Thermo bi-metals allow buildings to ‘breathe’. This innovative rethinking of the building’s skin could change the way we think about heating and cooling buildings.

A shape-changing, breathing building made from sheet metal has been created in Los Angeles. The building is an experimental design based on the idea that temperature changes can influence the physical properties of metals.

In this case bi-metals are used. Local professor Doris Kim Sung conceived the building using a laminated steel that allows a building to ‘breathe’. The skin comprises thousands of laser cut plates. These have different metals on either side, with different thermal expansion coefficients. When the sun’s rays heat the metal skin, the two sides expand at different rates or to different dimensions. As the plates are laminated, this causes the metal to curl one way.

The skin is composed of many, individually cut, plates. Gaps between the pieces allow for
variations in size, expansion and curvature. The metal skin is placed upon a steel substructure that forms a lightweight and strong monocoque.

The building’s skin ‘breathes’ because different parts of the façade heat and expand at different speeds and at various times of the day. Each laminate ‘tile’ reacts to the physical influence and slowly the building’s shape changes as it opens. The cooling principle is simple: air escapes through the holes. As the building cools, during the evening and night, the skin closes up, like the petals of a flower.

One very important aspect of such a responsive façade construction is that it works automatically, without any power supply. In principle, it would also work in any weather conditions, and it could be optimized for particular climates. Future applications could include sandwiching the thermo bi-metal between sheets of glazing, creating a solar responsive window system.

Facades that allow for temperature regulation are useful for homeostatic architecture, in which the building controls its own climate. Complete autonomy is some way off, but the highly thermally responsive character of metal is an important step on that road. And, as a result of this development and further experimentation, truly dynamic architecture is now becoming a reality.

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