|Title||Effect of room air recirculation delay on the decay rate of tracer gas|
|Publication Type||Conference Proceedings|
|Year of Publication||2004|
|Authors||Astrid H. Kristoffersen, Ashok J. Gadgil, David M. Lorenzetti|
|Conference Name||9th International Conference on Air Distribution in Rooms - RoomVent 2004,|
|Date Published||September 5-8, 2|
|Conference Location||Coimbra, Portugal|
Tracer gas measurements are commonly used to estimate the fresh air exchange rate in a room or building. Published tracer decay methods account for fresh air supply, infiltration, and leaks in ductwork. However, the time delay associated with a ventilation system recirculating tracer back to the room also affects the decay rate. We present an analytical study of tracer gas decay in a well-mixed, mechanically-ventilated room with recirculation. The analysis shows that failing to account for delays can lead to under- or over-estimates of the fresh air supply, depending on whether the decay rate calculation includes the duct volume.