UK Building Regulations require a SAP calculation to be carried out for all new build domestic properties as well as conversions and some extensions.
"RJ Energy offered us a seamless service when building our own home. They undertook our SAP calculation, air tightness testing, ventilation testing and water efficiency calculations. The process was straightforward and well managed, we wouldn't hesitate to use them again."
Jason Peters, Self-builder
New Build Properties
New build properties require a SAP calculation to show Building Control that the overall carbon emissions from the dwelling outperform the targeted emissions. The calculation models the thermal properties (fabric, ventilation, heating and cooling) of the dwelling and also shows that minimum performance values have been met throughout the specification. An Energy Performance Certificate (EPC) is generated at completion using the outputs from the calculation.
Buildings which are converted into dwellings (i.e. barn conversions or commercial premises) are also subject to a SAP calculation to show that minimum standards have been met throughout. There is no requirement to meet an emissions target. An EPC for the dwelling is produced at completion.
Some extensions will also require SAP calculations. These are dwellings which have large amounts of glazing and exceed the glazing tolerance set with Building Regulations Part L1B, as shown below.
The calculation is used to ensure that the proposed extension performs equal to or better than it would if the extension remained within the glazing allowance. Extensions with heavy glazing will need to improve other areas in order to improve performance, since glazing will lose more heat than walls and roofs would.