SAP Ratings
SAP (Standard Assessment Procedure) is the UK Government's standard methodology for home energy rating.
SAP ratings allow comparisons of energy efficiency to be made, and can show the likely effect of improvements to a dwelling in terms of energy use. The SAP rating is based on running costs for space heating, water heating and lighting, which are calculated taking account of the shape and fabric of the building, its thermal insulation, the fuel used, and the performance of the heating system.