The results of a SAP calculation will never be an accurate prediction of actual energy usage. First, the SAP calculation is based on standardised assumptions on occupation, and does not assess how the building is actually used. The calculation takes no account of:
- actual house hold size and
- ownership and efficiency of particular domestic electrical
- individual patterns of heating and selected internal
Secondly, energy use, and therefore calculation results, do not take no account of geo-graphical location. A house built in Berwick upon Tweed will have the same rating as one of the same design built in Brighton (unless the house includes space cooling, in which case the results will vary according to location).
The real value of SAP is a comparative tool for evaluating relative performance and enabling the effect of energy efficiency measures to be assessed.