Harmonised energy performance certificate registries of Spain's 17 autonomous communities

This dataset supports a research article comparing certified and actual household energy use in Spain (manuscript submitted for publication). It contains:(1) a harmonised dataset of 6,819,430 records from the open Energy Performance Certificate (EPC) registries of Spain's 17 autonomous communities, downloaded in September 2026. Every original record is kept under a common schema, with one flag per selection criterion. The main analytical sample comprises 4,453,017 existing dwellings certified between January 2016 and September 2026;(2) the third-party inputs used to estimate actual household non-renewable primary energy use: CNMC domestic electricity (2025) and natural gas (2020, scaled to 2025), CORES heating gasoil and LPG (2025), INE Census 2021, IDAE end-use breakdown and the official 2016 conversion factors;(3) the complete Python code, from the original downloads to all tables and figures, including an independent verification script;(4) the result tables and Figures 1–4. Across the 17 regions, actual non-renewable primary energy use is a median 43% of the certified value (aggregate 48%). Addresses, cadastral references, registry numbers, postcodes and coordinates have been removed for data minimisation. The code is released under the MIT licence and the data under CC BY 4.0; third-party inputs keep their original terms (see LICENSE.md).