Pedestrian wind in high-rise residential quarters

Abstract

Study intent Urban wind environment has significant impacts on pedestrian comfort and safety, as well as pollution dispersion and building energy consumption. This case study empirically examines the microscale effect of urban form, density and greenery on summertime and wintertime outdoor pedestrian-level wind environment and users’ thermal and wind comfort in selected high-rise residential neighborhoods in Shanghai. Based on the findings, proper design strategies are formulated for high-rise residential neighborhoods in the so-called hot-summer cold-winter (HSCW) climate zone in China, so as to optimize ventilation potential in hot-humid summer and transient seasons while protecting users from strong winds in cold season. Results and discussion In summer, the wind statistics indicates significant influence from urban geometry. The pedestrian-level wind velocity ratio (WVR) is significantly correlated with the “degree of enclosure” indicated by sky view factor (SVF), due to buildings and/or greenery. It suggests that within the practical range, increasing SVF by 10% could increase WVR by 7–8%. Under the observed weak wind environment, SVF could indicate the thermal buoyancy-driven airflow rate that is determined by solar radiation heating. At the site level, WVR is significantly negatively correlated with building volumetric density (floor area ratio, FAR). In the winter survey, the measured WVR is highest in the long-linear high-rise building layout, and is lowest in the mid-rise linear building layout; but the questionnaire survey reveals that there are still 87% of respondents felt fairly comfortable in the long-linear high-rise building layout, only 7% less than the mid-rise building layout. Overall, since winter wind is not harsh, summer ventilation should be prioritized in high-rise building design in Shanghai considering seasonal prevailing wind directions. Winter shelter, if needed, can be provided by proper landscape design.