HEM & Future Homes Standard \u2014 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 — dates below reflect the best available information as of February 2026.

Current Status Dashboard

Next Expected Milestone

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 closes 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.
• Q1 2026 (expected): Government response to the FHS 2023 consultation, with Statutory Instrument laid before Parliament.
• October 2026 (target): New HEM-based EPCs launch, running alongside the existing Energy Efficiency Rating.
• Late 2026 (expected): Future Homes Standard comes into force with SAP 10.3 as the only compliance route.
• 3+ months after FHS (expected): HEM approved as an FHS compliance route. The 24-month dual running period with SAP 10.3 begins.

2027 and Beyond

• Late 2027 (expected): Transitional period ends. All new homes must comply with the Future Homes Standard regardless of when the plot was registered.
• 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:

• Plots registered before the FHS commencement date (expected late 2026) may have until approximately 12 months later (expected late 2027) to begin construction under the current Part L rules.
• Plots registered after commencement must meet the full Future Homes Standard.
• Transitional arrangements operate on an individual building basis, not site-wide. Each plot on a site is assessed independently based on its own registration date.
• The definition of “commence” is expected to include drainage and foundation work, not just planning permission.
• An uptick in plot registrations is expected ahead of the commencement deadline, as developers seek to lock in the current rules for sites already in their pipeline.

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 February 2026, the key outstanding items are:

1. FHS 2023 consultation government response — the single most important milestone, expected early 2026. This will confirm final fabric specifications, heating requirements, and compliance rules.
2. FHS legislation laid before Parliament — this triggers the implementation countdown (approximately 12 months to commencement).
3. HEM: EPC consultation response — will confirm the four new EPC metrics and the timetable for HEM-based EPCs for existing homes.
4. ECaaS production readiness — the platform needs to move from limited beta access to full production availability for all accreditation schemes.
5. HEM approval date — confirmed as a minimum of 3 months after FHS launch, triggering the 24-month dual running period.

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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