[a_humean]

He knows that in the same way that all British people know that - we have lived in or know people that have lived in houses that look exactly like that house. The amount of uniformity to British housing stock can be surprising as much as their general shoddiness. Try playing UK geoguesser - every UK residential street looks the same.

There are actually very few enforced rules about house listings. The market is pretty unregulated. However that house has an epc of C which would suggest its not insulated beyond maybe roof insulation or else isn't well insulated. To get a B or above you need to have a reasonable amount of insulation that you mostly only see in new build properties.