8.9 million homes in England & Wales are below EPC band C

Of the 18.1 million homes in England & Wales with an Energy Performance Certificate, 8.9 million — 48.9% — are below band C. That is the retrofit gap: the distance between the housing stock as it is and the standard policy is steering it towards.

Band C is the line that matters. It is the level the now-confirmed 2030 rule for privately-rented homes sets, and the benchmark the Warm Homes Plan uses for the wider stock. A home below it — band D through G — is, in policy terms, a home with work still to do. Just under half of every rated home in England & Wales sits on the wrong side of that line.

The gap is closing — slowly, and only among new certificates

There is good news in the trend. Among homes certified each year, the share coming in below band C has fallen from 59% in 2012 to 36% in 2025— better building standards and a decade of upgrades working through the system. But a certificate is only issued when a home is built, sold or let, so the national stock turns over slowly. The 48.9% headline is the weight of millions of older homes that have not been touched.

Half the stock is below band C. The improvement is real, but it is arriving one transaction at a time.

Where the gap is widest

The retrofit gap is not spread evenly. It is a story of stock age and rurality far more than of wealth. The widest gaps are in rural and coastal authorities with old, hard-to-treat housing:

• Isles of Scilly — 83.3% below band C
• Gwynedd — 70.0%, the widest gap in mainland Wales
• Castle Point — 68.4% and Ceredigion — 67.9%

At the other end sit dense, new-build-heavy urban authorities. Tower Hamlets has the narrowest gap in the country at 20.3%, followed by Salford (30.3%) and Knowsley (31.3%) — places where a wave of post-2010 flats has pulled the average up.

You can see the full picture — every one of the 318 local authorities, coloured by its gap — on the interactive Retrofit Map, and read any area's detail on its own report page.

What it would cost

Bringing every below-C home in England & Wales up to band C would cost on the order of £76 billion in modelled measures — using the English Housing Survey's cost-to-band-C figures, which run from about £6,500 for a band-D home to nearly £19,000 for the worst F and G properties. That is the national bill; the policy question is who pays which share of it, and by when. For an individual property type and age, the cost-to-band-C calculator gives the relevant register cohort and measure breakdown.

If you own or manage property, the national number is abstract — what matters is which of your homes are exposed. Our portfolio exposure tool runs this same data against your own addresses.