I just discovered something horrifying. Energy Performance Certificates, which (nominally) measure how energy-efficient a house's thermal management is and which the UK government requires be listed for all rentals and probably homebuying transactions, are based on the estimated cost of energy at the time the certificate is made, and are held for ten years. The spec does at least normalize them based on energy prices, but changes in relative fuel prices will only be factored into new EPCs. EPCs also contain an estimated cost, and I don't know whether the government website updates that.