Airtightness testing is essential in the pursuit of various building certifications by ensuring that structures meet designated standards for energy efficiency, indoor air quality, and overall performance. This testing, typically conducted using methods such as blower door tests (e.g., ASTM E779, ASTM E1827), helps identify air leaks that could account for up to 30% of a building's energy usage, thereby supporting compliance with standards like the National Building Code of Canada. Certifications such as LEED, WELL, and Passive House all incorporate airtightness as a crucial criterion in their frameworks, emphasising both the reduction of energy consumption and the enhancement of indoor air quality. Professionals are trained through specialised programmes to ensure accurate testing, aligning with industry standards like ISO 9972, which further reinforces the reliability and consistency needed to maintain these building certifications.