cinema

This paper reports on the ventilation measurements in a cinema using the tracer-gas technique. Both the local and room air exchange efficiencies were measured. The two tracer-gas methods, "step-up" and "step-down (decay)", were used alternately when the cinema was in use to enable a continuous measurement of air-exchange efficiencies under various occupancies. The air exchange efficiencies were found to be very close to that for a perfect mixing, with little influence from the occupants. This might be due to that the cinema had a downward mixing ventilation with a large air change rate.