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Posts Tagged ‘qanat’

Yakhchals (Persian Yakh = ice Chal = pit)

If I told you that in 400BC Persians were able to keep ice from melting when temperatures often reach 40 degrees and without the luxury of electricity, you’d probably think I was making it up. In fact, it is true and I find the invention and use of a Yakhchal  fascinating. By keeping ice as ice for a prolonged period it meant that houses could be kept cool by using the blocks in the summer, and food could be “passively refrigerated” to substantially extend its shelf life in the heat.

 

Yakhchal and badgirs together

Yakhchal and badgirs together

Yakhchals are domed structures constructed from mud bricks with underground space excavated below ground level. The dome and underground chamber are also insulated with a very effective and delightful mixture of sand, clay, egg whites, lime, goat hair and ash up to 2 metres thick. We found a yakhchal and badgirs together on the outskirts of Na’in between the new town and the ancient citadel and I can vouch that the ice house is a very large building. Sadly, the ice house was locked and we were unable to find anyone who could let us in to take a look.

Ice could either be brought down from the mountains in early winter and stored until the following summer or, more commonly, the water from the Qanats was channelled into areas which were sheltered from the sun and wind so that it froze overnight in the notoriously cold winter desert temperatures. Blocks could then be cut and stored in the Yakhchal ready to use the following summer.

Whilst most of the ice houses in Iran are now abandoned in favour of electric white goods, some communities in desert areas across the globe are looking at the ice house method of keeping things cool as an alternative to using electricity-“off grid living”. Instead of ice blocks however, 2 litre bottles of water are filled and used. Not only are these easier to transport it also avoids unnecessary plastic going to landfill.

In this day and age of reduce, reuse, recycle, ice houses could still yet make a come back!

Further reading:

The ice houses of Iran by Hemming Jorgensen

Ancient ice houses of Iran (some great photos)

Badgirs (Persian Bad = wind, gir = catcher)

Badgirs, or windcatchers, do exactly what it says on the tin; they catch wind. Built from brick or mud and adapted to take into account the direction of airflow depending on its intended use, these structures are the forerunners of air-conditioning systems but again, without the need for electricity.

Badgirs were, and still are in some parts of Iran, used to cool buildings and act as ventilation. The Yadz area in particular is renowned for the high numbers of wind catchers in use and this is no surprise given its location on the edge of the desert. Badgirs are usually high towers and have either one, four or eight openings. For air-cooling a house, the tower would often have one opening facing the prevailing wind so that it drags the air down and into the house thus keeping the air continually moving whilst cooling.

When used alongside a Qanat, windcatchers can also be adapted so that they draw air up from the water tunnel which cools as it passes over the water and up through the cool ground. For this to happen, the opening will be facing away from the prevailing wind.

Strangely, windcatchers are also effective cooling mechanisms when there is no wind! In this situation, hot air travels up and out of the tower as a result of the pressure gradient created. This leaves the lower levels of buildings extremely cool and welcoming on hot days.

I am always impressed by the early engineering and construction skills of the Persians and these three structures are classic examples of their advanced thinking to the extent that countries today are looking to use these ideas as more sustainable alternatives to the energy-hungry modern equipment we currently use.

Not bad for a 2000 year old legacy.

Further reading:

The circle of ancient Iranian studies

Green Prophet

 

 

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My traditional pre-holiday reading was focussed on the extreme summer heat and not just how I was going to cope but also how the Iranians manage year after year during the seeringly hot summer months when temperatures can soar over 40 degrees centigrade in many areas. Inevitably, much of my research concerned water consumption and distribution in regions where much of the land is arid or semi-arid and how crops are grown in rural areas without regular rainfall. Was I going to be eating the luscious melons that Esfahan is so famous for or would they all be withered up left to dry out in the fields? I also wondered whether we would be subject to water rationing at home and, heaven forbid, would there be a ban on hosepipes?

 

It was when reading about these problems that I came across an ingenious solution to water distribution, the Qanat system. This underground aqueduct system is known to have been developed by the Persians sometime early in the 1st millennium BC, around the same time that we Britons were fighting off the Roman invasion led by Julius Caesar. Qanats were subsequently adopted by Arab and African countries further West and the remains of Qanats can still be found in China, Pakistan, Syria, UAE, Algeria, Greece and Spain.

So what is a Qanat? Simply, a Qanat is a series of shafts connecting ground level to sloping tunnels below ground. The theory is that the Qanats tap into the water underground so that it brings large quantities of water to the surface up the shafts without the need for a pumping mechanism. The water drains by gravity as it flows downwards from the aquifer source towards its destination. Because the canals are underground, there is little or no evaporation or wasteage and contamination is kept to a minimum. Qanats are usually contructed to cover a large area/distance which means that many fields and homes can be kept watered. Qanats were both expensive and time-consuming to build but it was considered a major investment by the communities who needed reliable water supplies for many years to come. That initial investment must have repaid them many-fold and the Qanats are a wonderful legacy.

Qanat cross section

Qanat cross section-diagram courtesy of the Middle East Institute

 

Building the Qanats is a skilled occupation and knowledge was generally passed through families from father to son. The gradient of the Qanat has to be just right if it is to be successful. Too shallow and the water will not flow; too steep and the heavy flow of water is likely to collapse the Qanat by washing it away. Bearing in mind that these shafts and tunnels were excavated by hand, without the sophisticated machinery we have today, they are amazing to see. If the Qanat diggers were lucky, they would initially hit the water aquifer at 50ft. Unfortunately for the labourers many of the shafts are 200-300 feet deep. Most Qanats are between 8-10 miles long with the longest Qanat in Iran being 18 miles long.

“In Persia, blind white fish live in the qanats.” This statement led four Oxford undergraduates to Iran in the early 1950’s to look for a new species of fish which apparently lived in the qanat water system and a book detailing their travels and exploits can still be found in secondhand bookshops. Keep an eye out for “Blind white fish in Persia” by Anthony Smith. It is well worth a read.

The Old Mosque in Na’in has a Qanat in the underground chambers although it is no longer in use. When it was used, it carried water for 1.2km to the left of the town and 1.5 km to the right thus serving much of the community around. Qanats are often used in conjunction with wind towers (Badgirs) and Yakhchals (ice houses) which are separate above-ground structures combining to cool air and water-an early version of air-conditioning and refrigeration and not a watt of electricity in sight.

“Necessity is the mother of invention” [Plato]

Perhaps these ideas can be adapted for future use as more sustainable options.

 

 

 

 

 

 

 

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