Researchers at the University of Stuttgart have won an award for designing a building façade that uses machine-learning to change its structure depending on the weather.

The FlectoLine adaptive shading system actively adjusts to changing weather conditions to optimise building energy efficiency. A prize was presented last month at the inaugural Award for Bio-Inspired Innovations Baden-Württemberg, recognising this project for its nature-inspired technological concept.

FlectoLine has been tested under real conditions for two years. The adaptive façade is installed on a greenhouse in the Botanical Garden in Freiburg. Adaptive means the system reacts in real time to environmental influences and thus helps optimise the energy efficiency and indoor comfort of buildings.

The 83.5 square metre demonstrator consists of 101 flaps, shading elements made of fibre-reinforced plastic laminates. Each flap is equipped with flexible hinges and can bend elastically with the help of compressed air:

In cold weather, the flaps fold together so as much light and therefore heat as possible penetrates into the interior of the building. In hot weather, they unfold to provide shade. The system’s controller uses machine learning to predict optimal settings for different scenarios. Integrated photovoltaic modules ensure sustainable operation.

FlectoLine was developed as part of the international research project Flectuation. The Institute of Building Structures & Structural Design (ITKE, www.itke.uni-stuttgart.de) and the Institute for Textile & Fibre Technologies (ITFT, www.itft.uni-stuttgart.de) at the University of Stuttgart and the PBG Plant Biomechanics Group at the University of Freiburg (uni-freiburg.de) were involved.

“The test system installed in Freiburg is based on over ten years of research,” said Edith Gonzalez, research associate at the ITKE. “It is the first fully functional, large-scale outdoor demonstrator of an adaptive façade made from pliable fibre-reinforced composites.”

The researchers drew their inspiration for FlectoLine from nature. The waterwheel plant and the striped bug served as models.

“The waterwheel plant is a carnivorous plant that can close its traps to catch small animals such as water fleas,” said Matthias Ridder, research associate at ITFT. “We were inspired by this mechanism. The striped bug provided insights into the material structure of the shading elements: by varying stiffness across different wing areas, it can precisely deform its wings to perform highly accurate movements, just like the shading elements of FlectoLine.”

For their clever, nature-inspired innovation, the researchers were honoured at the Award for Bio-Inspired Innovations Baden-Württemberg. This year saw the inaugural presentation of the award, organised by the Network for Bionic Developments Baden-Württemberg, with support from the Baden-Württemberg Ministry of Food, Rural Areas & Consumer Protection. The formal ceremony was held during the Sixth Bionics Congress Baden-Württemberg in Mannheim.

The FlectoLine team received the special prize from the MVV Foundation for the Future for their bionic and bio-inspired innovation.

“We are very proud of this recognition,” said Gonzalez. “In light of the challenges posed by climate change, architecture must take new directions. With FlectoLine, we have successfully demonstrated how much potential adaptive façades hold in this regard. FlectoLine maximises the comfort and functionality of the building while simultaneously improving energy efficiency and reducing CO₂ emissions.”