Lighting maintenance

Environmental ProtectionAgency

Air and Radiation 6202JEPA 430-B-95-009January 1995

LIGHTING

MAINTENANCEProper lighting system maintenance is essential to highquality, efficient lighting. Systematic lightingmanagement methods and services from lightingspecialists can help organize the process and assurecontinued high performance of any lighting system.CONTENTSACTION CHECKLIST.......................................1INTRODUCTION..............................................1LIGHT LOSS FACTORS...................................1MAINTENANCEPLANNING.........................................................4GETTING HELP................................................7EXAMPLE.........................................................7extremely adaptive to gradually changing lightingconditions, most occupants do not notice the gradualdecline in light levels. Eventually, however, the

reduction will affect the appearance of the space andthe productivity and safety of the occupants.

In the past, lighting designers have dealt with this

problem by increasing the number of fixtures or lampsto compensate for the future light loss. While this

simplifies maintenance, it is not an acceptable solutiondue to the added initial equipment cost, energy cost,and energy-related pollution.

ACTION CHECKLIST Group relamp to reduce lumen depreciation and

maintenance costs. Clean fixtures at the time of relamping, more often

in dirty locations. Write a lighting maintenance policy. Design your lighting upgrade projects to

incorporate effective maintenance. Get help when needed from the following

resources:

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lighting management companiesconsultantsdistributorsmanufacturers

LIGHT LOSS FACTORS

Three factors cause light loss.󰀪lamp and ballast failure󰀪lamp lumen depreciation󰀪luminaire dirt depreciation

Light loss gradually decreases system efficiency overtime. In combination, these factors commonly reducelight output by 20-60%. No corresponding energy

reduction is associated with light loss, except with lampand ballast failure.

INTRODUCTION

Lighting maintenance is more than simply replacinglamps and ballasts when they fail. Facility managerstoday must manage their lighting resources (i.e.,

fixtures, lamp/ballast inventory, labor, energy) to sustainthe quality of a lighting system.

The light output of a luminaire decreases with age anduse, yet the energy input remains unchanged. (SeeExhibit 1 on the next page.) Because the human eye is

Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

EXHIBIT 1

LOST EFFICIENCY OVER TIME

Energy InputEnergy Input/Light OutputTypical Lamp LifeIncandescentHalogenFluorescentSodiumMetal HalideMercury1-2,000 hrs2-3,000 hrs12-20,000 hrs12-24,000+ hrs8-20,000 hrs20-24,000+ hrsBallast FailuresBallasts last much longer than lamps. The operatingtemperature of the ballast primarily determines ballastlife. But operating temperature varies with the type ofballast, the heat retention characteristics of the

luminaire enclosure, and the fixture mounting method.This variation makes ballast life more difficult to predictthan lamp life. Electronic ballasts can be expected tooperate longer than magnetic ballasts because

electronic ballasts produce less heat. While there areno reliable long-term test data available, ballast life isgenerally described by ballast manufacturers as shownin the box below.

Similar to lamps, the ballast failure rate can be

expected to be small in the first 70% of average life andincrease beyond that point. By monitoring ballastfailures in a facility, it may be possible to predict thevalue of the potential maintenance savings achievableby replacing ballasts before failure.

Time

Lamp and Ballast Failures

When lamps and ballasts fail, they no longer providelight for the space. Often, failed lamps and ballastsremain in fixtures for months.

Lamp FailuresLamp manufacturers list the “average rated life” fortheir products. The average rated life is the number ofoperating hours after which one-half of the lamps canbe expected to have failed. A few lamps may fail soonafter installation, and the rate of failure will increase asthe time in use increases (see Exhibit 2). Severalfactors affect lamp life.

Typical Ballast LifeMagneticEfficient MagneticCathode CutoutElectronic10 -14 yrs12 -15 yrs15 -17 yrs15 - 20 yrs󰀪average operating time between starts󰀪type of ballast circuit󰀪improper installation

Based on the type of lamps in use and the operatingconditions, it is possible to predict lamp failure rateaccurately. Such predictions enable you to schedulethe replacement of all the lamps just before substantialfailures begin. This group replacement of lamps at70% of rated life will reduce the light loss caused bylamp failure and will reduce the time, effort, and

complaints associated with spot replacement of lamps.In addition, expired lamps left in the luminaire cancause ballasts to fail prematurely. The few lamps thatfail between group replacements can be tolerated orspot-replaced as needed.

EXHIBIT 2

LAMP FAILURE RATES

Percent Cumulative Failures100 80 60 40 20 0

Percent Rated LifeMetal Halide and

High Pressure Sodium

Fluorescent

Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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EXHIBIT 3

LAMP LUMEN DEPRECIATION

Source: US Department of Energy

PercentRelativeLightOutput

Hours of Operation in Thousands

EXHIBIT 4

PROCEDURES FOR DETERMINING LUMINAIRE

MAINTENANCE CATEGORIES

Source: IESNA

III Maint.CategoryTop EnclosureNoneq Noneq Transparent with 15% or more uplight through aperturesq Opaque with 15% or more uplight through aperturesq Transparent with less than 15% upward light through aperturesq Translucent with less than 15% upward light through aperturesq Opaque with less than 15% uplight through aperturesq Transparent unaperturedq Translucent unaperturedq Opaque unaperturedq Transparent unaperturedq Translucent unaperturedq Opaque unaperturedq Noneq Transparent unaperturedq Translucent unaperturedq Opaque unaperturedq Bottom EnclosureNoneq Noneq Louvers or bafflesq IIINoneq Louvers or bafflesq IVNoneq Louversq VTransparent unaperturedq Translucent unaperturedq VI Transparent unaperturedq Translucent unaperturedq Opaque unaperturedqLighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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Lamp Lumen Depreciation (LLD)

As a lamp ages (through use), the amount of light itproduces declines. This change is called lamp lumendepreciation (LLD) and is expressed as a percentage ofinitial lamp light output. Several factors can cause LLD,such as carbon deposits inside the bulb wall or

deterioration of the phosphor coating inside the bulb.Incandescent and high pressure sodium lamps haveminimal LLD (i.e., they maintain a high percentage oftheir initial output throughout their useful life).

Fluorescent, mercury and metal halide lamps, however,exhibit significant lumen depreciation (See Exhibit 3).To calculate average light levels, a lighting designerconsiders the light output of a lamp at the average agethe lamp is expected to reach in use. By replacinglamps earlier, it is possible to achieve the same lightlevels with fewer lamps and less energy.

The following Illuminating Engineering Society of NorthAmerica (IESNA) tables and graphs are used fordetermining LDD.

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Use Exhibit 4 to identify the luminaire category.

Use Exhibit 5 to identify the dirt condition for thespace.Use Exhibit 6 to estimate the luminaire dirt

depreciation factor once the luminaire category, dirtconditions, and cleaning cycle have been established.

MAINTENANCE PLANNING

Many maintenance managers are hesitant to replacelamps that are still operating. But group relamping andcleaning can be less expensive than sporadic spotmaintenance. Through strategic planning and

performance management of the overall lighting system,costs can be reduced and lighting quality improved.Group relamping is analogous to changing the spark

plugs in your car. All of the spark plugs are changed at thesame maintenance interval. This saves time and moneyand improves the overall efficiency of your car. As thespark plugs age, gas mileage of the car declines.Similarly with lighting, the efficiency and output of thesystem will decrease as lamps age. This change coulddecrease worker productivity. The most efficient

maintenance method is to group-replace your lamps, justas you would group-replace the spark plugs in your car.

Luminaire Dirt Depreciation (LDD)

Dust, smoke film, oil and dirt accumulate on the

reflective surfaces of fixtures, lenses and lamps. As aresult, less of the light produced by the lamps is

delivered into the room. This depreciation can be veryminor in closed fixtures located in clean rooms, but itcan be very severe in open fixtures in dirty

environments. Estimating the effect of dirt depreciationis important for determining fixture cleaning schedules.

EXHIBIT 5

FIVE DEGREES OF DIRT CONDITIONS

Source: IESNA

Very CleanGenerated DirtAmbient DirtRemoval orFiltrationAdhesionExamplesNoneNone (or noneenters area)ExcellentNoneHigh grade offices(not nearproduction),laboratories, cleanrooms CleanVery littleSome (almostnone enters)Better thanaverageSlight MediumNoticeable but notheavySome enters area DirtyAccumulates rapidlyLarge amountenters areaOnly fans orblowers if anyHigh — probablydue to oil,humidity, or staticHeat treating, highspeed printing,rubber processing Very DirtyConstantaccumulationAlmost noneexcludedNoneHighSimilar to Dirty butluminaires withinimmediate area ofcontaminationPoorer thanaverageEnough to bevisible after somemonthsOffices in olderMill offices, paperbuildings or nearprocessing, lightproduction, lightmachiningassembly,inspectionLighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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EXHIBIT 6

DIRT DEPRECIATION GRAPHS

Source: IESNA

Step 1: Define Existing Condition

Advantages of Group Relamping andCleaning555555Saves money, time, and energyImproves overall system efficiencyReduces maintenance time and costsTechnician does not have to wait for servicerequestsTechnician does not have to ‘search’ fora lamp and ladderTechnician does not have to travel to twoor more remote sites toreplace only a few lampsTechnician does not have to return the ladderand dispose of the lamps, one-by-oneEfficiently utilizes maintenance personnelReduces lamp and ballast inventoryReduces material costs through bulkpurchasing practicesProvides higher maintained light levelsPrevents unnecessary ballast degradationcaused by ballaststrying to start expired lampsThe first step in planning a lighting maintenance

strategy is to define the existing condition of the lightingsystems. You must evaluate the following.󰀮󰀮󰀮󰀮󰀮󰀮󰀮󰀮

type of lamps and ballasts in useaverage age of the lamps/ballaststotal annual hours of lighting operationproduct costs

spot replacement labor costsgroup replacement labor costsenergy costs

the rate of dirt accumulation

555555Step 2: Establish a RelampingInterval

You can identify an appropriate time to group relampthe lighting system. First, you must determine an

acceptable level of light loss and an acceptable numberof lamp failures (or spot replacements). Exhibit 2shows that after 70 percent of rated life, the mortalityrate of fluorescent lamps sharply increases. Therefore,group relamping traditionally occurs at 70 percent of thelamps’ rated life. For example, suppose a lamp is ratedat 20,000 hours and is operated 4,000 hrs per year.Then relamping should take place at 14,000 hours oflamp life, or at approximately three-year intervals.

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EXHIBIT 7CALCULATING MAINTAINED LIGHT LEVELfc = rated lumens x CU x BF x LSD x RSDD x LLD x LDD x LBOarea of room (ft2)CUBFLSDRSDDLLDLDDLBO=======coefficient of utilizationballast factorluminaire surface depreciationroom surface dirt depreciationlamp luminaire depreciationluminaire dirt depreciationlamp burnouts (%)manufacturing and other dirtyenvironments, RSDD can have asignificant effect and should notbe ignored. Refer to the 8thedition of the IES LightingHandbook for more informationon calculating RSDD.

Step 4: Develop aMaintenance Method

There are several factors to

consider when planning a lightingmaintenance strategy.

Step 3: Predict Light Loss Factor

Armed with the above information, it is possible toevaluate existing and future light loss. The mortality,lumen depreciation, and dirt depreciation curves areused to determine the maintained illumination, which isthe average illumination expected over time. An overalllight loss factor is applied to initial illumination value toobtain the maintained illumination value. The formulafor light loss factor (LLF) follows.LLF = LLD x LDD x LBO

Where,

LLD = Lamp lumen depreciationLDD = Luminaire dirt depreciationLBO = Lamp burnout, or lamp mortality rate

These are three of the recoverable components of lightloss that a good maintenance program can minimize.The equation for maintained illuminance on horizontalsurfaces, shows the significant impact these factorshave on light levels (see Exhibit 7). These factors aremultiplied, typically resulting in lumen output reductionsof over 40% in poorly maintained systems.

Although room surface dirt depreciation (RSDD) is arecoverable factor, it is often ignored in lighting

calculations and maintenance programs. Since mostoffices today are smoke-free, the RSDD is minimalrelative to the other light loss factors. However, in

󰀪Use existing staff, hire new staff, or use a

contractor.

󰀪Complete during regular hours, nights, weekends.󰀪Manage quality control.

󰀪Dispose of lamps and ballasts responsibly.󰀪Re-lamp building-wide or in stages.󰀪Establish product types.

󰀪Establish testing procedures for exit and

emergency lighting.

Step 5: Budget for Maintenance

Budgeting is the most difficult part of planning a

maintenance program. Spot maintenance of a lightingsystem can be sporadic on a daily basis, but the annualcost will be constant after the first few years. Strategicmaintenance, on the other hand, is easier to manage ona daily basis and may cost less overall, but the costfluctuates each year.

Suppose you want to maintain the fluorescent lightingon a spot basis in a facility that operates 4,000 hoursper year. This approach would require replacing about20% of the lamps every year. To maintain the samefacility on a group basis would require minimal

replacement for two years, and then 100% replacementevery third year.

Because budgets are often established a year in advance,it is necessary to predict relamp timing and budgetaccordingly. As an alternative, lighting maintenance

budgets can be leveled by completing an equal portion ofthe group maintenance each year. In the example above,for instance, completing a group relamp of 33% of thefacility each year will level the annual cost.

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Step 6: Write a LightingMaintenance Policy

For a lighting maintenance program to be most

effective, it needs to be carried out regularly over thelife of the lighting system. You can write a lighting

maintenance policy once you have completed a lightingmanagement analysis, developed a method, andestablished a budget. This will help in getting theprogram approved and will enable the plan to be

carried out by other personnel in the future or in otherfacilities. Include justification for the maintenance plan,so that future managers can understand the

importance of effective maintenance. Most important,it will assure a systematic continuation of the program.

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local factory representativesdistributorssoftware toolstraining programs

Lighting Management Companies

Lighting management companies (LMCs) are

maintenance or electrical contractors that specialize inlighting installation, upgrade, management, and

maintenance. Many offer a free or low cost service toidentify optimum lighting maintenance programs.Some LMCs may offer consulting services to helpdevelop in-house lighting management programs, butmost are interested in providing upgrade installationand maintenance contract services. Many of these areGreen Lights Lighting Management Company Allies.

Step 7: Implement the Strategy

A well-planned strategy can be easy to implement.Many companies use outside contractors to completemajor tasks and then use inside staff to provide spotmaintenance. Others contract with an outside lighting orelectrical company to completely manage the lighting.Similarly, an outside company can designate and train alighting management team within the company.Whichever method you select, strategic lighting willalso make lighting maintenance a predictable task andreduce unscheduled maintenance requirements.

EXAMPLE

The following example shows how strategically plannedlighting maintenance can reduce energy consumption,prevent pollution, and control costs. The assumptionsfor this example are as follows.

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GETTING HELP

As the demand for planned lighting maintenance hasincreased, so have the services offered by the lightingindustry. The following are some resources available tohelp analyze, plan and implement efficient lightingmaintenance.

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old office building25,000 square feet

250 luminaires (category V, CU = 0.70)4 F40T12/CW lamps per luminaire

no luminaire cleaning for the existing system20,000 hr lamp life4,000 hr/yr operation

Step 1: Calculating RelampingFrequency

The first step is to determine the average number oflamps replaced per year. This will depend on the typeof relamping practice chosen.

Lamp Manufacturers

Although strategic lighting management can save energyand labor costs, group maintenance will usually requirethe use of more lamps. As a result, lamp manufacturershave an interest in providing assistance in analyzinglighting management strategies. Most of this assistanceis valuable and reliable and offered free (or at low cost).Contact your lamp supplier or manufacturer for

information. Many manufacturers are also Green LightsManufacturer Allies. Assistance from lamp

manufacturers is available from several sources.

Average Annual Relamps for SpotRelampingThe average annual relamps for spot relamping iscalculated as follows.

Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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20,000 hrs life/4,000 hrs per yr = 5 year life1,000 lamps/5 years = 200 average annualrelampsGroup RelampingLLD for group relamping is the lumen depreciation atthe time of the group relamp. This is at 14,000 (20,000x 0.70) hours life for both the T8 and the T12 lamps.Referring to Exhibit 3, the lamp lumen depreciation at14,000 hours for the T8 is 0.93, and for the T12 is 0.78.

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Average Annual Relamps for GroupRelampingThe average annual relamps for group relamping iscalculated as follows.

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LBOSpot RelampingAfter 20,000 hours, half of the lamps will have failed.The LBO for spot relamping can vary significantly

depending on the promptness of the maintenance staff.For this example the LBO is 1.0 which assumes promptreplacement of failed lamps.

(20,000 hrs life)x(0.70 group relamping factor)/4,000 hrs per yr = 3.5 yearsuse 3 year relamping interval

1,000 lamps/3 years = 333 relamps per year(1,000 lamps)x(0.07 premature spot failures)/3 year interval = 23 spot failures per year333 + 23 = 356 average annual relampsq

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Group RelampingAccording to Exhibit 2, approximately seven percent ofthe lamps will fail at 70 percent of their rated life.

However, again an LBO factor of 1.0 is used. Note thespot replacement costs of the 7% premature failures isaccounted for in the financial analysis of Exhibit 9.

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Step 2: Determining Light LossFactors

The next step is determining the light loss factors —LLD and LDD. A value of 1.0 will be used for LBO,which assumes that lamps that burn out will be spot-replaced without a long delay. Exhibit 8 summarizesthe light loss factors used in this example. Following isthe rationale for the use of the various factors. Notethat group versus spot relamping practices will affectthese factors significantly.

LDDSpot RelampingFixture cleaning is not typically included in spot relampingpractices. This example assumes that the fixtures will becleaned at least once during their 20 year expected life.Therefore, a ten year cleaning cycle is used. To find theLDD for this extended period, the luminaire dirt

depreciation equation is used. For simplicity reasons, theequation is not presented in this text but can be found inthe 1993 IES Lighting Handbook. For this example avalue of 0.65 was calculated.

LLDSpot RelampingLLD for spot relamping is the average value of thelumen depreciation. The value for this example ischosen from the graph in Exhibit 3 at 40% rated life(or 8,000 hours). The T12 graph indicates that theLLD value is 0.82 at 8,000 hours.

Group RelampingRefer to the graphs in Exhibit 6 to determine the LDD,based on the following assumptions.

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a three-year cleaning cycleluminaire type Va clean environment

Results

Group relamping and fixture cleaning can reduce

maintenance and energy costs (see Exhibit 9). The T8system has increased light levels while reducing energyconsumption and pollution.

A further measure to reduce energy consumption wouldbe to delamp the T8 option from four to three lamps perfixture. This would produce approximately 44

maintained footcandles, and decrease energy costs byan additional 10 percent. There would also be

additional material and labor savings due to the fewernumber of lamps.

The LDD is 0.80 for both the T12 and T8 systems.

Step 3: Calculating Light Levels

The following light level calculations are based on theequation in Exhibit 7 and the factors for LLD, LDD, andLBO are tabulated in Exhibit 8. These factors weredetermined in the previous step.

T12 Spot Relamping󰀭

3,050 lumens per lamp x 250 luminaires x 4 lampsper luminaire x 0.70 CU x 0.53 LLF/25,000 SF = 45 fc󰀭

5A T8 and T12 system with grouprelamping and cleaning provides 18 to 33percent more light than the T12 basecase of spot relamping only.5The T8 system reduces energyconsumption by 35 percent ascompared to both T12 systems.5The T8 system reduces O&M costs by31 percent as compared to the T12group relamping case.5Group relamping and fixture cleaningsave $811 annually in labor costs.T12 Group Relamping3,050 lumens per lamp x 250 luminaires x 4 lamps󰀭per luminaire x 0.70 CU x 0.62 LLF/25,000 SF = 53 fc

T8 Group Relamping2,900 lumens per lamp x 250 luminaires x 4 lampsper luminaire x 0.70 CU x 0.74 LLF/25,000 SF = 60 fc

EXHIBIT 8

LIGHT LOSS FACTORS

T12SpotLLDLBOLDDTotal LLF*0.821.000.650.53T12Group0.781.000.800.62T8Group0.931.000.800.74* LLF = LLD x LDD x LBO

Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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EXHIBIT 9

AVERAGE ANNUAL O&M COSTS

T12 SpotRelamping

T12 GroupRelamping----$534$34----T8 GroupRelamping--------$712$46

Lamp CostsT12 Lamps (spot) 200 @ $1.50/lamp

T12 Lamps (group) 356 lamps @ $1.50/lamp

+ spot relamping of premature failures, 23 @$1.50T8 Lamp (group) 356 lamps @ $2.00/lamp

+ spot relamping of premature failures, 23 @$2.00

$300--------

Labor CostsT12 Relamp Labor (spot) 200 @ $7.50/lamp

T12 Relamp Labor (group) 356 lamps @ $0.75/lamp + spot relamping of premature failures, 23 @$7.50T8 Relamp Labor (group) 356 lamps @ $0.75/lamp + spot relamping of premature failures, 23 @$7.50

$1500------------$267$172------------$267$172

Fixture Cleaning CostsFixture Cleaning (group) 333 @ $0.75/fix.

----$250

$250

Energy CostsT12 Energy, 192W/fix. @$.07/kWh (assumes LBO=1)T8 Energy, 124W/fix. @$.07/kWh (assumes LBO=1)TOTAL ANNUAL O&M COSTANNUAL O&M SAVINGS

$13,440----$15,240BASE

$13,440----$14,697$543

----$8,680$10,127$5,113

Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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NOTES:

Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995

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GREEN LIGHTS

A Bright Investment in the EnvironmentGreen Lights is an exciting and innovative programsponsored by the US Environmental Protection Agency(EPA) that encourages major US corporations andother organizations to install energy-efficient lightingtechnologies.

Organizations that make the commitment to GreenLights will profit by lowering their electricity bills,improving lighting quality, and increasing workerproductivity. They will also reduce the air pollutioncaused by electricity generation.

For more information contact the Green Lights programoffice.

Green Lights ProgramUS EPA

401 M Street, SW (6202J)Washington, DC 20460

Lighting Maintenance is one of a series of documentsknown collectively as the Lighting Upgrade Manual.Other documents in the Manual are Listed below.Lighting Upgrade ManualPLANNING

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Green Lights ProgramImplementation Planning GuidebookFinancial ConsiderationsLighting Waste DisposalProgress ReportingCommunicating Green Lights SuccessTECHNICAL

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Lighting FundamentalsLighting Upgrade TechnologiesLighting MaintenanceLighting EvaluationsThe Lighting SurveyGreen Lights Information Hotline¤

Fax:

(202) 775-6650(202) 775-6680

󰀪To order other documents orappendices in this series, contactthe Green Lights Hotline at (202)775-6650. Look in the monthlyGreen Lights Update newsletterfor announcements of newpublications.Lighting Maintenance q Lighting Upgrade Manual q EPA's Green Lights Program q January 1995