Dezeen Magazine

Thermobimetal shutters by Doris Sung self-regulate the temperature of buildings

Buildings could be cooled with zero energy using the Invert shading system, made from a smart material called thermobimetal that changes shape in response to heat.

The invention of architect Doris Sung, Invert looks like a regular decorative shutter, but its metal pieces curl and flip over in the sun, altering how much light and heat can enter a space.

They make use of thermobimetal — a double-layered composite of two metal alloys, one that expands in heat more quickly than the other. The result is that the material warps. As the heated metal pieces warp they move and block the light.

Huge amount of energy used to cool buildings

Sung, who is based at the University of Southern California School of Architecture, has been working with thermobimetals for years in the hope that they can help cut fossil fuel emissions from the heating and cooling of buildings.

She points to statistics that show 38 per cent of energy consumption in the USA comes from residential and commercial buildings, and nine per cent was just from cooling.

Attention tends to be given to cars and factories but buildings consume huge amounts of energy

"There's so much attention on automobiles and coal-burning factories, but buildings are using more than so many of these other industries," she told Dezeen.

She quit architectural practice and moved into research to try to address this problem.

"I was a little frustrated as an architect, because we're limited by the kinds of materials you can specify," said Sung. "I thought, if I could do anything to try to reduce [energy use], even by one percent, that would be a really big deal."

Bimetallic coil in a thermostat inspired the design

Her search for a material that could change and move without energy led her to the home thermostat. These typically contain a bimetallic coil that switches on the heating or cooling. Sung wanted to see if she could use this same principle to make a surface material.

She has created several installations with the thermobimetal over the years. The most recent, Fuller at the Los Angeles Municipal Art Gallery, was inspired by Buckminster Fuller's geodesic dome and used the material's special properties for the purposes of connector-free assembly instead of heat regulation.

But Invert is the first product to come from her research. Having cleared the prototyping stage, Sung hopes to have it in production within the next year, following testing.

The idea is to one day offer several designs, but the current prototype features oval, leaf-like pieces of a thermobimetal that combines nickel, manganese, copper and iron.

The pieces are thin, almost like foil, and Sung says that when they move, they seem like fluttering butterflies.

System sits within double glazing of office blocks

In the Invert system, they sit inside the cavity of a standard double-glazed window. Sung admits this partially obscures the view, but only on a level similar to fritted glass.

She argues that in some ways, the views through Invert are more true than that in a typical office building with floor-to-ceiling windows, because those rely on protective coatings.

Thermobimetal shutters by Doris Sung
The double-layered composite of two metal alloys in the Invert system warps in the heat

"When you're inside these buildings, even though you think that you have a full view, you're actually looking out as if you have been wearing dark sunglasses all day long," she told Dezeen. "With Invert, we can get super high colour spectrum, retain about 70 per cent of the view, as well as get natural, indirect daylight."

Facade of the building develops "personality"

Given this, Sung believes Invert will have good wellness outcomes, but is curious to see if any adverse effects arise when the material is tested in situ on an office building this summer. There's a chance some workers will find the movement distracting or annoying.

Smart materials that regulate heat are an area of active research, with the University of Maryland creating a fabric from nanotube-coated fibres and MIT showcasing one activated by bacteria. But few are working on an architectural scale like Sung.

She sometimes calls thermobimetal a "living" material, not only because it looks and moves like something biological, but because it has "a mind of its own". Her team has even made little low-tech robots out of it, that seem to have a personality because of the way they waddle and scoot.

"There's a certain responsibility that I think is new to architects in that we can also map a personality onto a building," she said.

"I feel like with my materials, I could make a building facade annoying to you, I can make it pleasant, I can make it happy. We can almost give emotional value to facades by now making them move. People will react to them as if they are alive."