What the letter on an Energy Performance Certificate tells you, and when you need one

Most people meet an Energy Performance Certificate once, in a property listing, as a coloured bar with a letter on it. The letter is worth a closer look, because it measures something more specific than it seems.

An Energy Performance Certificate, or EPC, grades a home from A, the most efficient, to G, the least. It also shows estimated energy use and typical costs, and lists improvements that could raise the rating. A certificate stays valid for 10 years, and one is needed whenever a home is sold, rented out or built.

What the letter measures

The rating comes from a standard calculation carried out by an accredited energy assessor. The assessor records the building itself: its construction, insulation, windows, heating, hot water and lighting. The calculation then models what the home would cost to heat and run under standard assumptions about how it is used.

Two neighbours in identical houses can have the same rating and very different bills, because the certificate ignores household habits so that homes can be compared on the building alone. It is a rating of the house, not of the people living in it.

The bands from A to G

Behind each letter sits a numerical score, usually called the SAP rating, on a scale where higher is better. The bands are fixed ranges of that score.

Score ranges as published by the Office for National Statistics. The descriptions in the right-hand column are a general guide, not part of the official bands.

Because the bands are ranges, a home near the top of D and one near the bottom of C can be only a point or two apart. When comparing homes, the score is often more informative than the letter.

Reading the rest of the certificate

The certificate shows two ratings side by side: the current rating and the potential rating. The potential figure assumes that every cost-effective improvement on the list has been made. It is a ceiling for the building as it stands, not a forecast.

For each recommendation the certificate gives an indicative cost, a typical saving and the rating the home might reach once that step is done. The costs are broad ranges based on standard assumptions, so a quote from an installer is the figure to rely on for a real decision.

Many buyers read the recommendations alongside a survey. Our guide to the three RICS home survey levels explains how much of the building a surveyor looks at, which helps put the EPC suggestions in context.

It is a rating of the house, not of the people living in it.

When a certificate is needed

A valid EPC is needed when a home is built, sold or rented out. A seller or landlord should order one before the home is marketed. Under the long-standing guidance for England and Wales, they must make all reasonable efforts to have it within 7 days of marketing starting, with a further 21 days allowed if needed. The penalty for not having one is generally a £200 fixed charge for a dwelling, enforced by local trading standards.

A certificate lasts 10 years and can be used again for a later sale or let within that time. An owner can commission a fresh one at any point, for example after improvements.

Some buildings are exempt. GOV.UK lists, among others:

• temporary buildings used for less than 2 years
• stand-alone buildings with less than 50 square metres of floor space
• some buildings due to be demolished
• places of worship
• some listed buildings
• holiday lets rented out for less than 4 months a year

Individual rooms let in a shared house do not need their own certificate. In Scotland, the EPC must also be displayed inside the property.

Finding an existing certificate

Certificates for England, Wales and Northern Ireland are held on a single register on GOV.UK, which anyone can search by postcode. Scotland has its own Scottish EPC Register. A search shows the rating, the assessment date and the recommendations.

An older certificate may describe a boiler or loft that has since been improved, so the rating on file can understate the home as it is now.

The rules for rented homes

In England and Wales, most privately rented homes have had to reach at least band E since 1 April 2020, under the minimum energy efficiency standard. A landlord does not have to spend more than £3,500, including VAT, on improvements to meet it. Where a home still falls short after that, the landlord can register an exemption, which usually lasts 5 years. Local authorities can impose penalties of up to £5,000 per property.

The government has confirmed a higher target for the private rented sector in England and Wales: band C, measured on the new EPC metrics, by 1 October 2030. Its response published on 21 January 2026 sets a spending cap of £10,000 per property and estimates the average cost at £5,400. Homes that reach C on the current measure before 1 October 2029 will count as compliant until that certificate expires or is replaced. The maximum penalty is set to rise to £30,000. This is confirmed policy but not yet law: it needs primary legislation and then regulations.

Changes on the way

The EPC itself is being reformed. In England and Wales, new certificates are due to show four headline measures rather than one letter: energy cost, fabric performance, heating system and smart readiness. The 10-year validity stays. In March 2026 the launch was moved to the second half of 2027, and the current rating is due to keep appearing until at least the end of 2029.

Scotland is reforming separately. New Scottish EPCs are due from 30 April 2028, subject to approval by the Scottish Parliament. They will rate heat retention, the heating system and energy costs, and validity will fall from 10 years to 5.

Who this matters for, and what to check

The certificate is most useful to people buying, selling or letting a home, and to owners planning improvements. A few points are worth checking:

• The date of the assessment. A certificate up to 10 years old may not reflect later work.
• The score as well as the letter, especially near a band boundary.
• The heating system recorded. If you are weighing up a replacement, our guide to replacing an old boiler covers the installer rules and the Boiler Upgrade Scheme.
• The recommendations' indicative costs, treated as a starting point for quotes rather than a price.
• For landlords, whether the home meets band E now and how far it is from C.

The short version

An EPC rates the building, not the household, using a standard model of running costs on a scale from A to G. It lasts 10 years, is needed for a sale, a let or a new build, and can be looked up free on the official registers. Private landlords in England and Wales must meet band E today, and band C on the new measures is planned for 1 October 2030 once the law is in place. New-style certificates are due in the second half of 2027, and in Scotland from April 2028.