A SAP calculation is a series of calculations, taking into account: space heating, water heating, ventilation and lighting and also taking into consideration potential cost savings generated through the deployment of energy generation technologies e.g. renewables.

Data is collected from a number of sources, including: drawings (floor plans, elevations, site plan, etc.), build specifications, proposed heating and ventilation systems. This information is entered into an accredited software tool to create the draft SAP report. The SAP rating for the building is graded on a scale of 1 to 100 – where 100 represents zero energy costs.