The Standard Assessment Procedure (SAP)

The Standard Assessment Procedure (SAP) is adopted by Government as the UK methodology for calculating the energy performance of dwellings within Approved Document L1A - Conservation of fuel and power in new dwellings and Approved Document L1B - Conservation of fuel and power in existing dwellings.

The calculation is based on the energy balance taking into account a range of factors that contribute to energy efficiency:

  • materials used for construction of the dwelling
  • thermal insulation of the building fabric
  • ventilation characteristics of the dwelling and ventilation equipment
  • efficiency and control of the heating system(s)
  • solar gains through openings of the dwelling
  • the fuel used to provide space and water heating, ventilation and lighting
  • energy for space cooling, if applicable
  • renewable energy technologies

The calculation is independent of factors related to the individual characteristics of the household occupying the dwelling when the rating is calculated, for example:

  • household size and composition
  • ownership and efficiency of particular domestic electrical appliances
  • individual heating patterns and temperatures

Except where the dwelling has a fixed air conditioning system ratings are not affected by the geographical location.

The Standard Assessment Procedure was first published by the then DOE and BRE in 1993 and in amended form in 1994, and conventions to be used with it were published in 1996 and amended in 1997. Revised versions were published in 1998, 2001, 2005 and 2009.

The present edition is SAP 2012 in which:

  • climatic data has been extended to allow calculations using regional weather
  • an allowance for height above sea level is incorporated into external temperature data
  • CO2 emission factors have been extensively revised
  • fuel price and primary energy factors have been revised
  • the options for heat losses from primary pipework have been extended

Further information can be found at BRE or by downloading the following documents.


SAP 2012: Standard Assessment Procedure for energy rating of dwellings

This manual describes the Government's Standard Assessment Procedure (SAP) for assessing the energy performance of dwellings. The indicators of energy performance are Fabric Energy Efficiency (FEE), energy consumption per unit floor area, energy cost rating (the SAP rating), Environmental Impact rating based on CO2 emissions (the EI rating) and Dwelling CO2 Emission Rate (DER).

SAP ManualSAP 2012 edition

PDF file: 2.01MB, 172 pages


Archived copies of the Standard Assessment Procedure

SAP 2009 edition incorporating RdSAP 2009 (PDF file: 1.05Mb, 208 pages)
SAP 2009 edition (PDF file: 885Kb, 164 pages)
SAP 2005 edition: Revision 3 (PDF file: 848Kb, 167 pages)
SAP 2005 edition: Revision 2 (PDF file: 797Kb, 158 pages)
SAP 2005 edition: Revision 1 (PDF file: 815Kb, 149 pages)
SAP 2005 edition (PDF file: 1.61Mb, 74 pages)
SAP 2001 edition (PDF file: 395Kb, 42 pages)


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