Windcatchers: the birth of air conditioning and natural refrigeration?

The five thousand year old city of Yazd, located in the center of Iran and one of the driest of this country, is well known for its windcatchers and was recently registered as a UNESCO World Heritage Site.

Windcatchers are tall, chimney-like structures that protrude from the rooftops of older houses in many of Iran’s desert cities. In their simplest form, wind catchers harness the cool breezes and redirect them downwards either into the home or into underground storage rooms to refrigerate perishable foods. Studies have shown that wind catchers can reduce indoor temperatures by around 10°C.

 

 

The windcatcher's effectiveness had led to its routine use as a refrigerating device in Persian architecture. Many traditional water reservoirs are built with windcatchers that are capable of storing water at near freezing temperatures during summer months. The evaporative cooling effect is stronger in the driest climates such as on the Iranian plateau, leading to the ubiquitous use of windcatchers in drier areas.

Since windcatchers are located at the highest point of a building, they are especially susceptible to deterioration and decay. While the oldest windcatchers in Iran date only to the 14^th century, there are references to windcatchers in the writings of 5th-Century Persian poet Nasir Khusraw. Windcatchers appear to have been used also in traditional ancient Egyptian architecture. A painting depicting such a device has been found at the Pharaonic house of Neb-Ammun, Egypt, which dates from the 19^th Dynasty, c. 1300 BC.

The windcatcher approach has recently been utilised in Western architecture, such as in the visitor center at Zion National Park, Utah, USA, where it works without the addition of mechanical devices to regulate temperature.