HEM & Future Homes Standard: Timeline & Status

This page tracks the current status of the Home Energy Model (HEM), the Future Homes Standard (FHS), EPC reform, and the ECaaS platform. It is updated as new information becomes available. The timeline has shifted multiple times, and dates below reflect the best available information as of March 2026.

Current Status Dashboard

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Key Dates at a Glance

Detailed Chronological Timeline

1993–2022: The SAP Era

• 1993: SAP first published by BRE as the UK's standard method for assessing the energy performance of dwellings.
• 2005–2012: Successive SAP updates (SAP 2005, 2009, 2012) refine inputs and assumptions but leave the core monthly calculation method unchanged.
• 2019: The Climate Change Committee publishes UK Housing: Fit for the Future?, recommending that SAP be replaced with a next-generation assessment methodology.
• October 2019: The government publishes the first Future Homes Standard consultation, beginning the formal process of updating Part L of the Building Regulations.
• January 2021: Government publishes its response to the first FHS consultation.
• 2021: DESNZ commissions a BRE-led consortium to develop the Home Energy Model. A separate quality assurance consortium is led by Etude, including UCL and Levitt Bernstein.
• June 2022: The 2021 Part L uplift comes into force, requiring a 30% reduction in carbon emissions compared to the 2013 standard. This serves as an interim step towards the full FHS.
• 2022: The Climate Change Committee reiterates its recommendation to replace SAP in its progress report to Parliament.

2023–2024: Consultations and Development

• December 2023: The government publishes the HEM consultation and the FHS 2023 consultation simultaneously. The consultations include draft technical documentation, a test version of the HEM engine, and proposed FHS fabric and heating specifications.
• March 2024: Both consultations close, with the deadline extended from the original date due to a software issue with the HEM test environment.
• December 2024: DESNZ publishes a separate EPC reform consultation, proposing broader changes to the energy performance of buildings regime.

2025: Responses and Preparation

• February 2025: The EPC reform consultation closes.
• May 2025: The government confirms that a dual methodology will be permitted: both SAP 10.3 and HEM can be used for FHS compliance during a phased transition period.
• June 2025: The government confirms that virtually all new-build properties will be required to have rooftop solar PV installed under the FHS.
• Mid 2025: The HEM test environment is made available to industry stakeholders. Show-and-tell sessions with the development team begin in July.
• October 2025: DESNZ publishes the government response to the HEM consultation, confirming the half-hourly methodology, ECaaS delivery model, and open source approach. Updated technical documentation is released alongside.
• Late 2025: BRE approves the SAP 10.3 engine for use in FHS compliance assessments during the dual methodology period. The FHS government response, originally expected by the end of 2025, slips to “early 2026”.

2026: Implementation

• January 2026: The government publishes the HEM: EPC Assessment consultation, proposing how HEM will be used for existing dwellings and four new EPC headline metrics. The consultation closed on 18 March 2026. A partial response to the broader EPC reform consultation is also published.
• February 2026: Government confirms that SAP 10.3 will be the sole FHS compliance methodology at launch. HEM will follow a minimum of three months later, with a 24-month dual running period once HEM is approved.
• 18 March 2026: The HEM: EPC Assessment consultation closes. Government response expected later in 2026.
• March 2026: Heat pump planning rules relaxed. The 1-metre boundary rule is removed and air-to-air heat pumps are now covered by permitted development.
• April 2026 (expected): The Boiler Upgrade Scheme (BUS) is expanded to cover air-to-air heat pumps (£2,500 grant) and heat batteries (£2,500 grant).
• 28 May 2026: MCS 020 becomes the sole heat pump certification standard under permitted development rules.
• Mid-2026 (expected): Plug-in solar panels legalised. Regulations are being finalised for panels under 800W connected via a standard socket.
• 24 March 2026: The government publishes the final Future Homes Standard Approved Documents, including new Approved Document L (energy) and Approved Document F (ventilation), Building Circular 01/2026, the consultation response, and impact assessments. Solar PV is mandatory under a new Part L3, low-carbon heating is required, and SAP 10.3 is confirmed as the sole compliance methodology at launch.
• Second half of 2027: Reformed HEM-based EPCs launch (delayed from October 2026), running alongside the existing Energy Efficiency Rating.
• December 2026: ECO4 obligation ends (extended from the original March 2026 end date).

2027 and Beyond

• 24 March 2027: Future Homes Standard comes into force. SAP 10.3 is the sole compliance methodology. All new building notices and full plans applications from this date must meet FHS requirements.
• Mid-2027 (earliest): HEM approved as FHS compliance methodology (minimum 3 months after FHS). Dual running period with SAP 10.3 begins.
• 24 September 2027: FHS comes into force for higher-risk building work.
• 24 March 2028: Transitional period ends. All projects must comply with the FHS, even those with applications submitted before March 2027.
• 24+ months after HEM approval: SAP 10.3 withdrawn as an FHS compliance route. HEM becomes the sole methodology.
• October 2029 (target): The existing Energy Efficiency Rating is discontinued. All EPCs produced using the new HEM-based metrics only.

Transitional Arrangements

The transitional arrangements are critical for developers and builders planning current and future projects. Based on the best available information:

• Projects with applications submitted before 24 March 2027 (building notice, initial notice, or full plans application) can build to current Part L 2021 standards, provided building work commences before 24 March 2028.
• Projects submitted on or after 24 March 2027 must meet the full Future Homes Standard.
• Higher-risk buildings have a later start date of 24 September 2027, with separate transitional provisions.
• Old transitional provisions revoked: The government has revoked earlier transitional arrangements from 2013 and 2021 that allowed construction to 2010 energy standards. Uncommenced plots relying on those provisions must now meet the FHS.
• Transitional arrangements operate on an individual building basis, not site-wide. Each plot on a site is assessed independently.

Dual Methodology: SAP 10.3 and HEM

The government confirmed in May 2025 that both SAP 10.3 and HEM can be used for Future Homes Standard compliance. In February 2026, the government clarified the phasing:

• At FHS launch: SAP 10.3 is the sole approved methodology; HEM is not available
• 3+ months after FHS launch: HEM becomes an approved methodology alongside SAP 10.3
• 24+ months after HEM approval: SAP 10.3 is withdrawn; HEM becomes the sole compliance route
• SAP 10.3 has been updated with FHS notional dwelling specifications and revised carbon factors
• HEM assessments are carried out through the ECaaS platform

This means SAP 10.3 will be available for a minimum of 27 months from FHS launch (3 months solo plus 24 months dual running). See our full analysis of this announcement.

What We're Waiting For

As of March 2026, the key outstanding items are:

1. FHS Approved Documents - Published 24 March 2026. Consultation response, Approved Documents L and F, Building Circular 01/2026, and impact assessments all published. In force 24 March 2027.
2. HEM: EPC consultation response, which will confirm the four new EPC metrics and the timetable for HEM-based EPCs for existing homes.
3. ECaaS production readiness. The platform needs to move from limited beta access to full production availability for all accreditation schemes.
4. HEM approval date, confirmed as a minimum of 3 months after FHS launch, triggering the 24-month dual running period.
5. Plug-in solar wiring regulations. Final regulations for sub-800W panels connected via a standard socket are being drafted, with legalisation expected by mid-2026.
6. Warm Homes Plan, the successor programme to ECO4, which ends in December 2026. Details of the replacement scheme have not yet been confirmed.
7. BUS air-to-air heat pump grant. The expanded Boiler Upgrade Scheme covering air-to-air heat pumps and heat batteries (£2,500 each) is expected to go live in April 2026.

We update this page as each milestone is reached. To be notified of significant updates, sign up for our newsletter below.

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