An investigation of ventilation at ground level in high density cities - An initial study in Hong Kong

Abstract

Recently urban climate as one of important environmental issues in the process of designing has been received high attention. There are many urban climatic studies by researchers mainly from Europe and North America. Almost all of them focused on strong wind problems; research concerning the weak wind issues is seriously lacking. However, in subtropical high density cities, human comfort strongly related to the weak wind at pedestrian level. Thus, there is a need to address this research issue in high density cities, especially in Hong Kong. This paper presents the initial results of case study of Air Ventilation Assessment Systems (AVAS) on ventilation at ground level conducted in the typical hot humid summer day in Tsim Sha Tsui, Hong Kong. The findings of this study have revealed that air flow pattern within the densely built environment in the context of a high density city. For better understanding the condition of air ventilation at ground level in Tsim Sha Tsui, the field measurement data has been translated into wind velocity ratio. Then, based on the field measurement data, the urban breeze ways and air paths have been carefully examined. Finally this paper offers some urban design strategies in order to help planners, architects and developers produce good quality urban spaces. The study is still ongoing. Its ultimate is to aid better planning of Hong Kong and to contribute to the current knowledge gap on urban climate in high density cities.