Can a house fail an EPC? What a low rating means when you sell

Older homes with solid walls, single glazing, little loft insulation or old heating systems tend to score lower. So do homes heated by electric storage heaters or oil. A low rating says the home costs more to heat than a typical one, not that anything is wrong with it.

It can play a part. Buyers see the rating on the listing and many now look at running costs, and some lenders offer better rates on efficient homes. Research has linked better ratings with higher prices, though location, size and condition matter far more.

• Loft insulationTopping it up to around 270 mm is often the best value improvement.
• Heating controlsA programmer, room thermostat and radiator valves (TRVs).
• Hot water cylinderAn insulating jacket if it isn't already foam-lagged.
• Cavity wall insulationIf your walls have an empty cavity.
• Low energy lightingA small gain, but cheap to do throughout.
• EvidencePaperwork for insulation, a new boiler or windows, so the assessor can credit it.

Evidence matters as much as the work. Assessors can only credit what they can see or you can prove, and otherwise must use standard assumptions for the home's age.