The Future Homes Standard is now confirmed. Here’s how to prepare.

On 24th March 2026, the government published the final Future Homes Standard (Approved Document L 2026) — the biggest uplift to new build energy efficiency rules in a decade. If you need the full breakdown of what the standard covers, read our Future Homes Standard explainer. This page is the practical version: what architects, fabricators and installers need to actually do before the rules take effect.

When it applies

The Future Homes Standard becomes mandatory for new residential dwellings submitted from 24th March 2027, with higher-risk buildings (18m+, multiple residential units) following on 24th September 2027. There’s a transitional period running to 24th March 2028 for plots already under construction under Part L 2021 — after that, all new homes must comply regardless of when they were registered. If you’re planning projects now, they will very likely fall under the new standard by the time they’re built.

Step 1: Review your window U-value specification

The maximum U-value for windows has been tightened to 1.2 W/m²K, down from the 1.6 W/m²K standard most specifiers have been working to. This is a meaningful jump, not a rounding change. If your current specifications are based on the 2022 interim uplift, they will not meet the new requirement — every window schedule should be re-checked against 1.2 W/m²K before submission.

Step 2: Plan for SAP 10.3 assessment early

Compliance is calculated using SAP 10.3, the current approved methodology (the Home Energy Model, HEM, will eventually replace it, running in parallel for at least 24 months once approved). SAP 10.3 assessments take longer and require more detailed input data than previous versions, particularly around glazing specification by orientation. Build this into your project timeline now rather than at planning submission stage.

Step 3: Reassess airtightness detailing

Airtightness targets have been tightened significantly under the new standard. Junction detailing, particularly around window and door reveals, will need closer attention than under Part L 2021 to hit the new target on pressure testing. [Confirm the exact m³/(h·m²)@50Pa figure against the published Approved Document before this goes live — see note above.]

Step 4: Choose spacer bar technology that supports the tighter U-value target

Hitting 1.2 W/m²K reliably depends on more than glass specification — the edge of the glazing unit is where a significant share of heat loss occurs if left unaddressed. Warm edge spacer bars, such as Edgetech’s Super Spacer® range, reduce heat transfer at this junction and make the tighter U-value target easier to achieve consistently across a project, rather than relying on glass performance alone to close the gap.

Step 5: Don’t assume this only affects new build

The Future Homes Standard applies to new dwellings, but significant renovations and extensions to existing properties are also brought into scope, and will need to meet the same energy performance standards as new builds. If you work across both new build and refurbishment projects, review which of your current renovation jobs may fall under the new rules once it takes effect.

Get ahead of the transition

With enforcement from March 2027 and most current design work landing inside that window, the practical work — re-specifying U-values, briefing in SAP 10.3 assessments, and choosing components that support the new targets — needs to start now, not at the point of planning submission. If you’re a glazing installer, fabricator or specifier and want to talk through how Edgetech’s spacer bar range supports Future Homes Standard compliance, call 02476 639 931 or get in touch online.