Ventilation studies in nine air conditioned office buildings in Singapore.

One of the significant factors affecting the quality of air in the built environment, particularly in the context of hot humid climates, is the design and implementation of the air-conditioning and mechanical ventilation system. While most building regulations would incorporate minimum ventilation requirements al design, it is often difficult to quantitatively measure the adequacy of such ventilation provision in insitu buildings. A research initiative, aimed at obtaining status-quo measurements of the ventilation characteristics in air-conditioned office buildings in Singapore, has yielded a reasonably large database, which details are presented in this paper. Tracer gas techniques, employing the concentration decay method, were adopted to obtain the fundamental age of air values in nine buildings. Other ventilation characteristics such as the outside air change per hour, ventilation provision and air exchange effectiveness were subsequently computed. The measured air change per hour values in the building with the highest ventilation provision is almost eight times that of the building with the lowest ventilation provision. Apart from minor short-circuiting profiles in some zones, the air exchange effectiveness values have generally been observed to indicate well-mixed flow patterns.