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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
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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
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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
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4 Choose Green Report
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
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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 (
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6 Choose Green Report
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
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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
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8 Choose Green Report
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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TABLE 4
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Choose Green Report 9
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10 Choose Green Report
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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
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Choose Green Report 11
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
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12 Choose Green Report
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
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Choose Green Report 13
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
+0001 atadffusni 97 atadffusni 221
+02 993-051 57 08 77 09
999-004 atadffusni 201 atadffusni 301
+0001 atadffusni 611 atadffusni 121
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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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