Smart facade with energy-saving benefits

Smart Facade with Energy-Saving Benefits

The Challenge

Buildings account for nearly 40 percent of total energy consumption in Germany. Heating, cooling, and ventilating residential homes, office properties, and public buildings are particularly cost-intensive. Buildings with large glass facades, in particular, waste a significant amount of energy. As part of the BMBF “smart³” Twenty20 innovation initiative, researchers from Fraunhofer IWU, together with the Department of Textile and Surface Design at the Weissensee Academy of Art Berlin, developed facade components that react to solar radiation. These components significantly reduce energy consumption.

The Solution

Only the sun’s thermal energy is used to control the facade element. The “Solar Curtain” demonstrator is based on a design by a design student. It consists of a matrix of 72 textile components that resemble blossoms. Shape memory actuators are integrated into these modules. These are thin, 80-millimeter-long wires made of a nickel-titanium alloy. They “remember” their original shape as soon as they are heated.

When sunlight hits the facade, the wires heat up. They contract and open the textile components. This causes the open areas to close, preventing sunlight from penetrating the room. However, if the sun disappears behind clouds, the wires relax again. The modules close, and the facade becomes transparent once more.

This effect is created by a special lattice arrangement within the material. If the wire is bent and then heated, it returns to its original shape.

The facade element can be envisioned as a membrane that flexibly adapts to the time of day and the seasons. As a result, it provides optimal shading for every position of the sun.

Design and Applications

Developed for large glass surfaces, this solar protection can be easily retrofitted. Furthermore, it offers a wide range of design possibilities. The pattern, geometry, color, and reaction temperature of the modules are variable. Individual areas can be shaded independently. Thanks to its modular design, “Solar Curtain” even adapts to curved glass surfaces, ensuring the design remains independent of the building’s shape.