Building Lighting Design Tip Sheet

8/10/2019 Building Lighting Design Tip Sheet

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ENERGY CONSERVATION

BUILDING CODE TIP SHEET

BUILDING LIGHTING DESIGN

Version 1.0 (Reprinted) June, 2009

Credits:

E Source Technology Atlas Series - Lighting

Energy Eciency Manual - Donald R. Wulngho

Alliance to Save Energy

USAID ECO-III Project

International Resources Group

Phone: +91-11-2685-3110

Fax: +91-11-2685-3114

Email: [email protected]

Lighting is a major energy consumer in commercial buildings. Heat generatedfrom electrical lighting also contributes signicantly to the energy needed

for cooling of buildings. ECBC prescribes the amount of power for lighting,

species types of lighting controls, and denes situations where daylighting

must be used. This document (primarily adapted from E Source Technology

Atlas - Lighting and Energy Eciency Manual) provides guidance towards

the design of ECBC compliant lighting systems in commercial buildings.

In commercial buildings,

lighting typically accounts or 20-40% o total energy consumption.

Lighting is an area that oers manyenergy eiciency opportunities in almostany building, existing as well as new. Atypical commercial building has manylighting requirements and each normallyhas its own set o options or improvinglighting eiciency.

Centuries ago, a person could read by

the light of a single candle but today aperson in a typical office uses hundredsor even thousand times more light. Over

12 lm/80 W

0.15 lm/W

7.5-hour life

730 lm/13 W

56 lm/W

10,000-hour life

Notes: lm = lumen; W = watt.

730 lm/60 W

12 lm/W

1,000-hour life

180 lm/60 W

3.0 lm/W

50- to 100-hour life

CandleC o m p a c t

fluorescentTungsten-filament

incandescent

Carbon-filament

incandescent

Fig 1: Evolution of Lighting Technologies Source: E Source Lighting Atlas

1

the years, illumination standards haveincreased radically along with efficiencyof lamps (Fig. 1). Modern offices requirebetter illumination, specific activity-oriented lighting provisions, and goodvisual quality to maximize productivity.

People want light for different reasons,and a good lighting designer must keepthem in mind. Different tasks require dif-ferent amounts and types of light. For ex-ample, a surgeon needs lots of light with

low glare and excellent color rendering;restaurant owners and diners often wantlow light levels, warm tones, and a feeling

of intimacy; corporate boardrooms call forlighting that reinforces a feeling of impor-tance and success while adapting to audio-visual presentations; retail outlets in manysituations want to make their merchandisesparkle so that it draws the customers andencourages them to buy. An office workerneeds modest ambient lighting level, goodtask lighting on work surface, and mini-mal glare to effectively read and work oncomputers. Tus the quality of light in

majority of situations is as important as thequantity of light.While energy efficiency is an attractive

goal for many reasons, lighting designersmust also consider a host of other factors,including the effect of quality of light onthe visual comfort and health of the oc-cupants. Small improvement in lightingquality can improve productivity of theuser substantially.

Te right quality and quantity of lightcan be provided efficiently (with lessenergy) by using the right technology and

its effective integration with daylight.

DaylightingSunlight is ree and uses no electricity.

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Human beings by nature are accustomedto live and work more comortably in sun-light. Although our optical sensors (hu-man eye) can only see a very narrow por-tion o electromagnetic spectrum, theyare well adapted to s unlight (Fig. 2). Botheconomics and the imperatives o healthand aesthetics avour the practical use o

daylight in the buildings. Simply addinga large number o windows to a buildingto let the sun shine in can create exces-sive glare, make other spaces look dark bycontrast, and admit so much unwantedheat gain due to near inrared radiationthat the space could become virtually un-usable.

Poorly designed daylit areas can be worsethan spaces with no daylight. Whendone properly, daylighting coupledwit h energ y-e icient glazi ng and goodlighting controls can make new and

existing buildings eicient, delightuland healthy. he tools to do it right ex ist,and are being applied by a growing bodyo talented lighting designers.

Interactive Effects of Light-

ing

Lamps use electricity to produce light.Except or a small percent o energy usedin producing light, majority o energyused by interior lights ends up as heatinside the building. In most commercial

buildings, lighting is one o the largestsources o internal heat gain. Othersources o internal heat gains are peopleand equipment in building. Compared totypical lighting, energy-eicient lightingadds less heat to space per unit o lightoutput (Fig. 5). Each kilowatt-hour(kWh) reduction in lighting energy saves0.4 kWh in cooling energy.

Lighting Technology

Lighting is one o the astest developingenergy-eicient technologies: energy-

eicient 8 and 5 linear luorescentlamps, linear and compact luorescentdimming systems, long-lie electrode less luorescent lamp systems, white LEDs,

Fig 2: Solar Spectrum (Source: E Source

Lighting Atlas)

300 500 700 900 1,100 1,300 1,500 1 ,700 1,900

Near- infared

(52%)

Visible(45%)

UV(3%)

RelativeI

ntensity

Wavelength

(nanometers)

Spectral distribution

of Solar radiation

Eye Sensitivity

Curve

into account several human actors inspeciying lighting systems.

Lighting Design Tools

Lighting sotware helps designers tocompare lighting alternatives and makessure that the ultimate design choice willprovide qualit y light . Demands on lighting

designs are becoming more complex asboth lighting quality and energy eiciencyhave become high priorities. In addition,a wide range o variablesdierent lightsources, ixtures o varying eiciency andphotometric , and rooms with a wide ra ngeo geometries and surace inishesallmake lighting design a challenge worthyo computer modeling. In particular,the trend among ixture manuacturersto use specular relectors that send lightin particular directions makes modelingmore useul than it was with the old-style, white-painted diuse relectors.Most computer models can also simulatethe eects o daylight and can be used tohelp designers to develop eective controlstrategy or getting the optimum blend oelectric lighting and daylighting.

Once constructed, a computer lightingmodel can be easily modified so thatvarious fixture designs and spacings canbe evaluated and compared in terms ofhorizontal and vertical light levels. Designsthat give proper quality and quantity of

lighting can be evaluated for their energyconsumption, and the design that givesboth the desired lighting level and thelowest life-cycle cost can be selected.Output from lighting software can also beinput into software that models an entirebuilding to enable analysis of the impactsof lighting decisions on other buildingsystems. Lighting professionals who donot first model the design, face the riskof getting poor light distribution or morelight than they expect. Both the problems

can be difficult and expensive to correct.

Lamp Technologies

Incandescent LampsAn incandescent lamp consists o atungsten wire ilament that glows andproduces visible lig ht when heat ed to ahigh temperature. Unortunately, 90 to95 % o the power consumed by the hotilament is emitted as inrared (heat)radiation. Although ineicient rom anenergy standpoint, the luminous ila ment

can be made quite small, thus oeringexcellent opportunities or beam controlin a very small package.

and PV powered DC lighting systems.Selection of lamp should be the starting

point when deciding how to illuminatea space efficiently. Lamps are also theprimary actor in lighting efficiency, andthey determine both the electrical andcolor characteristics of the lighting systems.

When a lamp is coupled with its auxiliary

equipment (e.g. a ballast or choke) andinstalled in a luminaire (fixture), it becomesthe complete light source that is the basicelement of the lighting design.

It has long been recognized that anincandescent lamp is much less efficientthan fluorescent and High IntensityDischarge (HID) lamp, and that it hassmaller operating life. In recent years,further improvements in the efficiencyand color characteristics of fluorescentand HID lighting have increased theiradvantage over incandescent lighting.

LightDistribution

hough energy-eicient technologiescan cut down energy consumption andoperating costs, the light path originati ngrom the light source i not properlydirected and distributed to the task oractivity area through appropriate lampluminaires (ixtures), could adverselyaect the quality o light and reduceenergy eiciency gains. Consequently,luminaire selection and design should

go together with any energy-eicientlighting strategy.

Lighting Controls

Controls are the last step in the energy-eicient lighting design process andshould be designed ater high-eiciencylight sources have been chosen. hecontrollability o light sources varieswidely, wit h low-e icacy incandescentlamps being the easiest to control.echnological developments continue

to provide new control capabilities orluorescent and HID systems.

Efficient Lighting Design

Optimal lighting solutions can only bereached by considering the integrationo daylight, lamps, ixtures, controls,building conigurations, interiorurnishing, etc. Ideal lighting providesthe appropriate level o illuminationor the activity with minimum inputo energy, with required visual quality.For eicient lighting design, it is oten

necessary to involve a skilled lightingdesigner who combines energy eiciencywith good qua ntit y and qua lit y o lig htneeded or the activity and also takes


ECBC/TIP SHEET > Lighting


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Key Technical Terms

For implementing the ECBC provisionsin lighting system, it is important tounderstand the ollowing technical terms:

Astronomical time switch:An automatictime switch that makes an adjustment orthe length o the day as it varies over the

year.

Ballast: All fluorescent lamps need aballast to operate. Te primary unctionso a ballast are to provide cathode heatingwhere necessar y, init iate the lamp arcwith high-voltage, provide lamp operatingpower, and then stabi lize the arc bylimiting the electrical current to the lamp.Secondary unctions include input power-quality correction and control eaturessuch as lamp dimming or compensationor lumen depreciation.

Candela: It is a measure o the intensity(or brightness) o light source in a givendirection (Fig. 3).

Color Rendering Index (CRI): Measured

on a scale o 0 to 100. It specifies the colorrendition properties o a lamp. Te higherthe average CRI value, the better the lightsource. A cool white fluorescent lamp has aCRI o 62 to 70, 8 lamps range rom 75to 98 and standard high-pressure sodiumlamps have CRIs o about 27. Lamps withCRIs above 70 are typically used in officeand living environments.

Correlated Color Temperature (CCT):A measurement on the Kelvin (K) scalethat indicates the warmth or coolness o

a lamps color appearance. Te higher thecolor temperature, the cooler or bluer thelight. ypically, a CC rating below 3200

K is considered warm, while a rating above4000 K is considered cool.

Illuminance: Te amount o light thatreaches a surace. It is measured in ootcandles (lumens/f2) or lux (lumens/m2).

Installed interior lighting power: Te

power in watts o al l instal led general,task, and urniture lighting systems andluminaires.

Lighting Power Allowance:Interior lighting power allowance: thea)maximum lighting power in wattsallowed or the interior o a buildingExterior lighting power allowance:b)the maximum lighting power in wattsallowed or the exterior o a building

Lighting Power Density (LPD): Telighting power drawn per unit o areao a building type or space. It is usuallyexpressed as watts per square meter orwatts per square oot.

Occupancy Sensor:A device that detectsthe presence or absence o people withinan area and causes lighting, equipment, orappliances to regulate their operation orunction accordingly.

Reflectance:Te ratio o the light reflected

by a surace to the light incident upon it.

Visible Light Transmittance:Also knowas the Visible ransmittance, is an opticalpropert y o a light transmitting material(e.g. window glazing, translucent sheet,etc.) that indicates the amount o visiblelight transmitted o the total incidentlight.

Luminance: It measures the brightnesso a source when viewed rom a particular

direction. It is expressed in term ocandela/m2 o the light emitting surace.Luminance describes the intensity olight that is leaving a surace whereasilluminance describes the intensity olight that is alling on a surace. For lightreflected rom a surace, luminance equalsilluminance multiplied the reflectance othe surace.

Lumen:It is the unit i total light outputrom a light source o a lamp is surroundedby a transparent bubble; total light low

through the bubble is measured in lumens.Lamps are rated in lumens, which is thetotal amount o light they emit, not their

brightness and not the light level on asurace. ypical indoor lamps have lightoutput ranging rom 50 to 10,000 lumens.Lumen value is used or purchasing andcomparing lamps and their outputs.Lumen output o a lamp is not related tothe light distribution pattern o lamp.

Lux: It is the unit o illuminance andindicates the density o light that allson a surace. One lux equals one lumenper square meter o the surace while onelumen per square oot o the surace isequal to 1 oot-candle. One oot-candleequals 10.76 lux. Average indoor lightingrange rom 100 to 10,000 lux and averageoutdoor sunlight is a lmost 50,000 lux. hese lumens and candela aremeasured by special photometric instru-ments in laboratories and are used pri-marily or comparing light sources in-dependent o site conditions. Lux andoot-candles are measured in the ieldwith a meter and may be dependent on siteconditions because, un like candelas or lu-mens, they are in luenced by ix ture, roomsurace relectance, partitions, and otheractors.

Lamp Efficacy: Lamp Eicacy is ameasure o the output o a lamp in lumens,divided by the power drawn by the lamp.Its units are lumens per watt. Lamp

eicacy values are based exclusively on thelamps perormance and do not includeballast losses. Lamp system e icacy valuesmeasures the perormance o the lamp andballast combination and this includes theballast losses.

Light Luminaire (Fixture): A lightfixture, consists o the ballast, lamp,reflector, in some cases a lens, designed todistribute the light, position and protectthe lamps, and connect the lamps to the

power supply.

T#: As in 5, 8, 12 luorescentlamps. stands or tubular; the numberdescribes lamp diameter in one-eighth-inch increments. A 8 lamp is eight-eightso an inch (or 1 inch) in diameter; a 12is twelve-eighths o an inch (or 1.5 inches)in diameter.

A 1-candlepower light source delivers a luminous intensi ty

of 1 candela (cd) in all directions. Assuming that the sphere

has a radius of 1 foot (ft), the light source will deliver 1

lumen (lm) of light to each square foot (ft 2) of surface of the

sphere, so the illuminance is 1 foot-candle (fc).

1cd

1cd

1-ft2hole

Radiu

s=1ft

Illuminance

At any point on

this imaginary 1-ft-

radius sphere, theilluminance equals

1 lm/ft2, or 1 fc.

Luminous

intensity = 1 cd

One candle power

luminous source

Light ow=1lm/ft2

Fig 3: Relationship of light measurement

terms (Source: E Source Lighting Atlas)

3Version 1.0 (Reprinted) June, 2009 ECBC/TIP SHEET > Lighting


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are shown in able 1. Electronic ballasts,which have come to dominate the marketfor compact fluorescent lamps (CFLs), aremore efficient, weigh less, and are quieterthan magnetic ballasts.

Some argue that CFLs are such smallloads that their PF and HD should notbe o major concern, especially becausemany other end-use devices on the powergridpersonal computers, copiers, laserprinters , microwave ovens , televisions,stereos, variable-speed motor controls,and othersalso degrade power qualityin varying degrees and typically use armore power per unit.

Mercury is an essential ingredient formost energy-efficient lamps. Te amountof mercury in a CFLs glass tubing is small,about 4mg. However, every lamp productcontaining mercury should be handled

with care. Fig. 6 puts mercury pollution

Linear and Compact FluorescentLamps (CFLs)he basic luorescent lamp contains lowpressure mercury vapor a nd i nert gases ina partially evacuated glass tube that arelined with phosphors (Fig. 4). CFLs op-erate in the same manner as linear luo-rescent lamps. he high surace bright-

ness o CFLs requires the use o robustrare earth phosphors, such as those usedin modern 8 and 5 linear luorescentlamps, in order to provide acceptable lu-men maintenance.

he eicacy (lumens per watt) oluorescent lamps varies considerablywit h lamp wattage and balla st ty pe andquality (Fig. 5). he eicacy o a 5-wattCFL on a low-quality magnetic ballast,or example, can be as low as 27 lumensper watt (lm/W). At the other extreme,

two 36-watt compact luorescentlamps powered by a single high-qualityelectronic ballast deli ver nearly 77 lm/W.ypical incandescent lamps operate withan eicacy o 15 to 18 lm/W, so even alow-eicacy CFL is signiicantly moreeicient than the incandescent lamp itmight replace.

CFLs have been substituted or anincandescent lamp using the rule othumb that a CFL uses only 20-25%power to deliver the same lig ht output.

However, but many manuacturersproduct literat ure exaggerates CFLperformance by rounding up whenidentifying the equivalent incandescentlamp. For example, a CFL may beadvertised as a replacement for a 75-watt,1,200-lm incandescent lamp, but it mayonly produce 1,000 lm. A more accuratedescription would put the light output ofa CFL midway between that of 60W and75W incandescent lamps.

Te effect of CFL on power quality hasbeen debated widely for several years. Te

two primary issues are the Power Factor(PF) and otal Harmonic Distortion(HD) of the ballasts. ypical PF andHD ranges for various ballast types

Notes: Hg = mercury; UV = ultraviolet

UV photon

Hg

Visible photon

Fluorescent lamps maintain an electric arc th roughgas, in contrast to the continuous metal ilamentsused in incandescent lamps.

Fig 4: Fluorescent lamp operation

(Source: E Source Lighting Atlas)

from the use of CFLs in a broader context(mercury pollution from thermal powerplants generating power).

High Intensity Discharge LampsHID lighting sources are the primaryalternative to high-wattage incandescentlamps wherever an intense, concentratedsource o light is required. here are threebasic ty pes o HID la mps: Mercury Vapor,Metal Halide, and Hig h-Pressure Sodium.Although HID lamps can provide higheicacy, they have special requirementsor start-uptime, restrike time, saet y, andmounting position.

a) Mercury-Vapor LampsMercury-vapor (MV) lamps use a high-press ure mercury discha rge that directlygenerates visible light (Fig. 7). Someversions als o use a phosphor coating on

Table 1: Magnetic and Electronic Ballasts Characteristics for

CFLs

Ballast Characteristics Magnetic Electronic

CFL base compatibility Mostly two-pin Mostly four-pin

Lamp/ballast efcacy Low High

Weight High Low

Noise level Slight 120-Hz hum Very quiet

Cost Cheaper Expensive

No. of lamps powered/ballast 1 or 2 1, 2, 3 or 4

Dimmability No Available

Universal input voltage No Available

Power Factor 0.4 to 0.7 (normal; > 0.9 (better)0.4 to 0.7 (normal; > 0.9 (better)

Total Harmonic Distortion (%) 6-18 (normal); 15-27 (better) 75-200 (normal); 16-42 (better)

Source: E Source Lighting Atlas

Fig 5: Relative efficacy of major light sources (Source: E Source Lighting Atlas)

Standard incandescent

Tungsten halogen

Halogen infrared reecting

Mercury vapor

Compact uorescent 5120 W

Low-pressure sodium

Efcacy, including ballasts

(lumens per watt)

Fluorescent (Linear and U-tube)

Metal halide

High-pressure sodium

0 20 40 60 80 100 120 140




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the inside o the outer bulb to convert thesmall amount o ultraviolet (UV) lightgenerated by t he discharge into additionalvis ible lig ht that improves the color o thelamp. MV lamps have lower eicacy t hanluorescent lamps and other HID lamps.

b) Metal-Halide LampsMetal-Halide (MH) lamps are similarto MV lamps but eature an importantimprovement: the addition o iodideso metals such as thallium, indium, andsodium to the arc tube. hese metalsproduce a higher qua lit y and quantit yo light than mercury, and the halidesorm the basis o a regenerative cycle thatprevents the meta ls rom depositing on

the wall o the arc tube. MH lamps takethree to ive minutes to reach ul l output.Restarting ater a shutdown or powerinterruption may require as much as 10 to

proponents . LEDs use sol id-stateelectronics to create light. Major elementsin the packag ing o an LED include a heatsink to dissipate the energy that is notconverted into light, a lens to direct thelight output, and leads to connect theLED to a circuit. Fig. 8 shows a crosssection o an LED ixture.

LEDs are increasing in efficacy, lightoutput, and color availability whiledropping in cost. High brightness, narrow-band, or various-color LEDs are being usedincreasingly in vehicle signal lights, trafficsignal lights, exit signs, and decorativeand information display applications.Composite units of red, green, and blueLEDs, or of systems composed of a blueor violet LED plus a phosphor coating,are being used to create white light furtherexpanding LED applications.

able 2 shows the comparative

characteristics of different light sources.

Fixture & Reflectorhe ull potential or energy-eicientlighting comes only through intelligentintegration o many system variables.hese range rom the most minute detailso lamp design through the blending olamps, ballasts, relectors, lenses, andother components.

It is not enough to select good lampsand other components. However,

one must also understand how thesecomponents behave in the field. In thelab, fluorescent lamps are typically ratedin open-air fixtures at 25C ambienttemperature with a reference ballast thatdrives the lamp to its fu ll rated output. Inthe field, however, many ballasts underdrive or overdrive lamps. Te so-calledballast factor and the temperature of thelamps in field conditions can cause lightoutput to vary by 20 percent or more.Lamp positionwhether it is installedbase up or base downcan also have a

10 to 20 percent effect on light outputfrom certain sources, such as compactfluorescent lamps.

Fig 8: LED Operation (Source: E Source

Lighting Atlas)

Plastic lens

Silicone

encapsulate

InGaN

Semiconductor

Flip chip

Solder connection

Silicon submount chip with

ESD protectionHeatsink slug

Gold wire

Cathode lead

15 minutes or the arc tube to cool and themercury and metal-halide gas densities todrop beore the arc can be restruck, plusanother three to ive minutes to reachull output again. MH lamps producerelatively high levels o UV radiation thatcan be controlled with shielding glass inthe lamp or ixture.

c) Sodium LampsIn sodium lamps, a high-requency,high voltage pulse ionizes a rare gas,typically xenon, in an enclosed tube.he ionized gas in turn vaporizes asodium-mercury amalgam. An electric

arc through this vapor excites sodiumatoms, which emit visible lightmostlyin the longer wavelengths bet ween yellowand redwhen they return to theirground state. For high-pressure lamps,the gas mixture is sealed in a translucentpolycryst al line alu mina cylinder thattransmits 90 percent o the visible lightcreated inside it. Sodium lamps varywidely in thei r e icacy and color qua lit y,and their perormance is very sensitive tothe gas pressure inside the arc cylinder.

Improving the quality o light rom somesodium sources, signiicantly reducestheir eicacy.

Light-Emitting DiodesDuring the past ew years, solid-statelighting in general and Light EmittingDiodes (LEDs) in particular havereceived more attention than any otherlighting technology. his high level ointerest is based on the demonstratedperormance advant age s o LEDs in manyniche applications, and it is also ueled

by LEDs potential or substantial energysavings in general lightingapplications i the technology can meetthe perormance targets established by its

Fig 7: Mercury Vapor Lamp Schematic


Starting electrode

(probe)

Starting resistor

Trimetallic operating

electrode

Phosphor coatingQuartz arc tube

Visible light

2

2

33 Outer bulb

1

1 UV light

Electric

eld

Electrode

Electron Mercury

atom

Quartz arc tube

Environmental Impacts of MercuryUsed in Fluorescent Lamps

As energy -efficient lighting becomesmore popular, it is important that thelamp products are disposed o in a sae andresponsible way. Mercury is released intoenvironment when products with mercuryare broken, disposed o improperly, or

incinerated.In spite of the sensational reporting inprint and electronic media, the fact is thatCFLs present an opportunity to preventmercury contamination of air, where itmost affects the health. One of the majorsources of mercury in air comes fromburning fossil fuels such as coal, the mostcommon fuel used in India to produce

electricity. A CFL uses 75% less energythan an incandescent light bulb and lastssix times longer. A thermal power plantemits 10 mg of mercury to produce theelectricity to run an incandescent bulbcompared to only 2.4 mg of mercury torun a CFL for the same time.

Fig 6: Mercury Emissions by Light

Source Over Year Life (Source: US

EPA, June 2002)

12

10

8

6

4

2

0

Emissionsfrom coal

power point

IncandescentCFL

Emissions fromcoal power plant

2.4

10.0

4.0 Mercury usedin CFL

MiligramsofMercury



6/12

Table 2: Comparative Characteristics of Different Light Sources (Source: Energy Efficiency Manual)

CharacteristicsConventional

Incandescent

Halogen

Incandescent

Fluorescent

Tube Light Compact Fluorescentt

Lumen Output(lumens) 10 to 50,000

300 to 40,000 900 to 12,000 250 to 1,800

Lumen Degradation(% of initial lumens) 15 to 40 8 to 15 8 to 25 15 to 20

Service Life (hours) 750 to 4,000 2,000 to 6,000 7,000 to 20,000 10,000

Efcacy (lumensper watt)

7 to 22 14 to 22 30 to 90 25 to 70, Including ballast losses

Ballast EnergyConsumption (percentof lamp wattage)

None None5 (high quality electronicballasts) to 20 (cheapmagnetic ballasts)

10 (electronic ballasts) to20 (magnetic ballasts)

Potential for LampSubstitution andMismatch

Unlimited substitutionwherever the lamp ts thexture, provided that xtureheat capacity is adequate.

Unlimited substitutionwherever the lamp tsthe xture, providedthat xture heatcapacity is adequate.

Limited within narrowranges of wattage by lampsize, socket style, andballast compatibility.

Screw-in lamps substitute for eachother and for most incandescentlamps, except where they aretoo large to t. Cannot be usedin dimming xtures. Othercompact lamps have specializedbases that limit substitution.

Color RenderingIndex (CRI)

100 100 50 to 95 60 to 85

Effect of Temperatureon Light Output

Minimal. Minimal.

Serious loss of light

output above and belowoptimum lamp temperature(about 38C).

Serious loss of Eight output aboveand below optimum lamp temperature(about 38C). Lamps that use mercuryamalgam maintain light outputmuch better at low temperatures.

Starting Interval Instantaneous. Instantaneous.

Instantaneous for lamps withInstant-start ballasts. Aboutone second for rapid-startballasts. One to severalseconds for preheat ballasts.

One to several seconds. Units withmercury amalgam require about oneminute to reach full brightness.

Control of LightDistribution

Some styles allow verytight focussing.

Some styles allow verytight focussing.

Allows only loosefocussing. Most controlperpendicular to lamp axis.

Allows moderately tightfocussing, especially withunconventionally large xtures.

Acoustical Noise Minimal. Minimal.

All magnetic ballasts producesome noise, and defectivenoisy units are fairly common.Some electronic ballastshave noticeable noise.

Good units are quiet, cheapunits may be noisy.

Power Factor No problem. No problem.Ballasts with high powerfactor are available. Someballasts have low power factor.

Units with high power factor areavailable. Some have low power factor.

Harmonic Distortion None. None.

High distortion occurs

primarily In cheaperelectronic ballasts.

All units with electronic ballasts

have signicant harmonicdistortion. Cheaper units havemuch more than others.




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Mercury

Vapor

Metal

Halide

High-Pressure

Sodium

Low-Pressure

Sodium

0 to 60,000 4,000 to 160,000 2,000 to 50,000 1,800 to 35,000

o 45 30 to 45 25 to 35

00 5,000 to 20,000 10,000 to 24,000 18,000

o 65 70 to 130 50 to 150 100 to 190

rge lamps) to 50 (small lamps) 7 (large lamps) to 30 (small lamps) 10 (large lamps) to 35 (small lamps) ca. 20

titutions within type highly limitedallast compatibility. Some mercuryor lamps substitute for incandescentps without external ballasts, but theser minimal efcacy advantage.

Substitutions within type highlylimited by ballast compatibility.

Substitutions within type highly limited byballast compatibility. Some HPS lamps aredesigned as direct substitutes for mercury vaporlamps, offering major efcacy improvement butworse color rendering than other HPS lamps.

Substitutions withintype highly limited byballast compatibilityand specialized sockets.

o 50 60 to 70 20 to 85 0 to 20

imal loss of output above -29C. Minimal loss of output above -29C. Minimal loss of output above -29C. Minimal loss ofoutput above -29C.

8 minutes 3 to 10 minutes 5 to 10 minutes 7 to 15 minutes

ws moderately tight focussing. Allows moderately tight focussing. Allows moderately tight focussing.

Allows only loosefocussing. Mostcontrol perpendicularto lamp axis.

asts are magnetic, andduce some noise.

Ballasts are magnetic, andproduce some noise.

Ballasts are magnetic, and produce some noise.Ballasts are magnetic,and producesome noise.

asts with high power factor are available.e ballasts have low power factor.

Ballasts with high power factorare available. Some ballastshave low power factor.

Ballasts with-high power factor are available.Some ballasts have low power factor.

Ballasts with highpower factor areavailable. Some ballastshave low power factor.

or, assuming that thests are magnetic. Minor, assuming that theballasts are magnetic. Minor, assuming that the ballasts are magnetic.

Minor, assuming

that the ballastsare magnetic.



8/12

lighting) [ECBC 7.2.1.4 and 7.2.1.5].Maximum lighting power requirementsare also included for exit signs andexterior building grounds lighting[ECBC 7.2.2 and 7.2.3].As per ECBC, for Exterior Grounds

Lighting luminaires greater than 100Watts shall have a minimum efficacy of

60 Lumens/Watt, unless controlled witha motion sensor. As shown in Fig. 9,luminaires meeting these requirementsinclude fluorescent, mercury vapor andhigh pressure sodium.

Prescriptive RequirementsFor Interior Lighting Power requirements,[ECBC 7.3], the insta lled interior lig htingpower is irst ca lculated to include al llamps, ballasts, current regulators, andcontrols [ECBC 7.3.3]. Complia ncecan then be achieved by ollowing theBuilding Area Method [ECBC 7.3.1] orthe Space Funct ion Method [ECBC 7.3.2].Both methods compare installed lightingpower (as proposed) wit h maximumallowed lighting power densities (W/m2) presented in tables based on eitherbuilding area type or space unction.

Building Area Method:

STEP 1:Determine the allowed lightingpower density rom able 7.3.1 o ECBC

or each appropriate building area type.Sample LPD values are g iven in able 3.

STEP 2:Calculate the gross lighted loorarea type.

ECBC Compliant Lighting

Design Strategy

Many things can go wrong with thebuilding lighting system and well-intentioned attempts to make it energyeicient. Critical missteps to watch outor include:

Speciying the amount o light orgeneral usage without considering theneeds o speciic tasks (or example,supplying light or general oice workbut not addressing the eect o g lare oncomputer screens);Designing a daylighting strategy butnot enabling the lighting system todim or turn o when there is suicientdaylight in the interior space;Supplying inadequate control olighting by not allowing lights to beadjusted to speciic needs (i.e. turnedon in groups or banks, or dimmed),and not providing easily accessiblecontrol switches;Adding a large window area to theaade or daylighting but ignoringthe problems o solar heat gain and theneed or shading;Designing/sizing the buildings HVACsystem on rules o thumb and notaccounting or the reduction in coolingloads created through eicient lighting

system.

Compliance Approaches - GeneralECBC sets mandatory and prescriptiverequirements or lighting power densityand lighting controls. Compliance withprescriptive requirements can be shownthrough the Buildi ng Area Method or theSpace Function Method. In both cases,mandatory lighting requirements are stillapplicable.

Mandatory RequirementsLighting C ontrolAstronomical imersand occupancy sensors are required toautomatically turn lights o in mostenclosed interior spaces [ECBC 7.2.1.1].Control devices also required to overridean automatic shuto control (eithermanually or through an occupancysensor) [ECBC 7.2.1.2]. I Daylightingstrategy is used in the design, ECBCrequires controls that can reduce the lightoutput o luminaires in the daylit space,by at least hal [ECBC 7.2.1.3].

Tere are also control requirementsfor exterior lighting (with photosensoror time switches) and specialty lightingapplications (i.e. displays, hotel rooms, task

STEP 3: he interior lighting powerallowance is the sum o the productso the gross lighted loor area o eachbuilding area times the allowed LPD orthat building area types.

Space Function Method

STEP 1:Determine the appropriatebuilding t ype rom able 7.3.2 o ECBCand the al lowed lighting power density.Sample LPD values a re given in able 3.

STEP 2:For each space enclosed bypar titions 80% or g reater t han cei lingheight, determine the gross interior loorarea by measuri ng to the center o thepar tition wall . Include the loor area obalconies or other projections. Retailspaces do not have to comply with the80% part ition height requirements.

STEP 3:he lighting power al lowanceor a space is the product o the grosslighted loor area o the space timesthe allowed lighti ng power density orthat space. he interior lighting powerallowance is the sum o the lightingpower al lowances or al l spaces.

Exterior Lighting Power requirements[ECBC 7.4] require calculating the con-nected lighting power or building en-

trances, exits, and acades. hese mustall below the power limits listed inECBC or each lighting application.

Basic Light Design Concept

When designing or retroitting the

140

120

100

80

60

40

20

0100 200 300 400 500 600 700 800 900 1000

SystemEfcacy(Lumens/Watt)

System watts

High Pressure Sodium

Metal Halides

System Efciency < 60 lm/ W not allowed per ECBC unless controlled

by a motion sensor

Fluorescent

Incandescent

Fig 9: Exterior Grounds Lighting and specific Technologies (Source: Adapted from

ASHRAE/ IESNA Standard 90.1-1999)




9/12

Fixture eiciency is the proportion olamp light that escapes the ixture at anyangle, whereas CU is the proportion olamp light that reaches the work plane.

Te two are calculated differently and arenot interchangeable. All else being equal,a ixture in a room with a low RCR willhave a higher coeicient o utilizationthan i it were in a room with a highRCR. CU values are given by the ixturemanuacturer.

able 4 shows how rapidly the CU valuedrops as wall reflectance decreases or asRCR increases.

lighting, the general illuminance, oramount o light that reaches a sura ce, canbe assessed through manual calculations.he Illuminating Engineering Society oNorth America (IESNA) has establisheda procedure or determining how muchilluminance is needed or a given task.The Zonal Cavity or Lumen Methoddescribed below considers several actorsto determine type and number o ixt uresthat would be appropriate to meet theillumina nce requirements o the space.

Zonal Cavity Method: he basicormula used in this method spring romthe deinition o illuminance: 1 oot-candle (c) = 1 lm/t2. hat is, to maintainan average o 40 c in an area o 100 t2,one needs 40 x 100 = 4,000 lm comingout o the ixtures. But several modiyingactors must be considered: he ixture

is not absolutely eicient in dispensinglight; much o that light may be lost whilebeing relected o o various suracesbeore it arrives at the work surace. Also,light sources degrade with age and dirtbuildup.

o complete the zonal cavit y calcu lation,three undamental quantities must beknown: the Room Cavity Ratio (RCR),the Coeicient o Utilization (CU), andthe Light Loss Factors (LLF).

Room Cavity Ratio: Room Cavity Ratio(RCR) characterizes a room by shape a ndis calculated using the ormula below, us-ing the room dimensions and light ixtu redistance over the working desk . Reer Fig-ure 10, or the ca lculation shown below:

Coefficient of Utilization: CU is

a measure o the ixtures ability todistribute light down to the work planeusing the RCR value and the suracerelecta nce o the walls, loor, and ceiling.

4.55(10-2.5-1.5) (20+10)= = 20 X 10

5(H) (L+W)

L X W=RCR

Light Loss Factor: Light distributionis not only aected by the color andrelectance o room suraces andurnishings but also by change in lightingoutput over time, which is principally aunction o la mp lumen depreciation andixture dirt buildup. Lumen depreciationdata can be ound in technica l inormation

supplied by the lamp manuacturer, anddirt depreciation values can be takenrom graphs (IESNA) or various ty pes oixtures and dirt environments.

Once these Light Loss Factors havebeen taken into account, one has a morerealistic picture of the maintained foot-candle level. Te number of lamps (orfixtures) needed to attain that sustainedminimum light level over a lamps lifetimecan then be determined by the zonal cavityformula:

Te lumen method or zonal cavitycalculation is a quick and simple techniquefor predicting the average illuminance levelin a room. Te calculations have simpleinput requirements:

Physical characteristics of the room,1.including length, width and height;Ceiling, wall and floor reflection ( %2.of light reflected by the room surfaces);

Work plane height;3.Distance from the work plane to4.luminariesCoefficient of Utilization (CU) for5.

the luminaries.Number of lamps per luminaire and6.initial lumen output of each lampLight Loss Factors (LLFs)7.

he method can be used to calculate theaverage illumina nce incident on the workplane once the lig hting system has beendesigned.

Tis method is heavily dependenton several assumptions: that surfacereluctances are reasonably accurate, the

fixtures are evenly distributed in theroom; and other concerns such as voltage,room temperature, fixture temperature,and ballast factor are normal and willnot affect lamp lumen output. Te basicRCR calculation assumes that the fixturesare mounted on the ceiling; variations inthe RCR calculation method can accountfor direct/indirect fixtures mounted onpendants.

Fixtures that cause less glare are deeper(to conceal the lamp) and have lower CUvalues, meaning more light will be needed

to attain a given foot-candle level. Morewatts will also be needed, so care is essen-tial in weighing the need to avoid/reduceglare in upgrade situat ion.

Table 4: Typical Coefficient of

Utilization (CU) Values

Reflectance

(Wall)50 30 10

Reflectance

(Ceiling)80 50 80 50 80 50

1 67 56 65 53 53 51

2 66 54 63 51 51 49

3 65 52 61 50 50 48

4 64 50 59 48 48 46

5 63 48 57 46 46 44

6 61 46 53 44 44 42

7 59 43 51 42 42 40

8 56 41 49 40 40 38

9 54 40 47 38 38 36

10 51 39 45 36 36 34

Room

CavityRatio(RCR)

Table 3: Sample LPD Values (max. permissible) as per ECBC

Building Area

Method

LPD

(Watts/m2)

Space Function

Method

LPD

(Watts/m2)

Ofce 10.8 Ofce Enclosed/Open Plan 11.8

Library 14.0 Classroom/Lecture/ Training 15.1

Retail/Mall 16.1 Family Dinning 22.6

Cafeteria/ Fast Food 15.1 Hospital (Emergency) 29.1

Parking Garage 3.2 Corridor/Transition 5.4

Fig: 8

L=20ft

Fixture hangs below

ceiling 1.5ft H-6 ft

Task height=2.5 ft

Desk

Desk

W=10ft

Fig 10: Room Dimensions and Fixture Lo-

cation (Source: E Source Lighting Atlas)

10ft



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practice gla re control inc ludes the use oadjustable blinds, interior light shelves,ixed translucent exterior shading devices,interior and exterior ins, a nd louvers.

ControlDaylight strategies do not save energyunless electric lights are turned o ordimmed appropriately. ECBC requirescontrols in daylit areas that a re capable oreducing the light output rom luminairesby at least hal. It is important to haveproperly u nctioni ng controls that areplaced in appropriate locations and arecalibrated to provide a consistent level olighting. Good lighting design is criticalor an energy-eicient and comortablebuilding.

Install effective placards at lightingcontrols;Install dimmers to take advantage ofdaylighting and where cost-effective;Replace rheostat dimmers with ef-cient electronic dimmers;Combine time switching with daylightingusing astronomical timeclocks;Control exterior lighting with photo-controls where lighting can be turnedoff after a xed interval.

Design TipsMany oices that were designed to han-dle typing and similar horizontal oicetasks earlier are now illed with desktopcomputers and workstations (oten hav-ing relective suraces), which requirecareul consideration o both horizontaland vertical illumination in the oices.

Deal with each activity area and eachxture individually;Eliminate excessive lighting by reducingthe total lamp wattage in each activity

area;Lighting layout should use task lightingprinciple. Install focussing lamps orexible extensions wherever needed;

Te above discussion pertains to casesinvolving uniform light levels. In somecases, non-uniform levels are better, even ifexisting levels are uniform. Tis typicallyoccurs in merchandising, where one would

want products to stand out.

Tips for Energy Efficient

Lighting

Any lighting system generates heat thatneeds to be dissipated . By designing anenergy eicient lighting system that inte-grates daylig hting and good controls, heatgains can be reduced signiicantly. hiscan reduce the size o the HVAC systemresulting in irst-cost savings.

Daylighting Tips

Daylighting beneits go beyond energysavings and power reduction. Daylightspaces have been shown to improve peoplesability to perorm visual tasks, increaseproductivit y and reduce absenteeism andillness. Building enestration should bedesigned to optimize daylighting andreduce the need or electric lighting.Following tips can help in designing anintegrated lighting system:

Coordinate with design of electriclights;

Plan the layout of interior spacesusethe layout to allow daylight to penetratefar into the building (Fig. 11).Orient the building to minimize build-ing exposure to the east and west andmaximize glazing on the south andnorth exposures.Follow ECBC Visible Light Transmit-tance (VLT) requirements [ECBC4.3.3.1] for windowsto maximize lightand visual quality.

Eective daylighting strategy should in-

clude a combination o the ollowing:

Address interior color schemes;Interior suraces, and especially theceiling, must be light colored. Considerlight colored urniture and roompar tit ions to opti mize lig ht re lectance.Avoid urniture colors and placementthat will interere with light distribution.Keep ceilings and walls as bright aspossible.

Avoid glare

Inability to control glare is the mostcommon ailure in incorporatingdaylighting and especially importantwhere computer use is extensive. Bes t

Plan for future changes in activities and spacelayout. Install xtures and combinations ofxtures that provide efcient lighting for allmodes of space usage.

While selecting recessed lightingxtures, one must evaluate the reductionin lamp life as a result of higher junctiontemperature (Fig. 12).

Simulation Tips in Lighting DesignSimulation using a variety o computersotware tools is not only the way adesign proessional or team determinescompliance with the ECBC, but itmay be the best method or guiding a

design using a system-based approach.Lighting sotware helps users comparelighting alternatives and make sure thatthe ultimate design choice will providequality light. A wide range o variables

dierent light sources, ixtures o varyingeiciency and photometric, daylighting,and rooms with a w ide range o geometriesand surace inishesall make lightingdesign a challenge worthy o computermodeling.

In order to be useful, the mostsophisticated software tools requiretraining and experience on the part of theuser, but numerous simpler programs arealso available for the designer who doesnot need all the functionality of the most

complex products. A number of lightingsoftware tools are also available free ofcharge. Tey come from governmentagencies and private companies, and theyoffer a wide range of capabilities. Moreinformation about lighting softwareis available from the Building EnergySoftware ools Directory maintained onthe U.S. Department of Energy Web site.In addition, Te Illuminating EngineeringSociety of North America periodicallyconducts a survey of lighting software toolsand publishes the results in its magazine

Lighting Design and Application (LD+A).able 5 provides an overview of

lighting design tools used by the lightingprofessionals.

Top Lighting

Clear acrylic

glazing

Light Shelf

Side Lighting

White translucent acrylic glazing

he schematic shows a mix o top-lighting , side-lighting, light shelves, high re lectance ceilings and

wal l di usio n to p rovi de a irl y un ior m dee p-pl andaylighting without the glare o direct sunlight.

Fig 11: Simple daylighting Techniques


R2=0.96

T- point Temperature (deg c)

50000

40000

30000

20000

10000

0

35 40 45 50 55 60

Life(hrs)

Fig 12: Effect of Junction Temperature

on Life of LED Lamp (Source: Lighting

Research Institute)




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to be made to optimize a design or energyefficiency in lighting: reduction in firstcosts, reduced operation and maintenance,and increased occupant productivity andcomort. Consider the ollowing:

Good lighting also effects the operationand maintenance of a build ing. Asimpler and easy to control lighting

system will lower the rst cost of thesystem.

Relocate or reorient xtures to improvevisual qual ity;Modify existing xtures to reduce/eliminate light trapping and/or improvelight distribution. In xtures havingshades that absorbs light, modify oreliminate the shade;

Maintenance TipsTere are important considerations that need

Lighting Retrofit TipsReplace incandescent and other inef-cient lamps with lamps with higherlighting efcacy;Eliminate excessive lighting; disconnectthe ballast or remove the xture wherethey are not needed;Replace ballasts with high efciency

or reduced wattage types, or upgradeballasts and lamp together;

Table 5: Commonly Used Lighting Design Software

Software Discription Contact Information

AGI32Lighting calculation and visualization program. Latest release, 1.7, addsdaylight factor calculations, unied glare-rating calculations for discomfortglare in interiors. Company also offers a simplied version, AGI-Light.

Lighting Analysts Inc. Littleton,Colorado, USAPhone: +1-303-972-8852E-mail: [email protected]: www.lightinganalystsinc.com

Autodesk VIZThree-dimensional modeling, rendering, and presentationcapabilities. Includes daylighting calculations.

Autodesk Inc.San Rafael, California, USAPhone: +1-800-440-4198URL: www.autodesk.com

Building DesignAdvisor

A data manager and process controller that allows building designers touse several analysis and visualization tools throughout the building designprocess. The current version includes links to a simplied DaylightingComputation Module (DCM), a simplied Electric lighting ComputationModule (ECM), and the DOE-2.1E Building Energy Simulation software.

Konstantinos PapamichaelLawrence Berkeley NationalLaboratory Berkeley, CaliforniaPhone: +1-510-486-6854E-mail: [email protected]: http://gaia.lbl.gov/

DAYSIM

Daylighting analysis software that predicts the annual daylight availabilityand electric lighting use in buildings that use manual and automated lightingand blind controls. Based on Radiance software and available for free.

Christoph ReinhartNational Research Council CanadaInstitute for Research in ConstructionOttawa, Ontario CanadaPhone: +1-613-993-9703E-mail [email protected]: www.daysim.com

DIALux Lighting calculations and modeling from DIAL, a Europeanlighting services organization that is supported by manufacturers.Useful for simple calculations and available for free.

DIAL GmbH

Ldenscheid GermanyPhone: +49-0-2351-10-64-360E-mail: [email protected]: www.dial.de

LITE-PROLightin g design tool from Hubbell Lighting Co. Includesindoor and outdoor lighting capabilities and rendering.

Columbia Lighting, Spokane,Washington, USAPhone: +1-509-924-7000E-mail [email protected]: www.columbialighting.com/litepro/features.htm

Lumen Designer

The latest upgrade of the popular Lumen Micro product. Adds internalmodeling and daylighting capabilities. A highly interactive interfacefeatures a Design Wizard for setting up complex projects. Productalso includes plug-ins for roadway lighting and advanced rendering.Company offers a simplied version: Simply Lighting 2002.

Lighting Technologies Inc.Denver, Colorado, USAPhone: +1-720-891-0030URL: www.lighting-technologies.com

ProjectKalc

Helps the user compare the energy and operating cost impacts of alternativelighting upgrade solutions. It can handle lighting upgrades involving controls,relamping, delamping, tandem wiring, and more. It includes user-modiabledatabases of costs, labor time, and performance for over 8,000 commonhardware applications. The software is available free of charge through theU.S. Environmental Protection Agency (EPA) Energy Star program.

EPA Energy Star Program,Washington, D.C., USAURL: www.energystar.gov/index.cfm?c=business.bus_projectkalc

Radiance

An advanced lighting simulation and rendering package that calculatesspectral radiance values and spectral irradiance for interior and exterior spacesconsidering electric lighting, daylight, and inter reection. Used by architectsand designers to predict illumination, visual quality, and appearance ofdesign spaces. Used by researchers to evaluate new lighting and daylightingtechnologies and study visual comfort and similar qualities related to the visualenvironment. It is available for free. There is a project underway to develop anice interface to this extremely powerful application to improve its usability.

Charles EhrlichLawrence Berkeley National LaboratoryBerkeley, California, USAPhone: 510-486-7916E-mail: [email protected]: http://radsite.lbl.gov/radiance/HOME.htmlFree

VisualLighting analysis software for interior and exterior applications. Integratesanadvanced 3-D modeling environment with an intuitive interface. Professionalpresentation capabilities enable user to quickly develop, analyze, and modifyadvanced lighting designs. Basic version is available free of charge.

Acuity Brands LightingVisual Support Center, Conyers, Georgia, USAPhone: 800-279-8043E-mai: [email protected]: www.visuallightsoftware.com



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For more information:

Dr. Ajay Mathur, BEE ([email protected])

Dr. Archana Walia, USAID ([email protected])

Dr. Satish Kumar, IRG ([email protected])

USAID ECO-III Project

Phone: +91-11-2685-3110

Email: [email protected]

Web Site: www.eco3.org

provide iso -lux charts which discuss theillumi nation level in the space (Fig. 12).

Switching or Dimminghe irst primary decision ater deiningthe load and the application goals iswhet her to switch or dim the load .Switching and dimming are stand-alone

strategies but are oten used in the sameacility, and may be integrated in thesame control system. Dimming capabilityshould always be incorporated into areaswhere daylighting is the primar y lightingapproach. When using photo sensors ina dimming strategy, it is important toproperly commis sion and calibrate it.Failure to do so can sometimes result inmore energy use.

Degree of Automation NeededIt is worthwhile to determine the amounto local vs. central control that is neededrom the lighting control system. Manuallighting controls range rom a singleswitch to a bank o switches and dimmersthat are actuated by toggles, rotaryknobs, push buttons, remote control,and other means. Manual controls canbe cost-eective options or small-scalesituations. However, as the lightingsystem grows, automated systems becomemore cost-eective and are better atcontrolling light . Manual controls oten

waste energ y because the deci sion to shuto the lights when they are not needed isbased entirely on human initiative.

References:

Book Refe rences:E Source (2005): E Source Technology1.

Atlas Series - Volume I: Lighting,

Boulder, CO, USAEnergy Efciency Manual, by Donald2.R. Wulngoff, Energy Institute Press.Energy Conservation Building Code,3.Ministry of Power, May 2007.

Web References:Illuminating Engineering Society of1.North America ( IESNA),http://ww.iesna.orgAdvanced Build ings: echnologies2.and Practices,http://www.advancedbuildings.org/he Lighting Research Center at3.Rensselaer Polytechnic Institute,http://www.lrc.rpi.edu/Heshong-Maone Group4.http://www.h-m-g.com/he New Buildings Institute,5.http://www.newbuildings.org/light-ing.htmWindows and Daylighting , Lawrence6.Berkeley National Laboratory,http://windows.lbl.gov/

Fluorescent lamps last an average of10 times longer than incandescent andreduce re-lamping labor costs.Clean xtures and lamps at appropriateintervals to maintain optimum lightingoutput.

Lighting Controls Tips

Purpose o Lighting Controls: In manyapplications, the overall purpose o thelighting control system is to eliminatewaste whi le providing a produc tive v isualenvironment.This may enta il:

providing the right amount of light;1.providing light where its needed.2.

A ew issues to keep in mind whiledesigning controls are:

Install a separate control circuit foreach lighting element that operates on adistinct schedule;

Where l ight xtures are needed in apredictable variety of patterns, installprogrammable switches;Install lighting controls at visible, accessiblelocations;

Where l ighting is needed on a repetit iveschedule, use timeclock control;Install occupancy sensors in bathrooms,conference rooms, and other spaces notin constant use.

Controls, switches, shades, timers,and other lighting strategies can get

complicated. It is likely that adjustmentswill occur a ter occupancy. he easierthe lighting system is to understand andadjust to accommodate the occupants a ndbuilding unction, the less likely it is thatsensors will be disabled, disconnected,or bypassed. he ollowing provides astrategy or selecting the right controlsor your building.

Define Application Goalshe irst step in determining the right

control strategy is to thoroughly deineand understand the application goals.Lighting designers should be asked to

Align control circuits paral lel to daylight contours

when dayl igh t le vels var y ac ros s th e sp ace . In the se

pla ns a nd se cti on o a sid elit o ice a nd sk yli t a ctor y,

A experiences the most daylight and is turned o or

dimmed irst B is controlled second, C receives

the least daylight and is let at ull power to maintain

wal l br ig htne ss. he o ice p enden t di rec t-ind ire ct

luminaires are dimmed in response to daylight ry

luminaires are bilevel switched. I n the actory, the end

luminaires on the B row are controlled with C circuit to

maintain wall brightness.

Fig. 12: Plan Views of Daylight Isolux Contours (Source: Advanced Lighting

Guidelines, New Buildings Institute

B C C

C

B

A

B

A

C

A

800Lux 600Lux 400Lux 200Lux


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