Experimental characterisation of ventilation systems in buildings.

Reports experiments using sulphur hexafluoride as a tracer gas to obtain quantitative data on actual residence time distributions in rooms and hallways and contamination caused by reentry of laboratory fume hood exhausts into a building. Defines a factor k which gives a measure of the mixing of fresh withstale air in part of a room. Measured values of k varied from 0.3 to 0.7 insmall rooms without fans. Discusses two experiments to find the amount of exhaust fumes reentering the ventilation system of a building.