Fifteen million homes could drop a full EPC band under the new system taking effect on 15 June 2025. That is not a rumour, it is the direct consequence of switching from a fabric-efficiency metric to a cost-per-square-metre calculation. For a typical 3-bed semi in the Midlands, the difference could mean a D rating today becoming an E or F overnight.
As reported by Propertymark, the overhaul, confirmed by the Department for Levelling Up, Housing and Communities, will replace the current A–G scale with a new metric based on estimated annual energy cost per square metre. The government says this aligns with how buyers and tenants actually think: not in kilowatt-hours, but in pounds.
Who qualifies, and who doesn’t
Every home that needs an EPC for sale or rental after 15 June 2025 will be assessed under the new method. The change applies to England and Wales; Scotland and Northern Ireland have separate systems, though Scotland is consulting on similar reforms. Existing EPCs valid on that date will not be automatically recalculated, they remain legal until expiry. But any new certificate issued from that date will use the new metric.
The catch is that homes with electric heating, older boilers or solid walls will be hit hardest. Under the current SAP 2012 methodology, fabric efficiency (wall insulation, glazing, draught-proofing) dominates the score. The new SAP 2025, known as the Future Homes Standard methodology, weights fuel costs more heavily. A home with a heat pump and good insulation will score well. A home with a gas boiler, single glazing and no loft insulation will see its rating tank, even if its fabric is identical to a neighbour’s that got a B rating last year.
What it costs a typical 3-bed semi
Ofgem’s typical domestic consumption values (12,000 kWh gas, 2,900 kWh electricity) suggest the median home currently rated D could fall to E under the new system. That matters for two reasons. First, mortgage lenders increasingly use EPC ratings to set rates, some already offer green mortgages only for A–C homes. The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. If your rating drops, you may lose access to grants you would have qualified for under the old system.
Energy Saving Trust analysis shared with Axiom shows that a typical semi-detached home in the North West with a gas boiler and 200 mm loft insulation could see its EPC cost metric rise from £1,050/m² to £1,320/m², pushing it from a C to a D. The same home with a heat pump and solar panels would remain in band B.
But the timeline is tight, and the detail is thin
The government published the final methodology only in February 2025, giving assessors and software providers four months to retrain and recertify. Propertymark has warned that many assessors are not yet accredited under the new system, and the register of qualified assessors may be patchy in the first weeks. Homeowners who need an EPC for a sale due in July or August should book an assessment now, under the old rules, to lock in the current rating.
Landlords face a separate pressure. The government has committed to a minimum EPC C for new tenancies by 2028. With the new metric likely to downgrade many properties, a landlord who currently has a D rating may need to spend £5,000–£15,000 on insulation, heating or glazing just to get back to a C under the new system. The clock is ticking: the 2028 deadline has not moved, but the goalposts have.
What this misses is any grace period for homes that lose a band purely because of the calculation change. The government has not announced transitional arrangements for sales or rental compliance. A home that was compliant at D yesterday could be non-compliant at E tomorrow, with no time to upgrade.
What to do now
Order an EPC before 15 June 2025 if you plan to sell or let within the next 12 months. The current certificate will remain valid for 10 years from issue. The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. For homes with electric heating or solid walls, get a retrofit assessment now, the new metric will penalise those homes hardest, and the grant programmes are finite.
The change is not a disaster. It is a correction. But for 15 million households, it is a correction that arrives without warning and without a safety net. Book your EPC this month.
Frequently Asked Questions
Yes, if your EPC was issued before that date, it remains valid for its full 10-year term. Only new certificates issued from 15 June will use the new cost-per-m² metric.
It depends on your heating type and insulation. Homes with gas boilers and poor fabric could drop one to two bands (e.g., D to E or F). Homes with heat pumps and good insulation may stay the same or improve.
