CHEN AND GUERDAN: RESOURCE BENEFITS OF RELIGHTING PROGRAM

Resource Benefits of Industrial Relighting ProgramKAO CHEN, SENIOR MEMBER, IEEE, AND EDWARD R. GUERDAN

Abstract-The industrial relighting program can provide us an excel-lent opportunity for energy conservation as well as cost reduction. Elec-tric energy saved from relighting with high pressure sodium lampsindirectly reduces oil consumption for power generation, which has afar-reaching significance on the national economy. The necessary stepsin making a relighting study and different approaches to a relightingprogram, are outlined, as are the evaluation of its impact on energyconservation and cost reduction; and some prospective ways of resolv-ing inherent problems with this type of lighting today.

INTRODUCTIONS INCE the recent energy crisis, the lighting industry has

been facing one of its toughest challenges to date. On onehand, lighting plays an important role in every walk of life andshould be allowed to perform its intended function-enhancingthe quality of our lives. On the other hand, the lighting industryhas been called upon to make a contribution to conservingenergy. Many energy-saving lighting ideas can be incorporatedinto a new building design. However, new lighting systems areusually being completed at a rather slow pace. Their impact onenergy conservation will be limited. The more effective way ofachieving energy savings is to apply high pressure sodium(HPS) lighting to existing industrial plants, i.e., to replaceexisting incandescent or mercury vapor, even fluorescentlighting with a properly chosen high pressure sodium lightsource. This is the so-called "industrial relighting program".

In the last three years, within our corporation alone morethan 30 000 luminaires of mercury vapor, incandescent orfluorescent have been replaced with high pressure sodium. Therelighting program has provided us an excellent opportunityfor energy conservation as well as cost reduction. This paperintends to outline the necessary steps in making a relightingstudy and different approaches to a relighting program; evaluateits impact on energy conservation and cost reduction; and alsoidentify some of the imperfections inherent with this type oflighting today and prospective ways of resolving them in thefuture.

STEPS IN MAKING A RELIGHTING STUDYIn making a relighting study, the most difficult and perhaps

the most controversial determination is the approach onewould take to tackle the problems. Before one can proceed

Paper IUSD 7843, approved by the Production and Application ofLight Committee of the IEEE Industry Applications Society, forpresentation at the 1978 Industry Applications Society Annual Meet-ing, Toronto, ON, Canada, October 1-5. Manuscript released for publi-cation January 8, 1979.

K. Chen is with the Westinghouse Electric Corporation, Bloomfield,NJ, 07003.

E. R. Guerdan is with the Westinghouse Electric Corporation, Pitts-burgh, PA.

with his study, he must first obtain a plot plan of the plantproperty, showing all buildings with structural dimensions, andlighting layout drawings and construction bills of material tohelp identify and confirm the number, type, and wattage of alllight sources. The next step is to identify and categorize bywattage and lamp type of each light source in all areas, workingwithin one defined area at a time. The survey can best be doneby an on-the-scene count, rather than from lighting layoutdrawings alone. Information on the efficacies of various lightsources should be assembled both for the types of lights usedin the plant and for other types that will be proposed. Data onlamp life of various light sources should be available from lampmanufacturers. Ballast losses should also be determined. Ifthey are not available, 10 percent of lamp watts can be used asan approximation. Tasks to be performed in each area shouldbe established so that appropriate lighting level can be deter-mined accordingly.

After all necessary data are gathered, they can then beplugged into various study forms designed for the purpose.Our Lighting and Lamp Divisions designed an Energy CostManagement Analyzer folder, which contains essential lampand fixture data and provides working spaces for the presentlighting system and the new energy saving lighting system, sideby side. Each contains items such as annual energy charges perfixture, annual lamp replacement cost per fixture, annualcleaning cost per fixture, etc. The total of these items is equalto annual operating cost for the present system or the proposedsystem. From the difference between the two systems, onewill be able to calculate return on investment (ROI).

There are many different forms which one can use to makea relighting study, however, we have found that none would bemore complete and thorough than the cost analysis formproposed by Illuminating Engineering Society (IES) andother lighting authoritative publications. It is, therefore,recommended that this form be used in making any relightingstudies. Fig. 1 shows a typical lighting cost analysis form.

In going through the form, one will soon be confrontedwith some puzzling questions as to the best criteria for con-ducting the study. In making a relighting study, the followingbasic guiding principles must be observed.

1) Fixture for Fixture Replacement: This pattern of re-lighting represents one of the simplest conditions. A typicalcase for such a system is to replace 1000-W mercury vaporlights with 400-W HPS on a one-for-one basis. Usually thespacing to mounting height ratio is suitable for the new lightsource. The existing wire sizes are usually adequate and con-nections can be easily made. The overall installation costs ofthe relighting program will be low, and the ROI will be about50 percent. The footcandle level will stay practically the same

0093-9994/79/0500-0331$00.75 ( 1979 IEEE

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Cost of lighting analysis for

Lghtrhg system number

-s 1. Type of lamp (il., merc., preheat fluor., slimline, etc.)

Q 2. Lamp description3. Type of luminaire

cz 5 4. Number of lamps per luminaire

5. Rated initial lamp lumens per luminaire

6. Lamp life

7. Watts per luminaire (including auxiliary)

, 8. Coefficient of utilizationla.S9. Maintenance factor

m 10. Number of luminaires11. Average footcandles maintained

12. Energy rate ($ per kwh)

13. Estimated burning hours per year

14. Net luminaire cost (each)

15. Net additional accessory cost per luminaire

8 16. Estimated wiring & installation cost per luminaire

X 17. Not inifial lamp cost each (list less---% + tax): 18. Net initial lamp cost per luminaire (4 x 17)

19. Total initial cost per luminaire (14 + 15 + 16 + 18)

20. Total initial cost (10 x 19)

-3,21. Initial cost per luminaire less lamps (14 + 15 + 16)

2 22. Total initial cost less lamps (10 x 21)

23. Annual fixed charges ( %- of 22)

24. Annual no. lamp replacements (4 x IO x 13 6)

25. Annual cost of replacement lamps (17 x 24)

26. Annual cost of replacement parts (starters, etc.)

., 27. Total annual maintenance material cost (25 + 26)

° 28. Estimated labor cost to replace one lamp

.c 29. Total labor cost to replace lamps (24 x 28)X 30. Estimated cleaning cost per luminaire

31. Number of cleanings per year

c 32. Annual -leaning cost (10 x 30 x 31)

33. Total annual maintenance labor cost (29 + 32)

34. Total annual maintenance cost (27 + 33)35. Annual energy cost (7 x 10 x 12 x 13 -- 1,000)36. Total annual operating cost (34 4- 35)

a 37. Total annual cost (23 - 36)

j 0 38. Relative annual cost- 39. Annual cost per footcarndle (37 -- 11)

± 40. Relative annual cost per lootcandleUsuily 15%, assuming tO year a..oritation with 5% allowance for taxes, insurance and interest.

Fig. 1. Lighting cost analysis form.

as before since 1000-W mercury vapor and 400-W HPS deliveralmost equal lumens. The energy savings realized in this pro-

gram amount to 60 percent of the original consumption. Fig. 2shows a typical relighting program of this category. On theleft, 178 1000-W mercury luminaires were used to light theplant, and on the right the same number of 400-W HPS new

luminaires are in place.2) Energy Savings plus Improvement of Lighting Quality:

In some cases the relighting program can result in not onlyenergy savings but also improved lighting quality, such as

increased illumination levels and greater visibility. Warehouseswhich were lighted with high wattage incandescents usuallyfall under this category. Due to higher efficacy of the HPS

Fig. 2. Mercury vapor versus HIS lighting.

light source and usually ample mounting height, the number ofnew fixtures which will deliver a desirable higher footcandlelevel can be reduced. Consequently this type of relighting pro-gram can result in energy savings as well as operating costsavings. In addition, improvements in lighting quality areachieved as a bonus.

3) Lumen for Lumen Replacement: Lumen output of one400-W HPS luminaire is approximately equal to that of two400-W mercury vapor, or two super-high output fluorescent orthree high-output fluorescent, or four slimline fluorescent, orsix 500-W incandescent units. These simple relationships canprovide us a convenient replacement scheme so long as thespacing to mounting height ratio of the new HPS luminairesremains satisfactory. The replacement scheme can result inreduction of luminaires required to deliver an equivalentlighting level to an existing system. Energy savings can bereadily achieved.

4) Unfavorable Conditions: Favorable situations may notalways exist. If the relighting program cannot achieve bothenergy savings and improvements in lighting quality, then afair standard must be set as a guideline for the program todetermine whether it can be justified. The fair standard wouldbe that the relighting program be judged on its capacity to givean equal illumination level and visibility as the existing system,yet it can result in considerable energy and cost savings. Inother words, any results from the relighting which surpass thisstandard should be considered as a bonus rather than pre-requisite to the program.

RELIGHTING PROGRAM

The initial program was launched about five years ago.Since that time, the existing lighting systems in the Westing-house plants have been or are being relighted with nearly25 000 high pressure sodium units. The annual reduction ofelectric energy consumption as the direct result of the programis estimated to be 50 million kWh. The attendant annualpower bill savings by the corporation easily exceeds 1.5 milliondollars. In addition, the improved maintenance factors of allnew lighting systems can further improve return on the invest-ment to such an extent that 30 percent is considered to be acommon occurrence.

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CHEN AND GUERDAN: RESOURCE BENEFITS OF RELIGHTING PROGRAM

TABLE I

SUMArT OF RIUGH2T PROGBMAnnual * Annual Anwus.oiergy Total ln1err Operating TearsProject Footcandles savings Initial Cost Cost toIdtification Old System New system Before After (IkWh) Investmt S vin Saving Pay off

A (US) 331 186400W. Hg 400W. HPS 30 45 410,000 $28,000. $12,000. $ 9,000. 3.2

B (UC) 1603 410P90 Fluor. 400W. HPS 70 80 909,000 $107,000. $21,000. $31,000. 3.45

C (BI) 407 407500W. Inc. 150W. HPS 15 40 820,100 $64,000. $19,500. $22,500. 2.84

D (BD) 162 81400W. Hg. 250W. HPS 110 45 321,200 $13,000. $ 6,000. $ 6,ooo. 2.2Twin

E (LR)Plant 643 343

P90 Fluor. 250W. BPS 29 45 186,600 $52,800. $ 6,900. $12,100. 4.36Old Warehouse 240 123

300W. Inc. 250W. BPS 6 15 220,200 $18,940. $ 8,130. $11,540. 1.64New Warehouse 312 158

P96T12/HO 250W. BPS 18 21 185,400 $24,330. $ 6,970. $ 8,670. 2.8

Overall $96,070. $22,000. $32,310. 2.97F (OB) 709 488

400W. Hg. 250W. BPS 45 75 1,136,600 $73,930. $30,780. $31,000. 2.38

* Asse annual burning hours = 6,500.

Years to Pay off = total initial investment/aimual operating cost saving.

Statistics ofRelighting ProgramReduction of energy usage and the related economics are

not the only benefits nor motivation to relight existing indus-trial plants. In Table I several projects are listed which demon-strate some additional benefits that can be realized by relightingthese plants with high pressure sodium light source.

A) The prime objective at the location was to improve thelighting level. By more judicious placement of luminaires tocircumvent the shading effect of tall machines and the con-veyor system, an improvement of lighting level and qualitywas achieved with a reduction of the total number of luminairesby nearly 50 percent, and the project showed a three-yearpayback.

B, E) The original operating costs of the lighting system atthe facility were becoming excessive. An antiquated fluorescentsystem presents a maintenance headache to local managementbecause ballasts and other parts for replacement are hard toobtain and costly.

At first glance, economic justification seemed hopelesssince the fluorescent fixtures were troffer wired and relightingwould require an almost new distribution system. However,comparison of actual system efficiencies and maintenancecosts showed that an fairly attractive payback overall could berealized.

C) In this particular plant, a major investment in revampingthe plant electric power capacity was being considered in orderto accommodate more equipment for manufacturing activities.Relighting the plant with high pressure sodium source coupledwith power factor correction resulted in a 25 percent decreasein total current loading. Lighting level in the plant increasedby almost three times, and the program still resulted in a very

attractive payback, not to mention the deferment of majorcapital investment to expand service capacity.

D) The visual task requirements at this facility have beenreduced; wherein originally 100-fc was required, now 50-fc isconsidered to be adequate. Turning off over one-half the lightscould achieve the same objective, however, the remaining systemwould result in poor quality of lighting and consume still moreenergy than the new HPS system. Replacing 400-W mercuryvapor with 250-W HPS resulted in more uniform lighting andyielded an attractive 2.2 year payback.

F) Similar to system D) except in this case replacing 400-Wmercury vapor with 250-W HPS resulted in a much higherlighting level and an attractive 2.38 year payback. It must benoted that 75 fc represents an average lighting level rather thana uniform level, since the project was divided into manufacturingareas and warehouses, two distinctly different tasks.

IDENTIFYING PROBLEMS AND POSSIBLE SOLUTIONSIn the past, many problems existed in applying high inten-

sity discharge light sources to industrial plants, mainly becauseof limited choice of luminaires, unsatisfactory mountingheights, inadequate color rendition, ballasts and starting circuitfailures, etc. This was especially true during early developmentstage of high pressure sodium lighting. The operating voltageof HPS increases with age over a wide range. Costly ballastcircuits are required to control the lamp watts, which relatesdirectly to light output. A special magnetic constant wattageballast that meets the lamp's changing voltage needs is nowavailable. In recent years, most of these problems havebeen overcome. However, in spite of the many significant

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improvements, glare and color rendition remain to be themajor concerns of the HPS lighting.

1) Color Rendition: HPS lamps have a spectral distributionricher in golden white than other types of lamps. There isa concern with the HPS larnps as to whether their colorrendition of safety colors will make them unsuitable forindustrial application. However, tests show there is little differ-ence in the ability of the human eye to identify safety colorsunder incandescent, metal halide, or high pressure sodiumlighting. The overall color rendering properties of HPS lightingis satisfactory. So any fuss about the color of these lights andpeople's negative reactions are mostly psychological ratherthan factual. In a very rare case, the yellow color may actuallycause difficulty in color distinction. If this happens, auxiliarylighting such as fluorescent or even incandescent should beused for supplementary tasks. Recently one lamp manufacturerhas announced that it has discovered a technique to enhancethe color rendition of HPS lamps, making them suitable for afar greater variety of lighting applications.

2) Glare: Due to the inherent nature of high intensity dis-charge (HID) light sources, regardless of the types of fixturesthere is a hot spot which can cause a glare sensation when oneviews from a specific distance. However, at a normal 30 inworking plane, one will not be bothered by the hot spot.Diffused HPS lamps can reduce glare, however, their lightoutput is somewhat lower. Nevertheless, they do offer a choicefor the industrial users should glare become a serious problem.

3) Mounting Height: In order to provide even distributionof illumination for an area, it is desirable not to exceed certainlimitations of "spacing to mounting height" ratio (S/MH). Thevalue of S/MH in lighting fixture manufacturers' catalogs is themaxirnum spacing that will result in relatively uniform light atthe work plane. In an attempt to use a minimum number ofunits, the designer may endeavor to use maximum spacingwith high wattage lamps. This can result in annoying glare andunsatisfactory results. A good rule of thumb is to maintain aspacing to mounting height ratio of 1.5:1 or less. The overlapof light from adjacent fixtures and lamp shielding should becarefully considered.

IMPACT OF RELIGHTING PROGRAM ON ENERGYCONSERVATION

According to the reliable statistics, lights consume about 4-5 percent of the total energy in this country. As a rule ofthumb,1 kW power savings in lighting can equate to 600 gallons ofoil per year. From the six projects listed in Table 1, a total of715 kW has been saved as the result of our relighting program.This can be translated into approximately 430 000 gallons ofoil savings per year.

On a corporate level, the relighting programs saved morethan 100 000 barrels of oil per year. The direct savings ofenergy from relighting program benefits the corporation. Theindirect savings in oil help to conserve resources. At the presentoil cost of $0.35 per gallon, it would mean an additional $1 .5million savings per year on the national level.

CONCLUSIONSOf the more than 70 quads of energy consumed in the

United States annually, 40 percent is used by industry. Obvi-ously then, any serious effort to conserve resources must havethe cooperation of industry-all industry.

Although lighting as a whole represents only 4-5 percent oftotal energy consumption, the amount of oil and or other fuelsused to generate electricity for supplying the lights is far fromnegligible. From the amount of oil saved by replacing less effi-cient light sources with 25 000 HPS lights within our corpora-tion alone, it becomes obvious that the impact of relightingthe entire industry would be tremendous indeed. It is theauthor's hope that this paper would inspire the industry whichhas not begun relighting program to start one soon so thatthey too can enjoy the energy and cost savings and make con-tributions toward conservation of world resources.

ACKNOWLEDGMENTThe authors wish to acknowledge many valuable suggestions

provided by Mr. George Main ofWestinghouse Lighting Division,Vicksburg, MS, in the preparation of this paper.

REFERENCES[1] "Energy efficient luminaires-relight for savings now," Modern

Plant Operation & Maintenance, FaUl 1975.[2] K. Chen, "Lighting esthetics with energy saving ideas," IEEE

Trans, Ind. App!., vol. IA-12, pp. 35-38, Jan.!Feb. 1976.[3] P. Hughes and J. F. McNelis, "Safety color perception under

H.I.D.lighting," PlantEng., Sept. 16, 1976.[4] J. P. Frier, "Spacing H.I.D. luminaires in manufacturing areas,"

Plant Eng., Aug. 5, 1976.[5] K. Chen, "The energy oriented economics of lighting systems,"

IEEE Trans. Ind. Appl., vol. IA-13, pp. 62-68, Jan./Feb. 1977.[6] Product News, LD&A, Dec. 1977.[7] J. F. Combs and R. D. Schultek, "Determining optimum spacing

of H.l.D. luminaires," Plant Eng., Feb. 16, 1978.[8] K. Chen, M. C. lJnglert, and R. L. Malafa, "Energy saving lighting

for industrial applications," IEEE Trans. Ind. AppL, vol. IA-14,July/Aug. 1978.

Kao Chen (M'51-SM'56), for a photograph and a biography, please seepage 220 of the March/April 1979 issue of this TRANSACTIONS.

Edward R. Guerdan received the degrees ofB.S.E.E. in 1961 and M.S.E.E. in 1965, bothfrom Carnegie Mellon University in Pittsburgh,PA.

From 1964 to 1969, he was employed bythe General Electric Company, Schenectady,NY, and was involved in the design and devel-opment of brushless excitation systems forlarge synchronous motors and generators. Hejoined Westinghouse Electric Corporation in1972 and spent six years as Consultant, Con-

struction Technology Group involved with corporate plant constructionand plant engineering operations. He is presently Senior Engineer in theEnergy Audits subsection of the Process Design Department at theR&D Center in Pittsburgh, PA, and is involved in energy conservationefforts throughout the corporation.

He is a Registered Professional Engineer in the States of New Yorkand Pennsylvania.

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