Influence of Window Types on Natural Ventilation of Residential Buildings in Hong Kong

Hong Kong is of subtropical climate where summer is hot and winter is warm. Natural ventilation is most desirable for cooling and providing fresh air in residential buildings in moderate seasons for better indoor air quality and thermal comfort. The natural ventilation performance is affected by a combination of internal and external factors. External factors include the location, the orientation, the prevailing wind speeds and the building forms of the residential development, which are subject to constraints beyond the control of site planners and architects. Whilst for internal factors like the openings configurations and window types, site planners and architects are always given free hand for a proper design. The influence of each of the internal factors on the natural ventilation performance is therefore of interest to them. As one of the studies on this topic, this paper focuses on the influences of window types on the natural ventilation of residential units in Hong Kong. On-site tracer-gas experiments and measurements were carried out in a representative residential unit with side-hung window. Based on the measured data, CFD software Airpak was used to simulate the natural ventilation performance for the use of different window types commonly adopted in residential buildings in Hong Kong, which are end-slider; side-hung; and top-hung windows. The ventilation effectiveness and the air distribution in indoor spaces were simulated and compared. The studied results provide useful information for future designs of residential buildings for better natural ventilation.