Target emission rate TER

The Building Regulations set out requirements for specific aspects of building design and construction. Regulation 26 of the building regulations states that 'where a building is erected, it shall not exceed the target CO2 emission rate for the building…'.

The target CO2 emission rate (TER) sets a minimum allowable standard for the energy performance of a building and is defined by the annual CO2 emissions of a notional building of same type, size and shape to the proposed building. TER is expressed in annual kg of CO2 per sq. m.

The CO2 emission rate of the proposed building is calculated based on its actual specification and is expressed as:

Dwelling emission rate (DER) for self-contained dwellings and individual flats (excluding common areas). This is the annual CO2 emissions of the proposed dwelling expressed in kg/sq. m.
Building emission rate (BER) for buildings other than dwellings. Again this is the annual CO2 emissions of the proposed building expressed in kg/sq. m.

The DER or BER for the proposed building must not exceed the TER.

Before construction begins, a design stage calculation must be issued to the Building Control Body (BCB), setting out the TER, and BER or DER for the proposed building, along with details of its proposed specification.

Within 5 days of the completion of the construction, a report must be issued to the Building Control Body (BCB), setting out the TER, and BER or DER of the completed building, along with any changes that have been made to the specification, and an energy performance certificate (EPC). These ‘as-built’ calculations require that an air-permeability test is carried out to ensure that the building envelope has been constructed to a suitably high level of workmanship so that air (and with it, heat) will not ‘leak’ through the building fabric. In addition, the BCB is likely to require a commissioning notice.

For buildings other than dwellings, the TER and BER can be calculated and the EPC produced by following the National Calculation Method (NCM). This can be done by using approved simulation software (Approved Dynamic Simulation Models (DSMs)) or by using the Simplified Building Energy Model (SBEM), a ‘simplified’ compliance tool developed by BRE, which has a user interface called iSBEM.

For dwellings, the Standard Assessment Procedure should be followed. This can be done by using a computer program approved for SAP calculations by BRE on behalf of the government.

NB: 2013 changes to part L of the building regulations which came into force on 6 April 2014 introduced a Target Fabric Energy Efficiency (TFEE) rate for dwellings to sit alongside the Target Emission Rate. The TFEE is the minimum energy performance requirement for a new dwelling. The Dwelling Fabric Energy Efficiency (DFEE) rate is the actual energy performance of the new dwelling. The DFEE must not exceed the TFEE.