Methodology

This site covers domestic Energy Performance Certificates lodged in England and Wales. Scotland operates a separate register run by Energy Saving Trust on behalf of Scottish Government; Northern Ireland operates a third register through the Department of Finance. Neither is included here. Non-domestic (commercial) EPCs are a separate dataset and are also not included.

Each certificate represents a single energy assessment of a UK property. The same property may have multiple EPCs lodged over time (typically each time it changes hands or undergoes major works). We keep them all and link them where they share a UPRN.

An EPC rates a property's energy efficiency on a scale from A (most efficient) to G (least efficient), derived from a numeric score out of 100 (the “current energy efficiency” figure). A second score on the same scale records the property's potential efficiency if the recommended improvements were carried out.

An EPC is valid for 10 years from the date of issue. After that the certificate is technically expired, but the record remains on the register. Older certificates may not reflect changes to the property since the inspection date.

1. Each quarter, a scheduled job pulls the latest per-local-authority bulk CSV downloads from the EPC Open Data API.
2. Each certificate row is parsed and normalised: address fields cleaned, property types mapped to a stable slug, local-authority and constituency lookups resolved.
3. Rows stream into a new table epcs_new via Postgres COPY.
4. Indexes are built on the new table after loading completes.
5. A single atomic ALTER TABLE … RENAME swaps the new table in. The old table is preserved for 24 hours as a rollback safety.
6. Per-property-type, per-authority, and per-constituency aggregates are recomputed.

• Some certificates have no current efficiency score. These appear as “Not rated” in the band column.
• Address fields are as recorded by the assessor. Variant spellings, missing flat numbers, and inconsistent formatting are common.
• Older certificates use methodology that differs from current SAP/RdSAP procedures. Direct comparison across assessment vintages is imperfect.
• EPCs are a snapshot. A B-rated property assessed in 2014 may not still be B-rated today; new occupants may have changed boilers, lighting, or insulation.
• UPRN linkage is dependent on the assessor capturing it. Some older certificates have no UPRN, so “Other EPCs for this address” may be incomplete.

For corrections to the underlying record (your rating, address, property type) contact an accredited domestic energy assessor to lodge a fresh certificate. Our next quarterly refresh will reflect it.

If you spot a presentation error on this site, email [email protected] and we'll fix or remove the issue within 48 hours.

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