An energy performance certificate, or EPC, is a document that rates how energy efficient a building is on a scale from A (most efficient) to G (least efficient). It also estimates typical energy costs and lists improvements that could raise the rating. In the UK an EPC is needed when a home is built, sold or rented out, and a certificate stays valid for ten years. Countries across Europe use similar certificates, and other places have their own home energy rating systems.
What is on an EPC?
Layouts differ slightly between the UK nations, but a domestic certificate generally includes:
- The current rating and the potential rating, shown as coloured bands so the gap is easy to see.
- Estimated energy use and costs for heating, hot water and lighting.
- An environmental or carbon impact figure, based on estimated emissions.
- A breakdown of building features, such as walls, roof, floor, windows, main heating, controls and lighting, each marked from very poor to very good.
- Recommended improvements, usually with a rough indication of cost and the rating the home could reach after each one.
- Assessment details: the date, the certificate number and the accredited assessor who produced it.
What is an EPC rating?
The letter comes from a points score. For homes in the UK the calculation uses a standard method, often called SAP, which turns the building's features into a score, normally between 1 and 100. Higher points mean lower expected running costs. The points then map onto bands:
| Band | Points | In plain terms |
|---|---|---|
| A | 92 and above | Very efficient; typical of new, well-insulated homes, often with renewables |
| B | 81–91 | Highly efficient |
| C | 69–80 | Good; a common target for improvement work |
| D | 55–68 | Around the middle for existing homes |
| E | 39–54 | Below average |
| F | 21–38 | Poor |
| G | 1–20 | Very poor |
How the assessment works
An accredited domestic energy assessor visits the property and records what can be seen or evidenced: the age and type of construction, loft and wall insulation, windows, the heating system and its controls, hot water, lighting and any renewables such as solar panels. The assessor also measures the floor area, using much the same room-by-room method described in how to calculate square footage. The data goes into software that produces the rating and the recommendations.
The visit is non-invasive, so features hidden behind plaster may be recorded on default assumptions unless there is paperwork to prove them. Keeping receipts and certificates for insulation, new boilers or glazing can therefore make a real difference to the result.
Why the costs differ from your bills
An EPC assumes a standard household, heating pattern and set of prices so that properties can be compared fairly. Your own bills reflect how many people live there, how warm you keep the rooms and what tariff you pay. For actual usage, the guide on reading an electricity bill is a better source.
When an EPC is needed
- Selling: a valid certificate must be available to prospective buyers, and the rating normally appears in property adverts. Listing rules elsewhere follow a similar idea; in Germany, for example, energy details belong in adverts too, which is one reason a Munich property listing needs precise local detail.
- Renting out: landlords must provide one to tenants. In England and Wales most private lets must meet a minimum rating, currently band E, unless a registered exemption applies.
- New builds and major conversions: a certificate is issued on completion.
Rules on minimum standards are under regular review, so landlords and sellers should check the latest official guidance for their part of the UK, or ask a letting agent or solicitor, before relying on any threshold.
How to improve an EPC rating
The recommendations page is the obvious starting point. Common improvements include:
- Topping up loft insulation and insulating cavity or solid walls.
- Upgrading heating controls with room thermostats, timers and thermostatic radiator valves.
- Replacing an old, inefficient boiler, or moving to a heat pump where it suits the property.
- Insulating the hot water cylinder and exposed pipes.
- Switching all lighting to low-energy bulbs.
- Adding double or secondary glazing and draught-proofing.
- Installing solar panels or other renewables.
A full home energy audit goes further than the certificate, because it measures the actual house rather than relying on assumptions, and can help put these steps in a sensible order.
Quick answers
How long is an EPC valid?
Ten years from the date of issue. A new certificate is not required every time a home changes hands within that period, though an owner may choose to commission one after major improvements.
Can I look up a property's certificate?
In England, Wales and Northern Ireland, certificates are lodged on an official online register that can be searched by postcode. Scotland has its own register.
Is there an equivalent in the United States?
There is no single national certificate, but voluntary systems exist, such as the HERS Index, where a lower score means a more efficient home, and the Home Energy Score. Some cities and states also require energy disclosure for certain buildings.
Desk habits
Small routines that save time later
Picked up while writing the notes on this site.
Photograph the meter
A dated photo settles most arguments about estimated readings.
Name files by date
Year, month, day at the start of a filename keeps invoices and letters in order.
Sketch before you measure
A rough floor plan stops you missing an alcove or counting a strip twice.
Update the router
Check for firmware updates whenever you change your Wi-Fi password.
Put terms in writing
A short email confirming price and due date beats any verbal promise.
