EPC Atlas Research - UK Data Book 2026 Volume One v0.3

The EPC Improvement Gap: What 17.62 Million Searchable Records Reveal

More than half of the D-or-below searchable records examined also show potential A/B, highlighting a large gap between current and potential EPC performance.

Download aggregate data (CSV)Full Data Book (PDF)Methodology

4,318,888D-or-below + potential A/B

24.50%share of the whole corpus

50.41%share of D-or-below records

2,481,531also owner-occupied classification + House

The headline finding

Exactly 4,318,888 records are simultaneously current EPC D or below and potential A/B. That is 24.50% of the whole corpus and 50.41% of all D-or-below records.

Older buildings show a much larger divide

Pre-1900 records are 81.79% D-or-below, compared with 3.89% for the broad 2007+ category. Poor/Very Poor wall evidence is 91.59% for Pre-1900 records and 0.64% for 2007+.

Loft-depth evidence adds another layer

Among 8,006,520 House/Bungalow records with a known numerical loft depth, 2,336,683 are at or below 100 mm. Of those, 1,733,755 are also D-or-below. Missing loft depth is not treated as zero insulation.

A question for heating policy

Across qualifying local authorities, explicit off-gas share among records with known mains-gas status correlates about +0.854 with heat-pump-text share. This is an ecological association and does not establish property-level causation.

A recent methodology question

Potential A/B and window-efficiency distributions change abruptly in 2025-2026. EPC Atlas treats this as a methodology/data-generation discontinuity candidate until the source-method explanation is established.

Evidence boundary

The figures describe searchable EPC Atlas records and source fields. They do not automatically identify a current dwelling population, current legal ownership, current occupancy, live equipment condition, installation date, a building survey, a costed retrofit plan or measured energy use.

Source

EPC Atlas UK Data Book 2026, Volume One v0.3, dated 28 August 2026. The full corpus contains 17,624,989 searchable records across ten England-and-Wales regional datasets. Scotland and Northern Ireland are outside the corpus.