EPC legal requirements in 2026
Minimum Energy Efficiency Standards (MEES) in 2026: rented properties must achieve EPC band E to be lawfully let; band C by 2028 under the proposed PRS Regulations 2025 (currently in consultation, expected to commence 2028). Sale: an EPC must be commissioned at marketing and is valid for 10 years. Renovation trigger: a new EPC is required after any 'major renovation' affecting more than 25% of the building envelope, structural extension increasing floor area, full M&E refurbishment, or change of heating system. Listed buildings: legally exempt from minimum EPC standards, but most LBC applications now require energy improvement strategy.
How to achieve band C or B on a London Victorian renovation
Insulation: 100–150mm loft insulation £400–£900, internal wall insulation 60–100mm with vapour control £80–£150/m², solid floor insulation £50–£90/m². Glazing: secondary glazing in conservation streets (cheaper than full sash replacement) £400–£900 per window; double-glazed sash replacement £1,200–£2,800 per window. Heating: A-rated combi or system boiler £2,500–£4,500; air source heat pump £8,000–£14,000 with BUS grant £7,500 reducing net cost to £500–£6,500. Hot water cylinder upgrade £1,500–£2,500. MVHR ventilation £4,000–£8,000. LED lighting throughout: £300–£800. Smart heating controls £200–£600. Total cost to move a London Victorian terrace from band D to band C: typically £8,000–£18,000 depending on starting fabric and how much was already done.
EPC implications for extensions and lofts
New build extension floor area is added to the EPC calculation — high-performance fabric (U=0.18 walls, 0.12 roof, 1.4 glazing) routinely improves the whole-house EPC by 5–15 SAP points. Loft conversion typically improves EPC by 8–20 points because the loft insulation is brought up to current standards (U=0.13). Side return extensions can hurt EPC if existing solid wall is exposed during demolition without re-insulating. Always commission a new EPC after extension completion to record the improved rating — useful for resale, mortgage and (if rented) MEES compliance.
