The epc is an energy performance certificate which is required for all homes, when they are built, rented or sold. All home owners need certificate records which show how energy efficient a property is and which provides A-G ratings. These epcs are produced by means of standard methods about energy usage so that energy efficiency can be compared among several buildings.

For houses, there are two epc ratings: an energy efficient rating which is used to measure a home's overall efficiency and the environmental impact rating which measures the home impact on the environment in terms of carbon dioxide emissions. In the first case, the higher the rating, the lower the fuel bills will be while in the last case the higher the rating, the less impact it has on the environment.

The epc rating is made according to the performance of the building itself and its services and the certificate mentions the potential rating of the building. This rating takes into consideration the age, location, size and the condition of the building and the suggested measures are tailored in order to be realistic for a particular building. The epc also includes a recommendation report, offering information about how to improve the energy performance of the property. Furthermore, these recommendations include cost-effective improvements, listing the level of cost, the typical cost and the savings per year for each performance rating.

Other information that must be included in the epc is: reference information, which lists the type of the property, the unique reference number and the date of the certificate, estimated energy use, based on assumptions about occupancy and heating patterns, estimate of the current and potential energy use, carbon emissions and fuel costs for lighting, heating and hot water., energy assessor details such as the name of the assessor, accreditation number, company name and contact details, complaints and energy advice.

The commercial epc is similar to its domestic counterpart, looking the same and having the same ratings as for domestic energy performance certificates. The cost of the commercial epc is difficult to estimate as far as public buildings are concerned due to the nature of the construction, the complexity and the size of the building to be examined. This cost is difficult to ascertain because the inherent properties of a building vary greatly. The surveyor for this type of epc will offer quotes, prices and costs and this information is based on the facts supplied by the owner of the building.

In order to reduce the costs of the commercial epc the assessor must have as much information as possible because this will help the owner obtain a competitive price for the epc and reduce the price. Most of these epcs are based on how much information the owner can provide about his property and the commercial epc adopts similar practices for the inspection of the commercial property. There are some places which don't require epcs and these are: places of worship, buildings of less than 50 square meters, temporary buildings and buildings with a low energy demand.

All in all, the price of the commercial epc is market driven, being dependent on the size and complexity of the building. The assessor of the building is expected to look at the following factors: thermal characteristics of the building, air conditioning, artificial ventilation, solar systems, position and orientation of the building and indoor climatic conditions.