During air tightness testing, how many fans should generally be used?

The appropriate number of fans used during air tightness testing is generally two to three. This range allows for adequate pressure differentials to be established throughout the building's envelope, which is crucial for effectively detecting air leakage.

Using two fans can help create sufficient airflow to measure the building's airtightness, while a third fan can provide additional support and capture more data across different zones within the structure. This flexibility is particularly beneficial for larger buildings where leakage may not be uniform, enabling a more comprehensive analysis of the air barriers in place.

This practice aligns with industry standards aimed at optimizing the testing process, ensuring accurate results that reflect the building's performance regarding energy efficiency and indoor air quality.