Air ventilation in cities with dense high-rise developments

Ground-level air condition in inner city areas is becoming increasingly poor as buildings become taller and more closely spaced. This paper explains how wind flow in cities is primarily governed by the amount of air blowing in from outside and how this is modified by buildings, particularly taller ones. Based on experiences in Hong Kong, the paper shows how local topography affects the available wind and how city layouts, the configuration of building complexes and the geometry of individual buildings affect pedestrian-level wind speeds. Mitigation measures to improve air ventilation are proposed.