Flats with a recorded new-build sale in London are matched to an EPC certificate far less often than older flats — and this holds in every one of the capital's 33 boroughs, not just a handful of Docklands tower blocks. Across 1,035,546 London flat addresses checked against the Energy Performance Certificate register, flats with no new-build sale on record are certified 29.7% of the time (213,147 of 717,874); flats with at least one new-build sale on record are certified just 9.1% of the time (29,012 of 317,672) — a gap of 20.6 percentage points, or 3.25 times the match rate.
That is the opposite of what the raw numbers might suggest at first glance. New-build homes are required to have an EPC at the point of construction, under the Energy Performance of Buildings (England and Wales) Regulations 2012. On paper, every new-build flat should have a certificate from day one. In practice, a large share of them don't show up linked to an address in the public register at all.
A citywide pattern, confirmed borough by borough
This follows up on two single-borough tests. Tower Hamlets' new-build flats matched an EPC 6.8% of the time against 26.0% for older flats, and Birmingham's new-build flats matched 7.4% of the time against 35.1%. The open question was whether that was a quirk of large tower developments in those two specific markets, or a pattern that holds everywhere flats get built. Running the identical check across all 33 London boroughs gives a clear answer: every single one shows the same direction, with the size of the gap varying a lot by borough.
The ten boroughs with the widest relative gap:
| Borough | Older flats certified | New-build flats certified | Gap (times) |
|---|---|---|---|
| Harrow | 46.4% (6,611/14,237) | 5.2% (320/6,164) | 8.9x |
| Havering | 53.4% (4,615/8,635) | 6.5% (327/5,019) | 8.2x |
| Bromley | 29.0% (6,304/21,737) | 4.0% (229/5,662) | 7.2x |
| Hillingdon | 63.6% (8,763/13,778) | 10.6% (785/7,436) | 6.0x |
| Hammersmith and Fulham | 23.5% (6,163/26,229) | 4.3% (322/7,411) | 5.4x |
| Southwark | 26.3% (7,659/29,128) | 5.7% (1,073/18,765) | 4.6x |
| Lewisham | 35.3% (9,149/25,942) | 8.0% (736/9,238) | 4.4x |
| Merton | 39.8% (6,371/16,024) | 9.0% (402/4,457) | 4.4x |
| Newham | 50.5% (6,421/12,722) | 12.4% (2,140/17,246) | 4.1x |
| Greenwich | 37.9% (5,399/14,245) | 9.5% (1,741/18,363) | 4.0x |
Hillingdon and Harrow, two outer boroughs with substantial recent new-build estates, sit at opposite ends of the "older flats" column (63.6% versus 46.4% certified) but both still show their new-build stock matching an EPC in barely one case in ten.
The honest exceptions — where the gap narrows
A handful of boroughs show a much smaller gap, and are worth reporting rather than smoothing over. The City of London's new-build and older flats match at almost identical rates (2.0% versus 1.7%), though its flat stock here is small (under 3,000 addresses in each group, mostly City fringe conversions and a few residential schemes) and the whole borough has the lowest EPC coverage in London regardless of build status. Kensington and Chelsea's gap is the narrowest in a borough of meaningful size — 9.7% for older flats against 6.1% for new-build, a 1.6x ratio — consistent with a conservation-led, low-turnover prime market where EPC certificates are scarce across the board, not just for new stock. Enfield (24.0 percentage points but only a 1.8x ratio, because its baseline is higher on both sides) and Sutton (1.9x) round out the smaller-gap end.
London-wide, the pattern holds without a single exception: all 33 boroughs show older flats matching an EPC certificate more often than new-build flats.
Why newer flats match worse, not better
The likely explanation is not that fewer new-build flats are actually certified — new-build EPCs are a legal requirement at construction and at first marketing — but that large modern developments are harder to match between the Land Registry's record of a sale and the Energy Performance Certificate register's address formatting. A 40-storey block registered as "Flat 1102, Manhattan Loft Apartments, 22 International Way" can be recorded slightly differently across the two independently compiled datasets, and a single mismatch breaks the address-level join this analysis — and the one behind the homecost.uk postcode tool — relies on. Stratford's East Village, built for the 2012 Olympics and later converted into private and rented housing, illustrates it directly: 257 flats on the public register at this single postcode, every one of them currently showing no matched EPC rating on the tool, despite each having been required to carry a certificate.
Two further patterns across all 317,672 London new-build flats point the same way.
Resale narrows the gap. New-build flats that have been resold at least once since their original sale match an EPC certificate 15.3% of the time (19,721 of 128,534); new-build flats never resold since match just 4.9% of the time (9,291 of 189,138) — a resale more than triples the match rate. A later sale typically re-triggers an EPC assessment and gives the register another chance to link the address correctly.
The gap widens for more recent new-build sales. Among new-build flats never resold since, the match rate falls steadily the more recently they were first sold: 14.1% for a first sale before 2008, down to 4.9% (2008–14), 2.7% (2015–19), 2.1% (2020–22) and 1.8% for 2023 or later. If this were simply newer certificates not yet having made it into the data, the gradient would likely stop at some recent cut-off rather than declining steadily back to 2008. A gradual decline across nearly two decades is more consistent with a persistent matching problem than with reporting lag.
What this means if you're checking a new-build flat
An EPC rating missing from a flat's record on a property website or cost calculator doesn't necessarily mean the flat was never certified — for a new-build flat in London, it's now more likely than not to simply be a registration-matching gap rather than an absence of a certificate. The certificate itself, once issued, is a public document; anyone can look it up directly on the EPC Open Data register by address or postcode rather than relying on a single third-party match. For context on how London's flat and house coverage compares more broadly, see the full breakdown of EPC coverage by borough.
Try the homecost.uk postcode tool on Stratford's East Village to see how a large modern development shows up — or look up your own postcode to check what the register currently holds for it. For more on how England and Wales' EPC data behaves at scale, browse the cost-intelligence guides.
Based on 1,035,546 Land Registry-linked flat addresses across all 33 London boroughs and the national EPC Open Data register, fetched 27 October 2026.