Guidance

Standard Assessment Procedure

OverviewGuidance ofon how a home's energy performance is calculated using the Standard Assessment Procedure (SAP).(SAP) methodology, which underpins the Energy Performance Certificate (EPC).

Overview

The Standard Assessment Procedure (SAP) foris the methodology used by the government to assess and compare the energy ratingand environmental performance of dwellings. Its purpose is to provide accurate and reliable assessments of dwellings that are needed to underpin energy and environmental policy initiatives. The Simplified Building Energy Model (SBEM) is the methodology currently used by the government to estimateassess and compare the energy and environmental performance of homes.non-domestic properties.

The methodologygovernment hasis 2committed main uses:

  • to demonstrateincreasing compliancethe accuracy of newSAP. homesThe withmost Partrecent Lversion of theSAP Building10 Regulations(10.2)
  • to generatecame Energyinto Performanceforce Certificateswith (EPCs)the forupdated allPart homes,L whichbuilding adviseregulations occupants,in prospectiveJune buyers,2022, landlords, and rentersincorporated ofvarious changes to the energymethodology, performanceincluding ofupdated:

    • fuel aprices
    • CO2 propertyemissions
    • primary energy factors

    Non-domesticFor buildingsexisting usedwellings, a differentsimplified methodology,version calledof theSAP Simplifiedcalled BuildingReduced EnergyData Model (SBEM).

    SAP plays(RdSAP) ais keyused roleto inassess developing,their implementing,energy andperformance. monitoringAn governmentRdSAP policiesassessment onwill energyuse efficiency,a fuelset povertyof andassumptions heatabout decarbonisation,the anddwelling isbased usedon acrossconventions and requirements at the wholetime buildingit industry.was constructed.

    RdSAP 2012 is the current version used to produce assess energy performance in existing dwellings. The historygovernment ofis SAPworking on an RdSAP update (RdSAP 10.2) which we expect to publish in due course.

    Background

    SAP was was developed by the Buildingthe Building Research Establishment (BRE) for) for the former Department of the Environment andin was1992, as a tool to help deliver its energy efficiency policies. The SAP methodology is based on the the BRE Domestic Energy Model (BREDEM)., SAPwhich wasprovides firsta publishedframework infor 1993calculating andthe hasenergy sinceconsumption beenof updateddwellings.

    In periodically,1994 SAP was cited in 1998,Part 2001,L 2005,of 2009,the 2012,Building andRegulations mostas recentlya inmeans 2022.

    Inof 1994,assessing dwelling performance. Reduced Data SAP (RDSAP) was firstintroduced cited in the2005 Buildingas Regulationsa aslower thecost meansmethod of assessing the energy performance of existing dwellings. InSAP 2007and itRDSAP wasare adoptedused asto underpin the methodologydelivery behindof a number of key energy and environmental policy initiatives, for example:

    • to demonstrate that new dwellings comply with the Building Regulations
    • Energy Performance Certificates (EPCs).

      Reduced)

    • the data SAP (RdSAPmethodology underpins the EPC), waswhich introducedcan inonly 2005be asproduced by a simplerqualified and loweraccredited costassessor

    How methodSAP forworks

    SAP works by assessing existinghow dwellings.much Anenergy RdSAPa assessmentdwelling will useconsume when delivering a setdefined level of comfort and service provision. The assessment is based on standardised assumptions aboutfor theoccupancy dwelling,and reducingbehaviour. theThis volumeenables a like-for-like comparison of datadwelling anperformance. Related energyfactors, assessorsuch mustas collect.

    Currentfuel methodologies

    Thecosts currentand versionemissions of SAPcarbon isdioxide SAP(CO2), 10.2.can be determined from the assessment.

    TheSAP currentquantifies versiona ofdwelling’s RdSAPperformance isin RdSAPterms 2012.of:

    The

    • energy governmentuse isper currentlyunit workingfloor onarea
    • a an RdSAP updatefuel-cost-based (RdSAP 10),energy whichefficiency willrating be(the availableSAP forRating)
    • emissions useof inCO2 early(the 2024.

      Environmental Impact Rating)

    YouThese canindicators findof detailperformance are based on estimates of theannual upcomingenergy changesconsumption infor the RdSAPprovision 10of specification.

    Youspace canheating, finddomestic morehot informationwater, onlighting and ventilation. Other SAP andoutputs RdSAPinclude:

    TheFuture futuredevelopments of- SAP 11

    FollowingIn recommendations2020 bywe commissioned a scoping project for the Climatenext Changeversion Committeeof (CCCSAP) and- aSAP scoping11 study- commissionedto byadvise theon formerhow Departmentit can be enhanced to support net zero commitments for Business,buildings. EnergyA andconsortium Industrialled Strategy,by Etude carried out the governmentSAP is11 developingscoping project which made a newnumber methodologyof recommendations, including how to increasemake itsSAP accuracy,more robustness,accurate, robust and ensurefit itfor ispurpose fitto support the net zero.zero commitment.

    In DecemberOctober 2023,2021 we publishedappointed a consultationconsortium onof thisexperts newled methodologyby the HomeBuilding EnergyResearch ModelEstablishment (closing(BRE) onto 6develop MarchSAP 2024)/ RdSAP so11. thatThe industrySAP can11 participateproject inteam is working with stakeholders to consider the ongoingEtude developmentrecommendations process.

    Theand Homehow Energyto Modelimplement isthem. stillWe underlook developmentforward andto itsengaging firstfurther versionwith industry through our SAP 11 consultation which we plan to launch next year.

    SAP 11 will become implementedinto force in 2025, alongside the Future Homes Standard inupdate 2025.of the Building Regulations.

Published 22 January 2013
Last updated 1320 December 20232022 + show all updates
  1. Added link to a consultation on the Home Energy Model, a new methodology which will replace SAP.

  2. Updated information about Standard Assessment Procedure SAP10.2, and the timeline for the Reduced data SAP (RdSAP) update.

  3. Updated with information about SAP 10.2 which comes into force in summer 2022, and SAP 11, planned for 2025.

  4. Minor updates to the guide on SAP adding in new links to BRE.