Design Solution · Building Envelope
Design Solution · Dream about it
An envelope at ~0.10 W/m2K to slash heat demand.
A fabric-first envelope achieves an average U-value around 0.10 W/m2K, far below typical new-build levels, minimising heat demand before any services are added. Pushing the fabric this hard means small, cheap-to-run heating and meaningful resilience to fuel-price swings. It anchors the homes to the RIBA 2030 Climate Challenge targets.
Targeting a whole-envelope U-value around 0.10 W/m²K is roughly two to three times better than typical new-build practice under current Part L, and it positions the scheme to hit RIBA 2030 Climate Challenge space-heating targets before the services strategy is even decided — which is the correct order of operations for low-energy design. The fabric-first approach has strong theoretical and modelled backing as a strategy, and at this level of thermal performance the case for small, low-capacity heating systems becomes compelling: system cost savings partially offset the higher envelope specification cost over a long lease. Evidence state is claimed, so the 0.10 W/m²K figure is a design target rather than a verified in-use measurement, and the gap between designed and as-built thermal performance is a well-documented risk in highly insulated construction. The key delivery risk is airtightness: at this U-value level, thermal bridging and air infiltration become the dominant energy loss mechanisms, and achieving the designed performance in practice requires construction stage quality assurance — continuous supervision of insulation installation and air barrier continuity — that many contractors are not yet set up to deliver reliably. The long-term value is resilience: homes this well-wrapped are largely insulated from fuel price volatility, which is a durable occupier benefit that is genuinely difficult to price out of a proposal.
#fabric first #insulation #low energy