Standard Assessment Procedure
The Standard Assessment Procedure (SAP) is the methodology used by the Government to assess and compare the energy and environmental performance of dwellings. Its purpose is to provide accurate and reliable assessments of dwelling energy performances that are needed to underpin energy and environmental policy initiatives.
SAP was developed by the Building Research Establishment (BRE) for the former Department of the Environment in 1992, as a tool to help deliver its energy efficiency policies. The SAP methodology is based on the BRE Domestic Energy Model (BREDEM), which provides a framework for calculating the energy consumption of dwellings.
In 1994 SAP was cited in Part L of the Building Regulations as a means of assessing dwelling performance. Reduced Data SAP (RDSAP) was introduced in 2005 as a lower cost method of assessing the energy performance of existing dwellings. SAP, RDSAP and BREDEM are used to underpin the delivery of a number of key energy and environmental policy initiatives, for example:
- Buildings Regulations for England and Wales and the Devolved Administrations
- HM Treasury’s Stamp Duty exemption for zero carbon homes
- Energy Performance Certificates
- Code for sustainable homes
- Warm Front
- Green Deal
- Energy Company Obligation
- Local Authority stock reporting etc
How SAP works
SAP works by assessing how much energy a dwelling will consume, when delivering a defined level of comfort and service provision. The assessment is based on standardised assumptions for occupancy and behaviour. This enables a like-for-like comparison of dwelling performance. Related factors, such as fuel costs and emissions of carbon dioxide (CO2), can be determined from the assessment.
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 (the Environmental Impact Rating). 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.
SAP 2012 is the latest revision of the SAP document. It is not expected to come into force for building regulations compliance purposes until April 2014. This and SAP2009 can be downloaded via the following links:
This 2012 version of SAP has been published to support the 2013 Amendment to Part L of the Building Regulations for England, which is expected to deliver a 6% improvement in new dwelling performance. It is also expected to support the Building Regulations of the Devolved Administrations, Scotland, Northern Ireland and Wales.
The proposed changes to SAP 2012 were subject of a public consultation. Details of the consultation and responses can be viewed at the following links on the Consultation webpage.
The Government’s commitment that ‘new homes should be net zero carbon from 2016’ represents a challenge in terms of accurately and robustly assessing the performance of potentially lower-energy dwellings, given that some aspects of the performance may be delivered through off-site allowable solutions.
A key aspect of SAP’s future development will be to accurately reflect carbon emissions reduction from both on-site and off-site performance measures. Working with stakeholders, DECC intends to review SAP to determine how it may be developed to deliver this policy initiative. Reduced Data SAP will also be reviewed to ensure it remains fit to deliver the policy initiatives that it underpins.
The underpinning information, product performance and other relevant data that the assessment tools rely upon, must be produced to a high level of accuracy and reliability. DECC will be asking stakeholders to contribute to the achievement of that aim.