Air tightness testing sometimes referred to as air permeability testing, air leakage testing and air pressure testing measures the amount of uncontrolled air escaping through the external fabric of the building envelope.  

The air tightness test determines the amount of air leakage in cubic metres per square metre of internal surface area of the building. Or, to put it simply, air tightness testing measures the amount of air that escapes (drafts) through the gaps or building fabrics. Ideally, having an airtight building means that less energy will be wasted through the leakage of heated air.  

All new homes in Scotland require to have an air test carried out in accordance with CIBSE TM23