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SnapshotFinding the Proof of Energy Retrofits
By: Michael Bobker, Director, Building Performance Lab, CUNY
For: The Sallan Foundation
Date: September, 2010
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Snapshot
Finding the Proof of Energy Retrofits
Introduction:NYCLeadershiponEnergyEfficiencyinExistingBuildings
NewYorkCityispoisedtoexertgloballeadershiponenergyefficiencyinexisting
buildings.MuchhasbeenmadeoftheGreenerGreaterBuildingslawsthatspell
outanarrayofenergyrequirementspursuanttothegoalsofPlaNYC2030.Overthe
nextdecadewewillseewhatresultsareachievedinimplementinglegal
requirementsforenergycodecompliance,benchmarking,audits,retro
commissioning,andlightingimprovements.Keyplayers,ledbyNYCgovernment
itself,havecommittedtoearlyimplementationby2017.Thecurrent
administrationisbudgeting10%ofitmunicipalenergyexpenseforannualfunding
ofenergyefficiencyimprovementprojectsinmunicipalbuildings.Thisamountsto
$100millionperyear.
Bynewconstructionstandards,wherecostseasilyrunto$300persquarefoot,this
isnotahugesum.Butbystandardsofenergyconservationprograms,where
fundingtypicallyismorelike$10persquarefoot,ithisisindeedalargebudgetand
asubstantialopportunitywithglobalimplications.Theprogramisunderthe
managementoftheNYCDepartmentofCitywideAdministrativeServices,utilizingawellthoughtoutapproachthatfollowstheconventionalpracticeoftheenergy
servicesindustry:benchmark,audit,implement,train,operateandmaintain,meter
andmonitor.ii
Givenitshighstakesandpublicprofile,dueconsiderationmustbegiventothe
reliabilityofoutcomes.Thisleadstothequestionofwhatexperienceisavailable
thatcouldprovideinsightintolikelyprogramperformance.
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Snapshot
Finding the Proof of Energy Retrofits
Experience-basedGuidance.fromTexas
Thebestplacetolook,perhapssurprisinglytosome,isTexas.Since1988theTexas
EnergyOfficehasoperatedLoanSTAR,anenergyefficiencyrevolvingloanfundfor
municipalandstategovernmentfacilities.From$98.6millionincorefunding
(basedonpetroleumviolationescrowfunds),191loanstotalingover$240million
havebeenmadethrough2007iiithefundscapitalhasbeenrepaidtwiceover
andrecycledintonewloans.Theloanstargetpublicbuildingsschooldistricts,
governmentbuildings,highereducation,andhospitalsmakingitaportfoliomix
notunlikewhatcanbeanticipatedunderNYCsprogram.
WithTexasLoanSTARsmixoffacilities,rangeofretrofittechnologiesdeployed,
leveloffundingandsustainedmultiyeareffort,onecouldhardlyhavedesigneda
betterpilotprogramforNYCseffort.Mostimportantly,theprogramincludeda
rigorousevaluationeffortconductedbytheEnergySystemsLabatTexasA&M
University(ESLTAMU).TheESLTAMUappliedengineeringandarchitecture
facultyandgraduatestudentresourcesatasignificantlevelformorethantenyears.
Atanygiventimefourorfiveseniorresearchers,PrincipalInvestigatorsassignedtostatecontractedprogramtasks,wouldbeoverseeingtheworkoftentofifteen
facultyresearcherssupportedbythirtytofortygraduatestudentsandtechnical
staff.
Thisprogramproducedthenationsbestdocumentedanalysisofabodyofenergy
efficiencyretrofitstodate.AcomprehensivecatalogoftheESLspapersandreports
isavailablefordownloadfromTexasA&MUniversity.Theworkwasanimportant
precursortotheemergenceofenergyefficiencymeasurementandverification
(M&V).ESLTAMUstaffbecameimportantcontributorstothefieldskeydocuments,
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Snapshot
Finding the Proof of Energy Retrofits
theInternationalPerformanceMeasurementandVerificationProtocol(IPMVP)and
ASHRAEGuideline14.
FindingsonAuditsandActualPerformance
Sowhatwaslearned?
Evaluationofthismultiyearretrofitexperienceshowedthatenergysavingsfrom
retrofitsacrossaportfoliocouldberealized,documented,andmaintained.The
engineeringpredictionsfromenergyauditscouldbetrusted.Findingsfromstudies
conductedin1995and1996,iv
basedonover150buildingretrofits,showedthefollowing:
Savingsfrombaselineof24%26%atretrofitcostsof$23persquarefoot Overallaverage5.1yearactualpaybackversus3.8yearprojectedbyaudits
Butthereisacatch.Whiletheresultsfortheoverallsetweregood,theoutcomefor
anyparticularbuildingfellwithinawiderangefrompredicted.Savingsvoutcomes
wereseentofallalmostequallyoneithersideofalinerepresentinga1:1
correspondenceofpredictedtoactualsavings,oftenwithsubstantialvariation.
(SeeFigure1)
Wasthisuncertaintyinoutcomesafunctionofauditerror(prediction)orofretrofit
performance?
Theanswerturnsouttobesomeofboth.Audits,doneundertheLoanSTAR
programbyindependentengineeringconsultants,weresubjecttoTAMUstandards
butneverthelessproblemsinsavingsestimateswerefoundinsome2030%of
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Snapshot
Finding the Proof of Energy Retrofits
casesreviewed.Suchsavingsestimatesweremadesubjecttoposthocadjustment,
whichistosaythatnewpredictionsweredevelopedbasedonengineeringanalysis
andusedforcomparisontoactualresults.Butitwasalsofoundthatsystemswere
oftennotoperatingasintendedandthatperformancecouldbeimprovedby
adjustment.
Wasthisuncertaintyinoutcomesafunctionofauditerror(prediction)orofretrofit
performance?
Figure1:MeasureSavingsComparedtoEstimatedSavings
Source:TexasA&MEnergySystemsLab
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Snapshot
Finding the Proof of Energy Retrofits
Theanswerturnsouttobesomeofboth.Audits,doneundertheLoanSTAR
programbyindependentengineeringconsultants,weresubjecttoTAMUstandards
butneverthelessproblemsinsavingsestimateswerefoundinsome2030%of
casesreviewed.Suchsavingsestimatesweremadesubjecttoposthocadjustment,
whichistosaythatnewpredictionsweredevelopedbasedonengineeringanalysis
andusedforcomparisontoactualresults.Butitwasalsofoundthatsystemswere
oftennotoperatingasintendedandthatperformancecouldbeimprovedby
adjustment.
Inthefollowingplotofasampleofbuildings(againwiththeblacklineshowinga
1:1correspondenceofauditprojectedsavingstoactualperformance),verticallines
showsiteswheresavingsestimateswereadjustedwithoutchangeinperformance
andhorizontallinesshowsiteswheresavingsestimateswereunchangedbut
performancewasimprovedbysystemadjustment.Figure2addstothepicture
fromFigure1byshowingadjustmentsovertime.Wecanseeinthischartthe
significantopportunitytoimprovepostretrofitsystemperformance.Interestingly,
performanceimprovementcanbeachievedalmostasfrequentlyincasesthatwereexceedingpredictedperformanceasinthosecasesthatwereunderperformingin
relationtoprediction.
Oneimportantlessonherewasthatthepredictabilityofsavingsforanyspecificsite
couldbeimprovedbyfollowupbasedonMeasurementandVerification(M&V),
actingasfeedbackontheimplementationprocessandongoingoperations.A
secondlessonlearnedisthatbeyondjustpredictabilityinmeetingauditprojections,
absoluteprojectperformancecouldbeimproved.Thetendencyofproject
performancetodegradeovertime(ascontrolsandsettingsslipoutofadjustment,
forexample)couldbereversedbykeepingoperatorsalerttoperformance.With
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Snapshot
Finding the Proof of Energy Retrofits
M&Vbasedmonitoringappliedinthisway,theoverallportfolioperformedover
timeby20%betterthan(thetotalof)theauditprojections.vi
ContinuousCommissioning
ThevalueofM&VappliedasprocessfeedbackledtotheconceptofContinuous
Commissioning,eventuallytrademarkedbyESLTAMU.Commissioningsavings
couldbeattributedtotheadjustmentwork,independentlyoftheretrofitproject
andwereunderstoodtoconstituteasmuchas25%ofportfoliosavingsandat
muchlowercost.
Figure2:Multi-yearestimatedsavingsvsactualsavingsforLoanSTARbuildings19912000
Source:TexasA&MEnergySystemsLab
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Snapshot
Finding the Proof of Energy Retrofits
IntheLoanSTARprogram,commissioningwasdeployedinretrofitprojectsto
improvetheirperformance.Withthissuccessitbecamenaturaltowonderwhether
acommissioningapproachcouldbeappliedtoexistingsystems,withouttheretrofit.
Thus,theContinuousCommissioningexperienceledtoemergenceofthefieldof
ExistingBuildingCommissioning,RetroCommissioning,andOngoing
Commissioning.vii
Thiskindofmonitoringprocessreliesonintensivedataacquisitionandanalysis.On
anindividualbuildingbasis,itmaybeaccomplishedusingthecomputerbased
BuildingAutomationSystemsupplementedasnecessarybyportabledataloggers
andotherinstrumentation.Butforalarge,programmaticbuildingset,acoordinatedsystemisrequiredthatwillcollectdataandrecognizepatterns.We
havebecomeveryfamiliarwithextensive,complexnetworksintegratingmultisite
dataacquisition,storage,andautomatedanalysis.ESLsLoanSTARproject
Figure3:AnnualsavingsfromtheLoanSTARProgram
includingContinuousCommissioning,19902002
Source:TexasA&MEnergySystemsLab
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Snapshot
Finding the Proof of Energy Retrofits
pioneeredsuchanapplicationforenergymonitoring.Patternrecognitionofactual
versusperformancemodeledisalsoanongoingfieldthatiscriticaltokeepingtrack
oflargenumbersofsites.
Figure4:Pre-andpost-retrofitperformancedatapoints
plottedagainstboundedmodelprediction
Source:TexasA&MEnergySystemsLab
8/8/2019 Finding the Proof of Energy Retrofits | Snapshot | The Sallan Foundation
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Snapshot
Finding the Proof of Energy Retrofits
Conclusions
SowhataretheimplicationsforNYC?
Aprocessthatwillachieveitstargetedenergyandcarbonreductionentailsmore
thaninvestinretrofitsbecausethatwouldleavetheinvestmentopento
significantriskofunderperformance.NYCsplanincludesmeteringand
monitoring,butforthisefforttoreallypayoff,substantialinfrastructureisrequired,
intermsofbothhardwareandhumanknowledgeresources.Performancedepends
onfeedbackthroughsuchasystem.Itwillnotpaytoskimponthisphase.
TheCitysbudgetprocessissaidtobeskewedtowardscapitalimprovements.But
aswehaveseen,operations,whicharepaidforintheexpensebudget,reallymatter.
Completingbothretrofitsandthedataacquisitioninfrastructurewillnotmatterif
weareunabletoeffectivelyintegratethemintooperations.Hereisaprimecase
wherethebalanceofallocationbetweenthecapitalandexpensebudgets,can
significantlyaffectperformanceandoutcomes.TheCIUSBuildingPerformanceLab
hasdevelopedasimplespreadsheetthatallowsalternativeallocationstobe
exploredquantitatively.viii
References
iSeeMcGrawHillcitedinNREIResearchPaperTheEvolvingLandscapeofEnergyRetrofitsiiA.Maron,presentationatNREIconferenceonBenchmarkinginNYCBuildings,March2010iiihttp://www.seco.cpa.state.tx.us/ls/ivTAMUESLpublications951101and060702vSavingsarediscussedinenergyunits,notdollarsinordertoeliminatethevariabilityofenergyprices.vihttp://www.seco.cpa.state.tx.us/ls/
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viiSeePortlandEnergyConservationInc.,PECI.orgforacomprehensiveresourcelibraryonbothnewandexistingbuildingcommissioning.viiiM.BobkerIntegratingEnhancedBuildingOperationsintoMunicipalSustainabilityProgrammingProceedingsoftheInternationalConferenceonEnhancedBuildingOperations(ICEBO),2007SanFrancisco,CA.MichaelBobkerisDirectorofBuildingPerformanceLab,CUNYInstitutefor
UrbanSystems
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