Borrowing from nature

ARCHITECTS have long taken inspiration from nature. In ancient Egypt columns were modelled on palm trees and lotus plants, and building designers have borrowed the shapes and proportions of natural forms ever since as they strived to achieve aesthetic perfection.

Some architects now believe that such biomimicry has more to offer than simply making buildings look good. They are copying functional systems found in nature to provide cooling, generate energy and even to desalinate water. And they insist that doing these things using biomimetic designs is not just a gimmick, but makes financial sense. “It's often the case that green technology is considered to be commercially unattractive,” says Michael Pawlyn, an architect at Grimshaw, the firm behind the Eden Project, a highly acclaimed biome structure in England. That perception, he says, is wrong—and he has the designs to prove it.

So far, the use of biomimetic features in buildings has been driven as much by aesthetics as by function, and has been limited to relatively simple, passive systems. The Arab World Institute in Paris, for example, has an array of mechanical, eye-like irises on its south-facing façade. These open and close to control the amount of light entering the building, thereby regulating the internal temperature.

Similarly there are now several buildings that have ventilation systems based on those found in termite mounds. The Eastgate Centre, a shopping centre and office block in Harare, Zimbabwe, has a mechanical cooling system made up of vents and flues that help hot air out of the structure. “It's the same principle as the chimney effect, but a bit more controlled,” says Professor George Jeronimidis, director of the Centre for Biomimetics at the University of Reading. As hot air rises and flows out through vents at the top of the building, cooler air is drawn in at ground level.

Dr Jeronimidis is now taking this concept further by using adaptive materials that flex in response to the level of moisture in the air—an idea borrowed from the way pine-cones open and close. Using a cellulose-like fibre composite, he has created a vent that changes from one curved shape to another, depending on the relative levels of moisture inside and outside a building. When warm, moist air builds up inside the building, the vent opens to allow it to escape. But when the air inside is dry, the vent stays shut and moist air from outdoors is kept out. “In principle it can be made to respond naturally, without any additional power,” says Dr Jeronimidis.

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