Geometries of tall buildings improving wind comfort in London

The objective of the present study is to improve pedestrian-level wind (PLW) comfort by developing design procedures for tall buildings in London. While tall buildings address London’s increasing urban population and rising land prices, they introduce several wind microclimatic challenges, accelerating PLWs causing PLW discomfort and safety concerns. Previous research that has focused primarily on perpendicular façades has limitations for assessing the aerodynamic performances of London’s tall buildings, which have various façade angles. Extant studies using urban packing densities (plan area ratio [PAR], frontal area ratio [FAR] and façade area ratio [FAR′]) have gaps when examining the impacts of urban forms on PLWs in cases where two different urban typologies have similar PAR, FAR and FAR′. To advance knowledge regarding the aerodynamic performance of various building geometries, the analytical and simulation work was undertaken, using computational fluid dynamics (CFD) as the main methodology. A sensitivity study and field measurements were carried out to verify and validate the accuracy of the CFD results. A comparative analysis was undertaken between the isolated building condition (pure aerodynamic condition without impacts from the surrounding buildings) and London’s typical urban conditions to examine the aerodynamic interactions between the tall building and the surrounding buildings. The results suggest that wind comfort assessments of tall buildings should be undertaken in an urban context, as significantly different results were obtained between the isolated and urban conditions. The building parameters – façade angle, corner condition and height – and the urban parameter – open area ratio [OAR] – should all be considered when assessing the effects of tall buildings on PLW comfort in urban environments. The design guidelines, based on the new knowledge discovered by the current study, provide recommendations concerning the urban-related and building geometry-related design requirements.