Part L2A of the Building Regulations details the requirements for new build commercial premises. Part L2B of the Building Regulations covers those requirements that are necessary for conversions and extensions.
Approved document L2A of the 2006 Building Regulations requires all commercial and industrial buildings with a gross floor area in excess of 500M² – to be tested for air permeability to meet a minimum standard of 10m³ /(h.m² ) at 50 Pa. (I.e. An air leakage rate of ≤ 10 cubic metres per hour, per metre squared at a pressure of 50 pascals).
However, in the drive towards increased energy efficiency and increased comfort for the building’s occupants – a level of 3m³ /(h.m² ) has often been set for air-conditioned buildings and in some of the large superstores we have tested – the developers have set even tighter standards to achieve levels as low as 2m³ /(h.m²).