Energy Performance Certificate and the Asset Rating

For every building requiring an Energy Performance Certificate (EPC) the crucial outcome is the asset rating which reflects the potential energy efficiency of a building. The asset rating is the 'design' rating of a building reflected by the CO2 emissions of a building's design features on an A to G scale.

The asset rating is defined by the national calculation methodology (NCM). Using an approved calculation tool, your assessor creates a model of the annual CO2 emissions from the building.

The model takes into account the following factors:

  • The thermal characteristics of the building (thermal elements and controlled fittings as an envelope) including the air permeability.
  • The efficiency of the heating installation and hot water supply, including their insulation method.
  • The efficiency of the air-conditioning installation where installed.
  • The ventilation strategy, accounting for natural and mechanical means.
  • The artificial built-in lighting installation efficiency.
  • The position and orientation of buildings, including the weather location.
  • The use of passive solar systems and solar protection to reduce the need for cooling.
  • The indoor climatic conditions, including the designed indoor climate.
  • The activity of the building

Further reading

‘Improving the energy efficiency of our buildings: A guide to energy performance certificates for the construction, sale and let of non-dwellings' available from