Comfort, 82 Brightness Relationships, 85 Built-Up Lenses, 104

C Candela, 112 Candle Flame, 67 Cavity Ratio, 115 Ceramic Metal Halide Lamps, 126 Chromatisim in Light Refraction, 104 Circadian Cycle, 70 Circular Cell Louvers, 92 Circular Reflector Contours, 106

208

Classroom Lighting, 42 Clear and Coated Mercury, 67 Coefficient of Utilization (Cu), 113, 115 Coffer Lighting, 168, 169 Color and Circadian Rhythms, 70, 71 Color Association, 69 Color Descriptive Characteristics, 61 Color Filters, 72 Color Light Sources, 72 – 75 Color Mixing, Additive and Subtractive, 62, 63 Color of Light Descriptive Characteristics, 61 Color of White Light, 67 Color Perception and Adaptation, 65 Color Rendering, 69 Color Temperature, 67 Color Temperature and Light Levels, 64 Comfortable Luminance Ratios, 85 Compact Fluorescent Lamps, 67, 135 Complementary Color Afterimages, 65 Compound Light Reflection, 100 Concealment Zone, 80 Concentrating Downward Distribution, 3 Concentrating Multidirectional Distribution, 6 Concentrating Sideward Distribution, 5 Concentrating Upward Distribution, 4 Conditioned Association, 25 Control Techniques, 87 Controlling Visual Clutter, 26 Converging Lenses, 104 Corrugated Diffusing Panel, 90 Cosine Calculation, 119 Cove Lighting Placement Ratios, 167 Cove Lighting Representative Details, 166, 167 Creating Environmental Focus, 13 Creative Use of Light And Shadow, 24 Critical Angle in Light Refraction, 103

D Daylighting, 56, 57 DC Dimming, 151 Deluxe Mercury, 67 Design of the Luminous Environment, 31

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

INDEX Design Process Preliminary Guidelines, 32 Determine Angle of Incidence from the Cosine, 116 Determine the Directional Candelas, 115 Dichroic Glass, 91 Diffuse Distrib. and High Reflectance Finishes, 11 Diffuse Distrib. and Low Reflectance Finishes, 11 Diffuse Reflector Light Control, 109 Diffuse Surfaces, 79 Diffusing Downward Distribution, 3 Diffusing Multidirectional Distribution, 6 Diffusing Panels and Elements, 90 Diffusing Sideward Distribution, 5 Diffusing Upward Distribution, 4 Dimming Control, 150, 151 Dining Room Lighting, 55 Direct Distribution, 3 Direct Glare, 82, 83 Direct-Indirect Distribution, 6 Direct Light Transmission, 98 Discomfort and Disability Glare, 84 Distribution of Light, 1 Diverging Lenses, 104 Downward Distribution, 3

Fluorescent Ballasts and Circuits, 134 Fluorescent Color Lamp, 75 Fluorescent Lamp and Ballast Wireways, 136 Fluorescent Lamp Dimming, 150 Fluorescent Lamps, 132 – 135 Fluorescent Representative Lamp Types, 135 Flynn, John, 188 Footcandle (f c), 113 Footlambert (f L), 113 Formed Diffusing Panel, 90 Fresnel Lens, 105 Full Luminous Ceiling, 16, 176 Full Luminous Wall, 18, 175

E

Halogen Lamps, 137 Halogen Representative Lamp Types, 138 Healthcare Lighting, 50, 51 Hexagonal Cell Louvers, 92 High Performance Light Sources, Ballasts, 126 High-Pressure Sodium Lamps, 147 – 149 Horizontal and Vertical Brightness, 29 Horton, Jules, 190 HPS Representative Lamp Types, 149 Human Perception of Brightness, 85

Eating Area Lighting, 54 Edison’s First Lamp, 127 Edison’s, Thomas , 12 5 Effective Cavity Reflectances, 115 Efficiency of Color Sources, 62 Electromagnetic Spectrum, 60 Electronic Fluorescent Ballasts, 134 Elliptical reflectors, 106 Energy Audit, 97 Energy Management, 94 – 97 Exam and Patient Rooms, 54 Examples of Everyday Illuminances, 113

F

Feder, Abe, 185 Floating Luminous Element, 178

G General Design Concepts, 34 General Lighting Systems, 42 Glare (Bare Lamp), 82 Glare as a Function of Location, 82 Green LED Color Spectrum, 67 Grenald, Raymond, 196 Grilles and Screens, 92, 93

H

I

Illumination Calculations, 114 – 119 Illumination Measurement and Calculation, 111 Incandescent Lamp Dimming, 150 Incandescent Lamp Lampholders, 143 Incandescent Lamps, 139 – 143

209

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

INDEX Incandescent Representative Lamp Types, 141 Incandescent Watts to Lumens, 126 Indirect Ambient and Local Task System, 183 Indirect Distribution, 4 Indirect Lighting, 48 Integrated Luminous Environment, 20 Integration with Architectural Form, 20 Interference Filters, 72 Internal Reflection in Light Refraction, 103 Inverse-Square Law and Cosine Calculation, 119

K Kelly, Richard, 186 Kelvin Scale, 67 Kitchen Area Lighting, 54

L

Lam, William L.C. 194 Lamp and Ballast Wireways, 136 Large Cell Louvers, 92 Large Diffusing Elements, 91 LED Color Lamps, 74 LED Flat Panel, 90 LED Lamp Dimming, 150 – 1 51 LED Lamps, 122 – 131 LED Representative Lamp Types 131 Light and Color, 59 – 75 Light and Color Subjective Characteristics, 64 – 66 Light and Shadow, 24, 25 Light Loss Factor (LLF), 113 Light Patterns, 24 Light Reflection, 100, 101 Light Refraction, 102 – 105 Light Source Color Rendition, 69 Light Source Selection, 126, 127 Light Sources and Components, 125 – 149 Light Transmission, 98, 99 Lighted Ceiling Coffer, 1 68 – 1 6 9 Lighted Ceiling Cove, 166 – 167 Lighted Cornice, 170 Lighted Valance, 171 Lighted Wall Brackets, 172, 173

210

Lighted Wall Elements, 170 –173 Light-Emitting Diodes (LEDs), 128, 129 Lighting Application and Details, 153 – 183 Lighting Control Matrix, 96 Lighting Levels General Guidelines, 121 Lighting Quality, Comfort and Control, 77 – 109 Lighting Research, 36 – 41 Lighting Terms, Units and Definitions, 112 Living Area Lighting, 54 Lobby Lighting, 50 Louvered Ceiling Cove, 164 Louvers, Grilles and Screens, 92 Low Brightness Intensity, 12 Low Voltage Incandescent, 67 Lumen ( lm), 112 Lumen Method, 114, 115 Luminaires, 154 – 156 Luminance, 113 Luminance Ratios, 85 Luminous Architectural Elements, 16 – 19 Luminous Architectural Surfaces, 13, 14, 15 Luminous Ceiling, 16, 17, 176 Luminous Soffit, 177 Luminous Wall, 18, 175 Luminous Wall Panels, 174 Lux ( lx), 113

M Magnetic Fluorescent Ballasts, 134 McCandless, Stanley, 185 Mesopic, 78 Metal Halide Lamps, 144 – 146 Method For Evaluating Light Source Color Rendering, 69 Minimizing Veiling Reflections, 80 Modifying Spatial Proportions, 14 Modifying the Luminous Environment, 12 Multidirectional Distribution, 6 Multiple Lamp Wall Lighting, 160 Museum and Exhibit Lighting, 52, 53

FUNDAMENTALS OF ARCHITECTURAL LIGHTING

INDEX

N

Nuckolls, James, 187

O Office and Classroom Lighting, 42, 43 OLED Elements, 19 One Lamp Indirect Panel, 91 Open Wall Cove, 164 Optical Band Diffusing Panel, 91 Overhead Ambient-Task Uniform System, 180 Overhead Ambient and Local Task System, 182 Overhead Task-Ambient Non-Uniform System, 181

P PAR and R Lamp Beam Pattern, 162, 163 Parabolic Louvers, 92 Parabolic Reflector Contours, 106 Pattern and Sparkle Distribution, 7 Patterns of Brightness, 24 Pendant Lighting Systems, 42 Perception and Adaptation of Light Color, 65 Perception of Brightness, 26 Perception of the Luminous Environment, 26 – 2 9 Perimeter Lighting, 44 Phillips, Derek, 192 Photopic, Mesopic and Scotopic Vision, 78 P-n-Type Semiconductor, 129 Point-by-Point Method, 118 Preliminary Guidelines, 32, 33 Primary Colors, 61 Primary Colors Descriptive Characteristics, 61 Prismatic Control of Light Refraction, 102 Private Dining and Meeting Rooms Lighting, 49 Pulse Width Modulation Dimming, 151 Pyramid Diffusing Panel, 91

R Range of Human Vision, 80 Recommended Lighting Levels, 120 – 1 23 Reflected Glare, 79 – 8 1 Reflected Images, 88 Reflecting Material, 101

Reflection Characteristics, 100 Reflective Field of View, 80 Reflective Glare, 79, 80 Reflector Contours, 106 – 109 Refraction Characteristics, 102 Refraction Lenses, 104 Refraction of Light, 60, 102 – 105 Relative Attraction of Colored Light, 65 Relative Bare Lamp Brightness, 82 Relative Color Attraction, 65 Relative Light Output of Color Sources, 62 Relative Sensitivity of the Human Eye, 64 Remote Ballast Wireways, 136 Representative Daylighting Performance, 57 Representative Fluorescent Lamp Types, 135 Representative Incandescent Lamp Types, 141 Representative Luminaire Layout, 156 Representative Metal Halide Lamps, 146 Residential Lighting, 54, 55 Restaurant Lighting, 46 – 49 Restaurant Lighting Service Areas, 49 Retail and Display Lighting, 44, 45 Retail General Design Considerations, 46 Retail Quality, Ambient, and Accent Lighting, 44

S

Scotopic Vision, 78 Secondary Light Sources, 22, 23 Semantic Differential Scaling, 39 – 41 Semiconductor Materials, 130 Service Area Lighting, 49 Shemitz, Sylvan, 191 Shielding Angle, 88 Shielding Techniques, 88 – 93 Sideward Distribution, 5 Silicon Controlled Rectifiers, 150 Silver Bowl Lamps, 142 Simulated Skylight Coffer, 169 Sine Wave Cell Louvers, 92 Skylight, 67

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FUNDAMENTALS OF ARCHITECTURAL LIGHTING

INDEX Skyscape Diffusing Panel, 91 Small Cell Louvers, 92 Sparkle and Pattern, 7 Spatial and Visual Influences, 32 Spectral Energy Distribution, 68 Specular Reflector Light Control, 108 Specular Surfaces, 79 Sports Bar Lighting, 49 Spot and Flood Lamp Beam Patterns, 161 Spread Light Reflection, 100 Spread Light Transmission, 98 Square Cell Louvers, 92 Step-by-Step Method, 34 – 3 6 Steradian (Sr), 112 Subjective Appraisal, 37, 38, 39 Subjective Characteristics, 64, 65, 66 Subtractive Color Mixing, 62 Subtractive Primary Colors, 61 Sunlight 1 Hour After Sunrise, 67 Sunlight at Sunrise, 67 Supplemental Reflectors in Light Refraction, 105 Surface Blemishes in Frontal Diffuse Light, 24 Surface Blemishes in Grazing Light, 24 Surface Color and Brightness Contrast, 66 Surface Mounted Cove, 166 Surface Reflectance and Light Intensity, 23 Surface Reflectance and Materials, 10

T

Task Lighting, 178 Task-Ambient Lighting, 43, 179 – 183 Thomas Edison, 125 TM-30-15 Method For Evaluating Light Source Color Rendering, 69 Total Internal Reflection in Light Refraction, 103 Trans-Illuminated Elements, 174 – 177 Transistor, 151 Transitional Influences, 11 Transmitting Characteristics, 98 Transmitting Materials, 99

212

Transparent Surfaces, 81 Tubular Incandescent Lamps, 14

U Under/Over- Cabinet Lighting, 179 Units of Measurement, 112 Upward Distribution, 4

V

Veiling Reflections, 81 Visual Direction and Virtual Surfaces, 27 Visually Prominent Light Sources, 28 Visually Subordinate Light Sources, 28

W

Wall Lighting Elements, 171 – 174 Wall Lighting from One Direction, 157 Wall Lighting with Diffuse Reflector, 159 Wall Lighting with Specular Reflector, 158 Wall Lighting, 157 – 163 Warm White Fluorescent, 67 Warm White Mercury, 67 White Fluorescent, 67 White Light from Color Sources, 63 Wood Frame Diffusing Panel, 91 Work Plane, 113