As a way to reduce the amount of heat entering a building in the summer, researchers have developed a new shading system that adjusts independently over the course of the day without electricity or a motor. Shade-producing wooden planks move autonomously to reduce the need for cooling. According to Chiara Vailati, the designer of the system, she was inspired by pinecones because of how they react with humidity changes. She transferred the principle to multiple pairs of parallel planks that will contract at different levels of humidity.

“Like its natural model, the double layers of wood make use of changes in humidity throughout the day,” explains Vailati. In the humid morning air and at night, the planks are flat and vertical, while at midday, when the sun is high and the air is drier, they bend noticeably and thus provide shade.

This apparently simple idea required years of research. Vailati had to master two challenges in particular. First, it was necessary to increase the initially very small bilayer structures to the standard plank length of half a meter, without the material deforming uncontrollably.

Second, the system reacted too slowly compared to conventional motorized planks. “I had to find a way to accelerate the bilayer kinetics,” says Vailati. Striped patterns in the wood and a finely adjusted ratio of layer thicknesses helped to speed up the movement.

Finally, Vailati made use of her experience as a civil engineer: to increase the amount of shade, she coupled the bilayered planks. “That significantly increased the reaction time,” she says.

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