The Energy Performance Certificate (EPC) gives information about the energy efficiency of the building to owners, prospective buyers and tenants. An EPC has two parts a graphic rating and a recommendations report. The rating is calculated based on the performance of the building and its building services such as heating, lighting, air conditioning. It is known as asset rating and begins from ‘A’ to ‘G’, which shows how energy efficient the building has been designed and modified. An ‘A’ rating indicates that a building is very efficient, consequently reduced fuel bills. Α ‘G’ rating shows an inefficient building with higher fuel bills. EPC has to be accompanied with a description of the potential rating of the building if all the proposed cost-effective measures are carried out. The age, location, size and condition of the building are taken into account for the production of an EPC and depending on these characteristics a building’s rating varies.