Air Tightness Testing

What is Air Tightness testing?

Air Tightness Testing is a requirement of Part L1A & L2A of the Building Regulations for newly built Domestic and Commercial Buildings. Air Tightness Testing measures the amount of uncontrolled air flow (also known as air leakage) within a building as a result of unsealed gaps or cracks within the thermal envelope.
Building Regulations details a maximum permitted threshold for the air pressure test of 10 m3.h/m2. This generous air leakage rate is superseded by a target value detailed in the SAP Calculation (Domestic) as a result of the measured air leakage rate having a direct impact on carbon emissions.
The testing procedure involves using a large fan to de-pressurize the dwelling, compared to the outside atmospheric pressure. This effectively pulls air through any unwanted gaps in the fabric of the building. The calibrated equipment and software then calculates the amount of unwanted air that is leaked through the building. These results are compared to the SAP calculations to determine if the result passes its design target. An EPC certificate can then be issued.
Air tightness testing is becoming increasingly important to help produce greener developments, through reducing carbon emissions and reducing energy needlessly lost from residences. The amount of energy lost is known as the emission rate. New developments must meet specific requirements for air testing and emission rates.

Am I ready to test?

Common reasons for a failed air test