ETFE Membrane Facade: A Double Skin Solar Collector

Transparent Innovation for Energy-Efficient Buildings

Inspired by the use of ETFE membrane cushions in iconic structures like the Allianz Arena in Munich and the museum in Leicester, Petr Franta envisioned a transparent double skin facade for office buildings. By replacing traditional glass with a transparent film membrane, this design offers numerous advantages in terms of energy efficiency, acoustic protection, and aesthetics.

The ETFE membrane facade acts as a solar collector, harnessing the sun's energy to provide heating during the winter months. The hot air collected on the top floors of the building helps reduce energy consumption by up to 30%. Additionally, the double skin assembly provides acoustic insulation, making it ideal for buildings located in busy traffic areas.

One of the standout features of this design is the self-cleaning exterior of the ETFE membrane. The membrane is treated with a special additive chemical component that repels dirt, allowing rainwater to automatically clean the facade. This not only reduces maintenance costs but also ensures the facade retains its pristine appearance over time.

The realization of the ETFE Membrane Facade involves the use of 3-meter-wide ETFE cushions, which are installed diagonally and kept under constant air pressure. These cushions are anchored on a secondary structural steel system using aluminum extrusion clamps designed to withstand wind loads. With a weight that is only 1% of a glass installation, the ETFE membrane facade offers a lightweight and durable solution.

The interaction of the design is based on the double skin facade's ability to act as a solar collector. In the winter and transitional periods, hot outside air is drawn into the ventilation HVAC units from the south facade, while in the summer, it is drawn from the north facade. This intelligent system ensures optimal energy efficiency throughout the year.

The ETFE Membrane Facade was realized on the Czech Technical University in Prague campus for the Czech Institute of Informatics, Robotics, and Cybernetics. The project, which started in 2008, involved extensive research and collaboration with scientists, structural engineers, and manufacturers to ensure the design's feasibility and performance.

This groundbreaking design has garnered recognition in the form of the Bronze A' Design Award in Architecture, Building, and Structure Design. The ETFE Membrane Facade stands as a testament to the power of innovative thinking and multidisciplinary collaboration in creating sustainable and visually striking architectural solutions.