EUROPEANSTANDARDNORMEEUROPéENNEEUROP?ISCHENORMICS35.020;35.110;35.160-Part4-6:EnergyReuseFactorTobecompletedInformationstechnik-EinrichtungenundInfrasrukturenvonRechenzentren-Teil4-6:FaktorderEnergiewiederverwendungThisEuropeanStandardwasapprovedbyCENELECon2020-01-13.CENELECmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEuropeanStandardthestatusofanationalstandardwithoutanyalteration.Up-to-datelistsandbibliographicalreferencesconcerningsuchnationalstandardsmaybeobtainedonapplicationtotheCEN-CENELECManagementCentreortoanyCENELECmember.ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).AversioninanyotherlanguagemadebytranslationundertheresponsibilityofaCENELECmemberintoitsownlanguageandnotifiedtotheCEN-CENELECManagementCentrehasthesamestatusastheofficialversions.CENELECmembersarethenationalelectrotechnicalcommitteesofAustria,Belgium,Bulgaria,Croatia,Cyprus,theCzechRepublic,Denmark,Estonia,Finland,France,Germany,Greece,Hungary,lceland,lreland,Italy,Latvia,Lithuania,Luxembourg,Malta,theNetherlands,Norway,Poland,Portugal,RepublicofNorthMacedonia,Romania,Serbia,Slovakia,Slovenia,Spain,Sweden,Switzerland,TurkeyandtheUnitedKingdom.EuropeanCommitteeComitéEuropeendeNormalisationElectEurop?ischesKomiteefürElektrotechnischCEN-CENELECManagementCentre:RuedelaScience23,B-1040Brussels◎2020CENELECllrightsofexploitationinanyformandbyanymeansreservedworldwideforCENELECMembers.Ref.No.EN50600-4-6:2020E2EN50600-4-6:2020(E)Introduction 41Scope 7 73Terms,definitions,abbreviationsandsymbols 73.1Termsanddefinition 73.2Abbreviation 7 84Applicableareaofthedatacentre 85DeterminationofEnergyReuseFactor(ERF) 96Measuremento 7ApplicationofEnergyReuseFactor(ERF) 18ReportingandtrendtrackingofEnergyReuseFactor 18.1ReportingofEnergyReuseFactor(ERF) 8.1.1StandardconstructforcommunicatingERFdata 18.1.2DataforpublicreportingofER 18.2Recommendationsfortrendtrackingdata 8.3ERFderivatives,interimERF AnnexA(informative)ExamplesofERFuse 13AnnexB(informative)EnergyConversionFactors—EnergyMeasurementattheDataCentreBoundary 20Bibliography ListofFiguresFigure1—SchematicrelationshipbetweentheEN50600seriesofdocuments 5Figure2—Simplisticdatacentrecomponentsandboundary 9FigureA.1—Reuseofdatacentrewastehea FigureA.2—Schematicshowingreuseofheatwithinthedatacentre FigureA.3-Reuseofheatwithheatpumpsinsideadatacentre FigureA.4-Reuseofheatwithheatpumpsorheatexchangersoutsideadatacentreonl FigureA.5-Reuseofwasteheatwithheatpumpsandliquidcooledparts FigureA.6-Reuseofwasteheatwithmixedarrangements 19ListofTablesTableB.1—Energymeasurementmethodsatthedatacentreboundary 20EN50600-4-6:2020(E)3EuropeanforewordThisdocument(EN50600-4-6:2020)hasbeenpreparedbyCLC/TC215“Electrotechnicalaspectsoftelecommunicationequipment”.Thefollowingdatesarefixed:·latestdatebywhichthisdocumenthas(dop)tobeimplementedatnationallevelbypublicationofanidenticalnationalstandardorbyendorsementlatestdatebywhichthenational(dow)standardsconflictingwiththisdocumenthavetobewithdrawn2021-01-172023-07-17ThisdocumentisbasedonthetextofISO/IECDIS30134-6:2019.Attentionisdrawntothepossibilitythatsomeoftheelementsofthisdocumentmaybethesubjectofpatentrights.CENELECshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.ThisdocumenthasbeenpreparedunderamandategiventoCENELECbytheEuropeanCommissionandtheEuropeanFreeTradeAssociation.EN50600-4-6:2020(E)4Theunrestrictedaccesstointernet-basedinformationdemandedbytheinformationsocietyhasledtoanexponentialgrowthofbothinternettrafficandthevolumeofstored/retrieveddata.Datacentresarehousingandsupportingtheinformationtechnologyandnetworktelecommunicationsequipmentfordataprocessing,datastorageanddatatransport.Theyarerequiredbothbynetworkoperators(deliveringthoseservicestocustomerpremises)andbyenterpriseswithinthosecustomerpremises.Datacentresneedtoprovidemodular,scalableandflexiblefacilitiesandinfrastructurestoeasilyaccommodatetherapidlychangingrequirementsofthemarket.Inaddition,energyconsumptionofdatacentreshasbecomecriticalbothfromanenvironmentalpointofview(reductionofcarbonfootprint)andwithrespecttoeconomicconsiderations(costofenergy)forthedatacentreoperator.Theimplementationofdatacentresvariesintermsof:a)purpose(enterprise,co-location,co-hosting,ornetworkoperatorfacilities);b)securitylevel;c)physicalsize;d)accommodation(mobile,temporaryandpermanentconstructions).Theneedsofdatacentresalsovaryintermsofavailabilityofservice,theprovisionofsecurityandtheobjectivesforenergyefficiency.Theseneedsandobjectivesinfluencethedesignofdatacentresintermsofbuildingconstruction,powerdistribution,environmentalcontrolandphysicalsecurity.Effectivemanagementandoperationalinformationisrequiredtomonitorachievementofthedefinedneedsandobjectives.TheEN50600seriesspecifiesrequirementsandrecommendationstosupportthevariouspartiesinvolvedinthedesign,planning,procurement,integration,installation,operationandmaintenanceoffacilitiesandinfrastructureswithindatacentres.Thesepartiesinclude:1)owners,facilitymanagers,ICTmanagers,projectmanagers,maincontractors;2)architects,consultants,buildingdesignersandbuilders,systemandinstallationdesigners;3)facilityandinfrastructureintegrators,suppliersofequipment;4)installers,maintainers.Atthetimeofpublicationofthisdocument,theEN50600seriescomprisesthefollowingstandardsanddocuments:一EN50600-1,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part1:General一EN50600-2-1,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part2-1:Buildingconstruction;一EN50600-2-2,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part2-2:Powerdistribution;一EN50600-2-3,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part2-3:Environmentalcontrol;一EN50600-2-4,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part2-4:Telecommunicationscablinginfrastructure;一EN50600-2-5,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part2-5:Securitysystems;EN50600-4-6:2020(E)5一EN50600-3-1,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part3-1:Managementandoperationalinformation;一EN50600-4-1,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part4-1:Overviewofandgeneralrequirementsforkeyperformanceindicators;一EN50600-4-2,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part4-2:PowerUsageEffectiveness;一EN50600-4-3,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part4-3:RenewableEnergyFactor;一EN50600-4-6,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part4-6:EnergyReuseFactor,一EN50600-4-7,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part4-7:CoolingEfficiencyRatio;-CLC/TR50600-99-1,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part99-1:Recommendedpracticesforenergymanagement;-CLC/TR50600-99-2,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part99-2:Recommendedpracticesforenvironmentalsustainability;-CLC/TR50600-99-3,Informationtechnology—Datacentrefacilitiesandinfrastructures—Part99-3:GuidancetotheapplicationofEN50600series.Theinter-relationshipofthestandardswithintheEN50600seriesisshowninFigure1.ENEN50600-1GeneralconceptsEN50600-3-xResourcemanagementOperationCLC/TR50600-99-xSupportinginformationandTechnicalReportsRecommendedpractcesforenergymanagementRecommendedpracticesforenvironmentalsustainabilityGuidancefortheapplicationofEN50600seriesKeyPerformanceIndicatorsEN50600-2-xEN50600-4-xDesignFigure1—SchematicrelationshipbetweentheEN50600seriesofdocuments6consequenceandthatrEN50600-4-6:2020(E)7Thisdocument:a)specifiestheEnergyReuseFactor(ERF)asaKPItoquantifythereuseoftheenergyconsumedinthedatacentre;b)definesthemeasurement,thecalculationandthereportingofERF;c)describestheapplicationofERFanditsdiscriminationfromPowerUsageEffectiveness(PUE).TheERFdoesreflecttheefficiencyofthereuseprocess,whichisnotpartofthedatacentre.2NormativereferencesThefollowingdocumentsarereferredtointhetextinsuchawaythatsomeoralloftheircontentconstitutesrequirementsofthisdocument.Fordatedreferences,onlytheeditioncitedapplies.Forundatedreferences,thelatesteditionofthereferenceddocument(includinganyamendments)applies.EN50600-4-1:2016,Informationtechnology-Datacentrefacilitiesandinfrastructures-Part4-1:OverviewofandgeneralrequirementsforkeyperformanceindicatorsISO8601series,Dateandtime-Representationsforinformationinterchange3Terms,definitions,abbreviationsandsymbolsForthepurposesofthisdocument,thetermsanddefinitionsgiveninEN50600-4-1andthefollowingapply.ISOandIECmaintainterminologicaldatabasesforuseinstandardizationatthefollowingaddresses:—IECElectropedia:availableat/一ISOOnlinebrowsingplatform:availableat/obp3.1.1reuseofenergyutilizationofenergyusedinthedatacentretoanalternatepurposeoutsidethedatacentreboundary3.1.2handoffpointpointattheboundaryofthedatacentrewhereenergyismeasuredandishandedofftoanotherpartywhichutilizestheenergyoutsidedatacentreboundary3.2AbbreviationsForthepurposesofthisdocument,thefollowingabbreviationsapply.GPUGraphicsProcessingUnitHPCHighPerformanceComputing8KVMEDctotaldatacentreenergyconsuEEXCESSELIGHTINGenergyusedtolightthedatacentreandsupportspaces(annual)9DataDatacentreboundaryofEN506004seriesEDc=Em-EExcessOtherFKEYThermalenergyRe-useableenergyDtherenergyEnergyRenewable_reuse_reSourceconvertedtoRejectedenergy但_.◆EeEusE--→→ENOTE2EnergyreusedinsidethedatacentreboundaryisnotcountedtowardsERFasitalreadyisaccountedforinawheredistributionunits(PDUs),batteries,c)othersincludingdata1)ITequipm2)supplementalequipment(e.g.KVMswitches,monitors,andworkstations/manage,and/orcontrolthedatacentrb)kilowatt-hour(kWh)metersofthevoltage,current,andpowerfactorovertiEN50600-4-6:2020(E)alternatingcurrent(AC).Kilovolt-ampere(KVA)measurementscanbeusedforotherfunctionsinthedatacentre,ERFwithoutanysubscriptsshallbedeterminedasanannualizedvalue.ERFcanbeusedbydatacentremanagerstomonitorandreportreusedenergyinrelationtoenergyconsumptioninthedatacentre.ThisKPIcanbeusedindependentlybuttogetamoreholisticpictureoftheresourceefficiencyofthedatacentre,otherKPlsoftheEN50600-4seriesshouldbeconsidered.8ReportingandtrendtrackingofEnergyReuseFactor(ERF)8.1ReportingofEnergyReuseFactor(ERF)8.1.1StandardconstructforcommunicatingERFdataForareportedERFtobemeaningful,thereportingorganizationshallprovidethefollowinginformation:a)thedatacentre(includingtheboundariesofthestructure)underinspection;b)theERFvalue;c)thekindofenergyreused(thermal,electrical,chemical,mechanical);d)theterminationdateoftheperiodofmeasurementusingtheformatofISO8601series(e.g.yyyy-mm-dd).Asseasonalchangescanaffecttheamountoftheenergyreused,thereportedvalueshallbeannualized.8.1.2DataforpublicreportingofERFRequiredinformationThefollowingdatashallbeprovided,whenpubliclyreportingERFdata:a)contactinformation;Onlytheorganization'snameorcontactshouldbedisplayedinpublicinquiries.b)datacentrelocationinformation(address,countyorregion);Onlystateorlocalregioninformationarerequiredtobedisplayedinpublicinquiries.c)measurementresults:ERFwithappropriatenomenclature;d)thekindofenergyreused(thermal,electrical,chemical,mechanical).Supportingevidence(whererequiredbyauthoritieshavingjurisdiction)Informationonthedatacentrewhichshallbeavailableuponrequestasaminimumincludes:a)organization'sname,contactinformationandregionalenvironmentaldescription;b)measurementresults:ERFwithappropriatenomenclature;c)EDcandEReuse;d)measurement(s)startdatefk)percentageofserverm)averageageoffacilityequipmentn)datacentreavailabilityobjep)thekindofenergyreused(thermal,electrical,cheprefix“i”(interim)andAnnexA(informative)ExamplesofERFuseA.1Generaltemperatureofthewasteheat,inordeInthiscase,ERF=(F)((A)+⑤A⑤AOEN50600-4-6:2020(E)A.2.3HeattogenerateelectricityusedelsewhereTherearetechnologiesindevelopmentforreverseheatenginesthatcancreateelectricityfromwasteheat.Schematically,thiswouldbeequivalenttothatequipmentbeinginthesamelocationastheabsorptionchiller.Ineithercase,thereuseenergyismeasuredwhereitcrossesthedatacentreboundary.Onlythevalueof(F)shouldbeconsideredincalculatingERF.A.3.1HeattorunanabsorptionchillerorgenerateelectricityforuseinthedatacentreInthecaseofenergyreusedtodriveaprocessinsidetheboundary,thereusewillincreaseefficiencyofthespace,butthisbenefitwillbecapturedinPUE.Inthiscase,thatcapitalinvestmentismadetoimproveefficiencyofthedatacentreandassuch,PUEwillbereduced.FigureA.2depictsthisarrangement,withtheboundaryencompassingtheabsorptionchiller.Inthiscase,(I)and(H)bothleavethedatacentrebutneitherarereused.InthecaseofFigureA.2,ERF=0,0andPUE=(A)+(B))/(D).NotethatonewouldfullyexpectthePUEofthedatacentreinFigureA.2tobelowerthanthePUEinFigure1.ThebenefitoftheabsorptionchilleristakenintoaccountinthePUEofFigureA.2.ThePUEshouldbelessbecausetheaddedbeneficialcoolingfrom(G)wouldreducetheamountofcoolingenergyneededat(E)and,therefore,at(A).RejectedRejectedBoundaryUtility⑧CoolUPSC-PDUAbsorptionchiller-⑧IGFigureA.2—SchematicshowingreuseofheatwithinthedatacentreA.3.2Heatingadatacentresupportspaceorpre-heatingofdatacentregeneratorsTheheatfromthedatacentre,whentransferredtothebatteryroom,stayswithinthedatacentreboundaryandisthereforeaccountedforinloweringthePUEbyreducingelectricitydemandforheatingthebatteryroom.Asdiscussedearlierinthisdocument,reuseofdatacentreheattoheatthedatacentre'sbatteryspaceorelectricalspacewouldnotmakethatfacilityacandidateforERF.Thatreuse,whichsimplyreducestheamountofenergyneededtobeprocuredforthedatacentreoperation,willalsoreducePUEbutisnotpartofanyERFcalculation.Similarly,thecasewherewasteheatisusedtopreheatgeneratorsfordatacentreelectricityproductionisnotanapplicationforERF.Rather,itisaninvestmenttoimprovedatacentreenergyefficiencygainanditwillsimplyreducePUE.A.4Split-systemcomplications-HeattorunanabsorptionchillerWithreferencetoFigureA.2,ifthecoolingenergy(G)turnsouttobeusedbothinthedatacentre(withintheboundary)andinanon-relatedspace(outsidetheboundary),theamountofenergy(F)thatisreusedshallbeappropriatedforeachspace.Afirst-orderapproximationcouldbeassimpleasaratioofchilledwaterflow.If75%ofthecoolingfromtheabsorptionchillerwasusedoutsidethedatacentre,then75%oftheenergyEN50600-4-6:2020(E)reused(0,75×(F))shouldbeincludedincalculatingERF.Suchcomplexdesignsarebeyondthescopeofthisdocument,buttheguidelinespresentedshouldbeabletobeappliedtoallscenarios.A.5HeatpumpsandliquidcoolingA.5.1GeneralTheuseofheatpumpscanbereasonabletoreusewasteheatfromITspaceforheatingpurposesinnon-ITareasinsidethedatacentre.Itcanbealsousefulforsmalldatacentres(e.g.EdgeClouddatacentreswithlowlatencyclosetobuildings)orincountrieswithlowelectricitypricesandanotableheatdemand.Inothercases,liquidcoolingcanbeanoptiontoincreaseIT-densityandefficiency(e.g.HighPerformanceComputing(HPC),bladeserver,GPUcloud).Thosetechnologiesalloweusingwasteheatandcoincidentlysavingcoolingexpenses.TheexamplesofA.5.2andA.5.3showdifferentarrangementpossibilitiesforthesetechnologiesandKPIcalculationrules,whichmeetthedefinedsystemboundarymodelofERFandPUEaspreviouslyexplained.Heatpumpsaremachines,whichbringthermalenergyfromalowertemperaturelevel-togetherwiththeenginepower-toahighertemperaturelevelwiththehelpofmechanicalwork.TheefficiencyfactorofaheatpumpistheCoefficientofPerformance(COP),calculatedasbenefitdividedbyexpenses,referredtotheirhotsideindifferencetocoolingmachineswhereperformanceisreferredtothecoolingside.TocalculateannualamountsofenergytheseasonalperformancefactorsneedtobetakeninsteadoftheCOPprovidedbymanufacturer.Generallyaheatpumpissimilartoacoolingmachine.However,inmostcasestheemittedheatisonahighertemperaturelevelandiskeptconstantandwillbeused,whileacoolingmachineneedsheatexchangersoutsideanditsmainfunctionistocool.Theenergyintheformofgasorelectricitywhichisaddedtothisprocess-togettheprocessrunandtogettheneededtemperaturelevelforheatcustomerneeds-isincludedonthehotsideassumofwasteenergyandauxiliaryenergy.ThereforeitwouldbeincorrecttocountinforERFtheenergy,whattheheatcustomerusesorwhatisprobablydelivered.TheERFitselfsaysnothingaboutthevalueofthereusedenergy.AssoonasitisusedtodocalculationswiththeERF,itisnecessarytoimplementdifferentfactorsforelectricityandheat(e.g.differentpricesinkWhpowerandkWhheat,differentprimaryenergyfactors,differentCOzfactorsingco2/KWhpower/heat).Thehigherexergyvalueofelectricityandtheincreasingvaluebyhigherheattemperaturesareneededtokeepinmindastheheatenergyinkilowattperhouritselfdoesnotreflectthis.A.5.2HeatpumpsforreuseheatinsidethedatacentreonlyIncaseofoptimizingdatacentreenergyrequirements,heatpumpscanreusewasteheatfromITspacesbyaddingfurtherauxiliaryenergytoreducetotalsupplyenergyneeds(seeFigureA.3).Ifheatpumpsorheatexchangersareexclusivelyusedforreuseenergyinsideadatacentretoheatofficespaces,preheatdieselorfortheheatexchangersoftheventilationsystem,itwillneedasignificantsmalleramountofenergycomparedtotheITwasteheat.TheheatpumpisapartofthedatacentreboundarybythePUEdefinitionandtheneededauxiliaryenergyisaccountedforPUEratherthanERF,becausethereisnoreusedenergyleavingthedatacentreboundary.Ontheotherhand,thisresultsinlesscoolingenergyandloweroperationalcostforheatingandimprovesthePUEandotherKPls.EN50600-4-6:2020(E)BoundaryDC—)Jhigh-temp.JAHeatpumpAHeatpumpUtilityUtility①①1e.g.preheatingdieselgenerators,preheater&reheaterHVAC,heatingoffices,…FigureA.3—ReuseofheatwithheatpumpsinsideadatacentreERF=0andPUE=((A)+(B)+(N)+(L))(D)Theamountof(N)willbelowerbytheamountof(G)comparedtowithoutanyreuse.(A)isgettingsmallerbecause(E)becomesreducedbytheamountof(F).(L)shallbeaddedforthetotalDCenergyEoc.If(N)or(L)isnotelectricalenergy,therulesforconvertingenergyapplyasdescribedinEN50600-4-2.COPneating=(J)(L),while(J)=(F)+(L).A.5.3.1GeneralThethreecasesdescribedinA.5.3.2toA.5.3.4arepossibleifheatcanbedeliveredinliquidformwithareasonabletemperaturetoaheatcustomeroutsidethedatacentre.ItiscomprehensiblethatpossiblysomeofthishotwaterisusedaswellinsidethedatacentretoreduceoperationalcostasshowninFigureA.6.Butifsomeoneisdealingwiththesearrangements,itistoreuseheatthatismainlyusedoutsideofthedatacentrewiththeadvantagetosavecoolingcosts.Theheatenergythatispossiblyreusedinsidethedatacentrewillusuallynotbemorethan0%to5%ofthetotalwasteheat.ItbecomesclearthatsuchbiggerheatingsystemsareownsystemsthatdonothaveanythingtodowiththedatacentreenergyanditsKPls,eveniftheywerephysicallyplacedinsideadatacentre.WiththefollowingcalculationrulestheuseofheatpumpswillnotbepenalizedintheKPlsbyaddingtheauxiliaryenergytothedatacentreenergy(forrunningheatpumpsorpumpsonthesecondarycircuitoftheheatingsystem).ThiswouldresultinaworsePUEandapoorerERF,eventhoughhavingbettertotalcarbondioxideresults.Furthermore,aheatingsysteminthatscaleandwhenitdeliversheattoanothercompanyisaseparatesystemandshallbeincludedinthecalculationofvariousnon-data-centresKPlstocompareandoptimizeheatingsystemsthatcomplywithlocalenvironmentaregulations.A.5.3.2ReuseofheatwithheatpumpsorheatexchangersoutsideadatacentreIfthemainpurposeistouseheatpumpsorheatexchangerstodeliverwasteheatoutsidethedatacentre,FigureA.4appliesandanERF>0exists.EN50600-4-6:2020(E)RejectedBoundaryheatingsystem-RejectedBoundaryheatingsystem-Non-datacenterspaceBoundaryDC—datacentrespaceRejectedBoundaryDC—datacentrespaceRejectedAEAECoolairoriUtilityTairoriUtilityTCPDUUPS①CPDUUPSElectricity/GasFigureA.4—ReuseofheatwithheatpumpsorheatexchangersoutsideadatacentreonlyERF=(F)(A)+(B)+(N)).Inthecaseofreusingenergyofwarmairflowsitismoredifficulttomeasurethehandoffpoint(F),however(F)=(J)-(L)withnegligibleheatlosses.If(J)and(L)arenotknown,theenergyofairflowsshallbecalculatedbymeasuringvolumeflow(multiplicationofareaandspeed)andtemperaturechange.Anyauxiliaryenergyintheflow/returncircuitstomovetheenergy(F)insidethedatacentreboundaryarepartsofthedatacentreutilitypowerandarepartsof(A)forERFandPUEwithPUE=((A)+(B)+(N)>(D).Itisincorrecttoconsider(K)asreusedenergy,whenitcontainstheenergy(L),whichisneededtosupplytheheatingsystem.Inthecaseofliquidcooling,heatpumpsareprobablynotneeded.Aheatexchangercanmeettherequirementsandnoadditionalelectricity(L)isneededdependingonthetemperaturedemandsoftheheatcustomer.Wasteheatcountsas“0”fortheprimaryenergyfactorforindustrialexhaustair,ifitisusedtoheatbuildings,ifthereisno(L),evenifonlytheheatcustomerwillbenefitfromit.Dependingonthesizeof(F)thedatacentreownerwillbenefitovertheyearsfromlowercoolingcost(A),whichresultsinabetterPUEcoincidentlyandcanresultinadditionalrevenuesstemmingfrom(F)or(K).A.5.3.3HeatpumpsandliquidcoolingforreusewasteheatoutsidethedatacentreInsomecases,suchasHPC,someITcomponentscanbecooledmoreefficientlywithliquids,whichresultsinwasteheatintheairandadditionallyinacoolingfluid.Forabetterandefficienttransportandtheopportunityofreuse,itisanadvantageiftheheatenergyisinliquidformalready.Whenthisheatcapturedinaliquidisdeliveredtoacustomeroutsidethedatacentre,FigureA.5showstheener