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Sunday, December 27, 2015

Qanats, Quanat, Badgirs (Windwards)

http://mobile.reuters.com/article/idUSKBN0U90DX20151227 Iranian architecture at the central desert towns is not limited to the construction of ab-anbars (Ancient Refrigerators) and badgirs (Windwards), but its importance also is in house building and city planning. Another manifestation of Iranian architecture in Kavir lands is the construction of Quanat (underground water channel). It consists of a series of wells connected to each other through an underground channel, carrying water from underground depths to its surface. Excavation of quanat presupposed mastery of certain techniques of which only Iranians were fully aware. Heroclotus writes that Iranians were inventors of quanat. "Iranians were the first nation to carry water from underground channels, to the surface. They were inventors of quanat. Iranian architects have also created extremely valuable monuments in areas such as water and irrigation, dams, canals, and bridges or rivers. Excavation of Suez Canal between the Nile river and the Red Sea during the reign of Achaemenids was carried out under the supervision and initiation of Iranian engineers and architects. In the vicinity of the canal a stone inscription was discovered from the time of the Achaemenid king Darious the Great together with an account of how the canal was constructed. The Athos canal in Greece, too, had been another masterpiece of Iranian architecture. Remnants of the canal stand up to this day. A qanat tunnel near Isfahan. A qanāt (Arabic: قناة‎, Persian: قنات‎‎/کاریز) is a gently sloping underground channel with a series of vertical access shafts, used to transport water from an aquifer under a hill. Along the length of a qanat, which can be several kilometers, vertical shafts were sunk at intervals of 20 to 30 meters to remove excavated material and to provide ventilation and access for repairs. The main qanat tunnel sloped gently down from pre-mountainous alluvial fans to an outlet at a village. A qanat is an underground irrigation system fed by springs or groundwater. They are common throughout the Middle East, and they can be found all the way from the Gobi Desert to Spain. They have different names in different cultures: in Berber Arabic, they’re called foggara; in Persian, qarez; in Spanish, acequia, and in Turkish, qanat. Above is an image created by Sue Hutton showing a cross-section of a qanat in Oman. Structures of this type collect water in the rock, sand, and gravel aquifers at the edges of the mountainous region in northern Oman. They run underground for kilometers, and emerge at oases. In Oman they are also known as dawoodi or iddi falaj. Besides its use in irrigation, a qanat can also be used together with a windcatcher to cool a building without using any electrical power. Many qanat in Iraq were destroyed during the American invasion. -- SYNOPSIS: I spent most of the day walking through Yazd. The water museum shed light on the qanats (water channels). Restored historic houses made me understand the badgirs (wind towers). How effective ancient technology can be. Yazd is quite a big town, but for someone like me, most everything of interest is in the old town. Typical for the skyline of Yazd are the Badgirs or wind towers. Big and small, old and new, they define the roofs alongside the ever present domes. Invisible, on the other hand are the qanats, or water channels which crisscross the town way below ground. All these features represent ancient genius at work and prove that coping with the heat can be done, and the supply of water can be guaranteed, by simple, low-tech means. The domes are used for anything from mosques, to baths, to homes. Almost every mud-brick structure is built with a vault of some sort to avoid direct sun exposure. It proves to be very effective. I could not quite imagine though, how a tower on the roof could make much of a difference until I stood beneath one. Many of the traditional villas in town have been converted into restaurants, hotels, or museums and are therefore accessible. Today, I got the grand tour at one of the most beautiful of them, the Mehr Hotel. Many of the suites have their own badgirs. Directly beneath the wind towers it feels as if you had an air conditioner running! There are small sitting rooms into which you can retreat from the summer’s heat. Imagine how healthy this is. Badgirs can be small single-shaft towers, or they can have multiple compartments. Even the slightest breeze can be caught and transported down into the shaft. Hot air exits through different openings. Put a badgir over a pool and you can cool the water which in turn evaporates and cools its surroundings. Very impressive. I have come across many dried out qanats, but at the Mehr Hotel, the qanat was operational. One has to go down a narrow tunnel of steep steps until you reach a level easily 5-10 meters below ground. It is as if you had your own spring running through the house. Clear, fresh mountain water is supplied constantly and a room next to the water is equipped again for relaxation or to sleep there. Even in a torching 50 degrees Celsius outside, there will be a cooling 10-15 degrees down there! I finally understood a bit more about the qanats after visiting the water museum in Yazd. Extensive English explanations helped! To this day, there are crews of qanat builders. First, the crew identify a water source hopefully way up in the mountains. Then they figure out where the water needs to go. They start digging at the end, for example in Yazd, working their way backwards to the water source. A slope has to be created upwards to the source which controls the stream of water just right. It should not gush too fast and it should not trickle too slowly. The slope is literally determined by ropes and strings! Just like the Romans who transported water over hundreds of kilometers above ground, these qanats do the same below ground. No computer technology is at work here. The province of Yazd alone has over 3000 qanat channels, some very recent. The qanat workers dig tunnels no wider than 80 centimeters and tall enough to stand in. They dig channels with pick axes and remove the dirt with buckets. The men and the dirt ascend from the ground into shafts that are dug frequently via pulleys that look like small wind mills. The dirt then is deposited around these shafts which punctuate the desert landscape like moon craters. When the water level drops, the qanats can be dug deeper. But today, many of them lay dormant since the water level has dropped beyond reach and more modern canalization is used to supply water. I was surprised to see the pictures of the qanat diggers. Almost all of them are old men. This must be an extremely demanding physical job. I wonder, if the new generation is not interested in picking up this old trade, or if it was just a coincidence that the crew represented at the museum is an aging one. I love to learn about these things and thumbs up to the Yazd Water Museum for providing multi-lingual signage. I was trekking around town from 1 to 6 PM. No big deal if it had not been for a hot and sunny day. Despite my sun factor 50 sun screen, I returned burned. But worse, I returned with a fever. I will blame that darn scarf for it, but it may have happened without it. I never have taken heat very well and I remember my childhood days of sunstrokes well. I am heading straight to bed and hope that tomorrow, I will be over this. Good night. 5 comments so far Add Your Comment Reply Maria Torffield said: 2010.04.24 07:38 I was just now opening the search engine Bing.com and it opened with a photo of Badgirs. There was a link to a very interesting comment with more info to search and connect to other sites: http://www.metafilter.com/26911/BadgirsWindcatchers Reply Maria Torffield said: 2010.04.23 13:29 Elaine, Did you get to see Trumpey’s straw bale house? If yes, what was you experience? From what I have read he is using something that is called the stack effect in the building design industry. This effect has been used for ventilation all over the world for centuries in vernacular architecture. It is based on the temperature difference of the inside to the out side. Since hot air rises a natural flow will cause cool air to infiltrate the building thought openings on the bottom while the hot air is leaving the building through openings in the top. The physics of the Badgirs (wind towers) in Yazd are more advances, The towers are designed to create a down flow of warm air cooling it while going through the brick channel. Some times the air is channeled down further through the basement which is linked to the payab, the water level of the qanat, to cool the air even more through the mountain cold water. The warm air in the building will rise and leave in a channel on the opposite side in the tower. This is a far more complex use of natural cooling than the stack effect and I think really unique to this area and very remarkable!!! Regarding streams and springs running through houses, it is certainly very important to understand the nature and characteristic movement of water. Unfortunately this is something that has gotten lost in our modern approach and mistakes are often made when trying to integrate natural water sources into a house design. The old technology of Yazd shows an incredible understanding of natural, characteristic water flow. The water channels run thought out town and under foundations with out causing damage to the houses. Something we certainly could learn from in our western culture. If you like to know more check out the link I posted above! Best, Maria Reply Elaine Wilson said: 2010.04.19 09:39 Elisabeth: I know of two contemporary uses of the tower and water channel here in the US. The tower concept has been built into Joe Trumpey’s straw bale house in Grass Lake. There is a tower going above the center area of the house which I believe is being used to pull warm air up and out of the house. The house is made of straw bales with adobe on the outside and inside, so the walls are very thick. I was also in a house in Kansas a couple of years ago that belongs to the family of my brother-in-law. The house is built over a spring and stream which flow underneath. The spring keeps the house naturally cool in summer and warm in winter and you can hear it if you are quiet. It is wonderful, but has been something of a problem in terms of upkeep. I think the foundation keeps eroding… Elaine Reply Solveig said: 2010.04.15 09:52 Hi Elisabeth and Maria, Thank you for enlightening me. This is indeed fascinating architecture. I hope to see this with my own eyes one day … and install a badgir on my roof. Reply Maria Torffield said: 2010.04.11 19:27 Hi Elisabeth, I hope by now you are back to your energetic self. I am very excited you saw the Qanats and Badgirs, this is such a great example of vernacular architecture. I found a great article about these methods with detailed explanations and drawings. here the link for readers who want to know more about it: Title: RESOURCE QUALITY CASCADES IN TRADITIONAL LOW EXERGY TECHNOLOGIES: THE QANATS AND BADGIRS OF YAZD by Prof. Susan ROAF http://www.irbnet.de/daten/iconda/CIB14196.pdf

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