EPC floor area: what it measures, what it misses, and when to trust it

Every price per square metre on this site is a division, and the denominator comes from one place: the total floor area recorded on the home’s Energy Performance Certificate. That makes the EPC the load-bearing document of the whole measure, so it is worth being precise about what it actually records, where it goes wrong, and why the statistics survive errors that would mislead you about a single home.

What the number includes

The EPC’s total floor area is the internal usable floor area of the dwelling, measured room by room by an assessor, recorded to the whole square metre. It counts habitable rooms, kitchens, bathrooms, hallways and heated conservatories. It excludes garages, unheated porches, balconies, lofts that are not converted, and any space under a ceiling lower than 1.5 metres, which is why a “700 sq ft” listing with a garage can carry a 55 m² EPC and both be right, about different questions.

How wrong can it be?

For a single home: wrong enough to matter. Assessors measure quickly, older certificates (EPCs go back to 2008, with a ten-year life) can describe a home before its extension, and the Office for National Statistics, comparing EPC floor areas against survey measurements, found that only a minority agree to within a few per cent. If you are buying one specific home, treat its EPC area as approximate: pace the rooms, or trust the surveyor’s measurement over both the EPC and the agent’s brochure.

For an area statistic: the errors mostly cancel. A district median is computed over hundreds of matched sales, some EPCs a little generous, some a little mean, and the middle of that distribution is stable in a way no single certificate is. In CF11, the June 2026 median rests on 409 matched sales; in E14, on 585. One mismeasured flat moves those medians by nothing visible at the three significant figures we publish.

Not every sale can be matched

RealScout matches each HM Land Registry sale to an EPC by address. Nationally, 474,761 of 599,244 sales in the 12 months to June 2026 matched, about 79%. The rest, new addresses the register has not caught up with, address quirks, homes that predate EPCs and have not been marketed since 2008, are still counted and still listed on every page. They are only excluded from the per-square-metre ratio, because a division needs a denominator. That is why every £/m² figure on this site prints its matched count beside it: that count is the figure’s own denominator, and the methodology page shows the match rate area by area, along with what the unmatched sales would have cost the figure.

Where to find and check an EPC

The Energy Performance of Buildings Register is public and free: search any England & Wales address and read the certificate, including the floor area and when it was assessed. Three practical checks when a figure matters to you: the certificate date (does it predate an extension?), the floor area against the listing’s square footage (divide the listing’s sq ft by 10.7639), and the property type (a certificate for “the annexe” is not the house).

See the measure in action on any district page, where each area shows its own match rate, or read the glossary for every term used here. All figures: June 2026 dataset, HM Land Registry sold prices matched to EPC floor areas, rebuilt monthly.