Importance of Building Regulations
Building Regulations set the minimum performance standards for design and construction of buildings in England and Wales. For new builds and major refurbishments, compliance with Part L of the Building Regulations — which covers energy efficiency and carbon reduction — is mandatory. Builders are required to carry out air tightness testing at the appropriate stage of construction to demonstrate that the building meets the required air permeability standard.
The Building Regulations set a maximum air permeability level, though the specific performance target for any given unit will be determined by the project’s SAP or SBEM calculations. These calculations establish whether the building’s Design Emission Rate (DER) falls at or below the Target Emission Rate (TER).
Which Parts of the Regulations Apply?
- Part L1A — Applies to all new dwellings
- Part L2A — Applies to all new non-domestic buildings
- Part L2B — Applies to large extensions to non-domestic buildings
The UK Government has committed to reducing CO² emissions from energy consumption by 60% by 2050. The two major contributors to poor building energy performance are air leakage and discontinuities in the insulation envelope. Air testing must be carried out by a competent, accredited person. Only upon achieving the required standard will Building Control issue a Completion Certificate for the development.
Why Compliance Matters
- A Completion Certificate cannot be issued without a passing air test result
- Poor air tightness leads to higher energy bills and greater carbon emissions
- Failure to comply can delay practical completion and affect property sales
- Early engagement with air tightness requirements during design reduces the risk of failure at testing stage