An EPC or Energy Performance Certificate is a legal document, mandatory in Northern Ireland. EPC’s are required when selling, renting or remortgaging a property. The EPC must be available for display before the property is marketed or advertised. This means an EPC is the first step on the selling or renting ladder. It will contain information regarding a property’s energy usage and typical energy costs. An EPC is graded on a rating from A (most efficient) to G (least efficient).