Integrated impacts of building height and upstream building on pedestrian comfort around ideal lift-up buildings in a weak wind environment

Abstract

Unfavorable wind comfort and intense thermal discomfort are degrading pedestrian comfort in high-density cities. The lift-up design has proved to be a promising way to improve wind comfort and thermal comfort around buildings. Previous studies have identified building height as a crucial factor influencing wind comfort around lift-up buildings. However, the correlation between building height and wind comfort has not been fully understood yet and few parametric studies have been focused on thermal comfort. This study thereby aims to evaluate the integrated effects of building height and upstream building on pedestrian comfort around lift-up buildings from aspects of wind comfort and thermal comfort. Computational fluid dynamics (CFD) simulations were performed to reproduce mean flow fields around single building models and double building models. An integrated method combining on-site observation data and CFD simulation results was employed to calculate physiological equivalent temperatures. The findings show that increasing building height, being under a diverging flow, removing upstream buildings, and making the target building taller or shorter than the upstream building can improve wind comfort in the lift-up area. However, their effects on thermal comfort vary seasonally. For improving wind comfort and thermal comfort in the podium, making the target building taller or shorter than the upstream building or under a diverging flow is beneficial; but increasing building height and removing upstream buildings are not necessarily favorable. The outcome can provide some inspiration for city planners to improve pedestrian comfort in high-density cities.