How Termites Inspired A Building That Can Cool Itself

Passively Cooled Building Inspired by Termite Mounds

Termites teach us a great deal about self-sustainable cooling systems in a building construction

The Eastgate Centre

In 1991, an investment group in Harare, Zimbabwe hired Mick Pearce, the building’s architect, to design nearly 350,000 square feet of office space and shops which was the largest office and retail building in the country. They also requested to cut the cost of air conditioning as much as possible to cool the large building. So that left Pearce with a seemingly impossible challenge.

Coincidently, he saw a nature show about termites and mounds built by them. He was inspired by the insects which created their own air conditioning systems that circulated hot and cool air between the mound and the outside.

Millions of termites live inside a mound, some of which stretch an astonishing 30 feet high. Although these termite skyscrapers may look solid from the outside. They are actually covered in tiny holes that allow air to pass through freely. Like a giant lung, the structure inhales and exhales as the temperatures rise and fall throughout the day.

This was how the large office and retail building, Eastgate Centre created.

The building is made from concrete slabs and bricks. Just like the soil inside the termite mound, these materials have high “thermal mass” — which means they can absorb a lot of heat without really changing temperature. The exterior of the building is prickly like a cactus. By increasing the amount of surface area, heat loss is improved at night, while heat gain is reduced during the day.

Inside the building, low-power fans pull in cool night air from outside and disperse it throughout the seven floors. The concrete blocks absorb the cold, insulating the building and chilling the circulating air. When morning comes and the temperature rise, warm air is vented up through the ceiling and released by the chimneys.

Thanks to this innovative design, temperatures inside stay at a cool 82 degrees Fahrenheit during the day and 57 degrees at night. Not to mention, it uses up to 35 percent less energy than other similar buildings in Zimbabwe.

Since opening its doors in 1996, Mick Pearce’s 90% natural climate control system has made the Eastgate Centre a global landmark for sustainability.

Scott Turner, a physiologist revealed how pores in a mound help manage gas flow and drainage. “If you look at the physics of gas exchange in the lung, it’s very much the same way as the termite mound is organized,” said Dr. Turner.

Stirring from wind, much like a muscle contraction, allows gases to mix and reach important places like a termite nest or human blood. “If you think about what the mound is,” he said, “it’s literally an organ in physiology that’s constructed out of the dirt by a bunch of little termites.”

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The team also thinks the pores may help regulate temperature. But Dr. Turner says in other nests soil does this; more research is needed.

Builders typically focus on mechanical ventilation — fans, heating, and cooling — that uses fuel and is easier to control. Eco-friendly buildings are typically smaller scale because human comfort is difficult to achieve in systems dependent on varying climates. “Wouldn’t it be nice if people could do a building that does both?” he said.

“There is a danger to see beautiful forms and shapes in nature and simply copy them,” said Mr. Pearce. “We’re not copying forms. We’re copying the process that made the form.”

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