CFD evaluation of new second-skin facade concept for wind comfort on building balconies : case-study for the Park Tower in Antwerp

High wind speed around high-rise buildings can lead to wind discomfort or wind danger at building balconies. This paper presents the evaluation of a new facade concept that is intended to significantly reduce the wind speed and therefore improve wind comfort on the balconies of high-rise buildings. The concept consists of a staggered semi-open second-skin facade in front of the balconies, which partly shields them from the wind. The concept is evaluated for the new 78 m high Park Tower in the urban area of Antwerp, where it will be implemented. 3D steady Reynolds-Averaged Navier-Stokes Computational Fluid Dynamics (CFD) simulations are performed for the case with and without this facade concept. The simulations are made with the realizable k-epsilon turbulence model on a high-resolution grid. Validation is conducted using wind-tunnel measurements of surface pressure distribution on a building model with balconies. Wind comfort for the Park Tower is assessed with the Dutch wind nuisance standard NEN8100 for the case with and without the second-skin facade concept. The analysis shows that this concept is effective in providing a zone with pressure equalisation at the balconies. The related reduction in pressure gradients across the width of the facade strongly decreases the local wind speed. At many positions along the balconies this yields a wind comfort improvement of one or even two classes in the Dutch wind nuisance standard compared to the situation without implementation of this concept.