Future Homes Standard: Part L update (HEM / SAP)

25/07/2025

The Future Homes Standard (FHS) is the name of the next set of Part L building regulations that are due to be introduced later this year. Under the FHS, new homes built must produce 75–80% fewer carbon emissions compared to those constructed under 2013 regulations. Homes built to the FHS must also be ‘zero-carbon ready’ and designed so they won’t require retrofitting to benefit from the decarbonisation of the electricity grid and the transition to electrified heating. The use of fossil fuel heating systems, such as gas and oil boilers, will not be allowed in new homes under FHS.

The Government initially announced that the FHS will be introduced in 2025. It is now looking likely that the specification of the FHS will be outlined/confirmed in autumn 2025, but the regulations won't be introduced until 2026. Once introduced, the transitional arrangement will then allow one year for any project with planning permission granted against the current Part L regulations to be commenced. This means any new homes built in 2027/2028 onwards will be built to the FHS.

The Government has also announced that the assessment methodology for Part L of the building regulations will be updated from SAP to the Home Energy Model (HEM). It was initially proposed that HEM would come in with the FHS, but to allow for HEM to be properly developed and to not hold up the release of the FHS it now looks likely that SAP will remain the assessment methodology for the time being. HEM will then be introduced at a later date when fully developed and tested.