An Energy Performance Certificate is a legal document that gives an energy rating to commercial premises, much in the same way cars or home appliances are graded for their energy efficiency. You will need an EPC whenever a building or part of a building is constructed, sold or let. It will provide valuable information for potential purchases and tenants on the energy performance and efficiency of a building before they buy or rent. It will be accompanied by a recommendation report which will provide information on how to upgrade the energy performance and the payback period for carrying out any improvements.