The short answer
An Energy Performance Certificate (EPC) records an assessment of a building's energy efficiency. Domestic EPCs use a rating from A (most efficient) to G (least efficient), supported by a numerical score and a list of recommended improvements.
An EPC is designed to help a buyer or tenant compare properties. It is not an energy bill, a structural survey or a guarantee of future running costs.
What you will find on a domestic EPC
- Current and potential ratings — the assessed score now and the score the property might reach if the listed recommendations were completed.
- Estimated energy use and costs — standardised estimates for heating, hot water and lighting, not a prediction based on your household's behaviour.
- Building features — a summary of walls, roof, windows, heating, lighting and renewable technologies recorded during the assessment.
- Recommended measures — improvements shown in a suggested sequence, often with an indicative cost and potential score after each step.
- Certificate details — the date, expiry date, assessor and report reference number.
When is an EPC required?
In England and Wales, an EPC is normally required when a property is built, sold or rented. The seller or landlord must arrange it before marketing and make it available to prospective buyers or tenants.
Some buildings and situations are exempt. Do not assume that every listed building is automatically exempt: the legal test is more specific and can depend on whether compliance would unacceptably alter its character or appearance.
How long is an EPC valid?
A certificate is normally valid for 10 years. A property can be assessed again before the old certificate expires, particularly after improvements. The official register may therefore contain several certificates for the same address.
What does the score measure?
The score is produced using a standard assessment methodology. It models the building under standard assumptions so that properties can be compared consistently. Fabric, heating, hot water, ventilation, lighting and renewable generation can all affect the result.
Your actual bills also depend on occupancy, thermostat settings, weather, tariffs and how the home is used. That is why an EPC cost estimate and a real bill may differ substantially.
Area data versus one property's certificate
EPCScore aggregates certificates to show local patterns. Use it to understand whether an area tends to have newer, more efficient or harder-to-improve homes. Use the official GOV.UK register when you need the certificate for a specific address.