1.1 What it does in a nutshell
The FHS represents the most significant change to energy efficiency requirements for new homes in England in over a decade. Published on 24 March 2026, it requires all new dwellings in England to be “zero-carbon ready“. The standard does not apply to existing housing stock and carries no retrofit obligations. Whilst the detail is complex (and many technical challenges and ambiguities will need to be solved), the core proposition and intent is straightforward: new homes built to the FHS should not need any physical intervention to become zero-carbon once the grid decarbonises. This is a future-proofing standard, not an immediate zero-carbon mandate.
1.2 Background
Successive governments have tried for some time to regulate the “homes of the future”.
In 2006, Gordon Brown announced an ambitious goal to progressively improve the energy and carbon standards in Building Regulations, with a “zero carbon” target for all new dwellings by 2016. This was to be supported by tighter energy efficiency standards and a scheme that would allow housebuilders to deliver equivalent carbon savings off site. Some progress was made with the 2013 uplift to Part L of the Building Regulations (Part L 2013), but it was not until 2019 that the concept of the FHS became a stated government commitment once more. Successive delays in finalising the standard were driven by a combination of factors, including: supply chain immaturity (particularly in heat pump manufacturing and installation), housebuilder lobbying, political reluctance and wider economic turbulence (including the post-COVID supply chain crisis and the energy price shocks following Russia’s invasion of Ukraine). On 15 May 2024, the government stated that the FHS would come into force sometime in 2025, following a series of consultations – but again that target was missed amidst economic and political turbulence. Against this backdrop, the FHS’s publication represents the culmination of close to two decades of policy development.
1.3 Legislative framework
The FHS was finally published on 24 March 2026 and has been implemented via amendments to the Building Regulations under The Building Regulations etc. (Amendment) (England) Regulations 2026 (the “Regulations“) and through the publication of new statutory guidance that provides practical advice on ways of complying with the requirements of the Regulations. As a devolved matter in the UK, the FHS will apply to all new dwellings in England only.
The fundamental purpose of the FHS is to create a “zero-carbon ready” standard:
“New dwellings built to this standard will not require any retrofit work to achieve zero carbon emissions in use, once the electricity grid is fully decarbonised.“
This is significant. The FHS does not make homes zero carbon immediately – instead, the FHS works to future-proof dwellings, so that once the grid has decarbonised (the government’s stated target being 2030), these homes will automatically achieve zero operational carbon without further physical intervention. Crucially, the FHS imposes obligations on new dwellings only. There is no obligation to retrofit existing dwellings.
1.4 Technical Specifications
The FHS specification is set using a “notional building” approach: a reference building sets tailored performance targets, and developers’ designs must match the same level of performance in terms of energy usage, carbon emissions, and fabric efficiency.
The notional building specification suggests using a heat pump, on-site renewable generation, tighter fabric and airtightness standards, mechanical ventilation and wastewater heat recovery. Collectively, these changes would allow new FHS homes to achieve the performance target for carbon emissions, being at least 75% lower than the 2013 Part L baseline under the FHS. Importantly, these standards are not absolute: they are accompanied by a bundle of guidance which provides technical specifications, and details for when it may be deemed reasonable to diverge from the standards. Further, higher-risk buildings (“HRBs“), which are at least 18m/7 storeys tall and contain at least two residential units, care homes or hospitals, are exempt from the on-site renewables requirement.
The FHS also introduces the Home Energy Model (HEM), a new compliance methodology that will eventually replace the existing Standard Assessment Procedure (SAP). At present, only SAP (version 10.3) is approved to demonstrate FHS compliance, with HEM expected to be approved within approximately three months of the FHS taking effect. Once approved, SAP and HEM will “dual run” for at least 24 months before SAP is retired. Critically, HEM is expected to make it significantly harder to offset poor fabric performance with renewable technology bolt-ons, closing the well-documented “performance gap” between modelled and actual energy performance.
1.5 Transitional Provisions
The transitional arrangements for the FHS will be an area of focus and potentially debate. There will be a 12-month period between the legislation being laid and coming into force, followed by a further 12-month transitional period. In practice, this means that developers wishing to build to the existing standards (i.e. avoid incurring the additional design effort and expense that complying with the FHS will inevitably involve) have until 24 March 2027 to submit a building notice, initial notice or full plans application to the relevant local authority. Work must then be commenced on the dwelling before 24 March 2028. The transitional process differs for HRBs, which must submit a successful application to the Building Safety Regulator within 18 months of the FHS legislation being laid, with a further three years from that application to commence construction.