5. Building Porosity for Better Urban Ventilation in High-Density Cities

Given that building typology is one of the key elements in architectural design and that the drag force of surface roughness on airflow directly depends on building typologies, it is important to expand our understandings on wind environment from urban and neighborhood scale to the building scale. In this chapter, CFD simulation was conducted to provide the detailed understandings on pedestrian-level wind environment and building typologies. First, \( \kappa - \omega \) SST turbulence model was validated by comparing modeling results with data from the wind tunnel experiment. Second, the impact of various building typologies on pedestrian-level airflow were investigated in a parametric study, in which various parametric cases with different wind porosities were designed, and wind speed was classified based on PET to evaluate outdoor thermal comfort. Subsequently, critical design issues were identified, and the corresponding mitigation strategies were developed. From both the accuracy and practical point of view, this chapter introduces a study that allows architects to improve building porosity efficiently for better pedestrian-level urban ventilation.