high intensity discharge luminaires...principle of electric discharge similar to fluorescent...

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JULY 2000

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HIGH INTENSITY DISCHARGELUMINAIRES

nnually, the US commercial and industrial sectors account

for close to one trillion kilowatt-hours (kWh) of electricity

use. Lighting in offices, hospitals or hotels,

hallways and lobbies, factories, large retail

stores, and warehouses, combined with outdoor

lighting, can account for 25 percent or more of

total electricity use by these two sectors, or about

$20 billion by one estimate.

While proper illumination isneeded in commercial andindustrial settings, the selection ofthe right lighting system can makea significant difference in energyconsumption. Energy savings of upto 50 percent or more are possiblein some cases. Less efficient indoorlighting sources often create heatas well as light, and can be aserious source of excess heat inbuildings. The additional coolingenergy required to counteract thiseffect increases a building’s totalenergy use. Thus, efficient lightingdesign not only reduces lightingenergy usage and cost, it can alsomake a difference in otheroperational areas as well. ThisReport is the first in a series ofthree that will focus oncommercial and businessapplications of energy-efficientindoor lighting.

Energy derived from fossil fuelsor other non-renewable energysources can seriously impact theenvironment—mining andexploration can damage fragile

Installing

the right

lighting system

can make a

significant

difference in

energy

consumption.

Energy savings

of 50% or more

are possible

in some cases.

carbondioxideandmethane,the twolargestcontributors toglobal climatechange. Inaddition togreenhousegases,electricgenerationis a majorsource ofsulfuroxides(SOx),

areas; theburning offossil fuelsreleases

2 Choose Green Report

The Choose Green Report is pub-lished for Green Seal EnvironmentalPartners. To become an Environ-mental Partner, or to receive a copyof this report, contact Green Seal at(202) 872-6400 x 21 or [email protected].

Green Seal President and CEO, ArthurB. Weissman

Editor, Mark Petruzzi

Contributor, My Ton

Design, Cutting Edge Graphics

Funding for this report was provided bya grant from the U.S. Dept. of Energy

Printed on Green Seal-certifiedMohawk Satin Cool White Recycledpaper, 30% postconsumer content

Copyright © 2000, Green Seal, Inc.www.greenseal.org

GREEN SEALEnvironmental Partner

the leading cause of acid rain, andnitrogen oxides (NOx), the leadingcause of urban air pollution.Although energy use is the mainenvironmental issue associatedwith lighting, another is the use ofnatural resources required tomanufacture fixtures and lamps.Commercial and industrial lampdisposal can be a problem, sincethey may contain high pressuregases or mercury vapor.

Efficient, well-designed indoorlighting provides safe, effective,working conditions, and results insignificant cost savings. It alsobenefits the environment throughreduced energy use and fewerresources needed to manufactureand dispose of lamps and theircomponents.

Commercial &Industrial LightingConsiderations

Because of their high efficiency,high intensity discharge lighting,or HID, should be considered inplace of incandescent or even

fluorescent lighting for certainindoor commercial and businessapplications.

HID systems are well suited formany indoor uses. The best HIDapplications are situations whereuniform levels of illumination arerequired for long periods, andwhere frequent on/off switching isnot required. HID sources can alsobe alternatives to incandescentand halogen in spot and accentlighting—unlike fluorescentsystems, they can give sparkle topolished surfaces and produceshadows for dramatic displayeffects in the retail environment.

This Report covers HID lampusage for commercial andindustrial applications collectivelyknown as “high-” and “low-bay”—where a high amount of light isneeded from a point source, orwhere uniform general lighting isneeded in higher-ceilinged areas(generally, 12 ft or more), andwhere long periods of illuminationwith little or no switching controlis the norm. Suitable applicationsof these fixtures can include—

■ atriums

■ some office spaces

■ hallways and lobbies,

■ factories,

■ loading areas

■ indoor parking areas

■ large retail areas, and

■ warehouses.

For these applications, HIDluminaires (or lighting fixtures)generally provide the greatestefficiency and ease ofmaintenance. Pricing for theseproducts can range from less than$100 per unit with lamp, to over$400, depending on options,ballast selection and quantity.

Generally, choosing luminairesfor the above applications involvesthe selection of the followingcomponents—lamp technology,ballast type, reflector type (to focusor direct light output), andhousing. Depending on lamp type,some type of shielding may also berequired. A luminaire can beselected component by component(lamp, ballast, reflector, andhousing), or as a prepackagedfixture for a specific application.

For most of the applicationscovered above, the selectionprocess is quite simple. Thesections below provide anoverview of HID lamp and ballasttechnologies, and suggest criteriafor the selection of environmentallyresponsible HID luminaires.

Overview of HIDLuminaire Selection

Available HID luminaires canhave lamps that range from as lowas 35 watts up to 1,000 or morewatts, with lamp lumen outputranging from 1400 to 140,000 ormore (see box on page 11 for anexplanation of lighting terms).Because of their high lumencapacity and efficiency, replacingincandescents and evenfluorescents with HID systems canprovide many advantages,including:

■ Reduced lighting energy use

■ Fewer fixtures and bulbs persquare foot

■ Less frequent bulb replacement

■ Better beam control overfluorescent systems (fordisplays, for example)

■ Highly efficient lamp and bulbpackages

■ Reduction of excess heat inbuildings

■ Wide variety of fixture outputavailable

Choose Green Report 3

HID LampTechnologies andCharacteristics

The term “HID” actually coversa large class of lighting products.There are three distinct HID lamptypes—mercury vapor (MV), metalhalide (MH), and high-pressuresodium (HPS) and low-pressuresodium (lighting experts considerlow-pressure sodium, or LPSlamps, to be in a category knownas “miscellaneous discharge”).

HID lamps all operate on aprinciple of electric dischargesimilar to fluorescent lamps—HIDlamps emit light when the gasescontained inside the envelope (orarc tube) are activated by anelectric current, provided by thelamp’s ballast. One key differencebetween HID and fluorescentlamps is that the pressure insideHID lamps is much higher. Eachtype of HID lamp has its ownadvantages and disadvantages,briefly outlined below.

■ Mercury Vapor—MV lampscame into widespread use in the1940s and 1950s in industrialapplications, replacingincandescent technology due totheir higher lumen output andlonger life. These characteristics,plus low initial cost and colorstability, remain mercury vaporlamps’ best features. However, MVlamps are much less efficient thanother lamps in the HID family,have poor color renderingcharacteristics, and can lose up to40 % of their light output overtheir rated life.

■ Metal Halide—MH lampswere designed to improve uponmercury vapor’s poor lumenmaintenance, color rendering, andrelatively low efficacy characteristics.MH lamps function very much likemercury vapor lamps, but theaddition of iodides of metals(halides), such as thallium, indium,

and sodium, in the envelopeproduces more and higher qualitylight than mercury vapor alone.However, MH lamps have theirown particular drawbacks,including high UV levels andsensitivity to low temperature.MH light output is also extremelysensitive to lamp position. Theycan also explode under certainconditions.

■ Sodium Lamps—Sodiumlamps work by using a highfrequency, high voltage pulse toionize xenon gas in an enclosedtube, which in turn vaporizes asodium-mercury amalgam. Thismixture is further excited by anelectric arc, producing light.Sodium lamp performance isdirectly related to the gas pressureinside the arc cylinder—highpressure sodium lamps havehigher color rendering indices anda wider output spectrum than thealmost monochromatic yellowcharacteristic of low pressuresodium lamps. Long life and high-efficiency are HPS lamps’ bestfeatures. HPS lamps with higherCRIs trade efficacy and economyfor better color rendering.

Of the three lamp types, metalhalide and high pressure sodiumsystems are very efficient andprovide more lumens per watt(and more light output per fixture)than incandescent and evenfluorescent systems; mercuryvapor is the oldest and leastefficient technology of the three.

In general, MH lamps offer thebest compromise between colorrendering and efficiency. Recenttechnological improvementsinclude the ceramic metal halidelamp (CMH). This technology,when widely available, can bringMH color rendering ability in linewith good fluorescent lamps. HPSlamps, on the other hand, offerextremely long life and very goodeconomy, and can be well suitedfor warehouses, loading areas, andother industrial uses.

Table 1 (above) provides acomparison of available efficacy(light output in lumens per inputWatt) ranges of different lamptechnologies.

APPROXIMATELAMP TECHNOLOGY EFFICACY RANGE (LPW)

Standard Incandescent 7 to 15Tungsten Halogen 15 to 25Mercury Vapor 25 to 55White Sodium 35 to 55Compact Fluorescent 25 to 75Full-size Fluorescent 65 to 95Metal Halide 45 to 95High Pressure Sodium 45 to 110Low Pressure Sodium 80 to 150

Note: While the calculated efficacy of an LPS lamp is high, it is affected by theway our eyes register its output spectrum. When LPS lumen output is correctedfor human eye perception, it can be less than the actual lamp lumen output.

TABLE 1


HID BallastsTo operate, HID lamps require a

ballast to control the current to thelamp electrodes, and to deliver thestarting or restarting voltage.There are three common HIDballast types in use – all aremagnetic, employing coils toregulate current, and vary incomplexity. They can also beheavy, and are often noisy whennot properly packaged.

The three ballast types are—

■ Reactor—these are simpleand small units consistingprimarily of an inductor coil. Theytend to be inexpensive. Reactorballast designs do not toleratevoltage variations well, and can bethe cause of lamp flickering.

■ High-reactanceAutotransformer—these aresimilar in design to reactorballasts, but with the addition ofcircuitry capable of boosting linevoltage to start lamps. They alsoare inexpensive.

■ Constant-wattageAutotransformer—the mostcommon ballast type in use. Theseregulate lamp power better thanother ballast designs, controllingflicker and eliminating shutoffsfrom line voltage variations. Theycan cost more than reactor orhigh-reactance ballasts.

Electronic ballasts are nowavailable for some lower wattage(from 150 W to 400 W) metalhalide and HPS lamps. They canbe more expensive, but offer betteroperating characteristics such asbetter color control and startingtime, smaller size, and light weightin return. Electronic ballasts donot offer HID lamps the sameperformance boost as electronically-ballasted fluorescent lamps.

The latest innovation in MHballast & lamp design is the pulse-start ballast. This design uses anigniter system in the ballastinstead of a starting probe. Pulsestart is available for a range oflamp wattage. As the nameimplies, the pulse-start designintroduces extremely high-voltagepulses to start the arc and ignitethe lamp. This new designimproves cold weather starts,efficiency, lumen and colormaintenance, and can shortenwarm-up and restrike time by upto 60%. The design is available inboth electronic and magneticballast technologies, and involvesreinforcing the lamps and ballaststo withstand extremely highvoltages (at higher cost).

Luminaire SelectionCriteria

As discussed, the most commoncommercial and industrialapplications of HID, where uniformlevels of illumination are requiredfor long periods of time, includesome open office spaces, atriums,hallways and lobbies, factories,large retail stores, andwarehouses.

These areas are collectivelyknown as “high-” and “low-bay”areas, and luminaires—lamp,ballast and reflector systems—designed for these areas areknown as such. Because of thenumber of products available, theselection process can be as

16" ReflectorMaximum height is24 1/2" [622mm]

21" ReflectorMaximum height is25 3/4" [654mm]

16" [406mm] or21" [533mm]

Ballastassemblyandfixturehousing

TYPICAL HIGH-BAY LUMINAIRE

Reflectorandlampassembly

Source: Cooper Lighting


straightforward as determining therequired light levels and typesbased on user needs, and thendetermining the lamp, fixture type,and number.

■ “High bay” luminaires areused in high-ceilinged areas (20 ftor more) that require uniformillumination at eye, desk, or shelflevel (for example—retail/superstores, warehouses, atriums,etc.). High bay luminaires are high

RECOMMENDED APPROXIMATE SUITABLELIGHT LEVELS COLOR RENDERING LAMP

TASKS (footcandles) (CRI) NEEDS TYPE

Assembly & 50 to 70 for Medium Work Medium (50+) to MH orPackaging 75 to 100 for Fine Work High (70+) MH Pulse start

Engineering & 70 to 125 High (70+) MH orDrafting MH Pulse start

Food Processing 50 to 75 Medium (50+) MH

Loading Dock/ 30 to 50 Low (


An important consideration forselecting HID luminaires iswhether the fixture will fulfillillumination needs. The luminaireshould provide both adequateillumination levels (brightness infootcandles) as well as colorquality (CRI) needed for theparticular application. Table 3(page 5) outlines some typical IES(Illuminating Engineering Society)light levels and approximate colorrendering index requirements forvarious tasks. Note that theselevels are suggested levels, andcan be met with a combination ofboth ambient (general) and tasklighting.

Because of the combinationspossible with the components,when evaluating fixtures andcomparing one against another, itis important that characteristicssuch as ballast factor, bulb andreflector design, placement andtype are the same across fixturesin order to make a validcomparison (and also light outputpattern in the case of some lamps).

Lamp photometric and othertesting data provided bymanufacturers offer valuableinformation about their products’efficiency and performance.Manufacturer data can also beused to determine luminaireefficiency, testing information, andeconomic factors. With fewexceptions, care should also betaken to ensure that both lampsand ballasts have matching ANSI(American National StandardsInstitute) designations to avoidpremature lamp failure andpossible explosion.

EnvironmentallyResponsibleLuminaire Selection

Green Seal has developed a listof criteria below to help you selectluminaires that have less overallimpact on our environment. Thesecriteria take into account the mostobvious resource reductionopportunity—energy efficiency (inthe forms of lamp and systemefficacy).

We also considered theperformance of the luminaire, interms of lamp longevity andmanufacturers’ warranty andfactors such as safety testing, sincethese affect how soon a replace-ment system is needed, andbecause longer lasting productscan reduce the volume of wasteentering the waste stream.

Finally, where information isavailable from manufacturers, weconsidered the environmentalimpacts of the luminaire—themetals, plastic and othercomponents used as well as theluminaire production method.

Lamp Color Rendering—Where accurate color perceptionis needed, or the area to beilluminated will involve highprecision work, such as retail orassembly work, a high colorrendering index (CRI) HID systemis required, and a suitable highCRI system such as metal halidemay be necessary. If the area to belit only requires some degree ofillumination (a stock or warehousearea, for example), color perceptionmay not be as critical, and an HPSsystem may be acceptable.

Lamp type selection—Ingeneral, MH lamps offer better CRIand in a wider range, but somemedium wattage, high CRI MH canhave lamp life of less than 10,000hours. HPS lamps offer higherefficiency and longer life, but HPS

lamps have lower CRI and exceptfor “white sodium” lamps, give outa pinkish light. In summary, MHlamps offer the best compromisebetween color rendering andefficiency for most indoorapplications.

Ballast type selection—Depending on applications andbudget, ballast selection involvesspecifying electronic or magneticballast, and the specific typewithin each category, discussedabove. For energy efficiency,choose ballasts with lower losses.

Reflector type selection—HIDluminaires come with variety ofreflector options. In general, theycan be open or enclosed, and aremade of transparent, opaque,reflective materials, or acombination.

■ Transparent and openreflectors allow some light to beemitted above the horizontal planeof the luminaire, allowing bothdirect and reflected illumination;

■ Opaque reflectors andenclosures are used to direct all ormost of the light downward

Luminaire efficiency data (not tobe confused with luminaireefficacy rating, or LER) measuresthe light output in the 0 to 90degree zone, or the quantity andpattern of light being directeddownward. (Note—Luminaires areoften grouped by their “upwardefficiency” which measures theamount of light a luminaire directsupward.)

Reflectors are used to focus ordiffuse light patterns. They areused to ensure even lightdistribution in high bay units, andalso to control glare, especially inlow bay units, for example.Enclosed luminaires have bafflesor shields, which enclose the lamp/reflector assembly opening, and


Green Seal’s Lighting GuidelinesFOR OPEN OFFICE, HALLWAYS, ATRIUMS, MEETING AREAS AND GENERAL LIGHTING

❑ Metal halide (MH) lamps with CRI of 60+ are suitable for most indoor general lighting tasks.❑ If low-bay luminaires with horizontally oriented lamps are used, choose lamps capable of universal

burning position❑ Look for products that meet or exceed FEMP-recommended LER (if LERs are available from manufacturers),

and long life❑ Choose enclosed luminaires for further glare control and shielding❑ MH (and HPS) may not be suitable with occupancy-controlled areas, or where frequent

switching is the norm❑ Choose products with recycled content or less harmful production methods, where such information is

available

FOR GENERAL ASSEMBLY, MANUFACTURING AND RETAIL

❑ Metal halide (MH) and pulse-start MH lamps with CRI of 70+ are suitable for most generalretail and medium assembly work.

❑ Choose instant restrike HPS lamps or a backup lighting system for areas where constant illumination(24/7) is needed

❑ Look for products that meet or exceed FEMP-recommended LER (if LERs are available from manufacturers)and long life

❑ Choose open reflectors if you do not need further glare control or shielding❑ Choose products with recycled content or less harmful production methods, where such information is

available

FOR WAREHOUSES AND LOADING AREAS

❑ High pressure sodium (HPS) lamps are suitable for most illumination tasks where colorperception is not important.

❑ Look for products that meet or exceed FEMP-recommended LER (if LERs are availablefrom manufacturers), and long life

❑ Choose open reflectors for maximum light output❑ Choose products with recycled content or less harmful production methods, where such information is

available

FOR SPORT/GYMNASIUM AND SPECIALTY RETAIL

❑ Metal halide (MH) and pulse-start MH lamps with CRI of 70+ are suitable for high light output andwhere good color perception is needed.

❑ For specialty retail, low-wattage, white HPS lamps can be used instead of halogen lamps to provideenergy-efficient accent lighting

❑ Look for products that meet or exceed FEMP-recommended LER (if LERs are available from manufacturers),and long life

❑ Choose additional shielding for UV sensitive areas❑ Choose products with recycled content or less harmful production methods, where such information is

available


are used to further distribute light,control glare, or protect occupantsfrom UV or lamp fragments in caseof lamp explosions.

Energy Efficiency—In thisreport, the Federal EnergyManagement Program (FEMP)recommended luminaire efficacyratings (LER), derived from theNational Electrical Manufacturers’Association (NEMA) standardLE-5B, are used as a baseline foridentifying energy-efficientluminaires. This is a valid way toevaluate different products, but itmust be done with the sameballast, fixture type and bulb type/wattage ratings in order to makean equal comparison.

The term “luminaire efficiency”is sometimes used interchangeablywith “lighting efficiency” whereLER is concerned. LER is definedas: LER = (Luminaire efficiency xTotal rated lamp lumens x BallastFactor) ÷ Input Watts

Green Seal recommends thatyou look for luminaires that meetor exceed FEMP-recommendedLER found in Table 5 (page 13),and have been tested by aqualified testing lab for qualityand performance.

Lamp Longevity—Althoughmost HID sources are long-lived,various factors can affect systemperformance and reduce lamp life.The selection of a durable systemnot only ensures that less solidwaste will be introduced into theenvironment, it also means thatthe components have been testedto be used as a system, thusensuring user satisfaction andreducing failure incidents. GreenSeal recommends choosingsystems with rated lamp life of15,000 hours or more.

Electrical Safety—To ensurelongevity and safety of luminaires,Green Seal recommends thatluminaires be tested by anindependent laboratory, such as

Underwriter’s Laboratories (UL),the Canadian StandardsAssociation (CSA) or equivalent.

Warranty—At a minimum, werecommend products should carrya manufacturer’s warranty of 2years or more, to ensure both usersatisfaction while reducing failureincidents, replacement costs andwaste.

Production Methods andMaterials—We also recommendthat you consider products thatwere made using methods andmaterials that are less damagingto the environment, and productswith recycled content, where suchinformation is available.

The products listed in theenclosed product table includedavailable information frommanufacturers regarding theirproduct’s production method, lamplife, or recycled content. Table 4summarizes the selection criteriaand rationale.

SELECTION CRITERIA AND RATIONALE FOR RECOMMENDED PRODUCTS

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Cooper ............................... 410-517-1401

Holophane ......................... 740-345-9631

Lithonia ............................. 770-922-9000

MANUFACTURER CONTACT INFORMATION

NOTES: LER = Luminaire Efficacy RatingTotal Rated Lumens = Total lamp lumensInput Watts = System input WattsUpward Efficiency = Refers to the % light directed upwardby a luminaire* Lamp life is based on 10hrs/start

A = Glass prismatic reflector uses 35% recycled glass productB = No CFCs or volatile vehicles used in painting process. Allfixtures 90% recyclable.C = 5 Year warranty on productsD = ISO 9000 Certified FacilityAll listed products are tested by UL or equivalent. Efficiencieswere calculated with Ballast Factor of 1, except for Cooperopen luminaires at 0.8

Ruud Lighting .................... 800-236-7000

Spartan.............................. 800-255-5267


Ballast—The operation of lightsources such as fluorescent,high-intensity discharge, andlow voltage halogen requires aballast to control the current.Ballast can be magnetic, hybrid,or electronic. The latter typescan be found in better-qualityluminaires and permit bettercontrol of lamp operations.

Ballast Factor (BF)—BF is theratio of the light output oflamp(s) operated by a ballast tothe light output of the samelamp(s) operated at ratedcurrent and voltage.

Brightness—This term refersto the intensity of light striking asurface. Brightness is measuredin footcandles. One footcandle isequal to the light of onestandard candle striking onesquare foot of surface locatedone foot away.

Color CorrelatedTemperature (CCT)—Alsoknown as color temperature,and expressed in degrees Kelvin,it measures the colorappearance of the light thatcomes from a light source.Available lamp colortemperatures range from 1700degrees kelvin to 5000 degreesKelvin, with 2700 to 3500degrees Kelvin being thecomfortable range for mostpublic areas.

Color Rendering Index(CRI)—CRI measures the abilityof a light source to render thecolor of objects. CRI uses a scaleof 0 to 100, with 100 representing

time. Most light sources sufferfrom reduced output as theyage, some more drastic thanothers. It can be morenoticeable in longer-livedsources.

Luminaire—This term issometimes used interchangeablywith “fixture” and refers to ahard-wired, fixed-positionapparatus that houses a lightsource and related components(ballasts, reflector, sockets), andprovides illumination in aprescribed manner.

Luminaire Efficacy Rating(LER)—Measures the lumenoutput of a fixture as a functionof input power, enablingcomparisons between fixtures.The higher the LER, the moreefficient the luminaire. HIDsystem LERs can range from 64-122 depending upon thecombination of fixture, bulb typeand wattage.

Luminaire Efficiency—Measured as a ratio comparingthe lumen output by theluminaire compared to thelumen potential of the lampalone. HID luminaires are oftenclassified by their upwardefficiency, which refers to thepercentage of light directedupward from the luminaire. Thehigher the upward efficiency,the more light is directedupward.

SOME LIGHTING DEFINITIONS

a color rendering ability similarto sunlight. Light sources with“good” color rendering haveindices that range from 70 to 80CRI. Sources with CRI of 80+ areconsidered to have “excellent”CRI.

Efficacy—Efficacy measures alight source’s ability to convertelectric energy into light. It ismeasured in lumens per watt(lpw). The higher the lpw, themore efficient a light source.Efficacy can be measured forboth lamp as well as lamp/fixture combination (systemefficacy).

HID Lamps—Lamps are madeup of a glass envelope thathouses a high voltage arc tubeand gases which are activatedby an electric current to createlight.

Light Output—Also known aslight quantity, is the termused to described the quantity oflight from a source. It ismeasured in lumens. Lightquantity measurement is takendirectly at the light source and isa calculation of the flow of light.The brighter the light source,the higher its lumenmeasurement. For example, atypical 60 W incandescent bulbwill have the lumen output ofapproximately 700 to 800lumens.

Lumen Maintenance—Alsoknown as lumen degradation,is the term used to describe alight source’s ability to maintaina consistent light output over


The high efficiency of HID lampsis complicated by a number ofcharacteristics, some commonto all HIDs, others affecting onlya particular HID type. Thesecharacteristics are outlinedbelow, along with somestrategies to address them. Aswith any change in technology,they need to be carefullyconsidered, especially if HIDsare to be retrofitted in place ofincandescent sources.

Group Relamping—Somesodium and MV lamps’ wattageincrease as they reach the endof their useful life. In addition,MH and HPS lamps’ colorsshift over their lifetime,particularly after the lampshave reached about 70% of theirrated life. Group relamping isan effective way to deal withboth of these issues. Ceramicmetal halide (CMH) is a newimprovement on MH technology,which offers improved efficacyand color temperature stabilityin lower wattage ranges, but isnot yet widely available.

Back-Up and Instant-Restrike Systems—Becauseof their design, HID lampsrequire a warm-up period,anywhere from 2 to 10 minutes,before reaching full light output.MH lamps tend to take thelongest and sodium lamps takethe shortest. In addition, ifpower is interrupted, an HID’slamp arc will extinguish. Whenthis happens, the lamp mustfirst cool down before the arccan restrike. This cooling periodcan last anywhere from 1 to 15

minutes or more, depending onlamp design and features. Incertain applications, the longstarting and restrike time mayrequire a back-up lamp system,or instant restrike lamps in apercentage of the fixtures (atadditional cost). In general, HIDsystems are not recommendedfor use with occupancy sensorsand other areas where frequentswitching is the norm.

Dimming—It is possible to dimsome type of HID lamps usingspecialized ballast andelectronics. However, thedimmed lamp will result in colorshift, and will operate atreduced efficacy.

Lamp Orientation—Some MHlamps and luminaires aredesigned for lamp operation in aspecific position (such ashorizontal or vertical), and havespecific light output patterns.Operating lamps in positionsother than those recommendedby manufacturers can seriouslyaffect lamp life and performance.

Output Pattern—Some HIDlamp designs can cause thelamps to have highlyasymmetric light output. Inparticular, HID lamps using adouble-ended design tend tohave very uneven light outputpatterns. Lamps should be usedin the correct orientation andfixture to maximize output.

UV Filters—Both MV and MHlamps can be a source ofultraviolet radiation. While theUV belongs in the less

biologically harmful category,emissions still can affect fabrics,papers, and other UV sensitivematerials. Optional filters areavailable from fixturemanufacturers to cut UVemissions

Heat—Because of their design,HID lamps operate at extremelyhigh temperature, especially inthe higher wattage lamp sizes.Thus, appropriate handling andmounting precautions need to betaken.

Shielding—MH lamps arealso available with protectiveenvelopes or coatings tominimize effects in case ofenvelope breakage. Undercertain operating conditions(exceeding safe operation period,or incorrect orientation/ballast)MH lamps can explode (or“extinguish non-passively.”)Luminaires are available withprotective guards or shieldingfor use in sensitive areas.

HID APPLICATION NOTES


The retrofit consisted ofdisconnecting the 28

incandescent down-lightsand replacing them with

eight 460-watt surface-mounted MH

luminaires. Inaddition, the 90-

wattincandescentlamps

around theperimeter of the

lobby were replacedby 16-watt compact

fluorescent lamps.Through the retrofit, the branch

was able to reduce its lighting load

from over 10 kW to about 4 kW, a60% drop in lighting energyconsumption. The use of the MHluminaires alone was responsiblefor a reduction of 4.4 kW inlighting energy use (additionalkWh reduction from reduced air-conditioning load was notquantified).

Lighting conditions and qualityat the bank were improved by theretrofit. Illumination at desk levelsimproved three fold, from 30 foot-candles to over 90 foot-candles,and the white light produced bythe MH blended better with thedaylight from the bank’s windows.Source: NC Alternative Energy Center.

he UniversitySquare branchof the Central

Carolina Bank inChapel Hill, NCchose MH lampsto replaceincandescents inits lobby. Theretrofitted space has20-foot ceiling andwraparound, highwindows, formerly lit by agrid of 28 recessed down-lights, each with a 300-wattincandescent lamp, and 18 90-watt incandescent lamps aroundthe perimeter of the lobby space.

SUCCES

S

STORY

T

FEDERAL ENERGY MANAGEMENT PROGRAM: HID EFFICIENCY RECOMMENDATIONSTABLE 5

YCNEICIFFEDRAWPU EGATTAWPMAL ERUTXIFDESOLC ERUTXIFNEPOdednemmoceR elbaliavatseB dednemmoceR elbaliavatseB

EDILAHLATEM

0 993-051 14 46 atadffusni 38

999-004 35 76 95 98

+0001 77 38 atadffusni 011

01-1 993-051 85 07 atadffusni 35

999-004 26 76 46 07

+0001 atadffusni 99 68 801

02-11 993-051 75 96 atadffusni 76

999-004 55 37 96 57

+0001 78 78 atadffusni 811

+02 993-051 25 37 77 09

999-004 56 47 atadffusni 57

+0001 69 69 atadffusni 69

MUIDOSERUSSERPHGIH

0 993-051 85 67 86 67

999-004 36 78 48 89

+0001 atadffusni 49 atadffusni 59

01-1 993-051 46 37 36 48

999-004 28 101 98 111

+0001 atadffusni 29 907 121

02-11 993-051 atadffusni 98 37 78

999-004 atadffusni 19 49 001


+02 993-051 57 08 77 09

999-004 atadffusni 201 atadffusni 301


1001 CONNECTICUT AVE., NWSUITE 827WASHINGTON, D.C. 20036

NON-PROFIT ORG.US POSTAGE

PAIDWASHINGTON, DCPERMIT NO. 5515

I N T H I S I S S U E

— RecommendedHigh IntensityDischargeLuminaries

— HID Lamp Technologies

— Luminaire Selection Criteria

— Lighting Definitions

— HID Application Notes

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high intensity discharge luminaires...principle of electric discharge similar to fluorescent...

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