Urban Canyon Microclimate and Spatial Behavior in Extreme Climate Situations (Case Study: Downtown Pedestrian Street in Northern China)

Microclimate in open space affected by the urban layout and spatial forms plays an important role in the outdoor comfort, thus the outdoor activities based on the comfort sensation will directly affected by the spatial forms. An outstanding open space should satisfy different requirements of outdoor activities and create relatively comfortable place.Most studies have been conducted on these relationships only above 0 Celsius degree. However, only few have focused on extreme situations in both hot summer and cold winter. Therefore, from microclimate perspective, taking people’s comfort and spatial behaviors as criterions, this research discussed how the open space forms affect microclimate, thus affect comfort sensation and spatial behaviors. The outcomes may provide some useful insights for planners and architects to understand the relationship among microclimate, open space and people. Results showed that in hot season, shade and air-flow played crucial roles in outdoor comfort. More people tend to stay outside in the shade and the area with higher air velocity. After sunset is popular period for outdoor activities. The ambient temperature lower than 29.6℃, air velocity higher than 1.1m/s and relative humidity higher than 67% is needed to achieve neutral comfort sensation. In cold season, at the same ambient temperature, lower air velocity raised the comfort level. Shade also had influences on comfort sensation but do not affect spatial behaviors significantly. The ambient temperature higher than -14.4℃, air velocity lower than 1.6m/s is the thresholds for an acceptable outdoor environment.