Windcatcher

Known as "Badger" in Arabic and "Badger" in Farsi, a windcatcher (wind tower, wind scoop) is a traditional architectural element used to produce passive cooling and natural ventilation in buildings. Its shape varies greatly and includes height, cross-sectional area, internal sub-divisions, and filters. The first Windcatchers were employed in North Africa and the West Asian nations around the Persian Gulf, and evidence suggests that the first Badger was created by an ancient Iranian three thousand years ago.

Because windcatchers depend on regional weather and microclimate circumstances, not all design strategies will be effective everywhere. A windcatcher's design is determined by the predominant wind direction in that area; if the wind tends to come from only one side, it might simply have one aperture and no internal walls. There might also be radial interior walls, which split the wind tower into vertical pieces, in locations with more changeable wind directions. Stronger winds will cause windcatchers to have smaller overall cross-sections, while hot winds may need the use of numerous smaller shafts to cool entering air. The higher winds that are caught by the taller windcatchers are stronger, colder, and blow in a different direction with less dust. By enhancing ventilation at night, when the outside air is cooler, night-flushing cools the house; wind towers can help with night-flushing.

A windcatcher can also employ evaporative cooling to cool the air by pulling it over cool surfaces. Windcatchers that cool by drawing air over water also use the water as a heat sink if the air is dry. Some of the water is evaporated by the air's heat, which is trapped until the water condenses again. This method of chilling dry air works incredibly well.