Measurements are needed to verify the performance of ventilation systems and to test the air-tightness of the building shell. They are essential for commissioning, diagnostic analysis, design evaluation and research.

Various units are used to describe the rate of ventilation. These include:

Volumetric flow rate: Ventilation and air infiltration is commonly expressed in terms of a volumetric air flow rate e.g. litres/s (l/s) or m³/s.

The Air Infiltration and Ventilation Centre's first glossary of ventilation terms was published in 1981 as AIVC Technical Note 5 and contained definitions of over 700 words relating to air infiltration and ventilation. Since then, many definitions have been updated and new terms have been added.