Full scale measurements of air flow velocities, temperature, intensity of turbulence and air exchange rate are carried out on two rooms with different types of ventilation located in the department of architecture at Chalmers University of Technology. The measurements have shown that mixed ventilation gives variable mean flow velocities with a high risk of draught as compared to the room provided with displacement ventilation. Air exchange rate for the room with displacement ventilation is obtained from tracer gas monitor by employing decay and constant emission methods.
Ventilation by displacement is a type of ventilation where the air flow is thermally driven. By this arrangement one obtains two zones in the room - a lower zone with supply air conditions and an upper recirculation zone with extract air conditions. Cold climate causes downdraught from windows and external walls and results in a mixing of air from the upper into the lower zone. To avoid this problem during cold climate a new principle for ventilation by displacement is tested. Excess heat from the upper zone of the room is used for heating cold surfaces.
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