The Influence of Surrounding Buildings on the Natural Ventilation Performance of Residential Dwellings in Hong Kong

Natural ventilation in residential dwellings is very important for occupants’ health and comfort. Previous studies by the authors have concluded that natural ventilation performance in dwellings can be enhanced by positioning the two groups of window openings (bedroom windows and living room windows) in opposite directions or perpendicular to each other; and/or the use of side-hung windows. However, the buildings selected for those studies were located in an isolated site, for the purpose of focused evaluation of the influence of various configuration parameters and window types. However, in Hong Kong, buildings are tightly packed. In this study, the influence of urban environment was thoroughly considered. A residential estate was identified to represent typical characteristics of the urban environment in Hong Kong for CFD modelling and simulations. Bi-variate correlations and K-means cluster analyses were adopted to identify a set of probable local wind conditions, which took into account the combined influence of prevailing wind conditions, urban environment and building levels. Through side-by-side comparison of results obtained with and without considering the influence of surrounding buildings, it was found that surrounding buildings lower the wind power available in the vicinity of buildings by 2.5% to 86.8%, increase the angular spread of prevailing winds and adversely affect natural ventilation in residential dwellings. The increase in the mean age of air (MAA) is 0.6 times to 1.5 times. In respect of influence of openings configurations and window types, the conclusion drawn in this study was found to be in agreement with previous studies.