The wind-catcher (badgir) is a ventilating shaft which projects above the roof of a building with openings towards the favourable prevailing winds.
Its main function is to capture air from above and transmit it indoors, thereby providing the living quarters with ventilation. It is generally considered as a sustainable technology, a spectacular and ingenious climate modifier. It resembles a tall chimney and can be several metres high, the taller examples being found in the houses of richer families.
The city of Yazd on the central plateau of Iran has the greatest concentration and variety of wind-catchers of any city. It once had approximately 4,000 wind-catchers. The large number of badgirs in Yazd has been attributed to the economic success of the city between 1868 and 1900, when, as a result of the opening up of Hong Kong by the British as an opium port for China, Yazd became ‘the largest producer of opium in Iran, wind-catchers reflecting the great prosperity of the period for the city.
Wind-catchers have been in common use from North Africa to Afghanistan and Pakistan. They are also found in southern parts of the Persian Gulf, where the idea was brought by Iranians in the nineteenth century. In the old Bastakia quarter in Dubai a few wind-catchers still exist, built by Persian emigres within the last few hundred years.
Wind-catchers are alternatively called badgir in Iran, Iraq and the Persian Gulf, malqaf in Egypt, bating in Syria, and mungh or hawa-dani (literally meaning breeze container) in the local language of the Sindh province of Pakistan. In this research the terms wind-catcher and badger are interchangeably used.
Variety of wind-catchers
Wind-catchers take a variety of forms. They differ in terms of materials and size, ranging from relatively plain wind scoops that can receive breezes from one direction to elaborately decorated multi-directional wind towers with openings on several sides. The designs of wind-catchers vary regarding the height of the tower the cross-section of the air passages, the placement and number of openings and the placement of the tower which they are meant to cool.
The type of wind-catcher used in a place depends on the consistency of the wind direction. If the wind is variable, the wind-catchers are open on all sides. If there is a predominant wind, as in the Iran-Afghanistan border region, the wind-catchers face that particular direction. In Iraq the towers are oriented towards the prevailing northwest wind, whereas in Yazd in Iran the winds are more variable and the wind-catchers are open on all four sides.
The wind-catchers of Iran (badgirs) are very different in form and character from those found in countries such as Iraq and Pakistan. Of unknown date, but described as early as the fourteenth century, the badgirs of Iran are often considered to be more sophisticated, more spectacular and more complex structures than their counterparts in other regions. They are multi-faced and multi-directional towers with openings on two or four sides, and with several vertical shafts. They are mostly square or rectangular in plan with four faces, but some of them may have up to eight faces.
They are also used on a ‘more modest scale on the village houses of the general populace, whose dwellings are orientated to make the best use of shade for the summer room’.
Although simple towers may be less than three metres high, more elaborate examples reach a height of five metres or more. The wind-catchers in Iranian towns like Yazd often carry ornamentation and elaborate decoration.
Construction of Yazdi wind-catcher
A traditional badgir consists of a top (head), a brick tower, the internal shafts of the tower, and the space (room) under the tower. The brick tower, called locally the pa-ye badgir (foot of the badgir) or sotoun (column of the tower), is a baked or sun-dried mud-brick tower rising high above the building. It is covered with mud plaster (with fine or coarse straw chopped into it) or occasionally with fine white gypsum plaster. The tower of the wind-catcher is reinforced with wooden beams that extend outwards. These small beams are used as scaffolding for cleaning and maintenance. The internal shaft is divided by internal partitions made of ajore-farshi (square brick tiles) or bricks on edge and plastered with rough straw plaster. The partitions are supported on a timber frame. The wood used is often mulberry, which is said to be resistant to termites.
The above is a lightly edited version of part of a chapter entitled, ‘Vernacular Passive cooling systems in Iran’, from a book entitled, ‘Thermal Comfort in Hot Dry Climates; Traditional Dwellings in Iran’, written by Ahmadreza Foruzanmehr, published by Routledge Research in Architecture. The photo was taken from the book.