How to improve an EPC rating from D to C

Find out how close you are

Your exact score matters more than your letter. A home on 67 and a home on 56 need very different plans. Look up your certificate on the EPC register, then note the current score, the potential score and the date.

If the potential rating is C or better, the recommendations show one route. Each step usually shows the rating after that step, assuming the earlier steps are done. The Energy Saving Trust says the list is usually in order of cost-effectiveness, so work down it and stop when you reach C.

Check the certificate is up to date first

This is the step most specific to D-rated homes, and it costs the least. Some are already close to C on paper, but the certificate is old or incomplete. If you have replaced the boiler, added loft insulation or fitted new controls since the assessment, those changes will not count until a new certificate is lodged.

• Compare the walls, roof, heating and controls lines with what the home has today.
• Gather paperwork for insulation you cannot see, such as a cavity wall guarantee or an installer's certificate. An assessor can only record what they can see or evidence.
• The Energy Saving Trust suggests checking that the heating system and tariff were recorded correctly, particularly with electric heating.

A new EPC can be commissioned at any time, and it replaces the older one. Bear in mind that a new assessment could also go down, and that methods have changed over the years.

Measures that usually close the gap

At D, the big fabric problems have often been partly dealt with. The aim is to finish what is half done.

These are the Energy Saving Trust's typical figures, mostly for a semi-detached home in Great Britain. Costs vary with the home, the region and the installer, so treat them as a starting point and get quotes.

A typical order for a D-rated home

1. Do the cheap jobs first: cylinder insulation, radiator valves, low energy lighting and draught-proofing.
2. Top up the loft, and fill cavities if an installer confirms they are suitable.
3. Replace the boiler only if it is near the end of its life or is on your recommendations list.
4. If you are still short of 69, look at solar panels, or floor insulation where a suspended floor makes it practical.
5. Commission a new EPC once you believe you have reached C.

What you probably do not need

• Solid wall insulation. It costs about £12,000 to £15,000 for a three-bedroom semi, so try everything else first unless the walls are the main weakness.
• New windows for the rating alone. Unless they are on your list, double glazing is a poor way to buy points.
• Replacing a working condensing boiler. The gain is usually small because the efficient part has already been done.

Also be realistic about small jobs. If you need 12 points, lighting and a cylinder jacket will not do it. If you need 2, they might.

Rented homes and new-style EPCs

A D-rated home meets the current minimum of E for private lets. Landlords have a specific reason to act before the rules change. The government plans a C equivalent standard by 1 October 2030, and homes rated C on the current scale before 1 October 2029 are due to count as compliant until that EPC expires or is replaced. This still needs legislation, but for a home close to C, that route may be cheaper than meeting the new measures later.

Owner-occupiers have no duty to reach C. New-style EPCs are planned for the second half of 2027. Under current proposals, a home relying on a gas boiler could not score C on the separate heating measure, though the fabric measure is intended to line up closely with today's C and D boundary. That is another reason to prefer insulation when choosing what to do.

Help with the cost

D is the top band for the Warm Homes: Local Grant in England, which supports eligible lower income households where the council has funding. In Wales, Nest may help D-rated homes where someone has an eligible health condition; others go on a reserve list. Qualifying installations are zero rated for VAT until 31 March 2027.