Faced with heat waves, the bioclimatic lessons of an ancient Iranian city

Located not far from the Silk Road, Yazd is one of the hottest cities in the world. Surrounded by two deserts, its summers are hot and the rains extremely rare.

Its inhabitants have learned to adapt to it. With methods invented more than 2.500 years ago, when the Persian Empire dominated the Middle East.

Yazd is "living testimony to the intelligent use of the limited available resources necessary for survival in the desert", sums up Unesco, which inscribed it in 2017 on the World Heritage List.

This city of 530.000 inhabitants is "a source of inspiration for new architecture facing the challenges of sustainability", adds this UN organization.

Yazd is particularly famous for its 700 badguirs (“wind catcher” in Persian), traditional and elegant towers which surmount the flat roofs of the historic center.

"The badguirs played a key role in the prosperity of the city. For centuries, before the invention of electricity, they made it possible to cool the dwellings. Thanks to them, people lived at ease", explains Abdolmajid Shakeri, head of the Ministry of Heritage for the province of Yazd.

Similar to straight four-sided chimneys, badguirs feature large vertical slits and multiple flues inside. They let the slightest breath of fresh air into the dwelling while, under pressure, the warm air is forced out.

This method of refrigeration is "completely clean because it uses neither electricity nor polluting materials", underlines Majid Oloumi, director of the garden of Dowlat-Abad, where is located a badguir of 33 meters, the highest in the world.

"Simplicity"

This example of bioclimatic architecture inspires a growing number of architects around the world, such as the Franco-Iranian Roland Dehghan Kamaraji, based in Paris, who has extensively studied the functioning of badguirs.

They "demonstrate that simplicity can be an essential attribute of sustainability, belying the widespread idea that sustainable solutions must necessarily be complex or high-tech", he defends.

Among the most representative projects, he cites that of Masdar City, in the United Arab Emirates, whose "buildings are designed to take advantage of natural ventilation for cooling, like badguirs."

In Melbourne, Australia, Council House 2 is also a building with a passive cooling system, like the Eastgate Center in Harare (Zimbabwe), which "is inspired by termite mounds, an approach similar to that of badguirs".

In Yazd, towers and traditional houses are built of rammed earth, made of clay and raw earth, effective thermal insulators.

Well preserved, the Old Town is also organized around narrow streets and "sabats", these partly covered passages that protect from the sun. The contrast is striking with the avenues of the modern city, wide and straight.

"Unfortunately, the heritage transmitted by our ancestors has been forgotten", especially since the appearance of air conditioners, regrets Majid Oloumi. "Today, the architecture of the houses, coming from other countries, and the construction methods, based on cement, do not correspond to the climate of Yazd."

Internationally, Mr. Dehghan Kamaraji observes that many bioclimatic architecture projects remain hampered "by economic requirements and standards established by the industry", which still mainly favors the use of materials that consume fossil fuels.

Drying out

Specialists are also interested in another specialty of Yazd: the "qanats", these narrow underground galleries which carry water from the mountains or underground water tables to places of life.

Built more than 2.000 years ago for some, “these underground aqueducts constitute a source of water supply and make it possible to cool the dwellings and to preserve food at an ideal temperature”, explains Zohreh Montazer, specialist in qanats of Yazd.

The number of qanats in Iran is estimated at 33.000, compared to 50.000 in the middle of the XNUMXth century, a drop linked in part to the drying up of groundwater due to overconsumption of water, according to Unesco.

Anxious to preserve this heritage, the Iranian state has rehabilitated the longest and oldest qanat in the country, that of Zarch, which extends over more than 70 km in the province of Yazd.

This narrow gut is partially open to visitors, a way of making residents aware of the challenges ahead. “The day fossil fuels run out, we will have to go back to the methods” that have already been proven in Yazd, warns Ms. Montazer.