New Build versus Existing Properties

For domestic properties, ie houses and homes rather than commercial premises, there are two different assessment procedures used in the creation of EPCs.

For new-build properties, an EPC is generated using the Standard Assessment Procudure (SAP). This is based on engineering information about the materials used in the construction of the property, and is created by an On Construction Domestic Energy Assessor (OCDEA), without a visit being required to the property.

For existing properties however, i.e. properties that are more than 10 years old and where the original SAP EPC has now expired, a new EPC is generated using the Reduced Dataset Standard Assessment Procedure (RDSAP). This requires a visit from a Domestic Energy Assessor (DEA), and the methodology makes use of less detailed information, and standard assumptions are made about some aspects of the property.

The type of assessment procedure used for creating an EPC is specified towards the end of the certificate itself. Also, the appearance of the Features table on the EPC can indicate which methodology was used. SAP EPCs have technical numerical informaiton in the Features table,  wheras RDSAP EPCs generally don't.