EPC
Is there a free EPC API for UK properties?
Yes. The Department for Levelling Up, Housing and Communities publishes the official EPC register as a free API at epc.opendatacommunities.org. You register, receive an API key, and can query domestic, non-domestic and display certificates for England and Wales. Scotland publishes a separate dataset via the Scottish EPC Register; Northern Ireland publishes a quarterly bulk file.
The free DLUHC API has rate limits and returns flat certificate records — no joins to UPRN, sale price, council tax or risk data, and no historical comparison logic. For higher throughput, UPRN-keyed responses, Scottish + NI coverage in one schema, and joined property records, third-party APIs such as Homedata wrap the official feeds and add the missing fields.
Both routes are fine for read-only use. Which you choose depends on whether you need raw certificates or a property-keyed graph.
What this means in practice
The DLUHC API is paginated at 5,000 rows per response and capped at roughly 10,000 rows per query. To enrich a 50,000-property buy-to-let portfolio you would issue ten or more paginated calls per local authority, deduplicate certificates by LMK key, then pick the most recent per address — there is no UPRN field, so de-duplication runs on a postcode + address-line concatenation. A typical mid-sized portfolio takes 20–40 minutes to fully refresh end-to-end. The same job through a UPRN-keyed wrapper is one POST with a UPRN array and finishes in seconds.
Related questions
Does the EPC API include lodgement of new certificates?
No. The DLUHC open API is read-only. Lodging a new domestic EPC requires an accredited assessor logged into the register through their accreditation scheme (Elmhurst, Stroma, Quidos, ECMK). The new lodgement appears on the open API typically within 24–48 hours of submission. There is no third-party route to lodge.
Why do EPC ratings sometimes change between certificates?
The Standard Assessment Procedure (SAP) methodology is updated periodically — the move from RdSAP 2012 to RdSAP 10 in 2025 changed how floor area, secondary heating and renewables are scored, so an unchanged property can shift band on re-inspection. Improvements (loft insulation, new boiler, solar PV, heat pump) also move the score. Checking certificate effective dates and the assessor notes explains apparent inconsistencies.
Sources
Related reading
Building with UK property data?
Homedata returns 29 million UK properties — UPRN, EPC, Land Registry, risk — keyed by a single ID. Free tier, no card.
Get a free API key