Method benchmark
Why these figures differ from raw EPC maps
EPC datasets are open, but the method changes the answer. We're independent — on no one's payroll, not affiliated with any installer or agent — so we can state these differences plainly and let you decide how to cite them. This page shows where the Home Index should be cited differently from official statistics or raw certificate-count maps.
Data vintage 2026-Q2 · methodology 0.3.0.
This index
18,149,673
retained domestic dwellings, deduped to latest certificate.
Retrofit gap
48.9%
of rated dwellings below EPC C.
Matched-sale layer
44.1%
national Land Registry match coverage.
Comparison table
| Approach | What it is best for | Main caveat |
|---|---|---|
| The Home Index | Latest-dwelling EPC exposure, local rankings, matched-sale exposure and portfolio triage. | Covers rated dwellings; matched-sale signals are partial estimates and must be cited with coverage. |
| Raw EPC certificate maps | Fast public summaries of all certificates in the register. | Raw certificate counts can double-count homes with multiple certificates unless deduped. |
| ONS / official statistics | Official national and local statistical context. | EPC coverage is incomplete because certificates are mainly triggered by construction, sale, conversion or letting. |
| Property-data platforms | Broad property intelligence, comparables, planning and API workflows. | Usually broader-scope property intelligence; EPC exposure as a distinct citable metric is rarely the primary focus. |
Next: controlled C-or-above price/m² comparison
The current public spread is an observed matched-sale signal, not a causal premium. The next analysis layer will compare C-or-above and below-C homes within tighter cohorts: local area, property type, construction age, floor-area band and sale-year window, with sample size and coverage thresholds shown beside every result.