
Proposed Changes to Part L of the Building Regulations

SAP 10
SAP 10 is the methodology used to show compliance with Part L but is still to be BRE approved. However, reviewing the two options aforementioned of the Future Homes Standards and the reference values stated below, should provide an insight into how compliance is achieved.
The U-value or thermal transmittance is the rate of transfer of heat through a structure divided by the difference in temperature across that structure. The units of measurement are W/m²K. The better insulated a structure is, the lower the U-value will be. Important to note that heat transfer is closely related to CO2 emissions as more CO2 is generated to replace heat lost within a building thus less heat transfer – less CO2.
Currently, to comply with Part L, the Dwelling Emission Rate (DER) is to be no higher than the Target Emission Rate (TER). The Dwelling Fabric Energy Efficiency (DFEE) is to be no higher than Target Fabric Energy Efficiency (TFEE). In the next version of Part L, whether option one or option two is adopted, there will be new compliance measures:DER no higher than the TERDwelling Primary Energy Rate (DPER) no higher than the Target Primary Energy Rate (TPER)The Target Emission Rate (TER) & the Target Primary Energy rate (TPER) values in which efficiency standards are measured will incorporate PV systems. As a result, to achieve a Dwelling Emission Rate (DER) and Dwelling Primary Energy Rate (DPER) no higher than their target values it is expected that most new dwellings under the Fabric Plus Technology method, will require some form of Solar PV or low carbon technology, such as a heat pump.