Energy Performance Certificates (EPC) are a standardised system of rating the energy efficiency of UK buildings. There are two types of EPC: one for residential buildings, and another for all other buildings (i.e. non-domestic). The two types of EPC look similar and have the same uses and aims, but they use two separate calculation methodologies and rating systems.
An EPC is needed whenever a property is built, sold or rented as it is intended to inform the new occupier of the energy cost efficiency of the building. In theory, a home with a higher EPC rating should have lower energy costs than a similar house with a lower rating.
For homes, EPCs are produced using the Standardised Assessment Procedure (SAP) calculation methodology. The EPC will provide the home with a rating between 1 - 100 based on the estimated energy costs of the home. A higher rating indicates lower energy costs.
From the EPC rating, the home will be placed into one of seven graded bandings between A and G.
The average home in the UK would likely be a "D" rated building, while a newly built house would be "A" or "B" rated.