An EPC is an Energy Performance Certificate. It contains all the information regarding the energy efficiency of a dwelling or a non-dwelling. The efficiency is shown in a scale from G (lowest) to A (highest) and is accompanied by a report of recommendations on how to improve the performance of the building, however the suggestions produced are not compulsory.
In England and Wales EPC is required for almost every building when is constructed, sold or rented out in conformity with the European Directive 2002/91/EC on the Energy Performance of Buildings (EPBD).
EPCs are valid for 10 years and can be reused as required within that period. Consequently, if there is a change of tenancy or the property is sold, is not necessary to issue a new certificate provided that the EPC is not older than 10 years.
For a building to fall within the requirement for an EPC it must have a roof and walls and use energy to condition the indoor climate. Therefore it is absolutely necessary that the building presents any sort of services with the purpose to provide internal comfort like heating, cooling or ventilation system. Fixed services as hot water or lighting are not considered within these categories.
What does the EPC take into account when calculating the energy performance of a property?
There are a combinations of factors that impact these performances. First of all the building fabric in terms of U-values of the walls, the floors/ceilings, roofs, windows and doors. Secondly, the building services must be defined: type of HVAC used and DHW, the systems and its efficiency, the fuel. A very important factor is the air permeability value which must be provided by an air test conducted by an accredited assessor or otherwise it must be calculated properly.
The calculation process compares the carbon emissions of the building (BER) with those of a notional building (TER) similar in shape, size, activity. To achieve a ‘pass’ in the EPC generation process is required that the BER-value must be lower than the TER-value.