Field

TestIssu

e 1IN

TE

GR

AT

ED

SK

YL

IGH

T L

UM

INA

IRE

INTEGRATED SKYLIGHT LUMINAIRE

Demonstration and Evaluation of Lighting Technologies and Applications

ESTTIELDFLighting R

esearch Center

Project ProfileThe Lighting Research Center (LRC) fieldtested four prototype Integrated SkylightLuminaires in an industrial setting to deter-mine how the product performs in its in-tended application. For the field test facility,the LRC chose an open area in a storageand shipping warehouse. The IntegratedSkylight Luminaire was designed for thistype of high-bay facility, where traditionalskylights have had limited success. Oftenelectric lighting is not controlled to takeadvantage of available daylight. The Inte-grated Skylight Luminaire was designed toaddress these issues by pairing diffuseddaylight and electric light with a photosen-sor-controlled dimming system that main-tains intended light levels in the facility.

ContentsProject Profile ........................................... 2

Overview of the IntegratedSkylight Luminaire .................................... 2

Field Test Objectives ................................ 2

Product Description .................................. 3

Field Test .................................................. 4

Field Test Results ..................................... 7

Glossary ................................................. 11

References ............................................. 11

Findings and Recommendations............ 12

Field Test ObjectivesFew truly integrated skylight and electric light systemscurrently exist on the market, and information about theirefficiency is limited.1 Building evaluations have shown thatmany photosensor-controlled lighting systems do not meetenergy savings predictions because of inadequate photosen-sor design or inadequate commissioning of the electriclighting control systems.2–5 The LRC tested the IntegratedSkylight Luminaire in the field to:

• Test the logistics of installation and maintenance

• Check the functional performance of each component in theintegrated system

• Gather employee feedback about the product in its intendedsetting

• Measure daylight and electric light levels in an actualinstallation

• Quantify energy savings

Components of the Integrated Skylight Luminaire

Overview of the Integrated Skylight LuminaireThe Integrated Skylight Luminaire combines a skylight, a sunlight diffuser box, and an electric lighting sys-tem. A photosensor control system automatically dims or switches electric lights in response to daylight. Aportable wireless commissioning device performs initial setup and calibration of the electric lighting system.

The Integrated Skylight Luminaire was developed by the LRC for daylighting in flat-roofed, high-bay build-ings such as warehouses, factories, and “big-box” retail stores. High-bay buildings are ideal candidates forskylights because they tend to be single-story, large-volume spaces. Windows cannot deliver daylight tothe deep interior of these types of spaces. High ceilings that are typical of these buildings facilitate uniformlight distribution throughout the space and minimize the perception of glare from electric lighting systemsand skylights.

2 Lighting Research Center, Issue 1 Field Test

Fluorescent luminaire

Clear acrylic skylight

Photosensor(mounted in well)

White acrylic side panelsof sunlight diffuser box

Luminaire controller

Transceiver

Sandblasted clearacrylic bottom ofsunlight diffuser box

Product DescriptionThe Integrated Skylight Luminaire consists of a skylight, asunlight diffuser box, an electric luminaire assembly, and aphotosensor with an electronic luminaire controller. A smallportable device is used to commission the system and adjustilluminance thresholds to the desired levels.

Skylight and Sunlight Diffuser Box — The IntegratedSkylight Luminaire uses both clear and diffuse materials tocapture and distribute daylight. This feature differs fromtraditional skylights, which generally use one or the other.Traditional clear skylights allow direct shafts of sunlight topenetrate, producing a nonuniform light distribution andglare. Traditional diffuse skylights mediate sunlight distribu-tion but reduce light transmittance compared to clearskylights. The Integrated Skylight Luminaire combines thebenefits of these materials to maximize daylight collectionwhile avoiding glare.

A standard 4 ft x 4 ft (1.2 m x 1.2 m) double-glazed clearskylight is designed to fit into typical high-bay structuralspacing. A 4-ft-high (1.2 m) sunlight diffuser box mountsinside the space below the ceiling. The height of the sunlightdiffuser box optimizes daylight collection without interferingwith operations in the warehouse. The diffuser modifies thedistribution of sunlight so that it more closely matches theelectric lighting, easing the transition between electric lightand daylight without causing glare (see Electric LuminaireAssembly). The side diffusing panels are constructed ofwhite acrylic to maximize diffusion of direct sun. The bottomof the diffusing box is constructed of sandblasted clearacrylic, a material that provides a visual connection to theexterior and allows greater acceptance of interreflected lightfrom the side panels. In northern latitudes, the angle of thesun is rarely high enough to reach the bottom panel, so littlediffusion is necessary.

Electric Luminaire Assembly — Twelve linear fluorescentT8 lamps housed in four industrial striplights serve as theelectric luminaire assembly. The striplights are arranged in asquare configuration 4�ft (1.2 m) below the ceiling and areplaced outside of the sunlight diffuser box (rather thaninside) to eliminate loss from electric light reflecting offinterior surfaces of the diffuser box and back out the skylightaperture. Such light loss would requireincreased lighting power density for thesame illuminance.

The electric luminaire assembly in thisprototype is connected to the roofstructure, but it is suspended to alignwith the bottom of the sunlight diffuserbox. The electric lighting is designed forstep-switching or continuous-dimmingcontrol. This prototype has bothcapabilities. The luminaires are tandemwired, allowing uniform appearance inthe space when in step-switch mode.The outer ring of lamps can switchseparately from the intermediate andinner rings of lamps. Optional dimmingballasts allow all lamps to be dimmed tothe same level.

Photosensor Lighting Control System — The IntegratedSkylight Luminaire uses a photosensor and an electronicluminaire controller to automatically reduce the electric lightlevels when sufficient daylight is available. The photosensorcontrol system was custom designed based on LRC re-search showing that complicated commissioning procedures

and occupant dissatisfaction with the lighting provided werethe major barriers to the effectiveness of photosensor-controlled lighting systems.2,6

The luminaire controller is housed in one corner of theelectric luminaire assembly and is connected by a low-voltage wire to a photosensor mounted in the well of theskylight. The photosensor continually monitors levels ofdaylight entering the skylight well. Using these data, theluminaire controller continually adjusts the electric lightlevels based on the amount of available daylight. Theluminaire controller turns off the lamps entirely whensufficient daylight exists, a feature that allows significantenergy savings. A time delay prevents rapid electric lightfluctuations under scattered cloud conditions.

Upon installation of multiple IntegratedSkylight Luminaires, the control systemof each unit is commissioned separatelyto correlate measured daylight levels todesired electric light levels.

Commissioning Device — The initialsetup and calibration of the controlsystem is performed using a wirelessportable commissioning device thatresembles a remote control for atelevision set. The commissioning devicecontains a photosensor and an infraredtransceiver (which communicates withthe transceiver in the Integrated SkylightLuminaire), as well as buttons used tostart the fully automatic commissioningprocess. The commissioning device alsoincludes buttons for manually overridingprogrammed functions in the luminairecontroller, such as lights off or lights onat full power. Dials on the commissioningdevice change both the threshold atwhich lights are dimmed and the amountof overall dimming. These two settings provide a means ofaltering the balance between energy savings and occupantsatisfaction. The amount of overall dimming can be adjustedover a range from a 1:1 trade-off between daylight andelectric light illumination levels, to a 3:1 trade-off. At 3:1trade-off, illumination levels from daylight need to be triplethe initial electric light level before the electric lighting isturned off.

A single commissioning device can be used to commissioneach of the Integrated Skylight Luminaires within an installa-tion. The user places the commissioning device on a hori-zontal surface beneath the skylight and presses a button tostart the automatic commissioning sequence. Duringcommissioning, the luminaire controller measures thephotosensor-to-workplane illuminance ratio needed for theopen-loop proportional control algorithm used in the control-ler. If dimming ballasts are used, the Integrated SkylightLuminaire calibrates the dimming control output to thedimming response function of the particular ballast used.This procedure ensures uniform dimming response over thefull range of dimming control provided by the ballasts. Theluminaire controller can be remotely adjusted to accommo-date continuous dimming or step switching.

The commissioning process takes less than 3 minutes per unitand can be accomplished in any amount of daylight bynonexpert personnel. All measurements and calculations areperformed automatically by the luminaire controller using thephotosensor in the light well of the skylight and the commis-sioning device on the workplane.

Lighting Research Center, Issue 1 Field Test3

Photosensordetects collecteddaylight andsends informationto luminairecontroller

Commissioningdeviceautomatessetup andcalibration ofthe luminairecontrol system(see photo onpage 4)

4 Lighting Research Center, Issue 1 Field Test

Field Test

Test SiteThe Lightolier Distribution Center in Norwich, Con-necticut, was the site of the field test. It is a 214,000ft2 (19,900 m2) storage and shipping facility thatsupplies lighting products to customers across theeastern part of the United States. Pallets of lightingproducts arrive from Lightolier manufacturing facili-ties and are stored in vertical racks and horizontalbins before being shipped to customers.

Ceiling heights are approximately 31 ft (9.5 m), withan open bar truss structural system and exposedHVAC duct work and electrical conduits. Racks are18 ft (5.5 m) in height, with four shelves for shippingpallet storage. A few translucent wall panels areinstalled in some parts of the building, but mostspaces receive no daylight.

The facility operates 18 hours a day Monday–Fridayand intermittently on weekends. Thirty employeeswork the day shift, and five work the evening shift.

The majority of the existing lighting in this warehouseconsists of 400-W metal halide high-bay downlightswith a linear aisle-lighter distribution. Mountinglocations are spaced approximately 16 ft x 22 ft(4.9�m x 6.7 m) apart.

InstallationThe LRC installed four Integrated Skylight Lumi-naires in the center of the warehouse, also called thetube storage area, in a location that has no otheraccess to daylight. Four of the existing metal halidedownlights were removed, and each replaced with anIntegrated Skylight Luminaire. Electric light levelsusing the Integrated Skylight Luminaires meet orexceed those of the previous 2-year-old lightingsystem. The space now appears less cave-likebecause some light is directed toward the ceilingduring both day and night conditions.

Page 5 shows the photometric measurements at thefield test site. The “daylight only” measurements arenot intended to represent the wide range of photo-metric conditions at various times of day, seasons ofthe year, and weather conditions. However, themeasurements do show the impact of the sunlightdiffuser box on light distribution under sunny condi-tions and that daylight can make a significant contri-bution to illumination.

Four units were installed in the tube storage area

Commissioning device communicates with luminairecontroller in Integrated Skylight Luminaire (see page 3)

Storageracks

Structuralcolumn

NORTH

Existing metalhalide luminaires

Integratedskylightluminaires

22´

16´

0´ 8´ 16´ 32´

0m 2m 4m 8m

Tube storagearea

Lighting Research Center, Issue 1 Field Test5

50˝

abov

eflo

or

18´ –

0˝

Stor

age

Rack

(Und

er IS

L)

(Bet

ween

ISLs

)

(Und

er IS

L)

8

153

652

19

20

2122 23 24

26 2728 29

3031

10

13

11 149

17

18

74

1

25

16

12

Photometric measurements at the field test site

1 lux = 0.093 footcandleISL = Integrated Skylight Luminaire; MH = metal halide luminairesN/A = not available* Includes contribution from adjacent MH luminaires, which has added on average 190 lux horizontal and 60 lux vertical to peripheral measurements.** Daylight measurements taken on a sunny afternoon between 2:00 and 3:00 P.M. in early September. These values do not include the contribution of adjacent MHluminaires, which on average would add 190 lux horizontal and 60 lux vertical to peripheral measurements.*** One ISL experienced communications problems (see Performance of the Electric Lighting on page 8) and would not override control of electric lights to allowdaylight-only measurement.

)xul(ecnanimullIlatnoziroH )xul(ecnanimullIlacitreV m/dc(ecnanimuL 2)

tnemerusaeMnoitacol

,LSIcirtcele

*ylno

,LSIthgilyad

**ylnoHMsuoiverP

*)tifortererofeb(tnemerusaeM

noitacol

,LSIcirtcele

*ylno

,LSIthgilyad

**ylnoHMsuoiverP

*)tifortererofeb(tnemerusaeM

noitacol

,LSIcirtcele

ylno

,LSIthgilyad

**ylnoHMsuoiverP

)tifortererofeb(1 394 042 004 01 023 ***A/N 781 91 A/N A/N 000,752 074 022 673 11 032 ***A/N 521 02 A/N A/N 000,643 334 732 614 21 081 ***A/N 29 12 12 0032 A/N4 294 423 293 31 072 422 291 22 6 32 45 884 202 973 41 342 761 851 32 4 01 36 404 633 863 51 481 73 401 42 7 17 37 605 212 093 61 063 241 732 52 81 0732 A/N8 974 161 553 71 042 021 761 62 93 0064 000,919 404 ***A/N 123 81 881 14 621 72 0605 A/N A/N

82 0285 A/N A/N

92 83 0053 081,1203 54 0572 000,2113 24 0062 0053

6 Lighting Research Center, Issue 1 Field Test

MethodologyThe LRC monitored system performance and energy usageby:

• Conducting an employee survey and interviews to gatheroccupant observations and feedback about system perfor-mance and acceptability

• Retrieving and analyzing energy usage data recorded in theluminaire controller of the Integrated Skylight Luminaires

• Videotaping one of the units to monitor dimming perfor-mance under both continuous-dimming and step-switchingconditions.

The employee survey was conducted several months afterthe Integrated Skylight Luminaires were installed to ensurethat the employees had ample opportunity to see the systemoperating in the tube storage area during the daytime andafter dark. The survey consisted of a simple questionnairethat provided employee feedback on light levels, visualcomfort, and clarity. For comparison, the same questions(except for the daylight-related ones) were asked of the samegroup of employees about a similar open space, the shipmentstaging area (not shown in the drawings or photos). Thestaging area was lighted by conventional 400-W and 1000-Wmetal halide lamps in high-bay downlights. No windows orskylights were visible in the staging area. Employees wereasked to enter the tube storage area during midday tocomplete the survey. Then the employees were led into thestaging area where they completed another copy of thesurvey, reporting their assessment of the lighting in that area.Some employees also commented on their recollection ofnighttime conditions in the tube storage area.

The luminaire controller in each Integrated Skylight Luminairerecorded energy usage at hourly intervals by using anelectrically erasable programmable read-only memory chip(EEPROM). Energy usage data were calculated by a prede-termined function relating the dimming level to the powerdemand of the system and integrating over the 1-hour timeintervals. The data covering the 8-month test period fromMarch to November 2002 were retrieved from memory chipsusing the portable commissioning device and were thendownloaded to a standard laptop computer for analysis.

Environmental implications of the actual energy usage wereestimated using ISO New England’s publication, 2000NEPOOL Marginal Emission Rate Analysis, which lists NewEngland Power Pool’s aggregate emissions in the states ofConnecticut, Maine, Massachusetts, New Hampshire, RhodeIsland, and Vermont.7 LRC used this publication to correlatekWh saved to environmental emissions avoided.

The time-lapse video camera captured luminaire anddaylight activity of one of the units, recording 1 second ofvideo every 5 minutes, to enable visual verification that theunit dimmed down and finally turned off in response todaylight. Positioned in the foreground of the time-lapsevideo camera were a clock, an illuminance meter, and awatt meter. The watt meter was directly wired to the lumi-naire controller of the unit. The illuminance meter enabledthe LRC to verify that the control system was appropriatelydimming or switching the electric lights.

Tube storage area before and after installation of the

Before installation

After — Daytime with ISL electric lighting on

Lighting Research Center, Issue 1 Field Test7

Field Test Results

Employee FeedbackThe employee survey consisted of 10 statementsabout the lighting in the facility. To complete thesurvey, employees were instructed to indicate if theyagreed or disagreed with each statement. The tableon the next page gives the percentage (%) of em-ployees who agreed with each statement.

The results indicated that during the daytime, all theemployees questioned thought the Integrated Sky-light Luminaires provided good, comfortable lightingthat enabled them to easily see what they needed tosee. Compared to the metal halide luminaires in thisfacility, the Integrated Skylight Luminaire was lesslikely to be considered uncomfortable to look atdirectly and was much less likely to be consideredtoo bright. About two-thirds (69%) of the employeesquestioned said they would like to see the IntegratedSkylight Luminaire installation extended to the rest ofthe facility.

“[The Integrated Skylight Luminaire] fulfillslighting requirements better than a single

light because it is a larger area ofillumination.”

— an employee

On the negative side, some employees found theswitching of the fluorescent lighting during the dayto be disturbing. (“Switching” is the term being usedhere to encompass dimming down and up, turningoff completely, turning back on, and the coordina-tion of these stages among the 12 lamps in a unit,all in response to the daylight levels present in theskylight.)

“The skylights don’t work fully incooperation with each other.”

— an employee

Not enough employees were available to answer thesurvey about the Integrated Skylight Luminaires afterdark. Those who were available reiterated that theelectric lighting was comfortable and allowed them tosee what they needed to see. The fluorescent lumi-naires were considered more comfortable to look atdirectly than the metal halide luminaires in the stag-ing area. However, some employees found theappearance of the fluorescent luminaires less attrac-tive at night than by day.

Integrated Skylight Luminaires (ISLs)

After — Daytime with ISL electric lighting off

After — Nighttime

8 Lighting Research Center, Issue 1 Field Test

“I think they’re great. When I come in themorning, they’re on and I don’t bump

into things.”— an employee

Comments made by the employees showed that theconnection to the outside provided by the IntegratedSkylight Luminaires was appreciated to such anextent that some employees wanted the bottompanel in the diffuser box removed to allow a clearerview of the sky. Others commented that the bottomdiffuser panel was essential for safety reasons sothat employees driving forklifts were not exposed todisability glare from direct sunlight.

Performance of the Skylight and SunlightDiffuser BoxThe skylights are well-sealed at the roof penetration.The LRC detected no evidence of water leakage. Thelower sunlight diffuser boxes were custom-built forthis prototype installation, and they did show oppor-tunity for improvement. Insect deposits accumulatedin the diffuser box of each Integrated Skylight Lumi-naire. This indicated that some of the diffuser jointsor seams failed, allowing insects to enter the box.Joint or seam gaps may have been the result oftemperature fluctuations, which would have causedexpansion and contraction of the materials formingthe sunlight diffuser box.

Proposed Solution: Joints and seals of the sunlightdiffuser box should allow for thermal expansionand contraction while retaining the seal.

* Number of employees agreeing with the statement, over the total number who responded to the statement.N/A = not applicable

Performance of the Electric LightingSeveral employees commented that the electriclighting in the Integrated Skylight Luminaires some-times appeared to be malfunctioning. This impressionprobably occurred because of differences in theoperation of the four Integrated Skylight Luminaires.Custom-assembled electronics circuitry in one of theunits did behave erratically for most of the evaluationperiod and may have contributed to this impression.However, two deliberate features of the IntegratedSkylight Luminaire’s design may have also contrib-uted to the perception of malfunctioning. Every unit iscommissioned individually, so for the same daylightconditions, the electric lighting of each unit could beswitched at a slightly different time. This feature willbe particularly noticeable in step-switching mode,when one unit may have four lamps on while theadjacent unit has eight on. Also, because two unitswere adjacent to vertical racks in this installation,their commissioning values were slightly different,resulting in different operation.

Proposed Solution: Switching could be bettercoordinated by using a master–slave controller.One master unit with a photosensor could send acontrol signal to a larger group of slave units.

A second aspect of the Integrated SkylightLuminaire’s design may have contributed to theperception of malfunction. When in step-switchingmode, control of the outer, middle, or inner ring offluorescent lamps in each unit is determined byindependent luminaire controllers. Even if all of the

gnithgilehttuobastnemetatseeyolpmEyadybegarotsebuT

)esuniserianimuLthgilykSdetargetnI(emitynataaeragnigatS)gnithgiledilahlatemlla(

doogsignithgileht,llarevO )%001(*61/61 )%58(31/11eesotdeenItahweesotysaesiti,llarevO )%001(51/51 )%001(31/31

elbatrofmocsignithgileht,llarevO )%001(61/61 )%58(31/11

takoolotevitcarttasierutxifthgilehT )%37(51/11 )%45(31/7

yltceridtakoolotelbatrofmocnusierutxifthgilehT )%52(61/4 )%37(51/11

thgirbootsemitemossignithgilehT )%31(61/2 )%04(51/6

midootsemitemossignithgilehT )%13(61/5 )%72(51/4

srekcilfgnithgilehT )%31(51/2 )%02(51/3

saeraemosniswodahsgnortssetaercgnithgilehT )%0(61/0 )%92(41/4gnibrutsidsignithgiltnecseroulfehtfognihctiwsehT )%91(61/3 A/N

Lighting Research Center, Issue 1 Field Test9

units have one ring of lamps on, the units may eachbe operating a different ring of lamps (outer, middle,or inner). Although it may appear to be haphazard,switching of lamps was intended to be randomizedso that all of the fluorescent lamps would accumulatethe same number of hours of use, thus ensuringequal operation time of each lamp to minimizerelamping maintenance.

Proposed Solution: It might be more acceptable tooccupants either to adopt a time-based, system-atic rotation of the switching priority of the fluores-cent lamps to minimize relamping maintenance,or to use diffusers below the lamps to concealswitching patterns.

Despite careful attention, the installation experi-enced premature lamp failures when dimmingfluorescent lamps. During the first few months ofoperation, when the luminaire controllers were setto the continuous dimming mode, several lampsfailed and were replaced. Although investigation isongoing, two electrical issues have emerged aslikely causes: 1) poor electrical contact between thelamp and socket, and 2) signal interference in thetandem wiring used in the field test to enable bothcontinuous and step dimming.

Electrical Contact — Extreme end-darkening of somelamps indicated improper cathode heating. The mostlikely cause was poor or nonexistent electrical con-tact with one of the two lamp pins at each lamp end.For this prototype assembly, LRC selected off-the-shelf luminaires. The luminaires featured a type ofspring-loaded lamp socket that may work fine withinstant-start type ballasts, which need only onecontact at each lamp end to operate properly. Rapid-start dimming ballasts require two low-resistancecontacts at each lamp end to maintain expectedlamp life. After LRC replaced the luminaires’ instant-start ballasts with rapid-start dimming ballasts, thesockets provided unreliable electrical contact with thetwo lamp pins. End-darkening occurred even afterLRC attempted to improve contact by installingadditional spring-loaded cords to keep the socketsfirmly in place against the lamp pins.

Proposed Solution: If continuous dimming isused in future Integrated Skylight Luminairedesigns, careful attention must be paid to thetype of lamp socket. A “knife-edge” socket maybe the most reliable.

Electrical Signal Interference —The tandem wiringused in this installation was necessary to be able todemonstrate both continuous dimming and stepswitching. However, tandem wiring may have contrib-uted to premature lamp failure when using the con-tinuous dimming mode. Since wiring was not done inseparate wireways, interference (crossover of sig-nals) may have caused losses in the lamp drivecurrents to the adjacent wires, which may haveshortened lamp life. Separate wireways are espe-cially critical when dimming ballasts are used be-cause of low-level lamp drive and the importance ofproper cathode heating current. In both step-switch-ing and continuous-dimming mode, the safety shut-down feature of the dimming ballasts was occasion-ally falsely triggered in response to interference.Although not a contributor to shortened lamp life,intermittent ballast safety shutdown provided addi-tional evidence of interference problems.

Proposed Solution: When using dimming bal-lasts, avoid tandem wiring. Otherwise, tandemwiring done in shielded, separated wireways mayavoid mutual interference between lamp leads.

Performance of the Photosensor ControlSystemThe time-lapse video data closely corresponded todata recorded by the Integrated Skylight Luminaireunits themselves. Apart from the electrical problemsdiscussed above, the fluorescent lights dimmed andswitched appropriately and consistently in responseto the presence of daylight.

Performance of the Commissioning DeviceThe LRC verified that the integrated skylight lumi-naire was easy to commission using the commission-ing device. After override functions were used, onepress of a button allowed normal operation to re-sume without having to recommission the unit.

10 Lighting Research Center, Issue 1 Field Test

Energy SavingsWhen sufficient daylight waspresent, the Integrated SkylightLuminaire turned off the electriclighting rather than maintaining aminimum dim level (see Typicaldaily lighting energy use graph). Inthis installation, use of the Inte-grated Skylight Luminaires withtheir photosensor lighting controlsystems reduced energy con-sumption by 40% compared to theprevious metal halide lighting (seeEnergy savings graph). If lightingcontrols had not been used, theenergy savings would have been17% instead of 40%, due to amore efficient luminaire type andreduced ballast losses. Controllingthe electric lights in the IntegratedSkylight Luminaires providedenergy savings of 28%.

Energy reduction is greatest onsunny days. Since peak electricaldemand often coincides withsunny days, the Integrated Sky-light Luminaire may offer demandsavings as well.

Environmental Implications —The Integrated Skylight Lumi-naires at the field test site re-sulted in lower power plant emis-sions from reduced energy use(see table at right).

Reduced power plant pollution7 from 8 months use of three IntegratedSkylight Luminaires (ISL)

tnatulloP

htiwLSIfosgnivasnoissimEotderapmoclortnocgnithgil

HMgnitsixe

LSIfosgnivasnoissimElortnocgnithgilhtiw

tuohtiwLSIotderapmoclortnocgnithgil

sbl gk sbl gk

OS 2 7.11 3.5 7.6 0.3

ON x 6.3 6.1 0.2 9.0

OC 2 2082 1721 3061 827

Typical daily lighting energy use before and after installation ofIntegrated Skylight Luminaire

Fac

ility

clo

sed

400350

300250200

15010050

0

Wat

tage

500

450

Time of day

Mid

nigh

t

Mid

nigh

t1 2 3 4 5 6 7 8 9 10 11 1 2 3 4 5 6 7 8 9 10 11

No

on

SunsetSunrise

MinimumISL dimlevel beforeshutoff

Existingmetal halidelighting

ISL withcontinuousdimming

Ene

rgy

savi

ngs

Sulphur dioxide (SO2) is associated with visible pollution (haze) and acid rain. SO2 is also a directlung irritant. Nitrogen oxides (NOx) are a primary cause of ozone production (a main componentin smog) and acid rain. Carbon dioxide (CO2) is a possible contributor to future climate changes,such as global warming.

Energy savings from three* Integrated Skylight Luminaires (ISLs) March–November 2002

kWh

(8 m

onth

s)

0500

1000

15002000250030003500

400045005000

40% savings28% savings

ISL with lightingcontrol (actual)

Previous metalhalide lamps

ISL withoutlighting control

17% savings

* Data were available for three of the four units, including both step dimming and continuousdimming operation.

Lighting Research Center, Issue 1 Field Test11

GlossaryCommissioning — After installation of an automatic lighting controlsystem, the initial process of equipment setup, calibration, input ofcontrol settings, and tuning to adjust the system to the actual locationand conditions in which it is installed.

High-Bay — Building type with a tall ceiling, often single story, greaterthan 15 ft (4.6 m) in height, and with an unfinished appearance charac-terized by exposed structural trusses, ductwork, and other mechanicalequipment.

Interference — In this installation, crossover of electrical signals thatmay occur among adjacent unshielded electrical wires. In generalinterference is an electrical or electromagnetic disturbance, phenom-enon, signal, or emission that can cause malfunctioning or degradationof the electrical performance of electrical and electronic equipment.

Open Loop — Daylighting control strategy in which the photosensordoes not monitor the electric light that it controls. The photosensor iseither mounted outdoors, or is aimed such that it only receives lightfrom the exterior. A signal proportional to the exterior daylight instructsthe control system to dim the electric light by an amount proportional todaylight levels.

Tandem Wiring — Wiring lamps in one fixture to a ballast in anotherfixture. This method of wiring permits a uniform pattern of illuminationwhen used in step-switching applications.

Transceiver — An electronic device that transmits and receives data.

References1 Leslie, R., and J. Brons. 2002. An integrated skylight luminaire: combining

daylight and electric luminaires for energy-efficiency. In Proceedings of RightLight, 5:269-278. Stockholm, Sweden: Borg & Co.

2 Bullough, J., and R. Wolsey. 1998. Specifier Reports: Photosensors. Troy, NY:Rensselaer Polytechnic Institute.

3 Maniccia, D. A., B. Rutledge, M. S. Rea, and W. Morrow. 1999. Occupant useof manual lighting controls in private offices. In Journal of the IlluminatingEngineering Society, 28(2):42-56.

4 Mistrick, R., C. H. Chen, A. Bierman, and D. Felts. 2000. A comparison ofphotosensor-controlled electronic dimming in a small office. Journal of theIlluminating Engineering Society, 29(1):66-80.

5 Rea, M. S., and D. Maniccia. 1994. Lighting Controls: A Scoping Study. Troy, NY:Rensselaer Polytechnic Institute.

6 Bierman, A., and K. M. Conway. 2000. Characterizing daylight photosensorsystem performance to help overcome market barriers. Journal of the Illuminat-ing Engineering Society, 29(1):101-115.

7 ISO New England Inc. 2002. 2000 NEPOOL Marginal Emission Rate Analysis.Prepared for the NEPOOL Environmental Planning Committee. Table 2, page7. Accessed on 18 November 2002 at http://www.iso-ne.com/Planning_Reports/Emissions

Findings and Recommendations

Findings

• Significant lighting energy savings can be achieved using the IntegratedSkylight Luminaire, even if a facility is occupied long into the night.

• Skylights and electric lighting can be integrated to balance energy savingswith occupant satisfaction.

• Employees in a warehouse environment appreciate having the connection tothe exterior that skylights provide.

• Commissioning requirements need not be a barrier to the use of photosensor-controlled lighting systems.

Recommendations for Product Development

• When Integrated Skylight Luminaires are used in a large open space andstep-switching mode is used, it may look haphazard to have each luminairecontrolled separately. Occupants may prefer unified switching patterns.

• Joints and seals of the sunlight diffuser box should allow for thermalexpansion and contraction.

• When used with rapid-start dimming ballasts, fluorescent lamp sockets mustprovide reliable electrical contact with all lamp pins.

• When using dimming ballasts, tandem wiring should be avoided or provided inshielded, separated wireways to avoid mutual interference between lamp leads.

• For reduced product cost, use nondimming ballasts and step switching.

Current Product Status

• The Integrated Skylight Luminaire is not commercially available at time ofpress. Manufacturers are invited to commercialize this product. The lightingcontrols system described in this publication was developed by LRC and willbe made available to interested manufacturers.

12 Lighting Research Center, Issue 1 Field Test

Field Test DELTAIssue 1Integrated Skylight LuminaireJanuary 2003

Field Test DELTA evaluates new energy-efficientlighting products to independently verify fieldperformance claims and to suggest improvements. Aprimary goal of the Field Test DELTA program is tofacilitate rapid market acceptance of innovative energy-efficient technologies.

Program Director: Sandra Vásconez

Project Manager: Jennifer Brons

Product Development and Assembly: LightingResearch Center

Human Factors Interviews: Peter Boyce, OwenHowlett

Reviewers: Andrew Bierman, Peter Boyce, Russ Leslie

Editors: Marilyn Morgan, Virginia Brouns Harrison

Technical Assistance: Jonas Concepcion, David Cyr,Wendy Fujinaka, Nutron Manufacturing

Illustrations: Jonas Concepcion

Photography: Jennifer Brons (“before” and page 3–4photos); Randall Perry Photography (“after” and coverphotos)

Publication Design and Production: James Gross

SPONSORS

Connecticut Light and Power Company (CL&P)

New York State Energy Research and DevelopmentAuthority (NYSERDA)

CREDITS

Lightolier Warehouse: Bruce Roberts, Lead Mechanic;Cliff Jackson, Warehouse Manager

Lightolier Corporate: William Blitzer, Mete Kantar,Bob Wedekind

CL&P: John Mutchler, Ken Galanto, Sam Fankhauser

NYSERDA: Marsha Walton

Architect: James Vance and Associates Architects

General Contractor: G. Schnip Construction

Skylights: Wasco Products

Luminaires: Lightolier

Dimming Ballasts: Advance Transformer

Equipment Donors: Lightolier, Wasco Products

For publication ordering information, contact:

Rensselaer Polytechnic Institute

21 Union Street

Troy, NY 12180-3590

(518) 687-7100

email: lrc@rpi.edu ▲ www.lrc.rpi.edu

Copyright © 2003, Rensselaer Polytechnic Institute. Allrights reserved. Neither the entire publication nor anyof the information contained herein may be duplicatedor excerpted in any way in any other publication,database, or other medium and may not be reproducedwithout express written permission of RensselaerPolytechnic Institute. Making copies of all or part of thispublication for any purpose other than for undistributedpersonal use is a violation of United States copyrightlaw.

ISSN 1075-3966 Printed on recycled paper.