Numerical evaluation of pedestrian-level wind comfort around “lift-up” buildings with various unconventional configurations

Abstract

Lift-up design can increase building permeability without sacrificing land use, and its effectiveness for pedestrian-level wind (PLW) comfort improvement has been confirmed. However, the subjects of previous studies are primarily rectangular- or square-plan building models. Modern buildings are not uniform but have various configurations, which exhibit different aerodynamic features. The PLW comfort around an isolated lift-up building with various unconventional configurations has not yet been systematically investigated. This study thereby aims to fill the research gap. A series of computational fluid dynamics simulations were performed to evaluate the PLW comforts around lift-up building models with 22 unconventional configurations. The tested configurations include polygonal, slab-like, cruciform, trident, and assembled models, derived from existing buildings in Hong Kong. The results indicate that the PLW comfort around an isolated building is sensitive to the incident wind direction, building configuration, and precinct size. Lift-up design can dramatically improve PLW comfort in the near field of a building. However, the improvement efficiency weakens with the wider size of the research region. The impact of lift-up design on the full-field wind comfort around a building may become negligible or negative. Several configuration parameters were identified, including the number of sides, projected width, building depth, included angle, converging and diverging flows, surface curvature, and surface discontinuity. Their impacts on the PLW comfort and lift-up design's comprehensive effectiveness were also justified. These findings can considerably enrich the knowledge of lift-up design's performance for wind comfort improvement, and contribute to creating a sustainable and livable microenvironment.