Wind and Permeable Building Envelopes: Toward Future Tall Building Skins

Jens Fussing
Technical Director, Buildings
BG&E, Dubai

Surely, it is more than fifty years that tall building skins must reach arduous requirements, especially in terms of aesthetic value, energy efficiency, fire safety and acoustic performance. This a challenging task, and the use of Permeable Building Envelopes (PBE) seems one of the best ways to design safe and sustainable tall buildings of the future. Indeed, the wind permeability of a building skin can be the key point to achieve the desired energy efficiency. The internal cavities can also be ventilated to eliminate exhaust air, bearing in mind that they must not be a weak point for fire propagation. Moreover, many funding initiatives, such as part of the research and innovation program "Horizon 2020" of the European Community, have been paying attention to energy saving and generation from renewable power sources, pushing the boundaries of façade-technology development. The concept of "smart city" is also becoming popular, requiring always more complex building envelopes from future buildings. In this perspective, PBEs can be designed not only for energy saving, but also to take advantage of the building characteristics to generate energy: photovoltaic ventilated façade and building-integrated energy harvesting systems are only few of the many applications that show how high is the level the building design aims to. Finally, a PBE allows a wind-driven interaction between external and internal air, that in certain cases could also affect the overall building aerodynamics. Therefore, an iterative dialogue between experts involved in the design of such permeable façades is required. It seems that this multidisciplinary aspect will offer new possibilities for tall building façades, at least for the next fifty years.

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