Approved Document L2A adopts a similar approach to Approved Document L1A, taking the entire building’s performance and CO2 emissions into consideration. All new buildings other than dwellings must be designed and built with their Building CO2 Emissions Rate (BER) being no worse than the Target CO2 Emissions Rate (TER).
The TER is set from a Notional Building of the same size and shape to the actual building. There are three defined Notional Buildings; heated and cooled buildings (that are side lit or unlit), and toplit buildings. The specification for each building type is summarised in ADL2A. CO2 Emissions Rates for buildings other than dwellings are calculated using the Simplified Building Energy Model (SBEM) or other approved software.
In addition to meeting the TER, a new Target Primary Energy Consumption (TPEC) rate has been introduced for new buildings other than dwellings. Put simply, this new target is aimed at two factors – energy efficiency of the fabric and its building services. The TPEC ensures these two factors are carefully considered and prevents renewable technologies being highly specified to counteract a lower performing fabric or services standards.
If the building is built to match the Notional Building specification, its BER should meet the TER. Note that other factors need to be taken into consideration including continuous building fabric insulation, air permeability, thermal bridging, performance testing and limiting the effects of heat gains in summer.