The number is stark: 52% of homes in England and Wales are rated EPC D or below. That is 13.5 million properties, according to data from the Department for Levelling Up, Housing and Communities, as reported by The Intermediary. The average D-rated home costs roughly £2,500 a year to heat, about £500 more than a C-rated one, based on typical 12,000 kWh gas usage at current price cap rates. That is not an abstract policy problem. It is a monthly direct debit.
Who qualifies, and who doesn’t
The data splits by region. London fares worst: 60% of homes are D or below, driven by older stock and leasehold flats where owners cannot upgrade communal fabric. The South West is close behind at 58%. The best-performing region is the North East, where 44% are D or below, largely because of 1970s council housing that was retrofitted in the 2000s. But the national picture is clear: the UK housing stock is old. The average home was built in 1965, and 40% of homes have solid walls that cannot be cavity-filled. Those homes need external or internal wall insulation, which costs between £8,000 and £22,000 for a typical 3-bed semi, according to Energy Saving Trust estimates.
What it costs a typical 3-bed semi
A D-rated 3-bed semi with gas central heating and no loft insulation uses about 14,000 kWh of gas annually. At the current price cap of 6.24p/kWh, that is £873 for gas alone. Add 3,000 kWh of electricity at 24.5p/kWh, £735, and the total is £1,608. A C-rated home with 270mm loft insulation, cavity wall fill, and an A-rated boiler uses roughly 10,500 kWh of gas and 2,500 kWh of electricity, costing £1,268. The gap: £340 a year. Over a decade, that is £3,400, enough to pay for new double glazing. The catch is upfront cost. Loft insulation costs around £500 if professionally installed. Cavity wall fill is about £2,000. A new boiler is £2,500–£4,000. But grants exist.
Grants that actually help
The Great British Insulation Scheme, launched in 2023, offers free or heavily subsidised loft and cavity wall insulation for low-income households and those in EPC D or below. Eligibility depends on council tax band and income. Separately, the Boiler Upgrade Scheme provides £7,500 towards an air-source heat pump for homes in England and Wales. Heat pumps typically lift a D-rated home to C or B, because the EPC calculation rewards low-carbon heating. Ofgem, which administers both schemes, says 120,000 households have applied since April 2024. But the take-up is slow. The government target is 300,000 upgrades a year. At current rates, it will take 45 years to shift all D-rated homes to C.
What this misses
The EPC system itself has flaws. It measures fabric efficiency, not actual energy use. A home with solar panels and a heat pump but single glazing can score a C, while a draughty Victorian terrace with a modern gas boiler might scrape a D. The government is consulting on reforming EPCs to include smart meter data and actual consumption. That would help, but it will not fix the 13.5 million homes that need physical work. For homeowners, the message is blunt: check your EPC at gov.uk. If it is D or below, start with loft insulation and cavity walls. Those are the cheapest wins. Then look at the Boiler Upgrade Scheme. The deadline for the current grant rate is not set, but the scheme is scheduled to run until 2028. Act before the next price cap rise in October 2025.
Frequently Asked Questions
A home rated EPC D in the UK typically costs around £2,500 a year to heat, which is about £500 more than a C-rated property. For a typical 3-bed semi with gas central heating, the annual energy bill is roughly £1,608 at current price cap rates, compared to £1,268 for a C-rated home.
Upgrading a typical 3-bed semi from EPC D to C can cost between £5,000 and £28,000, depending on the work needed. Key costs include £500 for loft insulation, £2,000 for cavity wall fill, and £2,500 to £4,000 for a new A-rated boiler, while solid wall insulation runs from £8,000 to £22,000.
The Great British Insulation Scheme offers free or subsidised loft and cavity wall insulation for low-income households and those in EPC D or below. The Boiler Upgrade Scheme provides £7,500 towards an air-source heat pump in England and Wales, which can lift a D-rated home to C or B.
London has the highest proportion of homes rated EPC D or below at 60%, followed by the South West at 58%. The North East performs best with only 44% at D or below, largely due to retrofitted 1970s council housing.
At current grant take-up rates, it would take an estimated 45 years to shift all 13.5 million D-rated homes to C in England and Wales. The government target is 300,000 upgrades per year, but only 120,000 households have applied for schemes since April 2024.
