Ilumart - The Lighting Design Process (Ies, 1994)

IESNA OG-7-1994

The Lighting Desig~, Process

Excerpted from the IESNA Lighting Handbook, 8th Edition, 1993

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IESNA DG-7-1994

Copyright 1994 by the Illuminating Engineering Society of North America.

All rights reserved. No part of this publication may be reproduced in any form, in any electronic retrieval system or otherwise, without prior written permission of the IESNA.

Published by the Illuminating Engineering Society of North America, 120 Wall Street, New York, New York 10005.

IESNA Standards and Guides are developed through committee consensus and produced by the IESNA Office in New York. Careful attention is given to style and accuracy. If any errors are noted in this document, please forward them to Rita Harrold, Director Educational and Technical Development, at the above address for verification and correction. The IESNA welcomes and urges feedback and comments.

ISBN# 978-0-87995-108-7

Printed in the United States of America.

DISCLAIMER IESNA publications are developed through the consensus standards development process approved by the American National Standards Institute. This process brings together volunteers representing varied viewpoints and interests to achieve consensus on lighting recommendations. While the IESNA administers the process and establishes policies and procedures to promote fairness in the development of consensus, it makes no guaranty or warranty as to the accuracy or completeness of any information published herein. The IESNA disclaims liability for any injury to persons or property or other damages of any nature whatsoever, whether special, indirect, consequential or compensatory, directly or indirectly resulting from the publication, use of, or

reliance on this document

In issuing and making this document available, the IESNA is not undertaking to"rel1der professiol1al or other services for or on behalf of any person or entity. Nor is the IESNA undertaking to perform any duty owed by

any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reason­able care in any given circumstances.

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----- - -- . attributable to the IESNA and is solely the responsibility of the certifier or maker of the statement.

Contents

1. Overview .............................. . .......................................... . 2. The Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

2.1 Programming................................................................... 2 2.2 Schematic Design (Developing the Lighting Concept) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 2.3 Design Concepts . .......... .. ...................... ............ ........ .... ..... 8 2.4 Design Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 2.5 Contract Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 2.6 Bidding and Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 2.7 Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 2.8 Postoccupancy Evaluation (POE) .............................. . .................. 13

The Lighting Design Process

1. OVERVIEW

Lighting design is the creative process for developing lighting solutions for the safe, productive, and enjoyable use of the built environment. In the past there has been an overwhelming emphasis on assuring that an appropriate quantity of light is delivered to the task or work surface. Quality of light has been considered mainly in the limited sense of controlling direct glare from luminaires or reflected glare from surfaces and objects. However, lighting design extends far beyond these factors. Light is one of the tools used to shape our environment, visually and emotion­ally. Lighting design is a synthesis of light and shadow, color, form, space, rhythm, texture and proportion, achieved through an understanding of the technology necessary to produce these effects. Working with these elements is what distinguishes the work of the lighting designer from that of the artist, from whom the lighting designer draws inspiration, and from that of the engineer, from whom the designer learns prac­tical problem-solving techniques.

Part of the appeal of designing with light is its illusive nature: its effect can be almost palpable and may be visually arresting, yet the rays of light themselves are usually invisible. When designers or users talk of "light," they often mean the effect of light on a surface or object: highlight and shadow, soft gradations of light, or the sharp definition that comes with focused point sources. Light reveals form: wall planes, three-dimensional space, architectural details, furnishings, sculpture, the branching structure of trees. Light · can enhance· or diminish elements of the built environment and also the natural environment.

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Light profoundly affects our feelings of well­being, awe and wonder, mood, comfort, and motivation. It influences how we perceive all the other elements. Light patterns evoke psycho­logical responses such as "bright," "dim," "magical," "dull," "mysterious," "pleasant," and "forbidding . "

2. THE PROCESS

There are many factors that must be con­sidered to form a lighting design that provides the proper quantity and quality of light. The design must also be appropriate in terms of cost, energy, maintenance, style, availability, and a dozen other considerations. Because there are so many aspects to weigh together, there is no one perfect solution to a single lighting problem. There are a multitude of solutions, and each will be more or less successful depending on whose criteria are used in the judging.

The lighting design process is not a predictable, linear process. It begins with the formation of a design concept selected from a myriad of design considerations. Then, as it proceeds, it is filled with cross-checking and doubling back. However, most lighting design projects follow the phases that occur in architectural design:

• Programming

• Schematic design

• Design development

• Contract documents

• Bidding and negotiation

IESNA DG-7-1994

• Construction

• Postoccupancy evaluation

See Figure 1 for a schematic presentation of the lighting design process.

The players involved in the design process will vary according to the size and complexity of the project. Sometimes the lighting designer is hired by, and works directly with, a building owner or the owner's representative (called client in this guide). Other times, the lighting designer is hired by the architect or interior designer and works with the owner and other team members, such as the electrical engineer or landscape architect. Design team meetings may include the client and all team designers and engineers, or may be composed of just the architect and the lighting designer. Good communication among all of the parties is one key to successful design.

2.1 Programming

This is the important initial phase of a project when the lighting designer gathers information about user and client needs, preferences, and constraints. The lighting designer looks to the client and the design team for design objectives, such as image, maintenance, flexi­bility, and budget. This information is exchanged through meetings, written inquiries, or telephone conversations. Site visits to observe similar installations can be helpful for communication, since the client can point to what is and is not liked in both function and appearance. The site visit also gives the lighting designer a chance to see and experi­ence the visual tasks involved. Interviews with users of similar spaces can help identify potential lighting problems.

Here is a list of issues to address during the programming stage for either new or existing spaces: __ _ __________ _

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2.1.1 Owner and design team preferences and impressions

1. Space function, use

2.

3.

4.

5.

6.

7.

Building materials, room finishes, archi­tectural style

Space plan, furniture style

Important features such as art locations and signage

Comfort level and satisfaction of occu­pants, workers, and users

Need for flexibility of space function and uses

Exterior features such as image, security, and landscape

2.1 .2 Visual and perceptual needs

1. Age of occupants

2. Tasks to be performed: their importance and duration

3. Times of occupancy during the day and year

4. Psychological needs for light

5. The shape of the task, particularly in industrial areas

2.1.3 Security issues

1. Personal safety, including dangerous conditions, rotating parts, assault and theft potential

2. Vandalism

User needs and preferences Psychological needs Space function Visual task Quantity I quality 01 lighting Glare and visual comfort Architectural features Coordinalion with daylighling Color and color rendering Flexibility ot function Controls requirements ,S~curity Budget Operating cost Maintenance Energy and resources Building / electrical codes

Design Considerations

User needs and preferences Psychological needs Space function Visual task Quantity / quality of lighting Glare and visual comfort Architectural features Coordination with daylighting Color and color rendering Flexibility of function Controls requirements Security i Budget Operating

l cost

Maintenance Energy and resources Bui/ding / electrK:.a1 codes ,

Design Considerations

User needs and preferences Psychological needs Space 'unction VisuaJ task Quantity / quality of lighting Glare and visuaJ comfort Architectural features Coordinalion with daylighting Color and color rendering Flexibility of functIOn Controls design Security Check of budget Operating cost Maintenance Energy and resources Building / electr~ codes Coordination with bldg. systems Coordinahon with furniture Product availability check

Oeslg" Considerslions

Coordinate With architecture Electtlc / dayhghltng controls

Check for function changes Finalize controls design

Check budget

Verity maintenance Check energy COde compliance Check bldg./ elec. code compliance Coordinate with bldg. systems Coordinate with furn iture / built-ins Check product availability

Design Considerations

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I Concepts piesentation

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I Ughting and Controls Plan

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I Ughtlng and Controls Plan

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I Clarification forContr~~tors I

I Subminal R~~i~w _u u -,

I [C-on-StrUt-iion Observation

I [-Fleld-problemCoordlilatlon

I , Project Punch List

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I Flna' Adjustments

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I O~es project meet obj~~tiy-es? -­

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I ~~-;~N~ ---l-f SCHE~~T;C~;;'G~-I DESIGN D~L~-;:;';;NT- -1-[ CONTRACT DOCUMENTS I-I BIDDING and NEGOTIATION I-I CONSTRUCTION I-I POSTOCCUPANCY EVALUATiON"]

Figure 1. The Lighting Design Process

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2.1.4 Architectural opportunities and constraints

1.

2.

3.

4.

5.

6.

7.

8.

Architectural features, interior and exterior

Historical constraints

Ceiling heights, type of ceiling

Plenum depth

Location and size of structural mem­bers and mechanical ducts

Window and skylight locations and orientations

a. Types of glazing, wall config­urations

b. Shades, blinds, draperies, other sun control media

Construction and safety codes

Electrical system

a. Voltage b. Circuit capacity c. Lighting controls, including likely

locations and appropriate types d. Energy management system or

other automatic controls for build­ings

9. Construction schedule

10. Landscape features

2.1.5 Photometric considerations (illumi­nance, luminance, task size, and contrast) of existing installation and at similar sites during both day and night

·. 1. Critical vision: task areas and immed­iate surrounds

2. General field of view: highlights; ambi­ent levels

3. Distant surrounds: circulation areas, transition areas

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2.1.6 Budget

1. Initial cost (installed)

2. Maintenance and energy cost

3. Life-cycle cost

2.1.7 Energy limitations

1. Energy code requirements (federal, state or province, local)

2. Utility incentive programs

2.1 .8 Maintenance considerations

1. Lamp performance

2. Type of environment (clean, dirty)

3. Luminaire surface dirt deterioration

4. Room surface dirt accumulation

5. Planned maintenance program

The programming phase results in a list of project needs, preferences, constraints and design goals.

2.2 Schematic Design (Developing the Lighting Concept)

Once the programming phase data are gath­ered, the lighting designer must consider the needs and requirements of the space and how they work together. These include architectural elements and the psychological and visual requirements of the people using the space. During the development of the lighting concept, the designer establishes a framework to judge how a lighted space will feel to the user of that space. This concept .. provides a reference against which the final design can be judged.

The nature, feelrng~-quality, and other intangible -aspects of light in the space are often given only perfunctory attention, and most time is consumed analyzing the quantifiable aspects of the lighting system envisioned. However, meth­ods of lighting design based on calculating

various quantities to avoid fundamental mis­takes, such as an inadequate amount of light, are not sufficient. The question asked and an­swered is "will it work?" The question that is not asked is "is it appropriate?" (or, as architect Louis Kahn used to say, "what does the space want to be?").

An answer to the question of appropriateness will require a fundamental change in the way the designer thinks about lighting a space. In­stead of starting with a particular task and its characteristics, one will start with the needs and requirements of the space as a whole. These needs will be architectural needs, that is to say, based on the internal logic of the space as a volume, in which people engage in various activities, rather than simply the technical requirements having to do with human perform­ance of a visual task. Once this concept of the nature and feeling of the space (whether interior or exterior) is established, a much stronger schematic design can result. The designer will also have a basis upon which lighting design schemes may be evaluated.

The following questions are relevant to all lighting design projects:

Who uses the space? What are their ages and visual needs? The lighting designer needs to understand human vision (see IESNA Lighting Handbook, 8th Edition, Chapter 3). What are their activities? What do they like or not like in lighting? How is the space used? What activities will take place? At what time of day? What are the visual tasks? Lighting techniques have evolved for different applications, based on a syn­thesis of theory, engineering, and proven experience. (See the IESNA Lighting Handbook, 8th Edition, Appli­cation chapters and individual Recom­mended Practices [RPs].- A list of RPs­appears inside the back cover of this design guide.) Once the visual tasks have been identified, then ask:

IESNA DG-7-1994

How critical is the task being performed? A pharmacist could easily fill a prescription incorrectly if the doctors handwriting is misread. A bank clerk could make an expensive mistake if there is difficulty reading a check. If accuracy in performing the visual task is important, extra attention ,should be paid to providing an appropriate quality and quantity of light which will aid in performance and minimize the fatigue that can result from visual effort. Speed and accuracy can make the difference in being competitive or noncompetitive in our global economy.

However, in many spaces visual tasks are less important. In a romantic restaurant, reading the menu is secondary to creating an ambiance where patrons feel relaxed and unhurried, enjoy a sense of privacy, and can be visually enter­tained.

Where is the visual task located? It is important to remember that light need not be spread evenly across rooms. Energy-efficient lighting design often means putting high light levels only where the critical visual tasks will be located, and lower ambient levels elsewhere. Also, it is important to remember that not all tasks occur in the horizontal plane (that is, on the desktop). Storage racks and bookstack lighting are two examples of vertical­plane visual tasks. The lighting deSigner must select luminaires and locate them carefully so that the light is put where the user needs it.

What is the proper quality and quantity of light for the task? The lighting deSigner must understand the charac­teristics of visual tasks and know what direction arid quality of lighting ~- will

make- tne ~task easy to see. This in­cludes determining the luminance of each task, the areas surrounding the

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task, and the luminances in the user's peripheral view, since luminance values affect visual comfort as well as task performance: The geometric relationship between the lighting system, the user's eye, and the visual task is a critical factor in visibility. See the IESNA Lighting Handbook, 8th Edition, Application chapters for inform­ation on how to avoid reflections that reduce task contrast and for recom­mendations on balancing luminances for user comfort.

Will the space be a pleasant place for users to enter and in which to spend time? Often the appropriate question to ask during the design process is not "can the user perform the visual task in this luminous environment?" but "would the user want to?" The designer must understand how people perceive and interpret light patterns, and then know how to create luminous environments that evoke the desired response. It is most often the vertical surfaces in an environment (walls, columns, beams, windows, and sculptures in an interior space; trees, sign age, and building walls in an exterior space) that determine whether the space seems bright or dim, intriguing or mysterious, pleasant or forbidding.

Will the lighting system be compatible with the architecture? The lighting design does not exist independently. It must coordinate with the design of the building and work to reveal that design. It must be detailed as an integral part of the building, rather than appearing to be an afterthought.

This question, along with several others in this list, is a primary reason for the devel-

* The viewer does not "see" illuminance. Rather, the viewer sees luminance in the form of perceived brightness, and the world as an arrange­ment of objects and surfaces in varying brightness patterns presented in a three-dimensional array.

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opment of a strong conceptual design. The answers to these types of subjective questions are best tested by evaluating them against the overall lighting concept created at the outset of the project. Although they may have no absolute numerical basis, they may still be tested for appropriateness if the original concept is clear to all parties involved.

Will the lighting system work with available daylight? Will it work at night? Electric lighting systems can be con­trolled to lower the output when there is a useful daylight contribution from windows or skylights. This can reduce energy loads during peak demand hours for the electric utility. See IESNA Lighting Handbook, 8th Edition, chap­ter 8, Oaylighting, and chapter 31, Controls. Also, the lighting deSigner needs to be concerned about the effect of both interior and exterior luminaires and light patterns on the nighttime appearance of the building. See IESNA Lighting Handbook, 8th Edition, chap­ter 22, Exterior Lighting.

What color oflight is appropriate? Con­sider the objects, surfaces and people that will be lighted in the space. Should the color of the light be warm or cool, or something in between? How important is the color rendering ability of the light source? Will the light source color coordinate well with available daylight? Sources with good color rendering make merchandise more appealing, and can help people feel better about themselves because their skin tones look healthier. Plant foliage may appear dead under sources deficient in the short-wavelength (blue) region of the spectrum, so light sources used for landscape lighting. must be carefully

- selected for spectral composition. See IESNA Lighting Handbook, 8th Edition, chapter 5, Nonvisual Effects of Radiant Energy. A warmer color temperature light can help people feel relaxed because it reminds them of the warm light sources used in their homes.

Where color is critical, there is no substitute for viewing objects, skin tones, fabrics and finishes under the intended light source in a color booth or full-scale mockup. See IESNA Lighting Handbook, 8th Edition, chapter 4, Color, and IESNA DG-1-90, Color and /IIumination.

Will glare be a problem? The lighting designer must evaluate the lighting system under design so that uncomfort­able or distracting glare is minimized for th.e user. This involves knowing the location of the user, the angles of view, and the distribution of light on the room surfaces, as well as familiarity with the specified lighting products. Maximum luminaire brightness cannot always be derived from photometric reports, so the designer may have to view lumin­aire samples or rely on past experience to determine whether glare from a particular luminaire will be a problem. See IESNA Ughting Handbook, chapter 7, Luminaires. Glare from windows and skylights may require an architectural solution. See IESNA Lighting Hand­book, 8th Edition, chapter 3, Vision and Perception, for issues connected with glare.

Is the proposed lighting system within budget? Are its operating costs appro­priate? Life-cycle costing is often the best way to examine the expense of lighting. These numbers should then be discussed with the owner or client. There is no easy way to predict the exact value of a commercial or industrial lighting system in terms of production, safety, quality control, employee morale, or employee health; however, employee costs far outweigh

~. - ~ ~ - both initial · and operating costs of lighting. Small improvements in -em­ployee morale due to a comfortable and effective lighting system could quickly pay for the incremental lighting cost. See IESNA Lighting Handbook, chap­ter 13, Lighting Economics.

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Is the lighting system using energy and resources responsibly? Electric energy use affects environmental pollution and costs the building owner energy dollars. Disposal of lamps and ballasts may also contribute to hazardous waste disposal problems. The deleterious environmental effects must be bal­anced with the human benefits of the lighting system. See IESNA Lighting Handbook, chapter 34, Environmental Issues.

Is the lighting system flexible? If the client's needs are likely to change often, the lighting system should be designed to accommodate changes easily. Work­stations may be shifted in an office. Merchandise displays will be moved in a retail store. Plants may grow and necessitate modifications in an outdoor installation. Stack locations may change in a library. The likelihood of change must be weighed against the increased lighting system cost and energy cost that may result from the more flexible lighting design.

How will the lighting system be con­trolled? Lighting may be switched or dimmed, and the method chosen affects the choice of control devices and the ballasts. The lighting designer wi ll often be involved in determining where the controls should be located, and this necessitates questioning the client about how the space will be used. In most cases the controls should be located so that they are as convenient as possible for the client to use. In some cases, however, it is better for the controls to be hidden or locked to prevent the lights from being turned off in areas where security is a problem or tO cc.prevent ... us.ers .Jrom .adjusting the lights. (Imagili(f . a·~ restauranCwhere patrons could turn the lights up and down, distracting other patrons.) The designer frequently decides which lights will be controlled together, and specifies wall-box controls.

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VVhat are the applicable building, handi­cap, electrical, and energy codes? With the assistance of the architect and engi­neer, the designer must become famil­iar with all of the applicable codes per­taining to lighting for the locality of the project. These will include egress requirements, circuiting requirements, and, in some areas, energy restrictions. Among the newest govemment regula­tions are the Americans with Disabilities Act (ADA) handicap requirements and the component requirements for lamps and ballasts. The ADA requirements pertain to the allowable projection of wall-mounted luminaires. The compon­ent regulations cover lamp and ballast efficacy. See IESNA Lighting Hand­book, 8th Edition, chapter 14, Codes and Standards.

What are the lighting considerations particular to an industrial area? Lighting for industrial areas has many of the needs discussed above. In addition, it may be necessary to consider condi­tions which are unique to the industrial workplace. The following are indicative of some of these special conditions.

The tasks found in many locations are two­dimensional, whereas those found in industry are often three-dimensional. This requires spe­cial consideration when designing lighting to assure that the proper illuminances are pro­vided to allow the worker to see all aspects of the task. In addition, care must be taken in industrial lighting designs to assure that a stro­boscopic effect does not create a dangerous condition where rotating parts or machine com­ponents are involved. For a complete discus­sion, see IESNA RP-7-91, Industrial Lighting.

2.3 Design Concepts

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Design Concepts. The lighting designer is now ready to formulate design con­cepts. There are many ways to aevelop such ideas. Visiting sites with similar features and visual tasks helps the de­signer learn about lighting systems that worked or did not work in those spaces.

Communication Tools. Any step which helps the designer develop a design concept can also be a communication tool. Photographs of analogous install­ations, design sketches, and magazine photographs can all be used to illustrate the ideas to other design team members, the client, and the end users. This material should be saved for presentations.

Photographs are a quick way to document the lighting solutions in these existing spaces. The designer can also search for photographs and descriptions of similar installations in mag­azines and books. These can provide inspiration, although it may be impossible to judge from a photograph whether the lighting system satisfied the task requirements or cre­ated uncomfortable glare for the users.

The lighting designer's own sketches are inval­uable tools in the schematic design process because they illustrate the designer's mental images of the lighted environment. The space may be imagined as the inside of a box with its surfaces painted with light. The light can be applied to the walls, the desk top, the ceiling, or the floor. It can be applied in a regular or irregular pattem. It must provide an appropriate quality of light for the visual tasks performed, respond to the psychological needs of the users, and enhance architectural design fea­tures. The lighting designer may visualize an evenly lighted scene or one with notable contrasts in light and shadow. (Some of the design effects that can be achieved with light, such as "enlarging space with light" or "grazing" are discussed in Figure 2 and illustrated with sketches. The lighting sketches often show which surfaces are illuminated and the relative brightness of each.) The designer should be aware of the psychological and spatial effects created by the lighting patterns. Will users find this space "open," "bright," "intimate," "public," "restful," "gloomy," _"stimulating,"- "comfortable:~

-- "dramatic," - or "business-like?" See -IESNA ­Lighting Handbook, 8th Edition, chapter 3, Vision and Perception and also in the work of John Flynn.

- - ' - .-.- . . ------~- -'-.. _-- ------- _ . ~- .'-.- ~--- -----._.- - ~ - ~~~~.

Distribution of Light. Once the desired light patterns are established and the special needs of the area have been considered, the designer determines the appropriate distribution of light, direction of light, and light source. Light may emanate from a luminaire in a concentrated beam or as a diffuse wash; from a point source, linear source, or area source. The luminaire may be visible or concealed. It may be recessed, wall-mounted, or suspended from the ceiling. It may be portable or mounted to the fumiture. These require­ments lead the lighting designer to specific lighting products; but actual product selection takes place during the design development phase.

Lighting design concepts developed through this process must be tested and retested against the project's objectives and constraints. Concepts which continue to satisfy the pro­gramming requirements are presented to the design team and the client, and once approved, move on to the design development stage.

2.4 Design Development

In the design development phase, the lighting design concept is refined, and documentation is initiated. Mounting details are developed as well as detailing of any custom luminaires. More precise lighting calculations and energy use calculations may be performed. Lighting layouts (with exact luminaire lengths, lamp counts, spacings, and so forth) are firmed up.

Luminaire selection requires an understanding of photometric reports and the characteristics of light sources, and in many cases it requires an evaluation of a sample luminaire, either on the tabletop or in a mockup. The style of the luminaires should relate to the architecture and must be appropriate in terms of cost and

. energy use. -.

The lighting designer often finds that the desired luminaire does not exist as a standard, catalogued product. The designer may want a special look, finish, or optical distribution, and this necessitates working with a manufacturer to create a custom or modified lighting product.

IESNA DG-7-1994

Many manufacturers are willing to engineer and fabricate a custom product if the number of units is large or if it involves a minor modifica­tion to a product in the standard line. A smaller group of manufacturers is set up to produce small numbers of custom luminaires. Designers should be aware that custom luminaires have potential problems that standard products may avoid; long lead times for delivery, additional cost, UL listing complications, and poor product engineering (such as clumsy relamping). However, custom luminaires frequently contri­bute a unique look to the interior or exterior of a building. The premium cost is often minor or may be well justified. The designer, in conjunc­tion with the project team, usually makes the decision on the utilization of custom luminaires.

During the design development phase there may be extensive communication and coordi­nation with other design team members (architect, interior designer, engineers, and landscape architect) to ensure that the lighting is integrated into the whole of the building or site. Here are some additional issues to investi­gate in this phase:

Coordination with other building sys­tems. Is the lighting system coordinated with other building systems? The light­ing system must integrate with the structural, mechanical, acoustical, elec­trical, fire protection, and life safety systems in the building. Lighting hard­ware can be combined with air supply and extraction systems, for example, which may result in a more economical building and an architecturally coordi­nated ceiling appearance. By code, the luminaire housing must be rated for the area where it is mounted in the build­ing-for wet, damp or dry locations, hazardous locations, or insulated or noninsulated ceilings.

__ Coordination with fumiJl.lre_plan. Is the lighting system coordinated with the fumiture? In open office areas, workstation partitions may interfere with the distribution of light from ceiling-mounted luminaires. This may call for specialized ambient lighting systems and task lighting built into the

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...a. Figure 2. Creating Effects with Light 0 m (j) z >

---- ---.-- ---_. - _ .- _. ----_ ... ----_._ .. 0 Effects on People, Sketched G)

Effect Created by Light Sources Visual Effects Objects, and Tasks Suggestions Illustration I ...... _ ._- - ... _. - --- - .- -- I

Enlarging space Indirect or ambient Diffuse. point or Room dimensions Contrast and shadows are Direct shielded light ...... light. Brightly and linear sources. appear larger. diminished. helps focus attention to

to evenly lighted Incandescent. lighting more Objects become less on objects or work ~ ceiling, wall or fluorescent or HID. uniform. Less drama. prominent than surfaces. surfaces. Use accent floor surfaces; less contrast in room. Sparkle from jewelry. crystal. light 2 to 20 times as Surfaces should Colors less vibrant. hair sheen. shiny finishes is bright on special have high reduced. objects. reflectance. Architectu ral form of space is

more visible. Space appoars loss" crisp." Enlarging Space with Light Quality of light for reading tasks can be excellent. but is dependent on illuminance level and luminaire placement.

Making space look Direct. shielded Point sources. Room dimensions Creates dramatic. stimulating Add ambient light to smaller or more luminaires concentrated appear smaller. atmosphere. soften contrasts and intimate recessed in beam spreads. High contrast. Creates mood of intimacy. improve appearance

ceiling. or Usually Vibrant color and Sparkle and glitter enhanced. of faces. surface-mounted incandescent. glitter. Att racts attention to bright High-contrast setting on wall or ceiling. objects. maybe one of

Prominent shadows can several options on a enhance texture. but render programmable faces harshly. dimmer. High contrast may not be conducive to long-term performance of visual tasks. Making Spaces Smaller Position of luminaire and angle of light affect task visibility .

Grazing Well-shielded Point source. high Expands space. Adds visual interest. Use with other directional lumi- or low intensity. Emphasizes texture Draws attention to special lighting systems for naires. recessed Sometimes and color of surface . surfaces. balance. or , achievable with Reduces reftections Adds ambient light to space. Highly textured wall surface-mounted linear source. on specular grazed Can balance light from other coverings. brick do~nlight ; Incandescent. surfaces such as lighting systems. patterns or stone wail-mounted HID. or picture glass or shiny Will accentuate flaws and patterns will produce upllght. fluorescent. marble walls . unevenness in gypboard pleasing shadow Sh§rp angle of walls. patterns. incidence of light against surface.

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Grazing Washing Well-shielded Point or linear Provides even Calls attention to lighted Recommended for

directional lumi- source. high lighting across wall or surfaces. matte surfaces only. naires. recessed, or low intensity. ceiling surfaces. Soft. reflected light on faces. or else glary surface-mounted. Incandescent. Softens shadows. Bright surfaces make space reflections may wall-mounted. or fluorescent or HID. Extends space. feel cheerful. occur. floor-mounted. Adds ambient light. Use with other

lighting systems for balance.

Wall Washing

Framing Recessed or Point source, high Lights painting or Very dramatic effect on Use with other surface-mounted intensity. object only. artwork. lighting systems for

framing projector Low·voltage or Background goes Artwork seems to glow. balance. with adjustable line-voltage dark, creating very Sharp shadows on frame. shutters. incandescent. high contrast. Focuses attention an art.

Shutters allow Can be used for wall-hung confining light to the art, sculpture, rectangular artwork. No spill light. dining tables and other

horizontal surfaces. This technique may give an

Framing artificial look to artwork if the contrast between art and background is too high.

Accent Narrow·beam Point source, high Focuses light on Dramatic effect that draws Use with other recessed intensity. object with little spill attention to the lighted object lighting systems for downlights or Low·voltage or light on background. or surface. balance. surface-mounted tine·voltage Creates high Enhances color. Direct glare or luminaires. incandescent, or contrast. Creates sharp shadows which reflected glare may Adjystable aiming. compact metal often enhance the form in be a problems if light

halide. sculpture. is not carefully aimed Adds visual interest to the away from normal space. viewing angles.

Accent

Ambient General lighting, Diffuse, pOint or Light is Objects and background Use with other nondirectional. linear sources. nondlrectlonal. equally visible. lighting systems for

Incandescent, unconcentrated. Soft shadows. balance. fluorescent or HID. Look may be soft or, No highlights.

if too uniform, bland. Helpful in washing out harsh shadows and veiling reflections that could reduce visibility of some tasks.

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Ambient

Visible fixtures Wall-mounted or Diffuse, point or Contributes to Decorative luminaires add Reduce lamp wattage hanging linear sources. decorative style of visual interest. to a minimum if lurtlinaires. Incandescent, HID space. If lamps are visible and lamps are exposed, Permanently or fluorescent. May add sparkle or wattage is too high, luminaire Use other lighting installed, or Shielded or glare. may be glary and distracting. system to provide portable table unshielded. May add ambient Well-shielded lamps and task lighting. m lamps or floor light. chandeliers can provide larhps. needed ambient light.

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IESNA DG-7-1994

workstation. Veiling reflections, bright­ness ranges, and energy use must be evaluated both for task lighting and for ambient lighting. Lighting is often built into retail display cases. The built-in lighting product must be detailed so that it does not obscure the view of the mer­chandise, but enhances the displayed goods with color, sparkle, and highlight. See IESNA RP-2-85, Lighting for Merchandising Areas.

Localized and task lighting should be included in the design of industrial lighting systems, where required, to proper1y illuminate a task which may be located out of the normal distribution pattern for the general lighting system.

Maintenance. Is the lighting system easy to maintain? The lighting designer should imagine the job of the lighting maintenance person. How often does the lamp have to be changed? How difficult is it to get into the luminaire to change the lamp? Does it require spe­cial tools? Does it require special lifts, scaffolding, or intrepid workers? Are the lamps hard to order or find? Is the num­ber of different lamps on the job so large that it is impractical or confusing to stock them all? If any lighting prod­ucts have special maintenance prob­lems, the designer should change the specifications or else work with the cli­ent to set up a system for maintenance.

Design constraints to project com­pletion. Will the specified products be available in time? If there is a short lead time on a construction project, it may be necessary to specify quick-ship prod­ucts. There may also be a backlog in production of new, popular or cus­tomized lamps, ballasts, controls, or luminaires. VerftYing availability- early . on will help forestall urgent calls from electrical contractors during the con­struction phase.

Significant redesign may occur during the design development phase as a result of coor­dination activities or more precise cost estimates. At the completion of this phase, the lighting design should be well established and the design documentation well underway.

2.5 Contract Documents

In this phase of the lighting design process, effort is concentrated on producing a set of documents which are sufficiently clear and complete for the electrical contractor to bid the project, order the lighting and controls products, and install the lighting with a minimum of conflicts with other systems in the building or on the site.

Lighting design documents will vary from project to project, but normally wi" include:

• Electrical lighting plan (usually a modified reflected-ceiling plan) to indicate the loca­tions and luminaire types for all lighting within the scope of work. Control locations and circuits are also shown on the lighting plan.

• Drawings that show mounting details, build­ing section and elevations, custom luminaire details, and other supplemental information.

• Luminaire schedule to specify luminaire attributes, catalog numbers, and lamping.

• Lighting specifications to outline general requirements for the lighting system, such as ballasting, electrical requirements, applic­able codes and standards, approved manu­facturers, mounting restrictions, and custom fixture requirements.

• Dimming and controls schedule to specify control attributes and catalog numbers.

• Dimming and controls specifications to outline general requirements .aLthe controls system.

• Catalog "cuts" package to illustrate specified luminaires and controls.

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The lighting designer may be retained to review contract documents prepared by other design team members for coordination. At the conclu­sion of the contract documents phase, the package of lighting documents is turned over to the owner or owner's representative for bidding.

2.6 Bidding and Negotiation

During this phase, the lighting designer may be called upon to clarify points that the bidding contractors do not understand. He or she may also be asked to pre-approve lighting products other than those specified. The contractor may offer these substitutions in order to reduce the contractor's cost, improve availability, or facil­itate ordering of the product. The designer must review substitutions carefully to ensure that the design intent and photometric performance characteristics are met. The construction and reliability of the product must also be checked.

2.7 Construction

At this point, the bid has been awarded to an electrical contractor. The lighting designer is usually retained to review submittal drawings to ensure that the products the contractor is ordering comply with the intent of the contract documents. Product substitutions may be of­fered at this time, and it is the designer's responsibility to carefully review the substituted product's construction, appearance, and photo­metric performance so that the client receives a product that will perform just as well as the one specified. By approving the substitution, the designer accepts responsibility for the perform­ance of that product.

The designer may be called upon to help resolve field problems that arise when con­struction conflicts occur or when unanticipated

IESNA DG-7-1994

product and design problems manifest them­selves. This coordination and resolution may occur through written communication, tele­phone exchanges, or site visits. During the final site visit, the designer may prepare a punch list which enumerates any errors, flaws, or omis­sions that the designer can spot in the installa­tion of the lighting system.

If there are aimable interior or exterior lighting products on the project, or if there are controls that require the programming of presets, the designer may return to the job site for these adjustments after construction is complete. Often the aiming takes place after the client has moved in furnishings and artwork, so that lights can be aimed to produce the intended visual effect. Proper aiming of exterior facade or landscape lighting is extremely important in order to obtain successful results.

2.8 Postoccupancy Evaluation (POE)

After the lighting is installed and in use, it is important for the lighting designer to evaluate how well the lighting installation is performing. Put simply, the POE goal is to determine whether the general design objectives of the lighted space have been met. The desig,ner may ask, in the case of an office building: Does the lighting design work well for the various activities performed? Is it attractive and flatter­ing to the architecture? Does the lighted environment satisfy human needs? Is it com­fortable? Is it stimulating? Will people enjoy spending time here? If the answers are yes and the design has stayed within budget, complied with energy constraints, and satisfied the objectives established during the programming and design phases, the lighting design has been successful.

13

IESNA DG-7-1994

Bibliography

1. IESNA Lighting Handbook, 8th Edition, 1993. New York: Illuminating Engineering Society of North America.

2. Color and Illumination, IESNA DG-1, 1990. New York: Illuminating Engineering Society of North America.

3. American National Standard Practice for Industrial Lighting. ANSI/IESNA RP-7, 1991. New York: Illuminating Engineering Society of North America.

4. Flynn, J. E., Spencer, T. J., Martyniuk, 0., and Hendrick, C. A Guide to Methodology Procedures for Measuring Subjective Impressions in Lighting. Journal of the Illuminating Engineering SOCiety, (1975): 95-110.

5. Recommended Practice for Lighting MerchandisingAreas, IESNA RP-2, 1985. New York: Illuminating Engineering Soci­ety of North America.

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