Called HydroSkin, this façade material concept harvests rainwater and uses evaporation to cool buildings.

Extreme heat and heavy rainfall events with severe inundations have a significant impact on urban architecture, resulting in considerable personal injuries and material damage. In cities, the façade surface areas of tall buildings in urban environments are left largely unused, offering enormous potential.

Initiated by the University of Stuttgart, Germany, HydroSKIN is a lightweight textile façade element. The material absorbs rainwater that hits the building at an angle. This water is released in hot periods in order to cool the building interior and the urban space through evaporation.

The textile is a so-called spacer fabric, made up of two textile layers that are kept apart by threads, thus well-ventilated. The good air circulation helps the evaporation of water and increases the façade’s cooling effect. The fabric is covered by a water-permeable textile on the outside, which allows almost all raindrops to penetrate. In addition, it stops insects and leaves. A film on the inside deflects water to the lower profile system. There, it can either be saved in a reservoir or used directly in the building.

On hot days, water is deflected back in the façade element to evaporate and thus provide cooling.

Especially tall buildings offer a lot of potential. Not just because of their immense façade area, but also because due to high wind forces, rain hits the building’s façade at an angle the taller the building. From a height of approximately 30 meters, more rain hits the façade than a horizontal roof of the same size. In addition, high wind speeds increase the evaporation cooling effect, which means a cool airflow downward to the urban space.

Images: HydroSKIN / Christina Eisenbarth, ILEK, University of Stuttgart