EPC ratings explained, and the improvements worth making first

Every home sold or let in England needs an energy performance certificate, and buyers are paying more attention to them every year. Mortgage lenders now offer better rates on efficient homes, and landlords face rising minimum standards. Here is what the certificate measures and where to start if yours needs improving.

What the rating measures

The EPC gives a home a score from 1 to 100, grouped into bands from A to G. It is based on the fabric of the building and its heating: insulation, windows, the boiler or heat pump, hot water and lighting. It does not measure how much energy you actually use, so two identical houses will have the same rating however they are lived in.

The certificate also shows a "potential" rating: the score the home could reach if the recommended improvements were made. That is the number buyers increasingly look at.

Why it matters for value

Victorian and Edwardian houses in London commonly sit in band D or E. That is not a problem in itself, but it does mean buyers factor in the cost of improvement, and some lenders offer their best rates only to homes rated C or above.

Improvements worth making first

Not every recommendation is worth doing before a sale. In rough order of value:

• Loft insulation. Inexpensive, quick and usually worth several points.
• Draught-proofing. Sash windows and front doors leak heat. Proper draught-proofing keeps the original windows and makes rooms noticeably warmer.
• Heating controls. Thermostatic radiator valves and a programmable thermostat are cheap and count towards the rating.
• LED lighting. Replacing every bulb takes an afternoon.
• Secondary glazing. In a conservation area, where replacement windows may not be allowed, slim secondary glazing is often the best option.

Larger projects, such as a heat pump or solid wall insulation, can make a big difference, but are best planned with time rather than rushed before a sale.

Reading a certificate when you buy

When you are buying, look past the headline letter to the recommendations and their estimated costs. They tell you how much work the home needs to reach the next band, and give you a sound basis for negotiation.