How the EPC and recommendation report is produced

The government approved software programme uses data, together with standard performance tables, to assess the energy performance of the building and to produce the EPC and recommendations. The software also generates a 20 digit non-sequential reference number from the data.

The energy efficiency of buildings is assessed using a method known as Standard Assessment Procedure (SAP). SAP is used during the construction process to demonstrate that a new building meets energy efficiency targets. New buildings typically have a lot of information readily available for the calculation, such as detailed floor plans and specifications. Most new buildings complying with current Building Regulations will achieve a C or B rating. If new buildings are being specifically promoted as being environmentally friendly, you should expect them to be at the top end of the B band or possibly in the A band. When a building is constructed, the EPC must always be based on the full range of information required.

For existing buildings much of the information required to assess the energy performance is not readily available so a survey is needed to collect it. To minimise inconvenience for the homeowner, the method to assess the energy performance was adapted to include a set of assumptions about the building based on conventions and requirements at the time the building was constructed. This means that less information is required from the homeowner for the assessment than for a new build property. This adapted method is called Reduced data Standard Assessment Procedure (RdSAP).

Generally, for buildings being marketed for sale or rent RdSAP is the appropriate method of assessment. For certain types of building, however, the SAP method will give a more accurate rating. The types of property where the SAP method might give a more accurate rating include buildings constructed to current Building Regulations standards, or those that have been refurbished with advanced energy efficiency measures installed. Using the SAP method for an existing building will require more detailed and extensive information. When the SAP method is used for older buildings, the energy assessor will need to ensure that any recommendations proposed are appropriate for installation in the building.