EPCs carry ratings that compare the current energy efficiency and carbon dioxide emissions with potential figures that your home could achieve. Potential figures are calculated by estimating what the energy efficiency and carbon dioxide emissions would be if energy saving measures were put in place.
The rating measures the energy and carbon emission efficiency of your home using a grade from ‘A’ to ‘G’. An ‘A’ rating is the most efficient, while ‘G’ is the least efficient. The average efficiency grade to date is 'D'. All homes are measured using the same calculations, so you can compare the energy efficiency of different properties.

Around 27% of the UK’s carbon dioxide emissions come from domestic homes. Carbon dioxide contributes to climate change.

EPCs also provide a detailed recommendation report showing what you could do to help reduce the amount of energy you use and also reduce your carbon dioxide emissions.

The report lists:

• Suggested improvements, like fitting loft insulation
• Possible cost savings per year, if the improvements are made
• How the recommendations would change the energy and carbon emission rating of the property

You don’t have to act on the recommendations in the recommendation report. However, if you decide to do so, it could make your property more attractive for sale or rent by making it more energy efficient.

The certificate also contains:

• Detailed estimates of potential energy use, carbon dioxide emissions and fuel costs
• Details of the person who carried out the EPC assessment
• Who to contact if you want to make a complaint

Information about energy efficiency and carbon emissions is summarised in two charts that show the energy and carbon dioxide emission ratings. The charts look similar to those supplied on electrical appliances, like fridges and washing machines.

Who needs an EPC?*

You’ll need to provide an EPC if you are selling or letting your home.

However, the following buildings don’t need an EPC when they are built, rented or sold:

• Places of worship
• Temporary buildings that will be used for less than two years
• Standalone buildings with total useful floor area of less than 50 metres squared that aren’t used to provide living accommodation for a single household
• Industrial sites, workshops and non-residential agricultural buildings that don't use a lot of energy

The EPC Assessment - What happens?

The assessment is carried out at the property and normally takes between 30 to 90mins. Access will be required to all internal rooms and parts of the property including access to any loft void if it is safe and practical to do so. In some instances access to any surrounding garden areas may be required to enable external measurements of the building to be taken. Uninhabited outbuildings, sheds and detached garages will not normally need to be accessed.

The assessment is conducted by way of a ‘non-invasive’ survey. It is not necessary to clear cupboards, move furniture or roll back carpets.

Measurements will be taken either internally or externally to calculate the size of the floor area and the length of the heat loss perimeter. The following features will be recorded in order to calculate the energy performance:

• Age of the building and any extension/conservatory
• The construction method and materials
• The presence of any adjoining property for heat loss/gain
• Any roof, wall or floor insulation
• The type, age and size of the windows/glazing etc
• The proportion of light fittings with ‘low-energy’ light bulbs
• The type of heating and hot water installation
• Any other features contributing to energy performance

The assessor will need to take digital photographs of the above features in addition to external shots of the main building and any extension/conservatory.

Once the assessment is complete and all necessary data has been collected, the assessor will return to the office to prepare the EPC. The EPC will be lodged on the national EPC register, www.hcrregister.com , operated by Landmark, and can be retrieved from the register by any person, using the unique 24-digit Report Reference Number (RRN).

A paper copy of the EPC will also be forwarded to the customer if required.

*Crown copyright acknowledgement - For the benefit of complete accuracy, some of the above information is directly reproduced from the directgov website publication