5 NATURAL AIR-CONDITIONING DESIGNS INSPIRED BY NATURE

5 Natural Air-Conditioning Designs Inspired by Nature
By Brian Clark Howard, National Geographic News, 3 July 2013.

Designers are turning to biomimicry to develop better cooling technologies.

With heat waves gripping much of the planet, electricity grid operators are sweating even more than their customers. Air-conditioning uses a tremendous amount of energy, but a new group of designers think they can solve that problem by mimicking Mother Nature's craftiness.

Janine Benyus, a biologist, innovation consultant, and author of the book Biomimicry: Innovation Inspired by Nature, told National Geographic that copying the way plants and animals solve natural problems can provide many benefits, from environmental sustainability to economic efficiency. (See "Nature Yields New Ideas for Energy and Efficiency.")

"With biomimicry we're able to apply fresh thinking to traditional manufacturing, to undo the toxic and energy-intensive mistakes of the past," said Benyus, who is part of a group that hopes to lead a new revolution in design by imitating nature. "I wish we had been at the design table at the Industrial Revolution."

In natural systems, nothing is wasted, since everything can be used by something else. Instead of using large inputs of energy and toxic chemicals to make things and ship them across the globe, nature makes what it needs where it needs it, with water-based chemistry.

These designs suggest some of what could be learned by applying the lessons of biomimicry to the problem of air-conditioning in particular. (See "In Search of Green Air-Conditioning.")

1. Ventilation Inspired by Termites

Termite mounds have excellent cooling, even in blisteringly hot conditions.

Perhaps the most famous example of biomimicry when it comes to heating and cooling is ventilation inspired by termites. A few years ago, scientists observed that big termite mounds in Africa stay remarkably cool inside, even in blistering heat. The insects accomplish that feat with a clever system of air pockets, which drive natural ventilation through convection.

Architect Mick Pearce and engineering firm Arup borrowed that idea to build Eastgate Centre, a large office and shopping centre in Zimbabwe that is cooled with the outside air. The system uses only 10 percent as much energy as conventional air-conditioning to drive fans that keep the air circulating.

2. Countercurrent Heat Exchange Inspired by Birds

Image via The Writing Engineer

Ducks and penguins that live in cold climates have an innovative adaptation that helps them survive the elements. The veins and arteries in their feet have a countercurrent configuration, which ends up warming the blood that is closer to the animal's core and cooling the blood at the edges of its extremities. By keeping cooler blood closer to the snow and ice, such birds lose less body heat overall.

Shell tube heat exchangers in industrial-scale heating and cooling systems use a similar type of flow pattern to maximize efficiency, as Clayton Grow, author of  The Writing Engineer blog, has pointed out.

3. Moisture Absorption Inspired by Ticks

Image via The Writing Engineer

Grow notes that a system called a liquid desiccant dehumidifier also seems to follow a form of biomimicry. Such a system is designed to pull humidity from the air inside a building (traditional air-conditioning also reduces humidity). It uses a liquid salt solution - something similar to what the brown dog tick secretes to absorb water from the air.

(See "Seeking to Cool Air-Conditioning Costs.")

4. Efficient Fans Inspired by Tornadoes and Whirlpools

PAX Scientific’s fan. Image: PAX Scientific.

A company called PAX Scientific (slogan: Capturing the Force of Nature) is marketing a fan based on the logarithmic spiral shape found in such phenomena as tornadoes, whirlpools, and even airflow in the human trachea. The company says the fans have lower turbulence and higher efficiency for cooling.

(Quiz: What You Don't Know About Air-Conditioning)

5. Efficient Fans Inspired by Whale Flippers

WhalePower fan blades. Image via National Geographic.

In another take on better fan design, a start-up called WhalePower is developing fan blades that produce greater lift, and therefore move more air, thanks to the bumpy design of a humpback whale's flipper.

WhalePower says its fans move 25 percent more air than conventional fans while using 20 percent less energy. The company is also working on more powerful wind turbine blades.

Top image: A termite mound (via National Geographic)

[Source: National Geographic News. Edited. Top image added.]

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