Things You Need To Know About Energy Performance Certificate (EPC) Energy Performance Certificates (EPCs), similar to the multi-colored sticker on new appliances, tell you how energy efficient a building is and assign it a rating ranging from A (very efficient) to G. (inefficient). They'll tell you how much it'll cost to heat and light your home, as well as how much carbon dioxide it'll emit. An EPC also includes information on what the energy efficiency rating could be if the recommended improvements were implemented, as well as cost-effective ways to achieve a higher rating. Even if you rent your home, you could still make some of the EPC-recommended improvements, such as switching to more energy-efficient light bulbs. EPCs are valid for ten years from the date they are issued.