Comparison of performances of displacement and mixing ventilations. Part II: Indoor air quality

A numerical simulation using a validated computational fluid dynamics model is used to investigate and compare the performances of displacement and mixing ventilations (MVs), under different boundary conditions. A companion paper will report the results in terms of thermal comfort, while this paper investigates the indoor air quality (IAQ). The IAQ will be measured in terms of carbon monoxide, mean age of air and the three volatile organic compounds, toluene, benzene and formaldehyde, which are commonly found in indoor room furnishings. The case studies include offices, classrooms, retail shops and industrial workshops, under typical Hong Kong thermal boundary conditions. Compared with conventional MV, displacement ventilation may provide better IAQ in the occupied zone.