That is why biologist turned architect, Doris Kim Sung, is working on another energy efficient and passive method of ventilating buildings, taking inspiration from the human body in search of a more sustainable design. She is advocating the fairly simple yet ingenious idea of a breathable skin, like that of the porous human skin, to encase buildings.
I found a material that was so simple and has been around for about a hundred years
Sung says, “A lot of the things that my colleagues were doing required some kind of energy. They had some very cool ideas but I was looking for a material that would be smart but could just do it automatically. I looked high and low at all kinds of stuff and I found a material that was so simple and has been around for about a hundred years and I couldn’t understand why no one had applied it to this idea yet.”
The material she is talking about is a thermo bimetal strip (two thin pieces of metal such as copper and steel stuck together). These two metals expand and contract differently when heated and cooled which causes the metal to bend one way when hot and the other way when cold.
According to Sung, this is not a new design but has been in use for various applications for over a hundred years. She says, “The most common application for it is in thermostats. If you open up a residential thermostat, there is a metal coil and that is made out of bimetal. You also see it in thermostats in machinery and automobiles. There are different alloys you can laminate so that they can react at different temperatures. Obviously, in an automobile it will react at a much higher temperature than a residential thermostat.”
There are two main applications that Sung has in mind for the bimetal, both of which are ways of cooling the building without requiring any additional energy other than the sun – this approach in architectural parlance is called passive solar.
“I’m proposing to use it on the skin of buildings for a few different purposes. One is as an automatic sun-shading screen and the second basic application is for ventilation as a way to release hot air from the building.”
The definite hope is to reduce the necessity to require air conditioning
Taking the first application, when direct sunlight hits the bimetal strips they bend inwards and close together, shading the building. This can be especially useful with buildings that are largely made of glass and can turn into boiling sun traps in the summer. Similarly, with the second application, the metal could bend in such a way when the building heats up to open pore like holes in the skin of the building and release some of the heat.
While it maybe ambitious to be entirely rid of air conditioning in the near future, it could certainly help in reducing energy consumption. Sung says, “I don’t know if we will ever get to the point where we can truly be rid of air conditioning, especially in certain parts of the world, but the definite hope is to reduce the necessity to require air conditioning. It is trying to move to a more holistic way of building architecture. If we could reduce the amount of air conditioning or heating used just by making buildings more passively designed then we have saved a lot for buildings.”
Check out Doris Kim Sung’s TED talk to see the bimetal in action:
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