EvaluatingLowCarbonStrategies.

CaseStudy:Chalbury.Poole.

AndreaLuiseSchrader.

06098672@brookes.ac.uk

OxfordBrookesUniversity.

Abstract.

Inthispapertheauthorexplorestheenergyuseandlowcarbontechnologiesofthecasestudy:Chalbury, Poole, with focus on a single residential unit. The annual energy use is calculatedfromactualenergydataandaratingofCSH5isdefinedfor itsannualpoweruse.Analysisofthequalityofarchitectural fittingsandappliances, lightandthermaldelightwithintheunit isundertaken,withfurtherreflectiononcommunalspaceswithinthebuilding.Finallycomparisonismadetoanotherunit,toinvestigateanychangesinspatialqualitythatarisefromadifferingorientationwithin thebuilding.Conclusion isdrawnon theoverall successof the lowcarbonfeaturesofthecasestudy.

Chalbury. Planning Documentation. Whitelock Architects. Bournemouth. UK. 

SummaryofDevelopment.

Location:

Chalbury.34TheAvenue.Dorset.Poole.

Chalbury issituatedonthesoutherncoastofEngland inBranksomePark,Poole.Thisarea isadenseresidentialdistrictwithmaturevegetationandgreenlandscapingthroughout.Therearemanyprotectedtreeswithinthearea

(andtheChalburysiteitself)whichcanbeupto80/100ft.

TheChalburysitestemsoffTheAvenue,abusyarterialroadthatrunsfromBournemouth,throughBranksomeParktowardsSandBanksandtheBranksomeBaybeach.

Aerial Photographs taken from Google Maps (2008). 

CaseStudyUnit.5Chalbury. 

NetInternalArea(i.e.excludingterrace):1369sqft/127.184sqm

TheflatissituatedonthefirstfloorandpredominantlyconnectswiththeNorthfaçadeofthebuilding.

Plans courtesy of The Whitelock Group (2008) www.whitelock.co.uk.Bournemouth,UK. 

BuildingInformation.

Architect:TheWhitelockGroup.

DateOfCompletion:June2007.BuildingUse:Residential.

LG:CarParkingFacility.GF:ReceptionArea/Residential.

Floors01–05:Residential.BuildingMass:5storeysandBasement.TotalNetInternalArea:21270sqft.CarGarageSpace. 3954sqft.CirculatorySpace.(incl.riser/plant/cleaningstore) 3440sqft.UnitSpace. 13876sqft.Thisiscomprisedof16unitswithnetinternalfloorareas:

Type1:8X1050sqft.Type2:4X1369sqft.Type3:2X1420sqft.

EnergyDataAnalysis.

Assesmentofenergyperformanceinreferencetobenchmark.

So to improveaccuracy Iwillnowcompare tomoreconventionallyusedbenchmarks.TheCodeForSustainableHomes benchmarks on total energy consumption per squaremeter states that a usage of 73.943 kWh/sqm is

categorizedasCode5CSH.

FuelConsumptionFiguresfor5Chalbury(CaseStudyUnit):

SeparateEnergyCostsAndData=

AnnualElectricityBill=£534perannum(SouthernElectricrates,HistoricalFigures:2007/8)

5.75pperkWh:9286.957kWhperannum

0.550Kg/CO2/kWh:5107.826Kg/CO2/kWhperannum

AnnualGasBill=£452perannum(BritishGasDomestic,HistoricalFigures:2007/8)

10.52pperkWh:4296.578kWhperannum

0.190Kg/CO2/kWh:816.350Kg/CO2/kWhperannum

TotalEnergyConsumption=

9404.404kWhperannum

73.943kWh/sqmperannum

TotalCarbonFootprint=

5924.176Kg/CO2/kWhperannum/5.912metrictonnes/CO2/kWhperannum

=4.327Kg/CO2/sq.ftperannum

ClimaticContextAndNicolGraph.

TheNicolgraphshowsthatbetweenthemonthsofApriltoAugusttherearehighsolargainsthathavepotentialto

beutilizedinmaintainingTc,andapassivelyheatedenvironment.

 

 Nicol Graph showing climatic data from the Evesham area, closest weather station to the site. Historical data collated from the online database, Met Office. UK. (2006) 

According to theNicolGraph, thecomfort temperature foran internal spacewithin theBournemouth/Poole/

Eveshamarea fluctuatesbetween14and21degrees (peakingonlyat this temperature in JulyandAugust).Theproprietor of 5 Chalbury heats the flat to the peak of this at an estimated 21 degrees between themonths of

SeptemberandMay.

TheNicolGraphalsoshowsthereisconsiderablechanceforutilizingsolarheatgainswithinthemonthsofMay–

August. The proprietor stated that he defines the period at which he heats the unit by his perceived thermalcomfort. In it’syearofoccupation,theproprietorswitchedoffheating inMaydue internalconditionsbecoming

toohot.Itshouldbenotedthatthiscoincideswiththemonthsshownwithconsiderablyincreasedsolarirradiance.

Theproprietor claimed tobehappyat this constant21degree temperaturewithin theheatedmonths, butdidtakeinterestintheNicolGraphshown,andhasconsideredtestinglowertemperaturesofspaceheatingfromit’s

indicationofalowerTc.

CriticalEvaluationOfPassiveDesignFeatures.

Heating/Cooling.

Heatingwithintheflatunits isunderfloor.Hotwater isprovidedbyaVokeraMynutehighefficiencycondensingboiler category II2H3P.Hotwater is circulatedunderfloor in piped circuits to each room,which have individual

thermostaticcontrols.Therearesevenzoneswithinthecasestudyflat,andcanbepresumedmuchthesameintheotherunits.

Allowing each zone to be controlled separately reduces unnecessary heating and consequent energy use. The

authornotedthattheproprietorof5Chalburyheatedroomsoffrequentuseatahighertemperaturethanroomslessoccupied.

Thesystemisonatimerallowingthehousetobeheatedattimessuitingitsoccupancy.Theproprietorheatedthe

flatfrom4.30–8.00and16.30–20.00whichkeptitatacomfortabletemperaturethroughouttheday,withit’swarmestperiods(midmorningandearlyevening)attimesofgreatestoccupancy.

Underfloor heating allows greater user comfort at lower intensities of space heating. Unlike common radiator

systems, underfloor heating, starts heating at the lowest point, utilizing the convection of heat upwards topermeate thespacevolumequicker.Thisallowsheat to reachutilized (lower,andmorecentral) spacesquicker

andtheuserfeelswarmeratlowerheatsettings.

The communal spaces within the building core are unheated, relying on the thermal mass of the building to

maintainacomfortabletemperature.Thecirculationspaceiscentralintheplanandissurroundedbytheheatedunitsfurtherreducingheatlossestotheexternalandutilizesresidualheatgainsfromtheunits.Theauthornoted

thatthesespaceswereatanacceptablecomforttemperature(allyearincludingwintermonths)suitingthebrieftimetheyarewalkedthroughtoenter/exitflatunits.

ThermalMass/Insulation/Acoustics.

Theexternalwallsarecomposedofthefollowing:

StandardStone>100mlCavity>50mlKingspanThermal>100mlDenseConcrete>DryLining

Faces Insulation Block

AtfloorlevelthecavityisclosedoffbyRockwallfireseparatorandalsoatthepartywall.

AllwindowsandexternaldoorsarePVCdoubleglazed.Thisprovidespremiumthermalandsoundinsulation.The

authornotedthattherewassomeexternaltrafficnoiseheardinthemasterbedroom.Thermally,bothauthorandoccupantagreedthebuildingperformedwell.

Theoccupantinstalledshuttersinthelivingarea,inreplacementofcurtains.Theseareclosedintheevenings,and

theAuthornotedthatthisdoeshelpreduceheatlossesthroughtheglazing.

AppliancesAndPlugLoads.

Energydemandfromplugloadsisreducedbyfittingenergyefficientappliancesinthekitchenandbathroomsoftheunits.Thekitchenswerefittedtothearchitect/developersrequiredspecification.Allappliances;dishwasher,

washingmachineandfridgefreezer,areAorAAratedenergyefficient.ThehobisaBoschelectricinduction(thatuses soundwaves to provide instant heat and cooling) and the 2 ovens are Bosch thermo fan energy efficient

appliances. Showerheads, althoughoffering a “power shower” setting, canbe set to a reduced flow. Bathroomtapshaveanaeratedstream,furtherreducingwaterconsumption.

ArtificialLighting.

Lighting in the apartment is provided by low energy compact fluorescent, low voltage halogen and LED (latest

technologylightemittingdiode)lightbulbs.Lumens/wattforLEDlightsourcesareincrediblyefficientandcanlastmanyyearswithoutreplacement.

Commonareashavelowenergycompactfluorescent,lowvoltagehalogenandLEDinternallightingsystems.LEDlight sourcesprovidecontinuous low level lighting in corridors,whereasallother lighting is switchedbymotion

detectionsensorsthroughoutthebuilding.Outdooranddrivewaylightingislitbyhighpressuresodiumbollardsonalightsensorswitch.

Both author and proprietor agreed that lighting was pleasant and sufficient. Whilst lighting in the communal

spacesisdimmer,duetotheLED’sused,theygavesufficientlightforthepurposeofabrieflyoccupiedhallspace.

Theauthoralsonotedthattheproprietormaintainedastrictlightusepolicywithintheunit,onlyhavinglightsonintheroomsoccupiedatthetime.Thiswouldhaveaconsiderableaffectonenergyuse.

NaturalLighting.

Thesungetsconsiderablenaturallightthroughouttheday.Therearelargeglazedpanels(2100x1800withJuliettebalconies)fromthebedroom(Easternelevation),secondbedroomandofftheloungespace(Westernelevation).

Theauthornotedthesunpaththroughouttheday.Areasofconsiderablenaturalday‐lightingareasfollows:

Morning:

Midday:

Afternoon:

Entireterracewithsomeshadingfromnearbytrees.Livingspace.

Living/Diningspace.

Easternsideofterrace.Masterbedroom.

Theshuttersintheliving/diningareaareusedforsolarshadingwithintheday(ifnecessary),reducingglareand

improvingthermalcomfort.

Annotationforfigures:Fromtoplefttobottomright.

Fig.1:Afternoonsunlightinthemasterbedroom.

Fig.2:Thermostaticcontrolforunderfloorheating.Zonespecific.

Fig.3:LargeglazedwindowwithJuliettebalcony,inthesecondbedroom.

Fig.4:Kitchenspace,withlowenergylightfittings.(turnedonforpurposeofphotograph).

Fig.5:EnergyEfficientkitchenappliances:Hobtospec.asstatedintext..

Annotationforfigures:Fromtoplefttobottomright.

Fig.6:Boilerservicingtheunit.

Fig.7:OvenswithAAenergyrating.

Fig.8:LEDlowlevelcontinuouslightingincommunalspaces.

Fig.9:Passagetowindow/AOVallowingnaturallightintothecommunalcirculationcore.

Fig,10:LEDlowlevelcontinuouslightinginreception.

Fig.11:Morningsunenteringlivingspace.Notealsotheshuttersinstalledforsolarshading,privacyandinsulation.

Ventillation.

The windows in the living / dining space, master and second bedroom are 2100x1800 with Juliette balconiesprovidingoptimumventilation(largestpossibleconventionalwindowsize)andallowinguserstosustainagoodair

quality/CO2levelwithintheunit,abstainingissuesrelatedtoSickBuildingSyndrome.

There is however, minimal ventilation within the stair core / circulation spaces. The only connection wit theexternalenvironmentisthroughtheAOV(whichcanbeopenedmanuallybuttendtoremainclosed,onlyusedin

eventofafire)andGFreceptiondoors.Thisreductioninventilationisnecessarytomaintainthepassivethermalheating of this space from surrounding units and thermal mass. However, ventilation could be improved by

including a double glazed roof light for ventilation on the 5th floor roof level. This would allow “Stack Effect”naturalventilationwhilstutilizingasmallamountofsolargainonthisupperfloor.

ComparisonOfCaseStudyAndUnitOfOpposingOrientation.

Afterbriefinspectionofunit7,(secondfloorwithsouthwesterlyorientation)theauthornotedthatbothflatsgot

considerablesolargain.TheproprietorsofUnit7hadinstalledblindstocombatexcessivegainsinsummermonths.Theauthorfoundtheflat,atthetimeofthevisitinNovember,thermallycomfortable,contributedto

greatlybysolargains.

Fig.12:(left)Blindsaddedtoreducesolarglare

/improvethermalcomfort.

Fig.13:(below)Living/diningspaceofUnit7.Bothflatshadconsiderablenaturallight

throughoutthedayinthisarea.

Conclusions.

Theunitstudiedhasproventoperformwellagainstcontemporarybenchmarksoflowenergyuse.Ananalysisofitslowcarbontechnologiesshowsthatit’slowenergyuseiscontributedtogreatlyfromthearchitecturalfeaturesandfittings.

However,itshouldalsobetakenintoaccountthatthelowenergyconsumptionwillhavebeencontributedtobythereducedoccupancyoftheunit(2personaswithina3bedroomflat).Theproprietor’s use of communal spaces and consequential resultant energy use has not beenconsideredandmayhaveaneffectonthekWh/sqmfigurerecorded.

Fromobservationoftheflatusageoveraprolongedperiodoftime,theauthoralsoconcludesthat reductions in energy costs is contributed to considerably by the efficient energymanagementsustainedbyit’soccupants.