retrofitcost.co.ukA surveyor's working file. Q4 2026 Ofgem cap applied.
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Working file A4

Post-2000 new-build retrofit cost (UK 2026)

Post-2000 new-build retrofit cost: working capex envelope, sequenced measure cost, PAS 2035 risk path.

Working envelope (100 m² post-2000 build)

Scope is narrow. Typical capex: £11,000to£25,000(pre-grant). Net after BUS: £3,500to£17,500. The case for fabric work is usually limited; PV plus battery plus HP is the modal stack.

Sequenced cost

  • ASHP plus rads £8,000 to £14,000 net of BUS.
  • Solar PV 4 kWp £5,800 to £8,800.
  • Battery 5 kWh £3,500 to £5,250.
  • MVHR retrofit possible in well-built post-2010 stock.

Risk path

ASHPMVHRU 0.18 W/m²KU 0.15 roofU 0.18 wallU 0.22 floorPath A, post-2000 build
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 A4]
By Oliver Wakefield-Smith, Founder, Digital Signet. Corrections to oliver at digitalsignet dot com.