Working file M1
Fabric-first retrofit cost (UK 2026)
Fabric-first retrofit cost in 2026: EWI, IWI, cavity, loft, floor, glazing. PAS 2035 sequences this stratum before ventilation or heating.
Why fabric first
PAS 2035 sequences the fabric stratum first so that ventilation rates and heat-pump sizing follow the post-improvement heat-loss calculation. A heat pump sized against the pre-fabric house is the single most common over-spec in the UK installer base.
Measures
Surveyed 1 October 2026. Ofgem cap for 1 October to 31 December 2026 applied (gas 7.97p, elec 26.32p, gas standing 29.68p, elec standing 54.83p). Next scheduled review 25 November 2026 (January cap announcement). [ref M1]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.