The novel facade element that is powered by sunlight. Image: Bára Finnsdóttir.

Commercial buildings with glass façades could be retrofitted with a novel solar-controlled technology to cut energy use, research out of Germany has found.

Regulating the temperature of offices with glass façades can take a lot of energy, but research organisation Fraunhofer says a thermally reactive fabric blind could help buildings control heat loads more effectively.

The invention, a façade component that respond autonomously to sunlight, was a collaboration between the Fraunhofer Institute for Machine Tools and Forming Technology IWU and the Department of Textile and Surface Design at Weissensee School of Art in Berlin.

“We don’t need any power since we can rely solely on thermal energy to control the façade element,” André Bucht, researcher and department head at Fraunhofer IWU, said.

Professor Christiane Sauer from the Weissensee School of Art said the challenge for smarter buildings was bringing together innovative technology and design.

“Having designers and scientists work together is the key to pioneering concepts for smart building envelopes,” Professor Sauer said.

The concept by design student Bára Finnsdottir involves a matrix of individual fabric components shaped like flowers. Each textile module has shape-memory actuators integrated into it – thin 80-millimetre-long wires of nickel-titanium alloy that remember their original shape when exposed to heat.

When the façade heats up due to sunlight, the wires are activated and contract to open the textile components. The exposed surface of the façade is covered and sunlight can no longer penetrate into the room. As soon as the sun disappears, the components close again so that the façade becomes transparent.

“When you bend the wire, it keeps that shape,” Bucht said. “Then when you expose it to heat, it remembers the shape it had originally and returns to that position. Picture the façade element as a sort of membrane that adapts to weather conditions throughout each day and during the various seasons of the year, providing the ideal amount of shade, however strong the sun.”

The facade element can be attached on the outer layer of glass or in between a multi-layer façade. The researchers said the structure was easy to retrofit and could be customised for pattern, shape and colour of the individual components.

“For instance, you might want to replace the circular design with triangles or a honeycomb arrangement,” Bucht said. “You can also control the level of sun exposure for individual sections of the façade – just the top left area, for instance. What’s more, the membrane even fits on curved areas of glass. We’ve reached the point where the design has become independent of the shape of the building.”

Industry collaboration will be the next phase of the project, with the researchers hoping to develop a range of prototypes for private and office buildings, with the intention of testing them long-term on a detached house and on buildings at the institute.

“One priority will be to design fabric elements that are stable enough to withstand any weather,” Bucht said.

The researchers are also hoping to study additional functions for the facade element, such as for insulation and energy generation.

“It might be possible to store solar thermal energy and then release it when needed to heat the interior, for instance at night,” Bucht said. “Another idea is to coat the flower fabric components with malleable, organic solar cells in order to generate electricity that can be used within the building.”

The fabric facade is hoped to be ready for market in mid-2017.