2008 Research Paper - P.O.E. Energy Audit. Lighting Audit. (Part 03)

LIGHTING.

LIGHTINGCONTENTS.

SummerScenarioForThackleyEnd.

WinterScenarioForThackleyEnd.

LuxReadings.Flat29.

ArtificialLighting.Flat29.

LightingLoad.Flat29.

SavingsRecommendations.Flat29.

LuxReadings.Flat50.



LuxReadings.Flat40.



LuxReadings.Flat38.





DataSummary.

SummerScenarioForThackleyEnd.

This drawing illustrates the sunmovement in reference to the sun path diagram for theOxfordshirearea.Herewecanseethesunlightingdirectionandconsequentshadowsforeveryhourbetween8:00

–19:00forthesunpositionofJuly.

With thiswe can track the shadowmovementon site, and recordhow thebuilding cast shadowsoneachother.

WinterScenarioForThackleyEnd.

Thisdrawingillustratesthesunlightingdirectionandconsequentshadowsforeveryhourbetween8:00

–15:00forthesunpositionofJanuary.Itmustbenotedthatunlikethesummerscenario,wecanseewinter shadows create large darker areas on land before the overall daylight decreases. Occupantsmentioned that some flats have had problems during winter months from overshadowing

(consequentiallyreducingnaturallightintotheflats),andherethisissueisillustrated.

We have collated further data to record the natural lighting of Winter months within the flats: luxreadingswillberecordedandphotographicstudy.Thesewillfollowwithinthisreport.

AparticularcauseforconcernfornaturallightingThackleyEnd,isthedenserowofevergreentreesonthewestbuildingonthesite,which inwintermonthsobstructnatural lightentering intosomeof the

flatson that facade.This resulted in theoccupantsof these flats switching lightson indaylighthourswhenordinarilynotneeded.Thiscanalsoresultinalossofsolargainsatthistimeresultinginadditionalheatingloads.

LuxReadings.Flat29.

TimeTaken:13:00hrs

Orientation:Southfacinglivingroom/balconyHighestReading:560lux(livingroombybalcony)LowestReading:8lux(kitchen)/3Lux(bedroom)

This flat has a balcony of South facing orientation,which exposes it to ahighsolar irradiance.Thisresults inhighluxlevelreadingseveninWinter

months.ThisSouthern façade isalsoalmostentirelyglazedallowinga lotof this light topenetrate into the internal spacesand,mostnotably, intothe living space. Consequentially, the living room spaces enjoy an

outstanding degree of thermal delight and an elating ambience. Theoccupanthadpaintedtheeasternwallof the livingspaceabloodorangecolour,which,uponlightrefractionbouncedawarmglowinglightintothe

space.Itwouldhoweverbebeneficial,foroptimumspacelighting,tousealightercolourpaintonthiswallwhichwouldhavetheaffectofmultiplyingtheluxlevelsintheroom.

ArtificialLighting.Flat29.

Itmustbenotedthatthesereadingswerenottakenatnight,butinthedaywiththecurtainsdrawnand

the occupant’s usual evening lighting turned on. It does however attempt to show the patterns ofpooledlightaroundthelightfittings,aswouldbeexpectedinnighttimeconditions.Howeveritmustbenotedthattheremaybesomelightgainsonthereadingsthroughtheclosedcurtains(whichdidshow

somelightpenetrationatthetime).


TheoccupantofFlat29usesabroadrangeoflightbulbsofvariedwattlevels.

Therearesomeenergysavingbulbsinstalledwithintheflat,howeverthesavingsmadefromthesearecancelledoutbythehalogenstriplights(100Watts)inthelivingroomandbathroomthattheoccupants

claimedtousedaily.

Theannuallightingloadwascalculatedwiththeassumptionthattheoccupantsusedeachoftheirlightfittingsfor4hrseveryday:anestimatedaverageofthemeanactualusageofthecasestudyflats.

DailyLightingLoad:561Watts.

=12.02Watts/m2

FORANNUALLIGHTINGLOADANDEXPENSESSEEDIAGRAM


Replaceall lightbulbswith11wattsenergysaving lightbulbs:aneasyandrelatively low cost solution towards reducing lighting loads and resultantenergycostings.

For example, if we install the entirety of Flat 29 with energy saving light

bulbs the annual lighting load can be reduced to 160 kWh/year (from anoriginal 819 kWh/year). Through this reduction we can estimate thatoccupants canmake a saving of £50per year. The graph above shows the

actual load against the proposed load inWatts. There is a decrease of 10Watt/m2betweenactualandproposedloads.

LuxReadings.Flat50.

TimeTaken:14:30hrs.Orientation:SouthFacingLivingRoom/Balcony.

HighestReading:528lux(livingroombybalcony)LowestReading:4lux(bedroom)

Flat50islocatedintheSouthWestBuildingonthe3rdFloor.Asseeninthepreviouscasestudyflat(Flat28), this flathasabalconyofSouthfacingorientationwhichexposes it toahighsolar irradiance.Thisresults in high lux level readings even inWintermonths. This Southern façade is also almost entirely

glazedallowingalotofthislighttopenetrateintotheinternalspacesand,mostnotably,intothelivingspace.Consequentially, the livingroomspacesenjoyanoutstandingdegreeof thermaldelightandanelatingambience.

Thebedroom,becausenotasheavilyglazedastheliving/kitchenspace,hadlowerluxreadings(withahighestreadingof147lux,comparabletothehighestlivingroom/kitchenof528lux).Apartfromtwo

readingsby thewindowover100 lux the readingswereall below80 lux. This is also resultant to thebedroomwindow beingNorth facing therefore exposing it to less solar irradiance than the southern

façade,notablyinwintermonths.

The lowest lux reading recorded in the

living / kitchen space was near it’sentrance door. The kitchen unit, hadrelatively good lux levels, and more so

thanFlat28,duetotheopenplan layoutand lack of wall / shelving partition thatseparated Flat 28 living space and

Kitchenette.Flat 50 had painted the internal spaces

with a soft white cream matte whichhelped to bounce light back into theroom, improvingvisibility.However,byavoidingabrilliantwhite, this“lightbouncing”doesnotcause

unpleasantglare.There were Velux blinds installed

internally with occupant manual control.These helped glare reduction from theharshlightofbrightsummerdaysandthe

reflectionofnatural lightonto theceilingforoptimumuseoflightinthewinter.The

occupant confirms that she activelyutilizes thesetomaximizenatural lightingintheliving/kitchenspace.


Ofall thecasestudy flatsexamined,Flat50has themost light fittingsandhasanotablyhigh lightingload.Asseeninthepreviouscasestudyflat(Flat28),theflatagainshowsabigvariationinthetypesof

bulbsusedintheflat.

Onthediagramabovethelocationandtypesoflightfittingisshown.Itseemsfromthediagramthatthebathroomhas a disproportionately high amount of light fittings, however thewattage is lowerwhencompared to the other roomswithin the flat (the combined lighting load in the living room and the

kitchenaddupto360Watts).


=14.78Watts/m2


SavingRecommendations.Flat50.

Thelightingloadcanbereducedtoathirdofit’scurrentamountto242Wattsbyexclusivelyusing11kWhenergysavinglightbulbsinthesystem.Thisreducestheannualenergycostforlightingto£31,savingtheoccupantanapproximate£50‐60.

LuxReadings.Flat40.

TimeTaken:14:00hrsOrientation:Westfacinglivingroom/balconyHighestRecording:600+Lux(livingroombyglazing)

LowestRecording:4Lux(kitchen)v17Lux(bedroom)Flat40 is locatedon the4th (top) floorof theWestbuilding. Incomparisonwith theothercasestudy

flats it is clear that flat40 retains thegreatest solar irradiance.Thesouthwesternorientationof thelivingroom/bedroomandrelatedwindowsassiststhis.

Theoccupanthadarranged the furniture inaccordance toutilisingareasofoptimum lightand tonotimpedeonnaturallightpenetratingintotheflat.Theoccupantscomputeranddeskwereplacedatthe

pointwith themost light lux levelswere recorded,whilst furniturewasalsoplaced inpositionsawayfromwindowsurfacestoavoidobstructinglightfall.

Theoccupantisfortunatetobeontheupperfloorofthebuilding.Thisisbecausethelowerflatsofthisblockhavereduced levelsofdaylightpenetration fromshadingbythedense foliageofa rowof trees

(almostasallasthebuilding)obstructingtheSouthWesternfaçade.Thesetreesareunabletobecutback


Flat40haslesslightingfixturesthantheothercasestudyflats29and50.Unliketheotherflats,there

areonly3differenttypesoflightbulbbeingusedwithintheflat(energysavingbulbs,standardlightbulbsandparreflectors).

Thegraphaboveillustratesthelightingloadinaccordancetotheindividualroomsources.Itshowsthatthelivingroomspaceusestheleastlightingwhilstthekitchenrequiresthemost.Theoccupantinstalled

theparreflectorlightsinthekitchenareaasaresultoftheverylowluxlevelswecanseeintheluxleveldrawingshownpreviously.

Incontrasttothisspace,thelivingroomandbedroomarea’slowlightingloadscorrelatewiththeirhighluxlevelrecordingsandconsequentlyhighlevelsofnaturallight.


=9.5Watts/m2



Thesavingsthisflatmakes,byentirelychangingtheirbulbstocktoenergysavingbulbsisconsiderablylessthaninotherflats.Thisishoweverbecausetheflatalreadyhasalowwattage/m2.

Installing the energy saving bulbs brings down the annual lighting load to 192.72 kWh, with an

approximatecostof£15.Thisthereforeresultsintheoccupant,makingasavingof£40everyyear.

Thegraphaboveshownindicatesapossible7W/m2reductionbetweentheactualandproposedload.

LuxReadings.Flat38.

TimeTaken:15:30hrs

Orientation:Westfacinglivingroom/balconyHighestRecording:553Lux(livingroombyglazing)LowestRecording:2Lux(kitchenandbedroom)

This flat is locatedonthe3rd floorof theWesternbuilding.WhencomparedtoFlat40–asimilar flattype–theluxlevelsarenotablylower.Thisisforthefollowingreasons:

The lower flats aremore affected by dense foliage and resultant shading and – unlike Flat 40 – the

glazedfaçade(seenwithbalconyspace)isorientatedtowrdtheNortWest.

Savings/Recommendations.Flat38.

Lightbulbsinthispropertyarecurrentlyallthesame,withthelowestlightingloadof400kWh.Withtheannuallightingloadcalculatedat584kWhtheoccupantsspendsabout£50eachyearonlighting.


Byreplenishingthelightbulbstockwithallenergysavingbulbs,reducestheannuallightingloadfrom584kWhto96.3kWh.Thatwillresultinadropofalmost7Wattsforthisflat.

LightingLoads.Flat10.

ThereisconsiderablevariationinthedifferenttypesoflightbulbusedwithinFlat10:parreflectorson

tracklighting,regularlightbulbs,ahalogenstriplight,energysavinglightbulbsandfluorescenttubelight.

TheflatisEastfacingresultinginlessnaturallightintotheglazedeasternfaçadeandaheavylightingloadhadbeendesignedinthelivingroomspaceandtheflatasawhole.Thewattageofthelivingroom

is250+.ThereisonlyonelightingfittinginthekitchengivingindicationthatthenaturallighthittingtheSouthWesternfaçadeisutilizedasmuchaspossible.


=9Watts/m2



Byreplenishingexistinglightbulbstockwithenergysavingbulbsthecostofannuallightingloadcanbereducedbyapproximately£40.Theannuallightingload,withtheproposalbulbstock,willreducethe

yearlyloadto208.78kWh.

DataSummary.

InthechartbelowweseetheactuallightingloadWatts/m2forthecasestudyflats.

Inthechartbelowweseehowthecostsofenergyconsumptioncorrelatewithlightingloads.

0

1

2

3

4

5

6

Flat29 Flat40 Flat50 Flat10 Flat38

Ligh0ngload

(W/sqm

)

Flats

ligh0ngloadperSqminWaBs

lighlngloadperSqm

Herewecomparetherelativecostingsforenergyloadsofactuallightingenergydemandsandproposedusingentirelyenergyefficientbulbs.

Hereweseetheoverallannualsavingspossibleiftheflatsadapttheirlightingasrecommended.

0

200

400

600

800

1000

1200

£0

£10

£20

£30

£40

£50

£60

£70

£80

£90

£100

Flat29Flat40Fla50Flat10Flat38

Ann

ualCostin£

Flats

Annualligh0ngloadandcost

AnnualCost

AnnuallighlngloadsinkWh

£0£10£20£30£40£50£60£70£80£90

£100


Costin£

Flats

ActualVsAnnualcostwithenergysavinglightbulbsinstalled

AnnualCost

Annualcostwithenergysavingbulbs

£0

£10

£20

£30

£40

£50

£60

£70


AnnualSavings

AnnualSavings

Documents

2008 Research Paper - P.O.E. Energy Audit. Lighting Audit. (Part 03)