If you want to analyse UK house prices by property type, floor area or build era, you have to join two open datasets that share no key: HM Land Registry Price Paid Data and the Energy Performance Certificate register. This post explains what each dataset contains, why the join is hard, the address-matching strategy that works, the failure modes to expect, and what the result looks like for postcode district CR5 (Coulsdon, Chipstead, Old Coulsdon, Hooley and Netherne-on-the-Hill). Figures were calculated on 9 November 2026.

What each dataset contains

HM Land Registry publishes Price Paid Data under the Open Government Licence v3.0.…