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Future Homes Standard (ADL1 2026) — Free Download

Stage 2 FHS Compliance:
The 60-Second Checklist That Gets You Confident

Know exactly what decisions to lock in at RIBA Stage 2 — before a late heating system change becomes a £40,000 programme problem at Stage 4.

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One PDF. Six decision areas. Everything your Stage 2 design needs to meet FHS (ADL1 2026).

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What's inside

Six decision areas architects miss at Stage 2

The Future Homes Standard goes live March 2027. These are the decisions that can't wait until Stage 4.

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Heating & Hot Water

The most consequential Stage 2 decision. Gas boilers are non-compliant under the Future Homes Standard (ADL1 2026). This section covers heat pump specification, cylinder sizing, and client briefing.

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Thermal Fabric

FHS notional values are tighter than Part L 2021: wall ≤0.15, roof ≤0.09, floor ≤0.11 W/m²K. Set these early — they drive structure, build cost, and planning.

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Airtightness

An airtightness target below 5 m³/h·m² needs to be designed in, not tested in. This section covers the airtightness layer, service penetrations, and party wall strategy.

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Ventilation

MVHR is the expected FHS ventilation strategy. Duct routes and unit location need coordinating before structure is fixed — this is the section that prevents late-stage surprises.

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Solar & Renewables

FHS expects ~40% renewable energy contribution. This section covers PV sizing, south-facing roof area, battery storage, and DNO capacity — all Stage 2 decisions.

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Early Modelling

Catching a TER vs DER failure at Stage 2 costs hours. At Stage 4, it costs months. This section covers when to commission SAP 10 / HEM and what to do with the results.

Why Stage 2 decisions matter more than ever

The Future Homes Standard (England) comes into force March 2027 — replacing Part L for new dwellings. It requires tighter fabric, mandatory low-carbon heating, and whole-building energy performance. Getting these decisions wrong at Stage 2 doesn't just cost money. It costs programme.

75% carbon reduction vs
2013 baseline
Mar
2027 FHS comes
into force
60s to check Stage 2
compliance

Common pitfalls

What trips architects at Stage 2

"We'll switch the heating system later"

Gas boiler designs that retrofit to heat pumps need structural changes, cylinder space, and often larger radiators. Stage 4 specification changes are rarely cheap.

No MVHR duct space until Stage 3

MVHR duct routes need to be in the structure. Coordinating at Stage 3 means compromises. The checklist shows you what to fix in Stage 2 drawings.

Skipping PV until planning is approved

FHS solar contributions need south-facing roof area and structural load design. Coordinatingafter planning approval creates roof geometry conflicts that are expensive to resolve.

Assuming SAP 10 will pass without modelling

FHS primary energy and CO₂ targets are significantly tighter than Part L 2021. Early indicative modelling at Stage 2 catches failures when they're still design decisions.

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