An Energy Performance Certificate tells you how energy efficient a building is, on a scale from A to G. You need one to sell or let a home, and for landlords the rating decides whether a property can be let at all. Here is what the bands mean, how the rating is worked out, and what actually improves it in a typical London home.
What an EPC is
An EPC is produced by an accredited energy assessor after a visit to the property, and it is lodged on the government's register, where anyone can look it up by postcode. It is valid for ten years. It is needed when a home is built, sold or let, and the seller or landlord must make it available to buyers and tenants.
The A to G bands and SAP scores
The rating is based on a SAP score, the government's Standard Assessment Procedure. The higher the score, the more efficient the home.
- Band A: SAP 92 and above
- Band B: 81 to 91
- Band C: 69 to 80
- Band D: 55 to 68
- Band E: 39 to 54
- Band F: 21 to 38
- Band G: 1 to 20
New-build homes are commonly rated B. Older homes are more often D or E, and many London houses built before 1930 sit in band D because of their solid walls.
What the certificate shows
Current and potential rating
The headline graph shows the current band and the potential band if the recommended improvements were made.
Estimated running costs
The certificate estimates the cost of heating, hot water and lighting under standard assumptions. Your real bills depend on how you use the home.
Environmental impact
A second rating shows the property's estimated carbon dioxide emissions.
Recommendations
A list of improvements with their likely effect on the rating. This is the most useful page for planning work.
How the rating is worked out
For existing homes the assessor uses a reduced data version of SAP. They record the construction and age of the walls, roof and floors, loft insulation depth, glazing, the heating system and its controls, hot water, lighting and any solar panels or heat pump. Where something cannot be seen or proved, the software applies a default for the age of the building, which is why invoices and photos of hidden insulation can make a real difference.
When you need an EPC
- Selling: a valid EPC must be available when the property is marketed.
- Letting: a valid EPC must be given to tenants, and rented homes in England and Wales must currently meet at least band E unless an exemption is registered.
- After building work: a new EPC is required for new builds and some conversions, and is worth getting after major improvements.
Some listed buildings and buildings in conservation areas can be exempt where meeting the requirements would unacceptably alter their character. Check with the local authority if this might apply.
What improves an EPC rating most?
The biggest single improvement for many London properties is an efficient condensing boiler with proper controls. Other high-impact improvements include:
- Loft insulation: one of the cheapest improvements with a good effect where there is a loft to insulate.
- Cavity wall insulation: effective for later properties with unfilled cavities. Solid-wall Victorian terraces need internal or external wall insulation instead.
- Double glazing: replacing single glazing has a moderate effect, subject to planning rules in conservation areas.
- Heating controls: a programmer, room thermostat and thermostatic radiator valves improve the assessment of the heating system.
- Low-energy lighting: a small number of points, inexpensive and worth doing.
- Renewables: solar panels or a heat pump can make a large difference where the property suits them.
For landlords, our article on what an EPC rating of D means and our EPC C by 2030 page explain the proposed move to a higher minimum standard for rented homes.
Why the rating matters
For landlords, the rating decides whether a property can legally be let, and the government has proposed raising the minimum for rented homes from band E to band C. For owners, buyers increasingly look at the band and the estimated running costs when comparing homes, and some lenders offer better mortgage terms on more efficient properties. For tenants, a higher band usually means a warmer home that is cheaper to heat and less prone to condensation and mould. An improvement that lifts a home by a band can therefore pay back in several ways at once, which is why it is worth planning works around the recommendations on the certificate rather than guessing.
How to check your rating
Search the government's Find an energy certificate service by postcode to see the current certificate for any home that has one, including the score, the date and the recommendations.
Getting an EPC in London
- Book: tell us the address and property type.
- Assessment: an accredited assessor visits, usually for under an hour for a typical home, and records the property.
- Lodged: the certificate is lodged on the register and emailed to you the same day.
Book an EPC with GMAS Group or call 07498 597339. If the rating is lower than you need, we can carry out the insulation, heating and window improvements through one point of contact.
Frequently asked questions
What is a good EPC rating?
Band C or above is generally considered good for an existing home. Most new-build homes achieve band B. Older homes in London are commonly D or E.
How long is an EPC valid for?
Ten years. You can get a new one at any time, for example after making improvements, and the newest certificate on the register is the one that counts.
Does an EPC rating affect my energy bills?
The certificate estimates running costs under standard assumptions. A better rating usually means lower bills, but actual costs depend on how the home is used.
Who can produce an EPC?
Only an accredited energy assessor can produce an EPC, and it is only valid once it has been lodged on the government register.