Abstract
Designing the morphology of urban districts (building clusters and roads) to maximize ventilation during summer is an effective way to mitigate the Urban Heat Island effect (UHI). Using wind speed, wind direction, and temperature measurements taken at pedestrian level in 2004 and 2005 in several central urban districts in Yokohama, Japan, this paper uses 6 original simplified 2 dimensional urban morphological parameters (A: angle between upper air flow and road; SHO: ratio of frontal aspect height to plan; CVR: ratio of roughness element horizontal length to plan; DNS: street canyon height difference; RW: road width; and TOSU: number of roughness elements) to analyze the link between urban thermal environments and the shape of roughness elements placed downstream in a regional air flow. In addition to smaller SHO, CVR, and TOSU values; as well as larger RW values, better ventilation (and hence less intense UHI conditions) was observed when A was closest to upper air flow direction; DNS was such that leeward building height exceeded that of windward buildings, and especially with lower values of SHO and CVR.
