ABSTRACT
The airflow patterns should, in principle, be organized in order that new air is brought to the head of the occupants, so that they get fresh, clean air, and that contaminants be evacuated as quickly as possible, before being mixed with indoor air. However, air, as any other fluid, always follows the easiest path. This means that the airflow does not necessarily follow expected patterns. Since air is transparent, unexpected airflow patterns are noticed only when things go wrong. Depending on the airflow distribution in rooms and for a given airflow rate, the concentration of contaminants in the occupied space may vary by a factor of two or more. Therefore, measurements may be useful to check if the airflow patterns are as expected. Such measurements allow checks to ensure that:
the air change efficiency is as large as possible,
clean air is supplied to the right places,
air contaminants are quickly removed.
