Calculating the target primary energy rate and target emission rate

In compliance with the approved document section 1 & 2 (regulations 24, 25, 25B, 26, 26C, 27 & 27C) and in accordance with principles set out in L2A^[1] and the NCM Modelling Guide^[3], the BER / TER & BPER / TPER values are obtained from the simulated carbon dioxide emissions and energy use of two buildings.

The ‘actual building’, which forms the basis of the BER & BPER calculations, is the building as designed, but subject to standard operating conditions dictating levels and patterns of occupancy, internal gain and minimum ventilation.

The ‘notional building’, which forms the basis of the TER & TPER calculations, is a version of the actual building modified in accordance with rules relating to glazing area, insulation, system efficiency and other factors. The notional building is also subject to the standard operating conditions.

Both buildings are simulated over a typical year using standard weather data appropriate to the building location. Results are automatically fed into the BRUKL compliance calculator provided by BRE.

The standard operating conditions are functions of the building type and the activities occurring within each room. They are laid down in the National Calculation Methodology (NCM) Modelling Guide^[3]. It is important to note that the stipulation of standard operating conditions for L2 (2021) compliance calculations means that simulation results as calculated for L2 (2021) will in general be different from those calculated for the ‘real’ building (for example in the Apache View).

Note: The simulations may be run in series rather than parallel if notional PV areas require adjustment.