retrofitcost.co.ukA surveyor's working file. Q4 2026 Ofgem cap applied.
Home/Measures
Working file M0

Retrofit measures by stratum (PAS 2035)

The five PAS 2035 measure strata, costed in 2026: fabric, ventilation, heating, renewables, controls.

  1. Stratum 1FabricEWI, IWI, cavity, loft, floor, glazing£14k to £30k
  2. Stratum 2VentilationMVHR, PIV, dMEV£0.5k to £11k
  3. Stratum 3HeatingASHP, GSHP, hybrid, radiator upsize£9.8k to £18.5k
  4. Stratum 4RenewablesSolar PV, battery storage£8.3k to £14k
  5. Stratum 5ControlsSmart thermostat, zoning, weather comp£0.35k to £0.95k

Sequencing rule

PAS 2035 sequences fabric first because the heating capacity, the ventilation strategy and the renewables sizing all depend on the post-fabric heat-loss calculation. A heat pump sized to the pre-fabric heat-loss is the most common mis-design in the UK installer base.

Strata

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 M0]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.