An ancient engineering feat that harnessed the wind

By Shervin Abdolhamidi 27 September 2018

“I have water air conditioning too, but I prefer sitting under my natural air conditioning. Reminds me of old times,” Mr Saberi said, gesturing to the badgir (wind catcher) that we were sitting under. “More chai?”

In the 40C summer heat of Yazd, a desert city in the heart of Iran, a hot cup of chai would normally have been the last thing on my mind. However, a glance out from the breezy shaded patio where I sat onto the central courtyard, ablaze in the glaring evening sun, and all thoughts of bidding my host goodbye immediately evaporated. I leaned back and gazed up along the length of this remarkable technology that’s believed to be thousands of years old.

Wind catchers are tall, chimney-like structures that protrude from the rooftops of older houses in many of Iran’s desert cities. In their simplest form, wind catchers harness the cool breezes and redirect them downwards either into the home or into underground storage rooms to refrigerate perishable foods. Studies have shown that wind catchers can reduce indoor temperatures by around 10 degrees.

From ancient Persians and Egyptians to Babylonians and Arabs, civilisations have strived to adapt their architecture to the harsh, hot climates of their environments by developing natural ventilation methods. Examples of wind catchers can be found across the Middle East and Egypt, as well as in Pakistan and India.

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Since wind catchers are located at the highest point of a building, they are especially susceptible to deterioration and decay. While the oldest wind catchers in Iran date only to the 14th Century, there are references to wind catchers in the writings of 5th-Century Persian poet Nasir Khusraw.

There is an ongoing dispute between Iran and Egypt over the origin of the wind catcher. Paintings dating to around 1300BC discovered near modern-day Luxor depict two triangular structures atop Pharaoh Nebamun’s royal residence, leading Egyptian archaeologists to believe the first wind catcher was developed in Egypt. Meanwhile, ruins of a Persian fire temple dating to 4000BC feature numerous chimney-like structures, some of which have no trace of ashes, leading Iranian architects to posit that wind catchers originated in Iran.

According to Dr Abdel Moniem El-Shorbagy, assistant professor of architecture and design at Effat University in Jeddah, Saudi Arabia, wind catchers found throughout the Middle East, Pakistan and India, like the four-sided wind catcher of the 8th-Century Abbasid palace of Ukhaidir in Iraq, exhibit the impact of the traditional Persian architecture on these regions. One theory suggests that the wind catchers were adopted and spread to these areas after the Arab conquest of Iran in the 7th Century.

Later that day on the rooftop of the Yazd Art House, a former Qajari-era mansion converted into a cafe, I looked out over the city’s adobe skyline while listening to an Iranian song playing from a small radio hanging from the wall. As I savoured a cold glass of Sekanjabin (a local drink made of honey and vinegar poured into a cup lined with thin slices of cucumber), I scanned the dense cluster of wind catchers rising from the rooftops. They looked like miniature skyscrapers.

Most of the wind catchers in the residential buildings of Yazd are rectangular in shape, with inlets on each of the four sides to catch wind blowing from multiple directions. However, Moyeen, a cafe employee, told me that hexagonal and octagonal wind catchers are also common.

“The wind catchers here are multi-directional, because we have pleasant winds coming from all directions – unlike in Maybod [a small town roughly 55km north-west of Yazd], where the wind catchers have only one inlet to prevent harsh, dusty, desert winds blowing from the north from entering the houses,” he explained. “Here we are surrounded by mountains that block the desert winds.”

I stood atop the roof, trying to visualise the physics behind the wind catchers. Cooler winds blowing at higher elevations are directed downwards through the narrow, vertical slits, subsequently pushing warm air inside the buildings up and out through an opening on the opposite side of the wind catcher. Even in the absence of a breeze, wind catchers work as solar chimneys, creating a pressure gradient that pushes warm air up and out through the tower, leaving the interior of the home feeling cooler than the exterior.

With the scorching afternoon sun bearing down on me, I decided I’d rather be under a wind catcher than staring at them, and made my way to the Lariha House, one of Yadz’s best preserved Qajari-era houses. The building, which dates to the 19th Century, exemplifies the Persian architecture of the time, which featured a central, rectangular courtyard, as well as summer and winter sections – a division intended to optimise exposure to direct sunlight in the winter and minimise it in the summer. The wind catcher is located in the summer portion of the house.

Often the cool air from the wind catcher passes through an alcove in a room on the ground level, down through a vent into the zir-zamin (basement), where perishable goods are stored. In the Lariha House, I felt a slight chill as I descended the 38 steps into an even deeper cellar space called the sardab (meaning ‘cold water’ in Farsi), where water from the qanats (underground channels used to transfer water from mountains to cities) would cool the incoming air.

Like the qanat, which has been rendered mostly obsolete by modern technology, the wind catcher is a symbol of the past. Its usage has significantly diminished with the advent of modern air-conditioning. According to Abbas Farroghi, an 85-year-old resident of Lab-e Khandaq, one of Yazd’s historical neighbourhoods, many of his neighbours have left their traditional homes in favour of modern apartments.

“The houses become either empty, or get rented out to immigrants and workers,” he said. “The best situation is that it gets bought by some rich person in Tehran or Shiraz who converts it into a hotel.”

Mrs Farrokhi, who recently sold her house in the neighbourhood of Kooche Hana and moved into a new apartment a few streets away, often reminisces about the “good old days, where all the kids would gather and we’d sit under our badgir in the evening eating and laughing.” Her old home has since been renovated and now serves as a traditional hotel, the Royay Ghadim (meaning ‘dream of the past’).

“I still go visit my home once in a while,” she told me with a nostalgic smile. “It looks good now. I’m glad it’s being preserved.”

The city of Yazd became a Unesco World Heritage site in 2017, and while this provides a strong incentive to preserve some of the its historical architecture, Farsad Ostadan, who runs a local tour agency, believes more can be done.

“A few years ago, leading up to our acceptance as a Unesco site, the Cultural Heritage Institute started giving out loans, and people who’d bought these old houses were able to renovate them into hotels and restaurants and preserve these old houses,” he told me. “But now people wait for years [to receive a loan]. The government doesn’t have money now for these things.”

Yet Ostadan has hope for the city’s historical structures – especially the wind catchers. He reminisces about long summer days spent at his grandfather’s house lying under the wind catcher that was “just as good as the AC we have nowadays.” He continued, “I mean we didn’t even know what AC was in those days.”

“As long as tourists keep coming things will be OK,” Ostadan said, noting that the money coming in from tourism allows for the renovation and preservation of the old houses. “They care about the old town and the wind catchers, and we care, so hopefully we can preserve them.”

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