A windcatcher (Bâdgir; بادگیر) is a traditional Persian architectural device used for many centuries to create natural ventilation in buildings. For a topic outline on this subject see List of basic Iran topics. Architecture in " Greater Iran " has a continuous history from at least 5000BCE to the present with characteristic examples distributed over a vast area from Syria 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.
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Background
Central Iran has a very large day-night temperature difference, ranging from cool to extremely hot, and the air tends to be very dry all day long. Most buildings are constructed of very thick ceramics with extremely high insulation values. Furthermore, towns centered on desert oases tend to be packed very closely together with high walls and ceilings relative to Western architecture, maximizing shade at ground level. The heat of direct sunlight is minimized with small windows that don't face the sun.
Function
The windcatcher functions on several principles:
First, a windcatcher is capped and has several directional ports at the top (Traditionally four). By closing all but the one facing away from the incoming wind, air is drawn upwards using the Coanda effect, similar to how opening the one facing the wind would push air down the shaft. The Coandă effect ('kwandə is the tendency of a Fluid jet to stay attached to an adjacent curved surface that is very well shaped. This generates significant cooling ventilation within the structure below, but is not enough to bring the temperature below ambient alone - it would simply draw hot air in through any cracks or windows in the structure below.
Therefore, the key to generating frigid temperatures seems to be that there are very few cracks at the base of the thick structure below, but there is a significant air gap above the qanat. A qanat (from قناة) or kareez (from كاريز) is a Water management system used to provide a reliable supply of water to human settlements A qanat has quite a lot of water inside, because there are frequent well-like reservoirs along its path. Completely shaded from the sun, a qanat also aggregates the cold, sinking air of the night, which is then trapped within, unable to rise up to the less dense surface air. A windcatcher, however, can create a pressure gradient which sucks at least a small amount of air upwards through a house. This cool, dry night air, being pulled over a long passage of water, evaporates some of it and is cooled down further.
Finally, in a windless environment or waterless house, a windcatcher functions as a stack effect aggregator of hot air. Stack effect is the movement of air into and out of buildings Chimneys, Flue gas stacks, or other containers and is driven by Buoyancy. It creates a pressure gradient which allows less dense hot air to travel upwards and escape out the top. This is also compounded significantly by the day-night cycle mentioned above, trapping cool air below. The temperature in such an environment can't drop below the nightly low temperature. These last two functions have gained some ground in Western architecture, and there are several commercial products using the name windcatcher.
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. Adobe bricks are a Natural building material made from Sand, Clay, water and some kind of fibrous or Organic material ( Sticks, g. shabestan) in the middle of the day to frigid temperatures. Shabestan or Shabistan is an underground space that can be usually found in traditional architecture of mosques houses and schools in ancient Persia ( Iran)
So effective has been the windcatcher in Persian architecture that it has been routinely used as a refrigerating device (yakhchal) for ages. Architecture in " Greater Iran " has a continuous history from at least 5000BCE to the present with characteristic examples distributed over a vast area from Syria yakh-chāl (meaning "ice pit" ( Persian Language:یخچال is an ancient type of refrigerator Many traditional water reservoirs (ab anbars) are built with windcatchers that are capable of storing water at near freezing temperatures for months in summer. āb anbār آب انبار is a traditional Reservoir of drinking water in Persian antiquity High humidity environments destroy the evaporative cooling effect enjoyed in the dry conditions seen on the Iranian plateau; Hence the ubiquitous use of these devices in drier areas such as Yazd, Kashan, Nain, and Bam. Yazd (pronounced /jæzd/ (In Persian: یزد is the capital of Yazd province, "the second most ancient and historic city in the world" and a centre Kashan is a city in the province of Isfahan, Iran. It had an estimated population of 272359 in 2005. This is especially visible in ab anbars that use windcatchers. āb anbār آب انبار is a traditional Reservoir of drinking water in Persian antiquity
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. āb anbār آب انبار is a traditional Reservoir of drinking water in Persian antiquity Qazvin ( also spelled as Ghazvin) is the largest city and capital of the Province of Qazvin in Iran with an estimated population of 331409 in 2005 For a topic outline on this subject see List of basic Iran topics. 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.
Gallery
 The windcatcher of "Dowlat-abad" in Yazd, is one of the tallest extant windcatchers. Yazd (pronounced /jæzd/ (In Persian: یزد is the capital of Yazd province, "the second most ancient and historic city in the world" and a centre |
 Borujerdi ha House, in central Iran. Khāné-ye Borūjerdīhā or "Borujerdis' House" is a famous historic house in Kashan, Iran. For a topic outline on this subject see List of basic Iran topics. Built in 1857, it is an excellent example of ancient Persian desert architecture. The two tall windcatchers cool the andaruni section of the house. |
 Old-fashioned air-conditioning! The tower catches wind from four directions and channels it down into the house |
A Wind Tower (Persian:bad gir,Arabic: "barjeel" or badghir(from Persian)) is a structure seen on ancient buildings of the Middle East, particularly Iran and Bahrain. Arabic (ar الْعَرَبيّة (informally ar عَرَبيْ) in terms of the number of speakers is the largest living member of the Semitic language The Middle East is a Subcontinent with no clear boundaries often used as a synonym to Near East, in opposition to Far East. For a topic outline on this subject see List of basic Iran topics. The Kingdom of Bahrain (in مملكة البحرين,, literally Kingdom of the Two Seas) is an Island country in the Persian Gulf This acted like a natural air conditioner creating a soothing effect in the harsh conditions of the desert.
The emergence of a traditional Bahraini and Persian Gulf style of architecture arose as people migrated to Bahrain with the growth of the pearl trade. The Persian Gulf, in the Southwest Asian region is an extension of the A pearl is a hard roundish object produced within the soft tissue (specifically the mantle) of a living shelled Mollusk. With newfound wealth, the merchants built houses of note in the 18th and 19th centuries. The people of Ahvaz in Iran, for example, came and brought with them new architectural designs, including the distinctive wind tower which can be seen so prominently in the Awadiya area and elsewhere in Bahrain. The city of Ahvaz or Ahwaz (اهواز ahvāz or الأحواز is the capital of the Iranian province of Khūzestān. For a topic outline on this subject see List of basic Iran topics. This distinguishing feature was adapted locally with its own distinctive decorative motifs. The wind tower, an early and very effective form of air conditioning, has in fact been around for about 500 years and was developed from the early Wind Scoops first built about 2,000 years ago in Iran.
In Muharraq and also in parts of Manama there are many buildings, which are no more than two stories high and houses built with natural ventilation, using wind towers and badghirs, the devices for speeding up the flow of air and which consists of horizontal slats in the lower part of the walls. Muharraq ( (meaning Place of Ashes is Bahrain 's second largest city and served as its capital until 1923 Manama ( Arabic: المنامة, Transliteration: Al-Manāmah) is the capital and largest city of Bahrain with Badghir means ‘wind trap’ and is also the word used to describe the wind tower.
See also
External links
- Bahadori, Mehdi N. Architecture in " Greater Iran " has a continuous history from at least 5000BCE to the present with characteristic examples distributed over a vast area from Syria yakh-chāl (meaning "ice pit" ( Persian Language:یخچال is an ancient type of refrigerator This article refers to a device for ventilation For the power generation technology see Solar updraft tower. (February 1978). "Passive Cooling Systems in Iranian Architecture". Scientific American 238 (2): 144–154.
- Bahadori, Mehdi N. (August 1994). "Viability of wind towers in achieving summer comfort in the hot arid regions of the middle east". Renewable Energy 5 (5-8): 879–892. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- A. A'zami. Badgir in traditional Iranian architecture. Retrieved on 2007-07-17. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 180 - Twelve inhabitants of Scillium in North Africa are executed for being Christians
- 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.
- ventilation cowl on a ship
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