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Wind catchers – an elegant cooling design

The views expressed are those of the author and are not necessarily those of Scientific American.

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Dowlat Abad Garden in Yazd, Iran. Photo courtesy of Pedram Veisi.

Keeping with this month’s “cities” theme, I want to share a rather cool passive building design that has been around for centuries. Long before LEED Platinum ratings and green building programs, ancient persian architects were developing ways to keep cool in crowded cities baking under the sun. Wind catchers – or “barjeels” as they are called in Arabic – are both a defining architectural fixture among cities across the Middle East and a clever, natural form of air conditioning.

Before modern air conditioning systems existed – with their pumps, refrigerants, and heat exchangers – ancient designers and engineers made use of the natural differences in pressures and temperatures to cool down buildings and make them habitable.

Wind catchers are tall, box-like towers that rise up and out of buildings like large chimneys. By allowing the sides of the tower to heat up in the sun, air inside the tower is warmed and rises. Warm air then passes out of the opening at the top of the tower, drawing in cooler air, typically from underground where temperatures are cooler than outside air.

Wind catchers in Yazd, Iran.

I find the wind catchers charming because they are an elegant solution to a problem that is still a major design consideration in modern buildings (air conditioning represents approximately 8 percent of all energy used in commercial buildings). And many green building practices used today can be traced back to designs similar in nature to wind catchers. Use of natural sunlight, water reclamation, and natural material selection are hardly new or novel ideas and have their roots in ancient building design.

While ancient societies were not as technologically advanced by today’s standards, they demonstrated a clever mastery of the natural environment and limited resources to improve living standards, which is as relevant today as ever.

Photos courtesy of Pedram Veisi and birdfam on Flickr. For those interested in seeing more photos of wind catchers, there is a nice photo group on Flickr you can check out.

David Wogan About the Author: An engineer and policy researcher who writes about energy, technology, and policy - and everything in between. Based in Austin, Texas. Comments? Follow on Twitter @davidwogan.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. J.A. Gibbons 3:09 pm 08/17/2011

    Do you know how by how much a wind catcher typically lowers a buildings temperature?

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  2. 2. davidwogan 6:00 pm 08/20/2011

    The cooling effect depends on many factors including type of building and materials and whether or not air is pulled in from underground or across water. Air pulled in from underground or over water will cool temperatures more than normal air flow due to temperature/pressure differences. With that said, I don’t know a typical temperature range to expect, except that some designs allow for refrigeration, so you can imagine these buildings can get pretty cold.

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