An Energy Performance Certificate (EPC) gives your home a rating from A (best) to G (worst). It looks like an efficiency score, but it’s actually based on the modelled cost of heating, hot water and lighting per square metre.
A better rating (closer to A) usually means lower typical running costs compared to a home of a similar size.
Your EPC also shows information about carbon emissions.
In Scotland, there’s a separate Environmental Impact (CO₂) rating alongside the main rating.
In England, Wales and Northern Ireland, the certificate includes carbon emissions information (for example, tonnes per year). However, the A to G EPC band is still based on running costs, not directly on carbon emissions.