The energy efficiency of a new build domestic property is assessed using SAP (Standard Assessment Procedure), the Government's calculation methodology for assessing the energy efficiency of dwellings. It includes provision for accounting for (a) under-floor insulation and (b) under-floor heating.
Existing dwellings are assessed by Reduced Data SAP (RdSAP) which makes assumptions about floor insulation based on the age of the property.
The energy efficiency of the vast majority of commercial buildings is assessed using SBEM (Simplified Building Energy Model) which takes account of both under-floor insulation and under-floor heating.