SAP Thermal Proving
The Standard Assessment Procedure (SAP) is the
methodology used by the Government to assess and compare the energy and environmental performance of dwellings and
sometimes homes extensions.
Its purpose is to provide assessments of a dwellings energy performances that
are needed to underpin energy and environmental policy initiatives created by the government.
SAP applies to both new homes and to some home extensions where the proposed design exceeds a 25% floor area
limit of the new extension. If the new glazing to a proposed scheme is under 25% of the home extension floor
area then a SAP thermal proving calculation will not be required.
SAP was developed by the Building Research Establishment
(BRE) for the former Department of the Environment in
1992 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 and home extensions.
In 1994 SAP was entered in Part L of the Building
Regulations as a means of assessing dwelling energy performance. Reduced Data SAP (RDSAP)
was introduced in 2005 as a lower cost method of assessing the energy performance of existing
dwellings. BREDEM, SAP and
RDSAP are used to underpin the
delivery of a number of key energy and environmental policy initiatives.
SAP works by assessing how much energy a dwelling will
consume, when delivering a defined level of comfort and service provision. The SAP assessment is based on
standardised assumptions for occupancy and behaviour.
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).
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.
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
SAP 2012 is the latest revision of the SAP document. 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