Measurement of air flow rates and ventilation efficiency in air handling units.

The use of tracer gas is of great help in measuring airflow rates and detecting shortcuts in air handling units, and is essential for ventilation efficiency measurement. However, the planning of experiments, that is choosing tracer gas injection locations and air sampling locations, is not straightforward. Moreover, the mathematics used for interpretation are quite complex, and require elaborate calculations. Therefore, a measurement protocol and the corresponding interpretation algorithms are being developed and implemented in a user-friendly computer program. This development is based on several years of practice in such measurements, and includes the solving of mundane but serious problems such as proper tracer gas mixing in air and representative sampling strategy. The contribution presents the methods applied, the principles used in the test protocol, and an example of application to real air handling units.