A windcatcher, Badgir or (بادگیر) in Persian, is a traditional Persian architectural device used for many centuries to create natural ventilation in buildings. It is not known who first invented the windcatcher, but it still can be seen in many countries today. Windcatchers come in various designs, such as the uni-directional, bi-directional, and multi-directional.

It is believed that the windcatcher functions based on the difference of height between base and tip. The height difference creates a slight pressure gradient between the base (which is inside the house) and the tip of the windcatcher's column whenever a breeze or wind passes through the tip of the windcatcher (that is not felt at the base). The pressure gradient then helps suck out the warmer air inside the house up through the column leaving the denser cooler air behind. The cumulative effect over a 24 hour period is quite noticeable.

When coupled with thick adobe that exhibits high heat transmission resistance qualities (R-value), the windcatcher is able to chill lower level spaces in mosques and houses (e.g. shabestan) in the middle of the day to frigid temperatures.

So effective has been the windcatcher in Persian architecture that it has been routinely used as a refrigerating device (yakhchal) for ages. Many traditional water reservoirs (ab anbars) are built with windcatchers that are capable of storing water at near freezing temperatures for months in summer.

The structural design of badgirs are such that they do not seem to function as efficiently when used in humid conditions, as opposed to the dry conditions seen in the Iranian plateau. Hence the ubiquitous use of these devices in drier areas such as Yazd, Kashan, Nain, and Bam. This is especially visible in ab anbars that use windcatchers.

A small windcatcher (badgir) is called a "shish-khan" in traditional Persian architecture. Shish-khans can still be seen on top of ab anbars in Qazvin, and other northern cities in Iran. These seem to be more designed as a pure ventilating device, as opposed to temperature regulators, as their larger cousins in the central deserts of Iran are.

See also

• Persian architecture
• Yakhchal
• Solar chimney

External links

• Yazd, the city of windcatchers.
• The famous Dowlat-abad windcatcher in Yazd
• Windcatchers are incorporated into the architectural expression of traditional Persian buildings. Notice this sample, with 6 symmetrical badgirs, in Yazd.

Cooling technology | Iranian architecture

Badgir