When you see an EPC rating on a property listing: EPC C, EPC E, EPC A, it’s natural to wonder what that actually means in real life.
The EPC scale runs from A to G and shows how energy-efficient a home is. A is the most efficient, G is the least. Most UK homes sit somewhere in the middle.
You’ll usually look this up when comparing two homes on Rightmove or Zoopla, reviewing your own EPC during a sale, or trying to understand whether a heat pump or insulation upgrade would improve your banding.
Mortgage lenders also use EPC bands when offering “green” mortgage products or adjusting affordability.
The EPC is based on a Standard Assessment Procedure (SAP) score, a numerical score calculated by an accredited assessor, which is then converted into the familiar A–G band.
Below, we break down what each band means, how SAP scores map to bands, and what homeowners should take from it.
What is the EPC scale?
The EPC scale is a simple A–G label designed to make the energy efficiency of a home easy to compare. Under the Energy Performance of Buildings Regulations, every property marketed for sale or rent must have a valid EPC.
Behind the scenes, the assessor calculates:
- how much energy the home need to stay warm
- how much heat it loses
- how efficient the heating system is
- what it costs to run the property
That score is converted into a SAP number and then into a lettered band.
EPC bands A–G (and what they mean day-to-day)
Band A (92–100 SAP)
Extremely energy-efficient. Almost always new-builds with excellent insulation, airtightness and low-carbon heating such as heat pumps. Bills are very low.
Band B (81–91 SAP)
Well-insulated modern homes. Heating costs are low, and the home is usually comfortable year-round.
Band C (69–80 SAP)
A solid, efficient home. Many lenders consider EPC C the benchmark for green mortgage incentives.Often achievable with sensible upgrades like loft insulation or better glazing.
Band D (55–68 SAP)
The most common rating in England and Wales. Homes are generally fine to live in but may feel draughty or expensive to heat in winter.
Band E (39–54 SAP)
Noticeably less efficient. Heating costs can be high. Key upgrades are usually insulation and improving the heating system.
Band F (21–38 SAP)
Poor efficiency. Cold, leaky and expensive to heat. Significant work is usually required to bring the home to a comfortable standard.
Band G (1–20 SAP)
The lowest category. Very inefficient, often older or unmodernised properties. Expect high heating costs unless substantial improvements are made.
SAP score to EPC band conversion table
EPC bandSAP score rangeWhat it means
A 92–100 Best performance, very low running costs
B 81–91 High efficiency modern homes
C 69–80 Good efficiency with manageable bills
D 55–68 Average UK home
E 39–54 Inefficient, higher running costs
F 21–38 Poor energy performance
G 1–20 Very poor, major upgrades needed
Why EPC bands matter when buying or owning a home
1. Comparing properties on portals
Two homes can look identical on paper, but behave very differently in winter. The EPC helps you understand likely energy bills and comfort levels.
2. Understanding a low EPC during your own purchase
A low rating can signal costs ahead. Loft insulation, cavity wall insulation and heating upgrades are the most common fixes.
3. Planning heat pump or insulation upgrades
If you’re reading about heat pumps and see references to EPC C, it’s because insulation and airtightness heavily influence how well low-temperature heating systems perform.
4. Mortgage affordability and green products
Some lenders offer better rates for EPC A–C homes. Others adjust affordability on the basis that efficient homes cost less to run, leaving more disposable income.
5. Future-proofing your home
Energy bills, comfort, and long-term value are all influenced by a property’s efficiency. EPCs are not perfect, but they remain the UK’s main standardised efficiency measure.
Limitations of EPC ratings
EPCs measure theoretical performance, not real-life behaviour. They don’t account for:
- how you actually use your heating
- smart controls
- room-by-room temperatures
- the precision of installation quality
Still, they offer a consistent benchmark across millions of homes, which is why mortgage lenders, estate agents and regulators rely on them.
If your EPC is lower than you expected
Start with the simplest upgrades first:
- Loft insulation
- Draught-proofing
- Upgrading an old boiler or improving thermostatic controls
- Cavity wall insulation (if appropriate)
These often have the biggest impact for the least cost. For bigger improvements, a heat loss survey from a qualified heating engineer or retrofit assessor can help prioritise.