“Active Materials” and the Future of Buildings

As a field, structural engineering is currently undergoing revolutionary changes on a scale that I think I can safely say is without historical precedent. CAD programs are being developed more complex than ever before, allowing engineers to model the entire structural behavior of a building before the first foundation stone is laid. 3D printing- which I have previously written about- is still in its relatively early days but will soon allow engineers to create previously unthinkably precise and complex structural parts and systems. A third development that could potentially change the fundamental nature of buildings is the invention of active materials- structural elements that change in response to stimuli.

IAAC I

A mockup of how the IaaC’s material will appear

The latest research and development into active materials comes from the Instituto de Arquitectura Avanzada de Catalunya (Institute of Advanced Architecture of Catalonia) or IaaC. Students there have looked into the use of Shape Memory Polymers. This is a kind of polyurethane, a material more often used for creating fake leather or fake wood, that changes its form when heated up and reverts to its original form when reheated. The IaaC students developed a tessellation of triangles connected by SMP joints. The tessellation folds in different ways when different joints are heated, potentially by electricity.

IAAC IV

IAAC III

Details of the IaaC’s work

Since the IaaC is an architecture school, they developed the material mainly for aesthetic purposes, to create what they call transformative architecture. However, there are many practical uses from an engineer’s point of view. The material could be used to create quick assembly structures- flat packed then stimulated to expand. If the triangular sections were solar panels, the system could move with the sun to optimize energy intake. In high winds, the facade could change its shape to become more streamlined.

 

One use I am particularly interested in is as a mass damper. Two years ago, I researched and experimented with tuned mass dampers as a school project. They generally take up at least one level of a tall building and move in the opposite direction of a building’s sway to maintain its center of gravity. These sort of dampers could be replaced if facades built like the IaaC material were created. These facades could shift their weight in the opposite direction of the swaying, which could be more effective than a regular damper. This would also free up space inside the structure and create an interesting visual effect.

Homeostatic I

homeostatic II

 

The homeostatic facade open and closed
Other active materials have been developed recently. An example is the homeostatic facade, used in a building in New York City. A single, long ribbon of silver polyester traces across the facade. When electric current runs through it in response to changing current or temperatures, the ribbon expands, blocking out the sunlight. The SMP tessellation, the homeostatic facade, and other examples could gradually change buildings from passive shelters to active, responsive ones. Nearly a hundred years ago, the famed architect Le Corbusier called houses “machines for living”. Active materials could make that statement true in a literal sense.

 

Images of IaaC work from archdaily.com, pictures of homeostatic facade from materia.nl

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