In my small night, ah! The wind has a date with the leaves of the trees - Forough Farrokhzad, Iranian Poet

Ancient Engineering III

Badgir/Windcatcher or Windtower

 

The badgir, or windtower, is a traditional Iranian air conditioning system that lowers the air temperature in buildings. Badgir is strictly an Iranian architectural element, used in conjunction with the qanat, to create natural ventilation in buildings in hot, dry climates.

Abarkooh badgirs, Fars Province.

Flow of the air into the building.

The flow of air through a badgir.

The Badgir is very resourceful and the way it works is simple but quite ingenious.  It is basically a brick tower built with either four or eight openings at the top, although it can also have one opening (less common). These vents are decorated in brick, mud plaster, or ornately carved lime plaster. The height of the badgir is usually between a foot (30 cm) to 16.5 feet (5 m) above the roof. The tallest badgir was built in the Dowlat Abad Garden in Yazd and rises 110 feet (33.35 m) above the roof.

Detail diagram of the operation of a badgir.

Dowlat Abad badgir in Yazd stands 110 feet tall.

A dome is usually part of the traditional architecture of badgirs.

Badgirs are a dominant part of the skyline.

Working with a qanat (see post on Qanat). The tower’s orientation is adjusted by directional port at the top. With the open side facing away from the direction of the wind, air is pulled in, drawn down into the passage, and into the qanat tunnel. From there, the air is cooled as soon as it comes into contact with the cold qanat water. The cooled air is then drawn up through the windcatcher as it flows through the building, cooling off anything it comes in contact with.

 

A traditional home with typical interior courtyard and badgirs.

Agha Zadeh Mansion, Abarkooh, Fars Province.

The badgirs at Agha Zadeh Mansion, Abarkooh,
Fars Province.

A closer look at Agha Zadeh Mansion badgris,
Abarkooh, Fars Province.

Town of Aran Va Bidgol badgirs, Isfahan Province. 

The city of Kashan, leveled by an earthquake in 1778, saw an abundance in the construction of classic traditional Iranian residential buildings in the 18th and 19th centuries. These houses are now a focal tourist attraction in Kashan and one of the finest is the Boroujerdi House, built in 1857 by architect Ustad Ali Maryam. A wealthy merchant, Boroujerdi built the house for his wife which, besides having the traditional courtyards, holds fine examples of domes and badgirs. 

Boroujerdi House, Kashan.

Boroujerdi House badgirs, Kashan.

Interior courtyard of Boroujerdi House, Kashan.

The badgirs at Tekiehe Amir Chaghmagh, Yazd.

Badgirs are present in many Iranian-influenced (Persian-influenced) architecture throughout the Middle East. Unfortunately, with the development of modern air conditioning units, this amazing system of cooling the interior of the building was abandoned in favor of the electric machines and badgirs have become more of an element of architectural decoration. 

Life is only a flicker of melted ice – Dejan Stojanovic, Serbian Poet, The Sun Watches the Sun

Ancient Engineering II

Yakhchal/Ice Pit

I haven't had a chance to post the second part of the Ancient Engineering series due to the fact that I have been volunteering at VAFA Animal Shelter for long hours and have implemented the Trap/Neuter/Release system for the stray cats in my mother's compound. Yesterday, with the help of two VAFA volunteers and a neighbor, I was able to trap eight cats, take them to the vet, have them neutered, clip off the tip of the left ear for marking, took care of them during the night here at my mother's apartment, and then gradually released them back where I got them from today. All eight are doing fine. 

Now to the Yakhchal/Ice Pit. 

Ice in the desert without modern technology? You bet! By 400 BC, Iranian engineers had figured out a way of storing ice in the desert during the high peaks of summer and throughout the year.

Abarkuh Yakhchal in Yazd.

Inside Abarkuh Yakhchal, Yazd.

To do so, a structure was built with a vented, dome-shape top and an underground storage space. The dome could reach a height of 59 feet (18 meters) and the underground space around 180,00 cu ft (5,000 m³), keeping the temperature constantly cool during the day.

Working structure of a Yakhchal.

Side view and aerial view of a Yakhchal plan.

The structure of the yakhchal was always built slightly away from the town to avoid town-generated heat. The construction material was heat and water-resistant and was made of a special mortar called sarooj. Sarooj was a mixture of sand, clay, egg whites, lime, goat hair, and ash. The walls of the domed structure were 6.5 inches thick (two meters). The thickness of the walls combined with the sarooj mixture created an amazing insulation for maintaining ice throughout the hottest summer days.

 

Meybod Yakhchal, Yazd.

Inside entrance to Meybod Yakhchal, Yazd.

The pit of Meybod Yakhchal in Yazd. This deep pit remained cold throughout
the year, allowing the ice to remain frozen even during the hot summer days.

Once the dome and underground space were built, an east-west outdoor wall was added to the north side of the yakhchal. Water was brought down to this wall via a qanat during the winter (see previous post on qanats). The shade of the wall helped quicken the freezing of the water into ice. 

Water from the qanat was frozen by the wall next to
the Yakhchal and stored in the pit.

The heat-resistant sarooj mortar was an excellent insulation.

After a few days, when the ice was about 19 inches thick (50 cm), it was cut and stored in the pit of the yakhchal. This process continued until enough ice was collected to last the summer and well into the next winter.

 

Sirjan Yakhchal, Kerman.

The inside of a Yakhchal.

Ice in the yakhchals would be broken into pieces and sold in town. Chilled desserts and fruit drinks were kept in the yakhchals and enjoyed by the wealthy. Paloodeh, or Faloodeh, a cold dessert made of thin noodles, frozen sugar, rose water syrup, lime juice, and ground pistachios was made and enjoyed by people as far back as 400 BC. Paloodeh is one of my favorite deserts in Iran!

 

Paloodeh, an amazing, traditional ice dessert.

With the development of modern electric refrigerators, the use of these wonderful buildings declined and the few that remain standing today have become historic sites. Some are in decay, without any care given to them. In Iran, the term yakhchal is used to refer to all forms of electric refrigerators.

Good websites: 
https://misfitsarchitecture.com/2013/02/22/its-not-rocket-science-2-yakhchal/
http://www.solaripedia.com/13/407/6385/iran_ice_house_diagram.html

Let’s not muddy the water! Maybe, down the river a dove is drinking water - Sohrab Sepehri, Iranian Poet and Artist

Ancient Engineering I

Introducing Kariz/Qanats

Iran is a country surrounded in its entirety by mountains with Mt. Damavand reaching an elevation of 5610 meters (18,406 feet). In the center of the land lie two major deserts, Lout Desert and Namak Desert. To the north sits the Caspian Sea while in the south are the Persian Gulf and the Sea of Oman.

Geography of Iran.

Due to the arid climate in the country, only one-third of the surface is suited for farmland (see the post Nuts and More Nuts). Yet this one-third can produce an abundance of products. The key: Kariz/Qanats for water transportation.

* Note: From this point, I will use the more common, Arabic term qanat, although the Persian terms is kariz.

A qanat in Iran feeding the crop the much needed water.

A qanat in Kerman.

Qanat technology was developed in Iran around 1000 BC and gradually spread east through the Silk Road to Parthia, Aria, Bactria, and Sogdia (present day Afghanistan, Pakistan, Turkmenistan and parts of India), and into Xinjiang in Northwestern China. The technology spread west with the Arabs to North Africa and Spain and then to Mexico and South America via the Spanish. 

The spread of qanat engineering.

Diffusion of qanat technology to the rest of the world.

The way a qanat works is quite ingenious. Qanats tap into the subterranean water and efficiently deliver water to the surface without pumping. The source of the water is always above the destination, with gravity draining the water through downhill, underground tunnels. Because the water is transported through underground tunnels, it can travel long distances in hot, dry climates without contamination and loss of water through evaporation. 

The skilled laborers who specialize in building and maintaining qanats are called Moqanis.

 

Diagram of the qanat.

In order to start building a qanat, an aquifer has to be found near a slope or hill from which water can be extracted using a water well. An aquifer is an underground layer of water-bearing porous rock such as gravel, or loose materials such as sand or silt, through which water can flow. 

An aquifer.

The mountains surrounding the land provide ample aquifers and once one has been located near a hill or a slope, an initial water well is built. This water well is called Madareh Chah, or Mother Well. From there, vertical shafts are dug 20 to 35 meters apart (65.6 to 114.8 feet) and the shallower the qanat, the closer the vertical shafts are to each other. Each shaft supports the underground construction of the qanat, and later on, the maintenance of it. The shafts also allow for air to interchange through the qanat. The laborers transport the excavated material up the vertical shafts using leather bags.

Two different views of the construction of the qanat.

A qanat delivering water to farms in Iran.

Aerial view of the Qanat. The Circles are the openings 
to each vertical shaft going into the ground 
and reaching the water.

The underground tunnel of a qanat.

The average length of a qanat is 5 km (3.1 ml) with the longest qanat measuring at 70 km (43.5 ml) in Kerman. The depth of the shafts range from 20 to 200 meters (65.6 to 656 feet) with the deepest shaft measuring 275 meters (902 feet) in Khorasan.

Chesheme Ali Qanat in Rey, Iran.

Baghe Shazdeh Qanat in Kerman, Iran.

Niavaran Qanat in Tehran.

Shahrood Qanat near Semnan, Iran.

By the middle of the twentieth century, 50,000 qanats were in use in Iran.