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Standard Assessment Proceedure (SAP)

The Standard Assessment Procedure (SAP) is the Department of Energy and Climate Change’s (DECC) methodology for assessing and comparing the energy and environmental performance of dwellings.

SAP works by assessing how much energy a dwelling will consume and how much carbon dioxide (CO2 ) will be emitted in delivering a defined level of comfort and service provision, based on standardised occupancy conditions. This enables a like for like comparison of dwelling performance.

SAP was developed by the BRE (formerly the Department of the Environment) as a tool to help deliver its energy efficiency policies. In 1994 SAP was cited in Part L of the Building Regulations for England and Wales as a means of assessing dwelling performance. Reduced Data SAP (RDSAP) was introduced in 2005 as a lower cost method of assessing the performance of existing dwellings.

SAP and RDSAP are used to underpin the delivery of a number of key energy and environmental initiatives such as:

  • the Buildings Regulations for England and Wales and the Devolved Administrations relating to the conservation of heat and power, where SAP is the method specified for assessing compliance
  • HM Treasury’s Stamp Duty exemption for zero carbon homes, for this purpose the SAP model was extended to include appliance energy use
  • National Calculation Methodology, as specified by the Energy Performance of Buildings Directive, SAP and RDSAP are used to produce Energy Performance Certificates
  • Local Authority stock reporting etc. 

SAP quantifies a dwelling’s performance in terms of: energy use per unit floor area, a fuel cost based energy efficiency rating (the SAP rating) and emissions of CO2. These indicators of performance are based on estimates of annual energy consumption for the provision of space heating, domestic hot water, lighting and ventilation. Other SAP outputs include estimate of appliance energy use, the potential for overheating in summer and the resultant cooling load.