The government has confirmed that when the Future Homes Standard comes into force, SAP 10.3 will be the sole approved compliance methodology. The Home Energy Model will not be available at launch — it will follow a minimum of three months later. Once HEM is approved, both methodologies will run in parallel for at least 24 months before SAP is withdrawn. This is the clearest indication yet of the FHS compliance timeline and gives the industry a concrete planning framework.
Government Confirms FHS Launches with SAP 10.3 Only — HEM Follows at Least Three Months Later
· Source: Elmhurst Energy
The government has informed Elmhurst Energy that SAP 10.3 will be the only approved methodology when the Future Homes Standard takes effect. HEM will not be available as a compliance route at launch. Instead, HEM will become an approved methodology a minimum of three months after the FHS goes live, with a confirmed 24-month dual running period following HEM's approval. This means SAP 10.3 will remain available for at least 27 months from FHS launch — giving the industry a substantial window to transition.
This announcement resolves months of uncertainty about how the FHS compliance framework would operate. While the government confirmed the dual methodology principle back in May 2025, the question of whether both routes would be available simultaneously at launch had remained open. The answer is now clear: SAP 10.3 goes first, HEM follows.
This phased approach is consistent with a written ministerial statement from 28 January 2026 which stated that SAP 10.3 would be available “for a limited period” alongside HEM. Industry commentary from Stroma and BuildPass had also pointed in this direction, noting that HEM's ECaaS platform and supporting infrastructure were not yet ready for production-scale use.
What this means for the industry
For assessors: SAP 10.3 skills are immediately valuable and will be the only game in town at FHS launch. If you know SAP, the transition to 10.3 is manageable — the core methodology is unchanged, with updates to the notional dwelling, carbon factors, and reporting format. HEM training can continue in parallel but is not urgent for day one.
For developers: Compliance planning is now simpler. There is no need to choose between methodologies for initial FHS projects — SAP 10.3 is the only option. This removes a significant source of uncertainty from procurement and design programmes. Plan for SAP 10.3 now; HEM becomes an additional option later.
For architects: Design to SAP 10.3 targets for any project that will be submitted in the early months of the FHS. HEM's more detailed modelling — which better rewards good design decisions like orientation, thermal mass, and solar self-consumption — comes later. Designs that perform well under SAP 10.3 will generally perform at least as well under HEM.
For software providers: SAP 10.3 tools are needed immediately. HEM software has a runway of at least three months — but providers should not wait, as readiness at HEM launch will be a competitive advantage.
Elmhurst's SAP 10.3 Software Receives BRE Approval
· Source: Elmhurst Energy
Elmhurst Energy's “Design SAP 10” software has received BRE approval for the SAP 10.3 calculation engine. The updated application will be released as soon as the FHS regulations are formally published. Elmhurst is the first provider to publicly confirm BRE approval for SAP 10.3, though other major providers including Stroma and JPA are expected to follow. BRE has not yet published a formal SAP 10.3 approved software list — this is expected alongside the FHS itself.
What this means: At least one software tool will be ready from day one. Assessors using Elmhurst's platform can expect a familiar experience with SAP 10.3 updates built in. Others should check with their providers for readiness timelines.
24-Month Dual Running Period Confirmed for SAP 10.3 and HEM
· Source: Elmhurst Energy
The government has confirmed that once HEM is approved as an FHS compliance route, it will run alongside SAP 10.3 for a minimum of 24 months before SAP is withdrawn. Crucially, the 24-month clock starts from HEM's approval date — not from the FHS launch. Combined with the three-month minimum gap, this means SAP 10.3 will be available for at least 27 months total from FHS launch. This is the first time a concrete dual running duration has been confirmed.
What this means: The industry has a generous window to transition. Assessors can begin with SAP 10.3 and migrate to HEM when they are ready, without time pressure in the early months.
HEM EPC Consultation Still Open — Closes 18 March 2026
· Source: GOV.UK
Separate from the FHS compliance question, the government's consultation on using HEM for existing dwelling EPCs remains open until 18 March 2026. Today's announcement about the FHS methodology does not directly affect this consultation, which covers a different use case — assessing the 25 million existing homes currently handled by RdSAP. However, the confirmation that HEM is not yet production-ready for new builds adds context to the EPC consultation timeline.
What this means: The HEM EPC consultation is a separate workstream. Responding before 18 March remains important — see our consultation deep dive for guidance.
FHS Consultation Response Expected in Q1 2026
· Source: UK Parliament
A written ministerial statement from 28 January 2026 confirmed the government intends to publish the FHS consultation response and full technical specification alongside laying a Statutory Instrument in Q1 2026. The statement specifically noted that SAP 10.3 would be available “for a limited period” alongside HEM. With Q1 running to the end of March, the FHS publication could come within weeks.
What this means: The FHS regulations may be imminent. Combined with BRE-approved SAP 10.3 software already in hand, the pieces are falling into place for a launch in the first half of 2026. Our timeline tracks all upcoming milestones.
HEM Infrastructure Still Maturing — ECaaS and Software Lag Behind SAP 10.3
· Sources: Elmhurst Energy / Build Energy
The decision to launch with SAP 10.3 only reflects the current state of HEM infrastructure. The MHCLG test interface, released in August 2025, has seen limited updates since. Key outstanding items include the final Product Characteristics Database, industry conventions group formation, and ECaaS scaling for production use. Elmhurst has confirmed it is building a “Design HEM” application to connect to ECaaS, which will launch once HEM infrastructure is in place.
What this means: HEM is not delayed indefinitely — the three-month minimum gap suggests the government expects it to be ready relatively soon after FHS launch. But the infrastructure still needs work before it can support the entire industry at scale.
Background & Context
This announcement is the culmination of a year-long evolution in government thinking about FHS compliance. When the 2023 FHS consultation launched, HEM was positioned as the primary — and potentially sole — compliance methodology. Industry feedback made clear that this was unrealistic given the state of HEM development, and in May 2025 the government confirmed a dual methodology approach.
Today's confirmation takes that a step further: rather than launching both simultaneously, SAP 10.3 will go first, with HEM following once it is genuinely ready. This is a pragmatic decision that acknowledges the reality of software development timelines. SAP 10.3 is a relatively modest update to the existing SAP 10.2 methodology — incorporating a new notional dwelling, updated carbon emission factors, and a revised BREL report format — making it straightforward for existing SAP assessors to adopt.
The 24-month dual running period is significant. Previous regulatory transitions have not always provided such a clear window. This gives the industry confidence that SAP 10.3 is not going to be pulled out from under anyone — there is a guaranteed minimum period in which both routes are valid. For the broader context of how SAP and HEM compare, see our SAP vs HEM comparison.
Revised Compliance Timeline
Based on today's confirmation and the 28 January written ministerial statement, the FHS compliance methodology timeline now looks like this:
| Phase | Expected Timing | Available Methodology |
|---|---|---|
| FHS published | Q1 2026 (imminent) | N/A — regulations laid |
| FHS comes into force | Late 2026 | SAP 10.3 only |
| HEM approved | 3+ months after FHS launch | SAP 10.3 + HEM (dual running begins) |
| Dual running ends | 24+ months after HEM approval | HEM only — SAP 10.3 withdrawn |
For the full picture including EPC reform, transitional arrangements, and the ECaaS platform, see our Timeline & Status page, which has been updated to reflect today's confirmation.
What to Watch Next
The most immediate event to watch for is the publication of the FHS consultation response and regulations. The 28 January ministerial statement targeted Q1 2026, meaning it could arrive within weeks. Once published, Elmhurst's SAP 10.3 software will be released, other providers will follow, and the countdown to FHS enforcement begins.
The HEM EPC consultation closes on 18 March 2026. Today's news does not change the importance of responding — the EPC consultation covers existing dwellings, a separate workstream from FHS new-build compliance. See our consultation guide for what to say and how to respond.
Beyond these, watch for:
- BRE publishing the formal SAP 10.3 approved software list — expected alongside the FHS regulations
- ECaaS platform updates — production readiness is the gating factor for HEM availability
- Other software provider announcements — Stroma, JPA, and others are expected to confirm SAP 10.3 readiness
- Government guidance on the precise HEM approval date — currently stated as “at least three months” but may become more specific
Frequently Asked Questions
Which methodology will be used for FHS compliance at launch?
SAP 10.3 only. The government has confirmed that SAP 10.3 will be the sole approved methodology at FHS launch. HEM will not be available initially — it will follow a minimum of 3 months later. All FHS compliance assessments during this period must use SAP 10.3.
When will HEM become available for FHS compliance?
HEM will be approved a minimum of 3 months after the FHS goes live. The exact date has not been specified — 3 months is the floor, not the ceiling. Once approved, HEM runs alongside SAP 10.3 for at least 24 months before SAP is withdrawn.
How long will SAP 10.3 and HEM run in parallel?
A minimum of 24 months from when HEM is approved — not from FHS launch. This means SAP 10.3 will be available for at least 27 months total after the FHS goes live (3 months solo plus 24 months dual running). After dual running ends, HEM becomes the sole compliance route.
What should assessors and developers do now?
Prioritise SAP 10.3 readiness — it is the only route at launch. Assessors familiar with SAP will find 10.3 manageable. But do not abandon HEM preparation: it arrives within months and becomes the sole methodology eventually. Use the SAP 10.3-only window to build HEM familiarity in parallel. Developers should plan initial FHS projects around SAP 10.3.
Related Pages
SAP 10.3 vs HEM
Detailed comparison of the two FHS compliance routes and how to choose.
FHS Compliance Pathways
The notional building approach, metrics, and how to demonstrate compliance.
Transitional Arrangements
Deadlines, registration, and strategies for the FHS transition period.
Timeline & Status
Live tracker of HEM, FHS, and EPC reform milestones.