., fl "’1" 2. 11%“, 123‘: \ 'vy . ., ‘ A.) 7}th "« w "5"" “"Pa’. J . ’1 .m. , ‘ 4‘ 1.3%; X I ' ' Kai-fly: {[10 '3': 33% w"‘ "/0 4 [. lllllllllllllllllllllllllllllllllllllllllllllllillllll 1293 01016 9534 meats r v" This is to certify that the thesis entitled ECONOMIC ANALYSIS OF LIGHTING SYSTEMS FOR OPEN PLAN OFFICE ill-5 presented by SUTARTO HARTONO has been accepted towards fulfillment of the requirements for MASTER OF Wdegreeinw CONSTRUCTION MANAGEMENT Date 0” | 6/61 6 0.7539 MS U is an Affirmative Action/Equal Opportunity Institution _.-~ a. a— -4‘4 __ A. .‘__f— LBERARY Mlchlgan State J Unlverslty PLACE ll RETURN BOXtonmovomhehockoufl'omywmd. TO AVOID FINES return on or More data duo. DATE DUE DATE DUE DATE DUE ' 411‘; NAN r: it a "2 \3 t I MSU I. An Afflnnulvo Wat-l Oppomnlty Inflation . mm: ECONOMIC ANALYSIS OF LIGHTING SYSTEMS FTHRlOPEni PIJDJ‘OFFUIHB SEUKflE By Sutarto Hartono A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Building Construction Management Departement of Agricultural Engineering 1995 ABSTRACT ECONOMIC ANALYSIS OF LIGHTING SYSTEMS FOR AN OPEN PLAN OFFICE BY Sutarto Hartono Energy conservation is important because of the increasing demands for energy consumption in the form of electricity, petroleum, coal and natural gas. One approach to energy conservation jiS‘UD build energy consumption systems which are more efficient. Computer software that can analyze a proposed lighting system design from a lighting quality point of view and an economic point of view does not exist. The objective of this study was to develop and validate the computer software that would provide information about the quality and quantity of light in an open plan office space and analyze the system using a simple payback analysis and a life cycle cost analysis. The computer software was developed and compared with hand calculations for two existing open plan office spaces. The software is valid and can be used to evaluate alternative designs. Approved Approved Larry J Segerlind, PhD Robert D.V0n Bernuth,PhD Major Professor Department Chairman DEDICATION This thesis is dedicated to the Lord of Jesus Christ. iii ACKNOWLEDGMENTS The author is deeply indebted to his major professor Dr. Larry J. Segerlind, who provided not only technical and.moral support, but also friendship and guidance that will positively influence the author's way of life. He planted a good seed in the outhor's heart. The author~ is also grateful to jhis committee, Dr. Thomas H. Burkhardt and Jeanne M. Halloin, IES for their contributions, suggestions, hospitality and friendship. Their guidance led the way to enter a Master's program at Michigan State. Sincere thanks to Tim Mrozowski and Dr. John B. Gerrish for their much appreciated adviCe and friendship. The author is truly graceful to Joyo Winoto, Herr ‘ Soeryantono, Richard Setiabudi and.Ralph.Dicosty for all their help and friendship. Special thanks and appreciation is sincerely expressed to my parents and my parents in law for their prayer and love. Deepest appreciation goes to his wife, Riantea Juanita Liando, for her patient, love and sacrifice. Best love to their son, Kevin Valerian Sutarto. iv TABLE OF CONTENTS Page LIST OF TABLES . . . . . . . . . vii LIST OF FIGURES . . . . . .viii LIST OF SYMBOLS and ABBREVIATIONS . . . . . ix Chapter 1. INTRODUCTION . . . . . . . . l 1.1. Background and Problem Setting . l 1.2. Objective of the Study . . . . . 4 1.2.1. Government's concern . . . 5 1. 2.2. The Office Management Concern . 6 1.3. Scope of Study 7 2. ENERGY EFFICIENCY Of LIGHTING SYSTEM for an OPEN-PLAN OFFICE SPACE: a CONCEPTUAL FRAMEWORK . . . . 9 2.1. Lighting System . . . . . . 9 2.1.1. Flourescent Lamp . . . . . 11 2.1.2. Ballast . . . 16 2. L 3. Diffusing and. Shielding Media . 19 2.1.3.1. Lenses . . 19 2.1.3.2. Baffles and Louvers . . 20 2.1.4. Fluorescent Luminaire . . . . 21 2.1.5. Electrical Control . . . . 25 L 1.6. Quuantity of Light . . . . 25 2.1.6.1. Inverse Square Method . . 28 2.1.6.2. Angular Coordinate Direct or Direct Illuminance Component (DIC) Method . . 30 2.1.6.3. Flat Rectangular Source Method . 32 2.1.6. 4. Zonal Cavity Method . . . 34 2.1.7 Quality of Light (Open Plan Office Space) . . . 42 2.1.7.1. Glare . . . . . . 43 2.1.7.2. Color Rendering . 2.2. Key Concepts of the Study Operational Definitions . 2. 2. L The Energy Management Challange 2. 2. 2. Economic Analysis of Energy Efficiency. 2.2.2.1. Simple Payback Analysis 2.2.2.2. Life Cycle Cost Analysis 2.3. Management Renovation of a Lighting System Project . . 2.3.1. Renovation Management of a Lighting System Project 2. 3. 2. Decision Analysis of Lighting System 3. COMPUTER PROGRAM . 3.1. Modelling Process and Methodology 3.1.1. Lighting Design 3.1.2. Economic Analysis 3.1.3. Management 4. CASE STUDY . . . . . . . 4.1 Case 1. Office space . . 4.2 Case 2. The Taubman Company . 3 Example of Computer Output . 4.3.1. Inverse Square Method . . 4. 3. 2. Direct Illuminance Component . 4. 3. 3. Flat Rectangular Source Method . 4. 3. 4. S Curve, Renovation System Project 5. SUMMARY . . . . . 6. RECOMMENDATIONS GLOSSARY . . . APPENDIX A Conceptual Model APPENDIX B Procedure for determining illuminance LIST OF REFERENCES vi 47 48 48 49 52 56 56 63 66 66 71 72 72 73 77 81 81 83 87 88 92 93 98 99 107 LIST OF TABLES Table 10. 11. 12. 13. 14 Fluorescent Lamp Types and Typical Aplication Characteristic . . . . . The Burnout Rate of Fluorescent Lamps . . . Fluorescent Lamp Standards . . . . . Shielding Media . . . - . . . Maximum Luminance Ratios for Offices Containing VDTs . . . . . . . Economic Analysis of Simple Payback - New Fixtures . . . . . . . . Range of Forecast Evaluation Based On The Value of Needs in Open Plan Office Space . . . . Evaluation of Case 1: Office Space (based on the value of needs in Open Plan Office Space) . . Comparison between Simple Payback analysis and Life Cycle Cost of Case 1: Office Space . . . . Evaluation of Case 2: The Taubman Company (based on the value of needs in Open Plan Office Space) . Comparison between Simple Payback analysis and Life Cycle Cost of Case 2: The Taubman Company . Calculated Values for The Inverse Square Method . Calculated Values for The Direct Illuminance Component Method . . .' . . . Calculated Values for The Flat Rectangular Source - Parallel . . . .' . . vii Page 16 16 17 23 45 51 65 75 76 79 80 82 84 86 LIST OF FIGURES Figure Page 1. Fluorescent Ordering Code . . . . . 13 2. System Characteristic VS Ambient Temperature TL 80 lamp on Electronic Ballast . . . 15 3. Baffle and Louver Shielding . . . . . 22 4. Inverse Square Method . . . . . . 29 5. Geometry of DIC Method . . . . . . 32 6 Flat Rectangular Source Method . . . . 34 7 Zonal Cavities . . . . . . . 35 8. Evaluationn Procedure to Shorten a Project Schedule 62 9. Programming Process . . . . . . . 68 10. Computer Model . . . . . . . . 69 11. .Example of Inverse Square Method . . . . 81 12. Example of Direct Illuminance Component . . . 83 13. Example of Flat Rectangular Source . . . . 85 14. Example of S Curve . . . . . . . 87 viii bf CC cd CIE CRI CU CW DHSS DIC ER FC FRS fc GE GSA/PBS CC LIST OF SYMBOLS AND ABBREVIATIONS Area , ft2 Average annual cost Ballast factor Ceiling cavity Candela Commission internationale de l'exlairage (International lighting standard commission) Color rendering index Coefficient of utilization Cool white Department of health and social security Direct illuminance component / angular coordinate Illuminance Energy escalation rate Floor cavity Flat rectangular source Footcandle General electric General services administration/public services building Height of ceiling cavity ix HID IC IES ISM LCC LLF LDD LLD LPW 1x NEPA pf PVEC PVMC PVOR PVRC PVSC RC High intensity discharge Discount rate Initial cost Illuminating Engineers Society Inverse square method Number of lumens produced per lamp Life Cycle Cost Light loss factor Lamp dirt deprectiation Lamp lumen depreciation Lumen per watt Lux Number of year life Number of luminaire National energy policy act Namometer Power factor Present value of energy cost Present value of maintenance cost Present value of repair cost Present value of repair cost Present value of survaillance cost Repair cost X RR S/MH SPD VCP VDT YS Reflectance Replacement escalation rate Spacing to mounting height ratio Spectral Power Distribution Visual Comfort Probability Visual display terminal White Warm White Years between occasional replacement 1. INTRODUCTION 1.1. Background and Problam Setting Energy conservation is a key issue because of the increasing demand for energy consumption. Our society is becoming more technological, requiring greater use of computers, equipment and information systems that require electricity. (hi the contrary, the supply' of energy' is becoming more limited requiring energy conservation. Some alternative energy sources have the potential for commercial development. Some have already been developed. Nuclear power plants are operational, but the future of nuclear energy is uncertain since it is difficult to answer questions related to the environmental (Thorndike,l976). Solar energy technology has reached the marketplace and meets technical, economic, and environmental criteria; there are, however, political issues to be resolved" IResearch.and.development are on going in the areas of geothermal energy and synthetic fuels; while a few commercial plants have been constructed, there are serious limitations to large-scale operations (Thorndike, 1976). A The energy crisis cannot be abated in the next 10 years because conversion to renewable energy sources is a slow process (Reis et a1., 1985; Thumann, 1983). Improvements can be realized by immediate adoption of conservation measures, such as reduced consumption, energy storage and recycling, and improved efficiency of current systems. These approaches are practical and could have eased the strain 1 2 during the energy transition period of the 19808. There are two basic ways to improve energy efficiency. The first involves changes in the way that existing systems are operated, such as reduction in lighting levels in industrial and commercial buildings, and higher thermostat settings on room air conditioners (Stein and Reynold, 1992). These changes are characterized.by their low (or zero) capital cost, the speed with which they can be implemented, and the fact that all require operational (human) changes. The second type of change involves improvement in the technical efficiency of the energy systems (space heating and cooling equipment, appliances,Zbuildingnstructures, industrial process equipment). Examples include the installation of more efficient fluorescent lamps in industrial and. commercial buildings, or the replacement of existing lighting systems with energy efficient equipment. Both of these examples reduce energy consumption. Lighting has been one of the prime targets of mandatory standards to reduce energy consumptitmibecause of the apparent depletion of nonrenewable energy resources (Helms and Belcher, 1991). Most energy conservation programs in office buildings are directed toward. electrical consumption. and lighting use. Even though only 7% of the total, lighting is a primary target for energy conservation (Helms and Belcher, 1991; Philips-Office lighting, 1993). Decreasing energy consumption in lighting includes: 3 1. Lighting is "visible". PeOple don't think as much about other energy use, such as a manufacturing processes, Lighting is continually before us continually (Murdoch, 1985). 2. Lighting represents 30% to 50% of the operating cost of the building, which shows up as a monthly business expense (Sorcar,1982; Helms and ‘ Belcher,1991; Lindsey,1991). 3. There are ways to conserve energy in lighting without giving up the quantity and quality of light recommended. Therefore, the lighting systenlis an important concern in the economics of energy efficiency (Sorcar, 1982; Helms and Belcher, 1991; Lindsey, 1991; Murdoch, 1985). The office environment has become complex and highly specialized because of technological advancements including computers, cellular telephones, fax machine, control systems, and electronic mail, In today's automated office, a systems approach is necessary to increase productivity and maintain consistency of quality. Philips Lighting's Office Building states that a lighting system is one of the most important tools in optimizing office worker performance, ‘since its impact is measurable on the bottom line. Office space can be divided. by function into five categories: (1)0pen plan [general staff office .space], (2)Private offices, (3)Executive offices, (4)Drafting rooms, and (5)Conference rooms (Stallard et a1., 1984). In terms of 4 office management, every part of the office building should be connected to performance, comfort, ambiance (mood) and cost effectiveness. The problem of increasing the energy efficiency of the lighting system while maintaining the purpose of office management needs to be studied. Lindsey (1991) stated efficiency cannot be based on simple metrics such as lumens per watt or fixture efficiency since they ignore the basic purpose of a lighting system: to allow people to see in order to perform a visual task. 1.2. Objective of this Study There are two interrelated reasons for pursuing this study. The first is that federal and state governments have passed lows related to the energy efficiency of the lighting system and its impact on cost reduction. The second is the management concern and interest over the problems posed by performing visual tasks while maintaining an acceptable level of performance, comfort, ambiance, and cost effectiveness. 1.2.1. Government's concern The first document that was a direct outcome of the "energy crisis", caused by the OPEC oil embargo of 1973, regarding the visibility of lighting, was a General Services Administration/Public Building Services (GSA/PBS) publication, entitled "Energy Conservation Guidelines for Existing Office Buildings". It was published in 1974. The newest law is 5 public law 102—846-Oct 24, 1992, that Congress passed with the title " An Act to Provide for Improved.Energy'Efficiency". It deals with energy conservation for buildings and includes performance standards to :maximize jpracticable energy efficiency, as well as encouragement for states and local governments to adopt and enforce the standards. Regarding lighting, this energy. law commands minimum efficiency standards for selected.e1ectric lamps. IEighteen to thirty-six months after enactment, lamp manufacturers will no longer be allowed to produce many popular fluorescent, High Intensity Discharge (HID), and incandescent lamp types which do not meet the new efficiency standard. One example is the traditional T—l2 Med Bipin F4OCW, the most widely used fluorescent lamp prior to the law's passage. Specifiers will obtain direct energy savings by selecting from several alternative lamp types such.as the F4OSPEC30/RS/EW-II, F4OSPEC35/RS/EW-II, or F4OSPEC4l/RS/EW-II, Philips Lighting, (1991). Inefficient lamps are no longer a choice. The energy efficiency of the lighting system is now mandatory. 1.2.2. The office management concern From the office management point of view, a good lighting design would be one that addresses the range of age among workers and the tasks performed in each category of office space, meets the IES (Illuminating Engineers Society) recommendations for quantity’ of light, and. provides for quality in terms of visual comfort, ambiance, color rendition and cost efficiency. The energy efficiency of a lighting system for an office building cannot be based only on dollars as a function of lumens per watt, but must also account for the basic purpose of the lighting system which is to allow people to see well in order to perform a visual task accurately and comfortably. The lighting system should provide illumination of sufficient quantity and quality for the task being performed, at the lowest cost. The components of quantity, quality, and cost are - Cost refers to luminaire, installation, operation, and maintenance costs of the system. - Quantity'is:measured.as lumens per unit area, footcandles or lux. — Quality is related to the human as a user, concerning glare control and color. The elements of glare control and the color include Visual Comfort Probability (VCP) and Color Rendering Index (CRI). Lindsey (1991) stated a few dollars saved on power cost may be lost many times over if lighting levels are reduced below the requirement of effective seeing. V Regarding cost, quantity, and quality, how much light should. be provided for today's office tasks? The IES recommendations encompass a broad range of illuminance levels for a variety of seeing tasks. They are a function of (1)The age of the worker (an aging eye requires more light for the 7 same visual acuity), (2)The importance (ME the task (how critical are speed and accuracy), and (3)The difficulty of the task which depends on the size and contrast of the details GE—Office Lighting (1991). There are a wide array of existing cost-effective, energy efficient measures which represent an enormous and largely untapped energy resource. Adoption of these measures can substantially reduce growth in energy use, and save money for the consumer while having only a slight life-style effect on the user. In addition, an energy efficient lighting system can reduce the adverse environmental effects of energy production and conversion, and provide additional time to develop new energy resources. The objective of this study was to assess the energy efficiency of a lighting system for open plan office spaces that meets IES recommendation and provided quality lighting in the work environment, especially from the management point of View. 1.3. Scope of the study This study addresses three components: (l)A lighting system for open-plan office space, (2)Economics, and (3)Management of the lighting system (see conceptual model— Appendix A) There are many questions to be considered. How is energy efficiency calculated? What is a practical design method appropriate for the design of energy efficient lighting 8 systems? What are the fundamental concepts of lighting systems for an office building? What are the components of . the lighting systemfi’ What are the factors which significantly determine efficiency and quality of the lighting system? How should the lighting system be managed? A computer program has been developed for integrating the three components given above, to create an integrated program for the economic cost analysis, to design the lighting system and provide some graphics for the management issues. The results of this study are expected to provide a positive contribution. to (design decisions made in the selection. of efficient lighting systems for open. office spaces. 2. REVIEW OF LITERATURE 2.1. Lighting Systems Clearly, vision depends on light. A lighting system is provided to an environment in which people, through the sense of vision, can function effectively, efficiently and comfortably. Lighting systems produce an artificial visible light (Nuckolls, 1983). “Artificial" means that the light is produced by electrical power. Light can be artificially generated two ways. (hue is by sending electrical current through an element which may be surrounded by gases, such as in incandescent lamps. The other is by emitting radiant energy though the movement of atoms, such as light produced by fluorescent and high intensity discharge (HID) lamps. Fluorescent and HID lamps are controlled by ballasts that allow a surge of current to start the lamp and then regulate the electrical current during operation. This combination of lamp, ballast, fixture and other equipment designed to distribute the light is called the luminaire. Fluorescent light is the most commonly light source used in office buildings. The study of lighting systems involves the quantity and quality' of light. Quantity' of light in an area is the relationship between the amount of light leaving the lamp called light output (lumens) and the amount of light that actually reaches the surface area where people need it called light level (footcandles, lux). Quality of light describes 10 how light leaving the lamp, interacts with the work environment such as room surfaces, desk tops, computer screens and the like; and directly with human eyes. Just as people need the right amount of light to perform tasks productively so do they need good lighting quality to perform tasks comfortably. Ensuring’ proper lighting" quality' primarily involves controlling glare and color rendition. The sense of vision is based on the eye's ability to absorb and process selectively a portion of the electromagnetic spectrum. The visible portion of the electromagnetic spectrum extends from about 380 (deep blue) to 770 mm (deep red). The eye is most responsive in the yellow- green region (550-560 nm); sensitivity decreases toward deep blue at one end and deep red at the other (IES Lighting Handbook, 1984). Thus, color and brightness are the important factors of visual sensation. As an applied art and science, the discussion of conceptual lighting systems should include psychology. Ix detailed discussion of psychological factors in the lighting system was provided by Nuckolls (1983). A discussion of lighting systems in this study involved seven components: (l)Fluorescent lamp, (2)Ballast, (3)Diffusing and shielding media, (4)Fluorescent luminaire (5)Electrical Control, (6)Quantity'of light, and (7)Quality'of light (see Conceptual Model-Appendix A). 11 2.1.1. Fluorescent Lamp Sorcar (1982) explained that fluorescent lamps produce _light by creating an arc between two electrodes in an atmosphere of very low-pressure mercury vapor and some inert gas in a glass tube. The inside of the glass tube is coated with phosphor. The mercury vapor produces 253.7 nanometer (nm) ultraviolet energy that strikes the crystals of phosphor and excites them to produce light. Fluorescent lamps have hot cathodes in order to strike an electric charge in the lamps. Four types of hot cathode fluorescent lamps are now in use: (l)Preheat, (2)Instant start and slimline, (3)Rapid start, and (4)Trigger start (Sorcar, 1982). This study focused on the rapid start lamps since they are the most appropriate for office spaces (Sorcar, 1982; Steffy, 1990). A11 fluorescent lamps need ballasts to limit the current and to provide the necessary starting voltages. Fluorescent lamps are commonly manufactured in seven basic styles such as (l)Standard T12 ( "T12" means a tubular shape with a diameter of 12/8 " or 1.5 inches), (2)Improved efficiency T12, (3)Improved efficiency T10, (4)1mproved efficiency T8, (5)High output HO, (6)Large compact, and (7)Small compact (Steffy, 1990). High output lamps (HO) are designed to operate as high as 1.0 ampere (operate on a rapid start type circuit). For indoor application, they are usually operated at 0.8 amperes and for outdoor applications at 1.0 amperes (Philips Lighting, 1991). General applications of 12 these seven styles of fluorescent lamps are given in Table 1. Table l. Fluorescent Lamp Types and Typical Application Characteristic N N O .t : r: f3 a i 3 Application Characteristics 5 g g. E g 5 E .3 .- _- i's g "E :é S g . if: g 3 Low General direct lighting v Moderate general direct lighting v v v v v High general direct lighting v v v v v v Low to moderate general indirect lighting v v v v v Moderate to hight general indirect lighting v v v v v v Portable task lighting v Salt accent v Grazing wall washing (wall <_10') v v v v v Frontal wall washing (walls < 10 ') v v v v v v v Ballast required v v v v v v v Easily dimmable v v v Relative lamp cost (low. moderate. high) Lo Mo Hi M0 M0 Hi Mo Relative lamplballastlluminare efficiency) Lo Ho Ho Hi Lo Hi Mo Source: Steffy, 1990 Note: V means applicable Lo : Low : Mo: Moderate: Hi : High Lamp ordering codes for fluorescent lamps are based on ANSI standards that are a combination of letters and numbers representing different characteristics of the lamp. Figure 1 given an example using a Philips product. Each code carries a manufacturer's specifications. For example: TL 80 System - Lamp Specification: "Lamps shall be Philips TL 80 series lamps having: - Color rendering index of 85 - T-8 diameter bulb - Medium bi—pin bases 13 Color temperature of _ K (3000,3500 or 4100) Initial lumens of (1400, 2500, 3050, or 3800) Nominal wattage of (l7,25,32,40) Powered by electronic ballasts designed for 265 ma T8 lamps An Electrode guard TLaoswnrnGEflkh ‘_Dareter, 8/12 in sharfltbdafl Vtfls Floueeoerl Figure l. Fluorescent Ordering Code color or Spectral Power Distribution (SPD) curves for different types of fluorescent lamps depend on the phosphor coating on the bulb wall. Fluorescent lamps are commonly marketed in 41000' 1K (Cool White), 35000 K (White), and 30000 K (Warm White). Every typical fluorescent lamp has specific characteristics such as: (1)Color impressions, (2)Color rendering index or CRI, (3)Efficacy, and (4)Life time. The range of color impressions of fluorescent lamps varies from white, blue, green, gold, pink and red; and usually is represented as color temperature. 14 Color temperature is not a measure of actual temperature. It defines color only, and can be applied only to sources closely resembling a blackbody in color. The color temperature ratings sometimes given as a matter of convenience to the several types of "white" fluorescent lamps can be regarded only as approximations. Color Rendering is an evaluation of how natural colors appear under a given light source. For example, a red shirt can be rendered more pink, more yellow, lighter, or darker depending on the characteristics of the lamps. The standard measurement of color rendering called Color Rendering Index (CRI) was developed by the CIE (Commission Internationale De l'Eclairage) the International Lighting Standard Commission, Philip lighting (1991). Efforts to qualify lamps based on CRI have had limited success, however, this is the system being used today to describe color rendering. Fluorescent lamps are influenced by ambient temperature (IES Lighting Handbook, 1984; Sorcar, 1982; Helniet a1., 1991; Steffy, 1990; Craig, 1994). The pressure of mercury gas inside fluorescent lamps is based on the coolest point in the lamp. A low temperature decreases the pressure inside the lamp, enui it. generates smaller 'ultraviolet energy; thus decreasing the lumen output. This condition also occurs at high temperatures and lumen output decreases for high temperatures above 300C. Figure 2 shows that the wattage consumption ii; significantly' affected In! temperature 15 variation. 1U:higher temperatures, the lumen output and power consumption decrease more or less :hi the same proportion. Fluorescent lamps operate most efficiently at ambient temperatures between 25 to 35°C PERCENT 1a) Af,"-‘ta""=a watts e y / § . 1/ \ ‘ Q 85 ./ /lumens 80 75 5 15 25 5 45 55 AMBIENT TEMPERATURE ( C) Figure 2. System Characteristic VS Ambient Temperature TL 80 Lamp on Electronic Ballast Source: Philips lighting (1991) Lamp manufacturers publish rated life for their lamps in their brochures. Rated lamp life is an average because the life of each individual lamp cannot be predicted. Some individual lamps have a life time rating longer then average but others burn out before the average life. .Most T12 and T8 fluorescent lamps have a lamp life rating of 20,000 hours, GE Lighting, (1991). Regarding the life-rating, the burnout rates of fluorescent lamps rise sharply past 70% of rated life. Table 2 shows the percentage of burnouts. 16 Table 2. The Burnout Rate of Fluorescent Lamps Percent of Life time Percent of Burnouts 7 0 - 60% life 3% Burnouts 60 — 70% life 6% Burnouts (9% total) 70 - 80% life A 9% Burnouts (18% total) 80 - 90% life 14% Burnouts (32% total) 90 - 100% life 18% Burnouts (50% total) 4 (Source GE Lighting, 1991) The National Energy Policy Act (NEPA) of 1992 was signed into law on October 24, 1992. It mandated the energy efficiency standards for lamps in terms of lamp efficacy or LPW (Lumen Per Watts) and color rendering as seen in Table 3: 2.1.2 Ballast A ballast is a device used with an electric—discharge lamp to obtain the necessary circuit conditions (voltage, current and wave form) for starting and operating a fluorescent lamp. ‘Without a ballast to limit the current, the lamp would draw so much current that it would destroy itself. The fractional flux of a lamp operated on a ballast compared to the flux when operated on the reference ballasting specified for rating lamp lumens is called.the ballast factor. The light output, life, and starting reliability of a 17 Table 3. Fluorescent Lamp Standards . E 1 (LAMP _ Nominal Min CRI Min Ave- Wattage rage LPW ‘4-Foot Medium Bi-Pin >35 W 69 75 <35 W 45 75 2-Foot U-bent ' >35 W 69 68 <35 W 45 64 i 8-Foot Slimline >65 W 69 80 <65 W 45 80 ‘8—Foot High Output >100 W 69 80 ‘ <1oo w 45 80 (source: Phillips lighting-Nepa,1992) fluorescent lamp depends on the design of the ballast. ANSI specifies the requirements for good lamp performance. For example "class P" ballast contains a thermal protection device. If, due to abnormal conditions, the ballast begins to overheat, the thermal switch disconnects the ballast from the power source. When time ballast cools sufficiently, 112.18 reconnected to the power source and restarts the lamp. Electronic ballasts for fluorescent lamps are commonly used for energy efficiency. One reason for using electronic ballasts is that they are designed to produce the same amount of light from standard lamps as that from electromagnetic 18 ballasts, by using less power than magnetic ballasts (conventional ballast). Moreover, by‘ using an electronic ballast, the lamps can be controlled with a dimmer. Electronic ballasts are soundless, unlike magnetic ballasts, because an electronic ballast does not have the laminated core and coil . Ballasts are not interchangeable. They are designed specifically to provide the proper operating characteristics for only one type of lamp. For example a ballast fOr a 32-watt fluorescent cannot be used for a 40-watt fluorescent lamp. In order to reduce energy consumption, cut operating costs, and make the overall system work more efficiently, lighting equipment manufacturers have introduced a variety of new energy saving products in recent years. Two—lamp ballasts are used frequently to reduce ballast cost and installation cost per unit. An energy-saving ballast by definition has less internal losses than the standard, or commodity type, fluorescent ballast. The present energy—saving types of ballasts are tested and certified at full light output, and they reduce ballast losses without lowering lamp lumen output. An example is the Mark III, manufactured.by.Advance.i Interest in energy-saving ballasts increased over the last several years, while the cost of electricity continues to rise. The capacitor corrects tflma power factor [input watts/(line volts x line amps in an AC circuit)]. When a fluorescent lamp is operated in conjunction with a simple 19 inductive ballast, the overall power factor will be on the order of 50 — 60% (Thumann, 1983). The performance of this circuit is improved by adding a capacitor which compensates for the lagging current in the remainder or the circuit, improving the power factor, Philips - Fluorescent Lighting, (1991). The corrected power factor does not significantly change input watts, but decreases line current. 2.1.3. Diffusing and Shielding Media The main purpose of diffusing media such as lenses and louvers is to cover the lamps from.being in direct view and to spread the light intensity uniformly' over a large open. area, while controlling the light output in a settled manner. The shielding medium is a physical block controlling direct glare. One of the important factors involved in selecting a lens or louver is Visual Comfort Probability (VCP). 2.1.3.1. Lenses From. a jphotometric distribution, all lenses can be divided into two general types: diffusers and reflectors. Diffusers are clear prismatic lenses, flat transparent sheets, or combinations of either of glass or plastic. They are used on the bottom of luminaires to redirect or block the light and to reduce the luminance glare zone. Transparent diffusers disperse the light in all downward. directions uniformly; The transparency' is a function.of pigment density and thickness. The transparency of a 1/8 inch sheet is 45 to 20 70%. For the same type of material, this will drop 20 percentage points if the thickness is doubled to 1/4 inch. Diffusers generally'have low absorptions; thus luminaires with diffusers have lower efficiency than open-bottom or refractor types (Murdoch, 1985). For good performance and resistance to discoloring over time, lenses should be virgin acrylic (steffy, 1990) The fluorescent reflector is a simply bent sheet of metal finished with a highly reflective coating of an enamel paint (Nuckolls, 1983). Reflector finishes usually are based on two criteria: glare control and match to other luminaires' and/or surfaces' finishes (Steffy, 1990). 2.1.3.2. Baffles and Louvers A.baffle is usually'V shaped, installed parallel to and between lamps in multi-lamp luminaire (Figure 3a). .A louver is a group of baffles in an egg-crate arrangement, consisting of vertical fins set at right angles to form a series of repetitive cells (Figure 3b) . These louvers provide shielding for the fluorescent lamp and are typically supplied in 2 by 2 or 2 by 4 foot panels of plastic or metal. A variety of cell dimensions are available. The louver may be either straight or parabolic (Figure 3c). Some egg-crate arrangements have elaborate configurations on their visible edges. The shielding angle of a baffle or louver is the angle between the vertical (Nadir) and the line of sight at which all objects above are concealed, or the shielding angle is the maximum angle, 21 measured from.Nadir, at which the lamp element can be seen. It is shown as s0 in Figure 3d (Murdoch, 1985). W is the projected width at angle 5. A louver depth greater than three inches and a louver spacing of about 5 inches is suggested for good glare control. Louvers that are shallower than 3 inches in depth and greater than 6 inches in spacing should be carefully reviewed for glare (Steffy, 1991). The selection of shielding media should consider Visual Comfort Probability (VCP), efficiency (the ratio of the total number of lumens emitted.by a luminaire to the total number of lumens produced by the bare lamp), and cost. Table 4 shows the comparison of several types of shielding. 2.1.4. Fluorescent Luminaire If the lamp is responsible for the color of light and brightness, the luminaire (the one unit system of lighting) is responsible for holding, protecting, electrifying, and controlling the output of the lamp. The luminaire influences how light is distributed on room surfaces, work surfaces, tasks, and people. Luminaires are often developed to be used or'a specific category of functions, and also for appearances, since luminaires can be very noticeable and become a significant part of the overall look of a room. The luminaire description given on the brochure will usually consist of the nominal dimension, mounting or type, and shielding media. Luminaires for fluorescent lamps are installedans(1)ceiling-mounted :recessed, surface-mounted, I0 I\) loy0\ a. Baffle b. Multi Cells of Louver I: 1 I. l l i In] W >0" fi c. Straight or Parabolic Louver d. Shielding Angle Figure 3. Baffle and Louver Shielding Source: Murdoch, 1985 23 cans .ocaugona no “oouaom .co«ueoo~ owzdouooeo .oeuosouad aeuuuuoosu ou one aue> neoqum .ueuwecfiasd oooAQEoo uoc .xqco nqocod .vx.~ now noowud uoz .. DEOOH ueqaean uou nosed: on add-so: and: my> ..ue>o one .oox.ow. naoou eouod uou ceasefiuno auflaflnononm uuoLEoo Hoanfl> mmu . nmuo calm male ownm~ manna nwinn avian carom use: oduqeaaum uoaauuwo uceoaaucaua ue>aoa oaueeum uceosaoe-ua ue>soa done! onus: ue>soa anon: anon neuau-uom uo>soa owqonouam Haeu Hanan ue>soq owaon-uom aaou deed .. La. uuou «acqus ovinu nvinn mvinn main. onion melon china ochioo ue>ao4 ensu ~ooox xuec uo>=oa undonuuaa Esau -u§m ue>soa ensu Hope: moan: ue>soq odomeqm ucoozqncoue neaauuwo ucoosfincous nouaucdom uo>=oa ewaoneuom Adou dooo neon ufiuosnwum p.NucoLufiuum av ow nnnmn no on om-oe nmiom a ominm nonzuuwa acoosancouk uo>zoq cannodm ozonedncouh acoq caucEnfium nouwuoaom no>zoq onsu «ado: pawn: uo>zoq @930 dead: xuco uo>soq oflaonouom dado doom uo>aoq odqonouom quu AHQEm ‘ I I'll“ . . Aau>. accuses Auan> .czozn nowunfiuouoouono on» now uncuo undue-once cu no can coon on: eesaoo seem .ouoewxoudda oouooflncou on oaaozn can unouauonuacne aunt Eouu can.» coon o>oz no~ao~m -< .Uuo .cofiuznwuundo ucmwa .ONMn nuance .ueton campus .eu-Ao oeuueuuou .nucOlduunoeu euou Hooo~ .auAAADeun acuoo .>u-unecoo~u .ocwuen oudu condos“ uo penis: a an oenuuun: ozoae coauouecancoo nozuo .ocuoueuzn euqecwadq ocwquAOn cg nuuo ocean couooqncou coouo once oo.;u oz. o.n zoaom muouuoua ucoomousoau .v x .~ “mofidxa no“ oflumwuouomumzu Lo :Omdnmdeou .manma ocflenmnnm .v manna 24 or suspended, (2)Wall-mounted, and (3)Floor—mounted luminaires: light columns. Typically ceiling—mounted fixture sizes are 1 ft x 1 ft , 1 ft x 4 ft, 2 ft x 2 ft, 2 ft x 4 ft, or 4 ft x 4 ft. The character of fluorescent luminaires is affected by the shielding media. Luminaires can be designed to provide a variety of desired cut-off angles to reduce glare or to get better VCP by using a proper shielding media} and design. The photometry or optical performance of a luminaire is important to the success of a lighting system. Photometric information from manufacturers' data is useful in the development of the lighting design.for a project. In general, each type of luminaire has a specific photometry. The same fluorescent lamps placed in a*mariety of luminaires (fixtures) will give different light distributions. On the other hand, the same type of luminaire will give a different candlepower distribution when fitted with a different type of fluorescent lamp. A detail discussion of candlepower distribution was provided by Sorcar (1982). The luminous intensity is plotted at each angle on the polar coordinate. This represents the candlepower curve. In plotting the candlepower distribution, the luminaire is assumed to be placed at the center of the imaginary sphere in polar coordinate (Helms et a1., 1991). Spacing to Mounting Height ratios (S/MH) are also important data and are frequently used features of the 25 photometric report. As the luminaire spacing increases, the uniformity of light level in a space will drop. Uniformity of a lighting level depends on the luminaire spacings and the distance from the walls. The maximum allowable distance will vary with mounting height variance above the work plane. Each luminaire, depending on its type of beam.spread, has a:maximum S/MH ratio, which, when multiplied by the mounting height from work level (room cavity), determines the spacing limitation between luminaires. A detail discussion of spacing to mounting height ratio was provided by Helms and Belcher (1991). 2.1.5. Electrical Control Selective dimming and switching systems can help minimize energy consumption in unused spaces or in spaces where the intensity or pattern of use varies. Several methods of electrical control can be applied: (1)The connection of small groups of individual luminaires to manual switches allows unused luminaries to be de—energized at the occupant's discretion, (2)Timed controls can be used to adjust the lighting of spaces with predictable traffic patterns, or (3)Motion-detection.switchingcxnibe‘usedtx>activate lighting of spaces with continuously variable traffic patterns (Nuckolls, 1983). 2.1.6. Quantity of Light The Quantity’ of light implies the amount of light required to perform a visual task. The amount of available 26 light depends on the lighting system's lumen output and how much light is actually received by the workplane, called illuminance (DiLouie, 1994). Illuminance level (n: light level is the amount of light impacting the workplane and is measured in footcandles or lux with a light meter. The 1981 Application Volume of the IES Lighting Handbook introduced the method of determining the recommended illuminance value, E for various tasks. IES adopted a r! procedure that established a range of three illuminance values for nine task categories. The choice of one of the three illuminance values is based.cniaa set of weighting factors. The E value ranges will be referred to as: (1)Lower value, (2)Middle value, and (3)Upper value. The illuminance selection procedure requires knowledge of the: (1)Type of task, (2)Age of the worker, (3)Importance of speed/accuracy, and (4)Reflectance of room.surfaces or task background. The method lists 9 illuminance categories, designated "A" though "I" covering illuminance levels form 2 to 2000 footcandles (20 to 20,000 lux). Categories A though C - where no task activity occurs or general lighting is used throughout a space. Categories D through F - where activities involve. a visual‘task Categories G though I - suggested. ea combination of 27 general anui supplementary lighting on the task. Appendix B shows the complete procedure to define the illuminance level. For categories A through C, two factors must be considered in determining the weighting factor: worker's age and room surface reflectance, which is the weighted average reflectance value. Helms and Belcher (1991) stated weighted average reflectance(WAR) is WAR: (CR X A(ceiling) ) + (M? x A(walls) ) +(F'R x A(floor)) A(ceiling)+A(walls)+A(floor) where: CR ceiling reflectance WR wall reflectance FR = floor reflectance A = area For categories D through I, three factors must be considered in determining the weighting factor: worker's age, importance of speed/accuracy and reflectance of the task background. 1 Procedure for determining illuminance: 1. Determine the category from table of recommended illuminance values (see Appendix B). 2. Determine the weighting factor by algebraically adding weighting factors (accounting for signs). 28 a. For Categories A through C, (1) If the weighting factor 5 -2, use " lower value". (2) If the weighting factor 3 +2, use "upper value". (3) If the weighting factor is from +1 to -1, use " middle value". b. For Categories D through I, (1) If the weighting factor 5 -2, use "lower value". (2) If the weighting factor 3 +2, use "upper value". (3) If the weighting factor is from +1 to -1, use "middle value". There are four basic design techniques for the determination of quantity of illuminance: 1. 2. Inverse square method (ISM method) Angular coordinate or Direct Illuminance Component (DIC method) Flat rectangular source method Zonal cavity method 2.1.6.1. Inverse Square Method The inverse square method (ISM) could be used in many situations to calculate the direct component of illuminance at a point and is illustrated in Figure 4. One restriction on 29 using this method is that the light source must be far enough away that it approximates a point source. In cases where this condition is not met, such as a very large source (a long fluorescent lamp), or a calculation point close to an area source, the inverse square method cannot be IMKKL This method does not take into account the light from any other source or reflected light. QUghtsource W h \x l \ ta I \TE I \ g ._.__.__ ____-:L r Figure 4. Inverse Square Method The light ray arrives at the point of calculation on a horizontal surface, at an angle 0 or 0 from vertical (Figure 4). The illuminance for a tilted plane or a plane perpendicular to line of light can also be determined. Referring to IE8 Lighting Handbook (1984), the equations are: Eh = I 00339 122 where Eh = Illuminance at horizontal workplane in 30 footcandles I = Luminance intensity of light source in candelas d = Diagonal distance Ibetween time light source and the point of calculation h = Vertical distance (height) between the light source and the point of calculation r = Horizontal distance between the light source and the point of calculation The candle power of the source is at some specific time. .The candlepower should be multiplied by an appropriate light loss factor. Light loss factor is a product of all considered factors that contribute to a lighting system's depreciated light output over a period of time including dirt and lamp lumen depreciation. 2.2.6.2. Direct Illuminance Component (DIC) Method The DIC method (IES, 1984; Helms and.Belcher, 1991) is an additional procedure for determining the direct component of illuminance at a point. It is most applicable to continuous rows of fluorescent luminaires, although it may also be used with.individual luminaires that are separated“ 'This procedure considers a flat luminous strip located in a plane that is parallel to the plane in which the calculation point lies. Figure 5 shows the geometry for the DIC method. The governing equation for E is Helm and Belcher (1991) evaluated this equation with the 31 E’ = LZZW m dy following result: where: LZZW x2+zz hl h2 atan hl 1 atan h2 1 hl ) (.x2+zz)2 (.x2+zz)2 .x2+zz+h12 i i 2(x2+22) 2 2(x2+22) 2 Illuminance Luminous intensity Vertical distance between the light source to the point of calculation Width of the light source Horizontal distance between the light source to the point of calculation Length of the light source The distance between the projection point of calculation to the light source and to the one edge of the light source. the distance between the projection point of calculation to the light source and to the other edge of the light source. 32 Figure 5. Geometry of DIC. Source: Helms and Belcher,l991 2.2.6.3. Flat Rectangular Source Method Many large sources in office lighting are rectangular, such as windows. To develop expressions for these sources when the inverse square method and the direct illuminance component method can not be applied, a flat rectangular source method can be used and is illustrated in Figure 6. The integral equation for a vertical workplane or parallel workplane (Ell) to light source (Figure 6), based on TBS Lighting Handbook (1984) is: E” = [VIII LDZdwdh " o o (D2+w2+h2)2 33 where: Ell = Illuminance at Paralel workplane L = Luminous intensity H = Height of source h = Partial of H W = Width of source Partial of W W Helms and Belcher (1991) solved this equation which obtained: 'EH =-' L H xarcsi W ——“L-—xarcsi h 2 W W W m For a horizontal workplane or perpendicular workplane (E|) (Figure 6), the equation is: 'E'=.[i[h Lthwdh ' o o (Di-’+wZ+hz)2 Helms and Belcher (1991) also solved this equation and yield: W E: =%(atan-f)' ((fih arcsin( W)» The maintained illuminance can be found by multiplying the illuminance with an appropriate light loss factor. 34 :1\ -—-—-—4\}\ \1“ 6» Pe icular plane h \\ . H \X ,. j/ffi> Parallel plane Horizonta / d reference Ii Figure 6. Flat Rectangular Source Source: Helm and Belcher, 1991 2.1.6.4. Zonal Cavity Method The zonal cavity method is used for calculating an average illumination level at the work surface when an even distribution is required through the space. This method is very suitable for an open office space, which has the possibility of relocating work surfaces. Light levels at a specific work surface will remain the same and not are a function of its location. In using the zonal cavity method, a room.ie; divided into three spatial areas or "Cavities" (Figure 7). The ceiling cavity (CC) exists if there is space between the bottom of the luminaires and the ceiling. The room cavity (RC) is the space between the bottom of the luminaires and the top of the principal work surface. The 35 floor cavity (FC) is the space between the floor and the top of the principal work surface. Each cavity has a specific effective reflectance with respect to the work plane and the other cavities. Figure 7. Zonal Cavity Source: IES Lighting, 1984 The calculation procedure of zonal cavity method: A. Determine cavity ratio B. Determine the effective cavity reflectance C Determine the coefficient of utilization D. Determine light loss factor E . Determine the number of luminaire A. Determine cavity ratio When the cavity sizes and finishes have been established, numerical relationships for each cavity are calculated; these are called room cavity ratios (RCR). 36 RCR=5 1””) LXW where h = the height of the room or space L = room length W = room width The ceiling cavity ratio (CCR) is determined using the following formula: h CCR==RCR;xlh“: IC where hCC is the height of the ceiling cavity and hrc is the height of the room cavity. The floor cavity ratio (FCR) is determined using the same formula but substituting hfc (height of floor cavity) for the hcc(height of ceiling cavity). hfc h [C FCR = RCR x B. Determine the effective cavity reflectance Charts are available for determining this data in the IES Lighting Handbook chapter 9. Effective cavity reflectances must be determined since the size of the room and amount of vertical wall surface determine the amount of light reflected in the space. Recommended surface reflectances for office space are: 37 pceiling 80 % or more pwall 4O % - 7O % pflOOI 20 % ‘ 4O % The governing equation fer tin; effective cavity reflectance is: 2143 _ _ Ab __ Papvf( A (1 f) f]+PBf2+PwZ(1 f)2 Peff“ AB 2 AB 11’qu (1‘f) ‘Pw l—ZTH—f) I N where peff Effective cavity reflectance AB, AW = Areas of the cavity' base and ‘walls, respectively. 9B! PW: Reflectance of cavity base and walls, respectively. f = Form factor between the cavity opening and the cavity base; where 2 2 05 . f=—3L{ln[(lfx )(1+y )] +Y(1+x2)“9tan‘ nxy +x(1+y2)1/2t 1+x2+y2 1 y (1+x2)1/2 where x: Cavi ty Length CavitymDepth and 38 ==Cavity'Width CavitynDepth Y' C. Determine the Coefficient of Utilization (CU) The zonal cavity method requires a knowledge of the Coefficient of Utilization is (IES Lighting Handbook): __ 2 - 5p1C1C3(1-DG)¢D 02C2C30U Psca (C1IC2) Down CU“ "l‘ + _ G(1'Pi) (1‘93)Co (1'92) (1'93)Co (1‘93)Co 1'93 where p1, p2, and 93 are the reflectance of the walls, floor, and ceiling, respectively. C1, C2, and C3 are the ratio of flux transfer in the workplane from the walls, ceiling, and floor, and are defined by: _ (1’91) (1‘f2213lG 2 - 591(1'f22-o3) +Gf2~3 (1'91) 1 = (1‘92)(1+f213) C 2 1+p2f213 = (1'93) (1+fz«3) C3 1+Pafz~3 C0 = C1 + C2 + C3 where: G = The room cavity ratio 39 f243= form factor f2_.3=0 . 026 +0 , 503expl‘0-027ORCR) +0 _ 470exp(—O.119RCR) RCR is the room cavity ratio (from step A) DG is the direct ratio calculated using 9 _ 1 DG-W E (KGNwN) T n=1 where 0T is the total lamp lumens 0D is the fractional downward flux from 10 1 “’0‘? 2 “’N T N-l where <1?N=thI(cose1 -cos02) I = Mid-zone intensity N = Zone _ -Amm5 Karexp‘ ’ KGN is the zonal multiplier, which is the percentage of flux contained in each zone on the workplane. A and B are zonal multiplier equations from the IRS Lighting Handbook. The fractional downward flux is 0D and the fractional 4O upward flux is 0U. These come from: _ 1 wb-Ti; glow. and 18 1 ¢'=-—- ‘0 U ¢T N=10 N CU can be define by using the table published by the luminaire manufacturer for this purpose, or the IES Lighting Handbook if a manufacturer's table is not available. D. Determine the light loss factors (LLF) The LLF is the depreciation of light quantity over time. This factor is obtained by multiplying the LLD (Lamp Lumen Depreciation) factor supplied by the lamp manufacturer and the LDD (Luminaire Dirt Depreciation) factor. The LDD is determined by the physical construction of the luminaire, the degree of dirt contamination in the space, and the frequency of cleaning the luminaire. The equation of light loss factor is: LLF = Nonrecoverable x recoverable factor or LLF = (LAT x W}: BF x LSD) x (LDD x RSDD xLLD xLBO) 41 where LAT = Luminaire ambient temperature VV = Voltage variation BF = Ballast factor LSD = Luminaire surface depreciation LDD = Luminaire dirt depreciation RSDD = Room surface dirt depreciation LLD = Lamp lumen depreciation LBO = Lamp burn out The detailed explanation and value of each factor can.be found in the IES Lighting Handbook (1984). In practice, LLF is defined by the multiple of LDD and LLD. E. Determine the number of luminaires required in the given space to pmovide the recommended illuminance. The IES Lighting handbook (1984) equation is: .EJtA rlqujtlllierU where N = the number of luminaires E = the illuminance n = the number of lamps per luminaire L = the number of lumens produced per lamp LLF = the combined light loss factors. CU = the coefficient of utilization A = the area of the working plane (or floor) that will be illuminated by the luminaires. Once this information is known, placement of the luminaires 42 can be worked out. It is important that the S/MH (space mounting height) ratio be considered.in working out the final layout. Computer program developed for entire lighting design in this literature review such as inverse square method, direct illuminance component method, flat rectangular method and zonal cavity method. 2.1.7. Qualityof Light(Qpen Plan Office Space) Within the lighting literature, quality has been discussed in numerous ways. For example, it has been described as light meeting biological, psychological, and aesthetic needs in contrast to quantity'which fulfills functional needs. Stein and Raynolds (1992) define lighting quality to include all factors in a lighting installation not directly concerned with quantity. Specific items referred. to are luminance ratios, diffusion, uniformity, chromaticity, uncomfortable brightness ratios, and the general. notion of visual discomfort. Nuckolls (1983) has suggested that good (high quality) lighting is realized. when the ‘mood created is consistent with the function of each space, when the lighting provides spatial clarity, and when it promotes productivity. Over the past decade, more office space has been designed as the open plan office space due to rising costs and more teamwork within corporations. In the open plan office, the "flow of production and communication" is more interactive and organizationable. From account handling to order 43 processing, from estimating to scheduling, time movements of the activities can be shortened. The purpose of the open plan office is to support the overall corporate activities in an efficient manner. Typically, the work performed in the office is repetitive and continuous task such as reading, writing, telephone work, data entry'at a‘VDT (Visual Display Terminal), typing, faxing, and copying; ‘VDT is the priority"when designing the lighting system in the office space. IES mentions that one must assume that VDTs will be used in every office space. The geometry of VDT viewing, vflfixfli has several variables including screen height and angle, position of the operator, and location of the VDT (which may be changeable), is factored into the lighting—design for visual comfort and good visibility. 2.2.7.1. Glare "Too much light" becomes unwanted brightness, known as glare. Glare is a major problem to visual performance and can result in eye discomfort and eye fatigue. Helms and Belcher (1991) identify two types of glare: (1)Direct glare which. occurs when brightness directly from the lamps falls in the field of view, and (2)Indirect glare which occurs when brightness from the luminaires comes to the eyes indirectly. There are two forms of indirect glare: reflected glare and veiling reflections. Reflected glare occurs when the image of the light source is reflected from a glossy working surface such as a polished desk, magazine, or VDT screen. Reflected 44 glare can be just as horrible in a VDT screen if light colored support columns are reflected in the screen; or if people in white shirts stand or walk behind the person viewing the screen. Veiling reflections can occur when the angles of incidence for light on the horizontal work surface are within the observer's viewing zone or task zone. Three zones are usually considered in terms of contrast relationships in lighting quality. The first zone refers to the task itself. A task is anything that is within the primary focus of the eye. The second zone is the surfaces immediately surrounding the task. The third zone is the general surrounding area. For example, when reading a book at a table, the book is zone one, the table top becomes zone two, and the room's walls and floor comprise zone three. The contrast comparisons are important between zones one and two and between zones one and three. It is unusual practice to directly compare the relationships between two and three. These comparisons are luminance ratios. When there is a large change in lighting levels between zones, eye fatigue result from eye adaptation . . In terms of office space containing'VDTs, the IES , Examine need for "Investment Determine whether investment worth reducing time lsitworthwh'lle? ““ ‘ ‘ tnvestlgeb job that mm Iognest time on shifted CP Examine need for Imestment approval ‘ Possibletoredlce V V Y mum I Reducingtimeimpossible Figure 8. Evaluation Procedure to Shorten a Project Schedule Source: Mizuno, 1979. 63 The purpose of forecasting is to give some idea to the decision maker about the trend or prediction of the case, especially if planning can not be done because of lack of data/information. Brondon and More (1983) used the DHSS (Department of Health and Social Security) formula for forecasting the progress curve or S curve. That formula is: Y = s [X+CX2-CX-%((6X3-9X2+3X)] where Y = cumulative timely valuation X = time in which expenditure Y occur divided by the contract period S = contract sum C & K constants depending on contract value. 2.3.2. Decision Analysis of Lighting system Using an economic analysis, either simple payback or life cycle analysis, several cost alternatives for the lighting system can be produced for comparisons. The selection of a lighting system should not be made on the lowest cost because a lighting system should provide quality light for tasks being performed. A decision analysis can be used to select the type of lighting systenh A model for decision analysis is (Markland et a1., 1987) 64 4 P(Ai) = (S'IAi) where P(A = The total value of lighting system evaluation A1 = The alternative of lighting system Sj = The needs of open plan office space, such as performance, comfort, ambiance, and cost effectiveness Philips lighting developed the maximum value of each lighting system's need in open plan offices (Column 2-Table 6). .Assume the ranges of values is in Column 3-Table 6. More detail about the application of this model is given with the case study projects. 65 Table 7. The Range of Forecast Evaluation based on the Value of Needs in Open Plan Office Space I Description of Need Max Value Range Performance 5 5 — above or on the min light level 2 — below the min light level Comfort 3 3 - CRI : 90 - 100 2 — CRI : 80 - 90 l - CRI : 70 - 60 I O - CRI : 50 - 60 Ambience 1 l — above or on i 35000K V o - below 3500 0K Cost Effectiveness 5 5 - the lowest cost 1 - the highest cost 3. COMPUTER PROGRAM 3.1. MODELLING PROCESS In developing a computer program, one needs to understand the tasks that are to be solved as well as how a computer works, what its limitations are, and how problems should be structured for the computer. Figure 9 shows the process (QuickBasic, Microsoft., 1991). Start - Start the computer Understand the task - Refer to the previous explanation Design the program - Apply the logic thinking of this thesis Write the program - Use QuickBasic computer language Test for errors - Refer to the actions that determine whether a program runs correctly. Debugging - i the subsequent activity of finding and removing the errors. One objective of this study was to write a computer progranlwhich.combines lighting design, economic analysis, and management decisions (Figure 10). The general. principles involved in developing a computer program.can be summarized as follows (Brandon and Moore, 1983): 1. Develop subprograms consisting of several modules. 66 67 Modules within the system should be accessible to other related modules of the subprogram. 2. Every subprogram should.be debugged.before it integrated with the other subprograms using main menu. 3. Data within the data base should be properly structured and addressed in a uniform manner for ease of access by any subprogram. 4. The operation of the system should.be such that users can quickly and efficiently access and operate any part. 5. The system should.be able to be expanded when required to encompass new data. It is necessary in many'programs to actually validate the model used (particularly if it differs manual techniques) and to test it before its implementation into the project. Many programs have failed, not because they are ipoor at calculations or the model is inadequate, but because they are not suited to project practice. The test for errors in the computer programs developed for this study focused on comparison between the design obtained IES tables and the values calculated using the computer program. 68 START WAN.) Tl-ETPS( Fngea Renegamirgpooess WWW 1991 69 .me 1 E5 _ n3wI 1229.50“ szFzOo _ bZEn. _ _ 3mao m . wszDOm om._<2( .500 w40>0 mm... m_m>._._._._><0 4m 02:10.... w 70 The general principles involved in developing a computer program can be summarized as follows (Brandon and Moore, 1983): 1. Develop subprograms consisting of several modules. Modules within the system should be accessible to other related modules of the subprogram. 2. Every subprogram should.be debugged before it integrated with the other subprograms using main menu. 3. Data within the data base should be properly structured and addressed in a uniform manner for ease of access by any subprogram. 4. The operation of the system should.be such that users can quickly and efficiently access and operate any part. 5. The system should.be able to be expanded when required to encompass new data. It is necessary'in.many programs to actually validate the model used (particularly if it differs manual techniques) and to test it before its implementation into the project. Many programs have failed, not because 'they are poor at calculations or the model is inadequate, but because they are not suited to project practice. The test for errors in the computer programs developed for this study focused on comparison between the design obtained IES tables and the values calculated using the computer program. 71 Each category in Figure 10 can be explained as follows : 3.1.1. Lighting Design In many developing countries, the availability of data for lighting system designs is not sufficient for obtaining a valid calculation. Many luminaire manufacturers provide brochures with limited.information. The available data.have to be evaluated. in order to get the essential values such as the coefficient of utilization. The tabulated data which is available in many handbooks often is not usable because of a different approach. for determining lighting factors. Therefore, the computer program.should calculate these factors using the appropriate formulas. A.good starting place in lighting design is to define the source of the artificial light. The lighting source can be considered to be a point, a line, or an area. There are four methods of lighting design analysis. The equation for each method were given in chapter 2. 1. Inverse Square Method The Point of interest (pivot point) is evaluated by a lighting source as a point. 2. Angular Coordinate-DIC Method The point of interest (pivot point) is evaluated by treating the lighting source as a line. 3. Flat Rectangular Source Method The point of interest (pivot point) is evaluated by considering the lighting source as an area. 72 4. Zonal Cavity Method) The zonal cavity method treats the lighting source as a point, a line or an area with the concern being to produce an even lighting distribution on the work plane. This method is detailed in the IES Lighting Handbook. 3.1.2. Economic Analysis Economic analysis of a lighting system in this model enables the users to analyze a number economical option for lighting systems with economical options. After evaluating the selected lighting design, the next step is to conduct the economic analysis. There are two options in this analysis: first, a simple pay back analysis gives an idea of the break even point of the investment of the new lighting system compared to the existing systems. Second, the full economic analysis (life cycle) considers depreciation, escalation, and discount rate for economic analysis (Chapter 2). 3.1.3. Management In this portion, the program.addresses the progress curve or S-curve projection. The purpose of using this curve is to givean idea of how well the progress of the project matches the schedule. The model used to predict the 8 curve is same as the S curve model discussed in Chapter 2..A.QuickBasic program was written based on the information given by Brandon and More (1983). 4. CASE STUDIES 4.1 Case 1. Office Space This case study is a redesign of the lighting in an existing office space that has adequate light but with glare making visual tasks difficult. After a survey, it was found that the office has 2'x4‘ fluorescent troffers using prismatic lenses. There were 44 fixtures producing 75 footcandles. Each fixtures contained four, 40-watt cool white fluorescent lamps. There were workstations with 65" panels in most of the office area which was 2542 ft2. A study of the office area started with a measurement of the existing illuminance. The average illuminance was 75 fc. Using the IES recommendations and the procedure discussed in Chapter 2, it was determined that 75 fc was enough for the lighting level in the office. After the recommendation of lighting level was determined, several lighting design options were evaluated using the' computer program created in for this study. This study used lighting option : — Fixtures from Metalux-Cooper Lighting (see reference) Lamps from GE Lighting (see reference) Ballast from GE Lighting (see reference) The lighting system data and results are summarized: 1. Table 7 which is based on the value needs in the open plan office space (see Table 6 in chapter 2) and simple pay back analysis shows that alternative two is the best alternative. Alternative two consist of: 73 74 Fixture: 2PZGAX-34OSB6H (see reference Cooper Lighting) Lamp : F32T8/SP35 (see reference GE Lighting) Ballast: Electronic Rapid Start (see reference GE Lighting) 2. Table 8, which is a comparison between simple payback and life cycle analysis, shows that alternative one has the lowest average annual cost of life cycle analysis. Alternative one consist of: Fixture: 2P2GAX/34OS36H (see reference Cooper Lighting) Lamp : F40T8/SP35 (see reference GE Lighting) Ballast: Hi efficiency (see reference GE Lighting) The best alternative in this case study is alternative two, because of electronic ballast. Since the purpose of the study to provide~a good quality of lighting system, electronic ballast is more preferable (see ballast subdivision.in chapter 2) 75 Pvép Neg. wmép xiv VNN pmé «Na cad Ffin mud sfldw mwéfl oudn cod? far adsoo vndflflz Nwdmfio cognac Nvdmfiv ooéuhp mafiam FCONPF mméeow Fmdaow Nb nod 506 had 590 qu 8.0 and mad and and use .33. 285m ”.53 Remake“. ”83 gamma fleas“. tam 28m esteem ”3.8 552261 ”2.5 .883-5~-x 05 co oommav 83w 850 ”v 88 co c2335 .o 23... 76 Table 9. Comparison between Simple Payback Analysis and Life Cycle Cost of Case 1: Office Space NooI _f Simplgl'iaypacernalysls Lcc Alter- DESCRIPTION Power Installation Replacement Simple Average native Saving($) (3) petLamp($) Payback annualoost (Salmon) Period (Yr) 1 Fixture: 2P26AXI340836H 1888.21 4488.42 13.1 2.23 3983.93 Lamp: F40T8ISP35 Ballast Hi efficiency 2 Fodure:2P26AX/340$36H 1841.88 8087.89 18.08 3.11 4281.03 Lamp: F32T8/SP35 Ballast Electronic Repld span 3 Fixture: 2P26AX-2U6844H 1178.11 8759.92 29.75 8.84 8388.82 . Lamp: F4OWIUOIWM Ballast Electronic Rapid sun 4 Fixture: 2PAGAX-2U1-5/8855I 995.33 10358.54 24.15 9.38 7189.51 IammFMWWWMNM Ballast Electronic Rapid Start 5 Fixture: 2P26AX-44OS48H 1721.88 8074.2 10.24 3.29 4481.24 Lamp: F32T8ISP35 Ballast Electronic Rapid Start 77 4.2 Case 2. The Taubman Company The president of the Taubman Company requested a review of the lighting for on the third floor of the West wing of the building cdiices, on 200 East Long Lake Rd,in Bloomfield Hills, Michigan. The office plan is attached. .The president stated that his current office space has plenty of light but that he is getting complaints about glare on the computer screens. He also stated that the present fluorescent lighting makes people look pale. During a visit, it was found that the office has 2'x4' fluorescent troffers with prismatic lenses. There were 330 fixtures in the third floor west wing of the building area 21049 ft2 producing 100 footcandles. Each fixture contained four, 40-watt cool white fluorescent lamps. There were workstations with 65" panels in two-thirds of the open area- which contained. The analysis of this problem Istarted with the measurement of the existing illuminance which was 100 fc. After doing some research based on IES recommendations, and following the procedure discussed.in.Chapter 2. It was decided that 75 fc was more than enough for the office space. After the .recommended.of the lighting level was determined, several lighting design options were evaluated using the computer program. This study used lighting option : - Fixtures from Metalux-Cooper Lighting (see reference) - Lamps from GE Lighting (see reference) 78 - Ballast from GE Lighting (see reference) The lighting system data and results of case 2 are summarized: 1. Evaluation of Table 9, which is based on the value needs in the open plan office space and simple pay back analysis, shoWs that alternative five is the best. Alternative 5 consist of: Fixture: 2P2GAX-44OS46H (see reference Cooper Lighting) Lamp : F32T8/SP35(See reference GE Lighting) Ballast: Electronic Rapid Start (See reference GE lighting) 2. Table 10, which is a comparison between simple payback and life cycle analysis, shows that alternative five has the lowest average annual cost of life cycle analysis. The best alternative in this case study is alternative five. 79 tam 38m $885 833 88352125 5.: Se . m 2.4. 8.8. .85 8.089 8a and 3 zoemoevx CC noted guinea-3 828 885 85 Sages 5%.: E 39:8 .32 _see 88 E .8280 Based is.» Essa-.8: 85.38. 83a sdaez “1.... no 6:anme as? [IE-.6 8828 real: 3.8%.... .8 cameo 5 oz 80me 850 :86 :80 5 woos: .6 83.9, 85 co 388 23:30 5898. of. no. 88 Lo coamagm .9 838. 80 Table 11. Comparison between Simple Payback Analysis and Life Cycle Cost of Case 2: The Taubman Company No 01 Simple Payback Analysis LCC Alter- DESCRIPTION Power Installation Replacement Simple Average native Saving (5) (8) Lamp (5) Payback annual GRMMEBSOI%M«HYO can 1 Fixture: 2PZGAXI340$36H 14146.56 33498.15 98.26 2.23 26325.84 Lamp: F4078ISP35 Ballast. Hi efficiency 2 Fixture: 2P26AXI340 836 H 13981.44 44813.62 133.1 3.05 25778.04 ummemnaSPms Ballast: Electronic Rapid Start 3 Future: 2P26AX-2U6844H 8835.84 65699.42 223.1 6.84 41618.84 Lamp: F40WIU6IWM Ballast: Electronic Rapid Start 4 Fixture: 2PAGAX—2U1-5/8855I 10301.18 59922.2 139.73 5.37 35167.91 Lamp: F4OBXISP35 Ballast Electronic Rapid Start 5 Fixture: 2P26AX-440846H 13893.89 41102.1 138.53 2.79 25196.49 Lamp: F32T8/SP35 Ballast Electronic Rapid Start 81 4.3 Examples of Computer output 4.3.1. Inverse Square Method The Inverse Square Method of_ calculating illuminance does not account for light reflected from walls and ceilings, and is based on the assumption that the luminaries is relatively small. It is generally used as a hand calculated technique to evaluate accent lighting or the light falling on a task. Calculations were done for the open office space shown in Figure 11. The computer output is given in Table 11. Figure 11. Example of Inverse Square Method 82 Table 12. Calculated Values for The Inverse Square Method Inverse Square Method CASE 3 OPEN OFFICE SPACE DATA VALUES S o u r c e = 9450.00 cd H e i g h t = 10.00 ft Horizontal = 10.00 ft RESULT VALUES Illuminance = 33.41 fc GENERATE TABLE Start Height 7.00 ft Start Distance 8.00 ft | HI 8 | 9 | 10 | Illuminance 9450 cd 7 48.81 52.13 55.01 55.1 44.6 36.4 8 45.00 48.37 51.34 52.2 43.3 36.0 9 41.63 45.00 48.01 48.7 41.2 34.9 10 38.66 41.99 45.00 45.0 38.8 33.4 83 4.3.2. Direct Illuminance Component A row of three 2 x 4 ft, fluorescent luminaries, which . has a luminance of 200 cd/ftz, is mounted 10 ft above the work plane, and the distance to the point of calculation is 5 ft as shown in Figure 12. The computer output is given in Table 12. Figure 12. Example of Direct Illuminance Component 84 Table 13. Calculated Values for The Direct Illuminance Component Method CASE 4 RENOVATION DATA VALUES Luminance = 200.00 cd/ft2 H e i g h t = 10.00 ft Distance = 5.00 ft W i d t h = 2.00 ft Pivot length1= 4.00 ft Pivot 1ength2= 8.00 ft RESULT VALUES Illuminance = 27.35 fc TABLE I 3 I 4 I 5 I uminance 200 cd 23.20 29.74 35.54 50.9 41.9 33.6 20.56 26.57 32.01 44.9 38.4 31.9 18.43 23.96 29.05 39.6 34.7 29.7 16.70 21.80 26.57 34.9 31.2 27.4 85 4.3.3 Flat Rectangular Source Method The illuminance produced by’ many large rectangular sources in architectural lighting is important. The computer program evaluated the illuminance using Flat Rectangular Source Method such as 6 ft. x 6 ft. windows, at the point of calculation P on a 6 ft. line perpendicular to one corner of the source, or leEi 6 ft. plane parallel to the source as shown in Figure 13. The calculation values are given in Table 13. .“: ‘ 5- \ """4‘ \L \‘x c whiter plane h ' “ \~- il=Gfl \~ >x /T>‘5 Parallel plane Figure 13. Example of Flat Rectangular Source Hmem // d =68 nbmmnr 86 Table 14. Calculated Values for The Flat Rectangular Source - Parallel CASE 5 DATA VALUES Luminance = 100.00cd/ft Source Height= 6.00 ft Source Width = 6.00 ft Pivot Point = 6.00 ft RESULT VALUES Illuminance = 22.20 to TABLE Start Height 3.00 ft Start Distance 4.00 ft Start Width 3.00 ft IHI 4| 5| 6| Illuminance 100 cd/m2,width= 6 ft 3 53.13 59.04 63.43 26.7 20.9 16.6 4 45.00 51.34 56.31 29.3 23.9 19.6 5 38.66 45.00 50.19 29.9 25.4 21.4 6 33.69 39.81 45.00 29.4 25.7 22.2 87 4.3.4. S Curve, Renovation Lighting System Project Jack Up, a contractor prepares a forecasting of his expenditure for a lighting system project. The contract sum is $ 300,000 and the contract length is 10 weeks. The computer program given assistance with his forecasting using the Department Health and Social Security expenditure method for forecasting. A computer output of the results are given in Figure 14. Contract Sun =$ 300000.00 Contract Length = 10 weeks CASE 6. FORECASTING LIGHTING SYSTEM PROJECT Forecast Difference 1 --* 19431 2 ..... * 48308 3 ......... * 83970 4 .............. * 123754 5 ................... * 165000 5 ....................... * 205045 7 ............................ * 241229 8 ............................... * 270891 9 ................................. * 291368 10 ---------------------------------- * 300000 Figure 14. Example of S Curve 5. SUMMARY The national Energy Policy Act (NEPA) of 1992 mandated energy efficiencyu In the section related to lighting design, the minimum.efficiency for selected electric lamps is defined, forces architects and designers to lower the energy consumption while delivering high quality lighting to an office. This will be accomplished using new innovative lamps, luminaires, controls, and design techniques that-are now available. Quality lighting not only determines "how well" or "how poorly" the workers see, but also how well they perform visual tasks. Light quality includes factors of uniformity and glare, which can change significantly within a room. Uniformity is affected by the light distribution form luminaires and the amount of space between the luminaires. In order to avoid uneven lighting levels, the space-mounting height ratio from the manufacturer's test data should be followed. Investment decisions on lighting projects are base on a variety of economic analyses. In this study discussed a simple payback analysis and a life cycle cost analysis were discussed. 2% simple payback analysis considers the lumens life, and lamp cost. A.Basic:measure of lighting value was developed using the idea of cost per unit of light delivered. This method has been labeled the "cost of light" by GE Lighting. The "cost of light" was also evaluated using life cycle analysis. the 88 89 reasons for this analysis are: 1. The lowest initial or first cost may appear the most efficient option in the short run, but over a long-time period it may not be the most cost effective option. Life cycle cost analysis is broadly applicable. It can be applied to many different facility decisions, such as whether to accept or reject a lighting system option or what is the most cost-effective system. A benefit of using life cycle cost analysis as a decision aid is that you must make an explicit estimate of the future. Life cycle cost analysis like any procedure has its limits. It only can be used to compare functionally comparable projects. llzdoes address qualitative factors that can affect decisions. It is not applicable to all aspect of uncertainty and risk that are associated with decisions concerning the future. However, there are other decision aids that supplement and support life cycle analysis. They address qualitative factors, uncertainty and risk. A computer program, written using the QuickBasic language, was developed. This software incorporated, calculations for lighting design using the equations given in the lighting literature with the economic options of the simple payback method, life cycle cost analysis, planning and forecasting. 90 The development of the software was the primary part of this study. The availability of data for lighting system design in Indonesia is not sufficient for obtaining good results. Many luminaire manufactures provide brochures with limited information. The available data is basic data and calculations are needed to obtain the design values such as the coefficient of utilization. The tabulated data available in some handbooks often con not be used-because the data for some of the parameters is not available. The software developed for this study incorporated the basic data and calculates several of the parameters provided by the companies that manufacture lighting fixtures in the United States but are not provided by similar companies in Indonesia. The individual components of the lighting calculations, such as the inverse square method and direct illuminance component method, were check against values given in tables. Sample outputs for these individual components are presented in the thesis. The analysis of an open space lighting system were done by hand and using the software to verify that the software performed the complete set of calculations correctly. Two different open space office lighting system were analyzed. Five different design were proposed and analyzed for each. The lighting system selected by the weighting method that incorporated the lighting quality and the economic analysis seemed to be a reasonable selection in each case. The analysis of an open space lighting system indicated 91 that a triphoshor lamp such as T8/SP35 and an electronic ballast were the best selection. The effect of the longer life time for an electronic ballast was significant. 6. RECOMMENDATIONS The computer software should be used to solve 10 to 20 more problems in order to validate its accuracy, to evaluate the user interfaces and determine if any other lighting calculations should be incorporated into the software. Extend the computer software to include graphic layouts of the office space. the calculated values given by the computer software should be validated with experimental data. Further study on the optimal lighting system components under different project conditions is recommended. 92 Alternative Candela (cd) Candle power (cp) Candle power Distribution Curve Coefficient of Utilization (CU) Color Rendering Index Color Temperature Cost effective 93 GHJDSSEECY The different choices, propositions or methods by which objectives may be attained. The international unit (SI) of lumious intensity. The term. has evolved form considering 21 standard. candle. Some time the term "Candlepower" is used to describe the relative intensity of source (see "Lumen"). See "Candela". A. graphic presentation of the distribution of light intensity. A percent of initial lamp lumens that reaches the work plane as determined by surface reflectances, room shape (RCR) and fixture efficiency. The method that indicates how colors will look under a given source. A color rendering index (CRI) number is assigned to a light source based on its ability to make pigments look as they’ would under certain test sources when compared to other sources having the same color temperature. Apparent color temperature (or correlated color temperature) of a light source indicates its degree of warmth or coolness with the highter number being cool. Estimated benefits (savings) from an energy conservation investment project are equal to or exceed the costs of the investment, where both are assessed over the life of the project. Depreciation Discount rate Economic life Efficacy Electromagnetic spectrum Equivalent uniform annual cost Footcandle Footlambert 94 Depreciation is the allocation of the original cost of a facility or equipment to those time periods in which the asset is used. A rate used to relate present and future dollars. This is expressed as a percentage used to reduce the value of future dollars in relation to present dollars to account for the time value of money. It reflects the fact that dollars spent or received in the future are worth less than dollars spent or received in the present. The discount rate may be the interest rate or the desired rate of return. The economic life is defined as that period over which an investment is considered to 1x2 the lowest cost alternative for satisfying a particular need. See "Lumens per watt" An orderly arrangement of radiant energy by wavelength or frequency. In the visible spectrum 380 nanometers (violet) and 780 nanometer (red). The total of all costs for a given decision or alternative, expressed as a uniform annual equivalent over the years in the analysis life cycle. The unit of illuminance equal to 1 lumen uniformly incident upon an area of 1 square foot; also equal to the illuminance at a point- 1 foot distant from a 1 candela source. Light striking a surface. The unit of luminance or brightness equal to 1 lumen uniformly reflected or emitted by an area of 1 square foot. Visual impression. Future worth (Value) Initial capital investment cost Interest rate Glare Illuminance (E) Life cycle costing Light loss factor (LLF) Lumen Luminaire efficiency Lumen per watt 95 The future value of a present amount, given the time value of money. Costs associated vdiji the initial planning, design and construction of a facility. The interest rate represents the annual time value of money and is referred to as the discount rate. Visual discomfort caused by excessive brightness; can be direct or indirect. The quantity of light (footcandles, lux) at a point on a surface. Life cycle costing is a method of expenditure evaluation which recognizes the sum total of all costs associated with the expenditure during the time it is in use. The product of all considered factors that contribute t1) a lighting system's depreciated light output over a period of time including dirt and lamp lumen depreciation. The international unit of luminous flux or quantity of light. If a uniform point source of 1 candela is at the center of a sphere of 1 foot radius which has an opening of q‘ square foot area at its surface, the quantity of light that passes through is called a lumen. The ratio of lumens emitted by a luminaire to those emitted by the lamp or lamps used. A ratio expressing the luminous efficacy of a light source. Light out divided by power watt. Luminance (L) Lux Mounting height Nanometer Payback period Present value Reflectance Room cavity ratio (RCR) Spacing to mounting height ratio Time value of money 96 Practically, the brightness of an object: that which the eye perceives. Luminance of a surface is equal to: illuminance multiple by reflectance (see footlambert) ' The SI (international system) unit of illumination: one lumen uniformly distributed over an area of one square meter. Distance from the bottom of the fixture to either the floor or workplane, depending on usage. A unit of wavelength equal to 10‘9 meter The payback period is the length of time necessary to recover the initial investment of a project. Present value is the concept that a sum of money invested today will earn interest. It is based on the premise that a dollar today is worth more than a dollar to be received in the future by the amount of interest it earns. The ratio of light reflected from a surface to that incident upon it. Takes into account length and width of room and height from the fixtures to the work plane. Ratio of fixture spacing to mounting height above the work plane. Sometimes called spacing criterion. The time value of money is the difference between the value of a dollar today and its value at some future point in time if invested at a stated rate of interest. Ultraviolet radiation Veiling reflections Visual comfort probability Visual task Work plane 97 For practical purposes, any radiant energy within the range of 100-380 nanometers. Some wavelengths (180-220) produce ozone: Some (220-300) bactericdal; and (280-320) erythemal (reddens human skin); and others (320- 400) cause secondary luminance (blacklight). Effective reduction i11 contrst between task and its background caused by the reflection of light rays. Sometimes called reflected glare. VCP is a ratio of a lighting system expressed as a percent of people who when viewing from a specific location and in a specific direction find the system acceptable. The objects and details that must be seen to perform an activity The plane at which work is done and at which illumination is specified and measured. Unless otherwise indicated, this is assumed to be a horizontal plane 30 inches above the floor having the same area as the floor. APPENDIX A 98 APPENDIX A fc.—(8 Subga <3th % _§_ + é g3!§8£o§3=8052§.§383§m58m Juno: 4