The procedure calculates a monthly energy balance for space heating and aggregates these figures over a heating season spanning October to May inclusive. It then takes account of hot water energy demand based on the size of the dwelling, of heating system control, responsiveness and efficiency characteristics and of fuel characteristics. Finally, account is also taken of calculated lighting energy (electricity) requirement in determining the overall results.

Calculated results are not affected by the geographical location, so that a given dwelling specification will yield the same result in all parts of Ireland in respect of Building Regulations compliance and BER.

The procedure used for the calculation is based on the European Standard IS EN 13790: 2004, and draws heavily on the UK’s Standard Assessment Procedure (SAP) 2005.