Energy Efficiency Assessment - SAP Ratings

SAP is the Government's Standard Assessment Procedure for Energy Rating of Dwellings. The current version of the software is SAP 2009 and can be accessed via the 'Related Sites' section of this page. SAP software was adopted by the Government as part of the UK national methodology for calculation of the energy performance of buildings. It is used to demonstrate compliance with Building Regulations for Dwellings - Section 6 in Scotland - and to provide energy ratings for Dwellings.

The indicators of energy performance are energy consumption per unit floor area, an Energy Cost Rating - the SAP Rating, an Environmental Impact Rating based on CO2 emissions - the EI Rating and a Dwelling CO2 Emission Rate or DER.

The SAP Rating is based on the energy costs associated with space heating, water heating, ventilation and lighting, less cost savings from energy generation technologies. It is adjusted for floor area so that it is essentially independent of Dwelling size for a given built form. The SAP Rating is expressed on a scale of 1 to 100, the higher the number the lower the running costs.

The Environmental Impact Rating is based on the annual CO2 emissions associated with space heating, water heating, ventilation and lighting, less the emissions saved by energy generation technologies. It is adjusted for floor area so that it is essentially independent of Dwelling size for a given built form. The Environmental Impact Rating is expressed on a scale of 1 to 100, the higher the number the better the standard.

The Dwelling CO2 Emission Rate is a similar indicator to the Environmental Impact Rating, which is used for the purposes of compliance with Building Regulations. It is equal to the annual CO2 emissions per unit floor area for space heating, water heating, ventilation and lighting, less the emissions saved by energy generation technologies, expressed in kg/m2/year.

The method of calculating the energy performance and the ratings is set out in the form of a worksheet, accompanied by a series of tables. The methodology is compliant with the Energy Performance of Buildings Directive. The calculation should be carried out using a computer programme that implements the worksheet and is approved for SAP calculations.

Details of the requirements of SAP can be found at the SAP website via the 'Related Sites' section on this page, or through one of the accredited SAP Assessors, see 'Related Downloads' for a current list of these.

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