Aerodynamic characteristics of tall buildings with porous double-skin facades: State of the art and future perspectives

Double-skin facades (DSFs) have been increasingly implemented on tall buildings with the goal of improving building energy efficiency, natural ventilation and visual appearance. It is commonly known that wind and earthquakes represent major environmental load types impacting tall buildings. However, at this point, the aerodynamic characteristics of tall buildings equipped with porous facades are still relatively unknown, although it may be expected that the addition of porous outer skins will substantially affect the overall building aerodynamics. The scope of the present study is therefore to carefully review all the relevant parameters playing an important role in the aerodynamic characteristics of tall buildings with porous facades. Fluid flow and turbulence through porous surfaces were reviewed first with an emphasis on the wake and pressure drop behind perforated plates to analyze the phenomena of fundamental fluid mechanics relevant for porous surfaces. As the inflow characteristics predominantly dictate the aerodynamic characteristics of tall buildings, it is therefore useful to review major wind types, including the atmospheric boundary layer (ABL) and strong local winds, which have previously proved to cause major structural damage and failure. In order to be able to properly assess the aerodynamic loading of tall buildings with porous facades, it is necessary to understand the aerodynamic features of tall buildings with smooth surfaces. For this reason, the aerodynamic performance of smooth tall buildings was reviewed, as were the design features commonly adopted to mitigate adverse wind effects. The existing and rather sparse current knowledge of the aerodynamic characteristics of porous DSFs of high-and lowrise buildings is outlined. Based on the provided information, it is clear that a substantial amount of knowledge still needs to be acquired in the future in regard to various aerodynamic features of tall buildings with porous DSFs, particularly concerning wind loads, building energy efficiency, pedestrian wind comfort, renewable energy aspects, air pollution dispersion and dilution. It is expected that the optimal approach to advancing this topic is in combining field measurements, laboratory experiments and computational modeling.