Quick one for anyone watching the Future Homes Standard like a hawk: on 8 June 2026 the government quietly pressed pause on the Home Energy Model (HEM) launch. HEM was widely expected to arrive around now — the Future Homes Standard documents had flagged it would be approved “no earlier than three months after publication,” which pointed to a June 2026 window. Instead, it’s being held back for final internal assurance, and is now expected “in the coming months” rather than on any fixed date (HEM Guide timeline, verified against GOV.UK).
So, no panic. Nothing has gone backwards.
What this actually changes
Practically? Very little changes today — and that’s the point. SAP 10.3 remains the sole approved methodology for Future Homes Standard compliance. It was always going to be the only route at the FHS launch on 24 March 2027, with HEM following at least three months later and then running alongside SAP 10.3 for a minimum of 24 months. This delay just nudges the start of that dual-running period a little further out.
In other words: the methodology you’ll be using for FHS submissions on day one hasn’t changed. SAP 10.3 — updated with the new FHS notional dwelling specs and forward-looking carbon factors — is still the tool of the moment, and now for a touch longer than some had pencilled in.
Why a delay is genuinely good news
We’d rather have a robust calculation engine than a rushed one. HEM is a big leap — half-hourly modelling (17,520 timesteps versus SAP’s monthly 12), centralised calculation through the ECaaS cloud platform, and a serious step up in the volume of input data it expects. Getting that right before it becomes a compliance route matters far more than hitting an arbitrary launch month. A delay for “final assurance” is the regulator doing the sensible thing.
What this means for you
If you’re an assessor or developer, here’s the chilled-out version:
Keep building your SAP 10.3 confidence — it’s the route that counts at launch and for a good while after. Don’t down tools on HEM prep, though: when it arrives, HEM will punish missing data with deliberately punitive defaults, so the teams who start collecting detailed product, geometry and junction data now will be the ones gliding through later.
And one detail that’s easy to miss in all the heat-pump-and-solar headlines: thermal bridging still matters under both routes. Whether you’re in SAP 10.3 today or HEM tomorrow, junction psi-values feed straight into your fabric performance — and HEM expects a psi-value for each junction or an accredited construction detail reference. Sloppy thermal bridging is one of the quietest ways to fail your fabric energy efficiency target.
Sort your psi-values the easy way
That’s exactly what ΨMonkey is for. It calculates thermal bridging psi-values to BS EN ISO 10211 in your browser — no clunky desktop software, no PhD required — so your junctions are nailed down whichever compliance route you end up taking. Give it a spin and take one variable off your plate while everyone else waits for HEM to wake up.
Sources: Home Energy Model timeline & status (HEM Guide) · FHS compliance pathways · GOV.UK — Home Energy Model consultation