Businesses providing Energy Performance Certificates assess the energy efficiency of homes and commercial buildings. An accredited energy assessor gathers information about the property, such as its age, construction, insulation, heating and hot-water systems, windows and lighting. The assessment may involve a visit to the premises and, where necessary, checking available plans or building records. The assessor uses the relevant method for the type of building and prepares an EPC showing its energy rating, generally from A (most efficient) to G (least efficient). An EPC also gives an estimate of typical energy use and carbon emissions, together with recommendations for potential improvements, such as better insulation or more efficient heating. These suggestions are not a guarantee of actual energy bills or savings. EPCs are commonly required when a property is built, sold or let, subject to applicable exemptions, and the certificate is lodged on the official register.