We have been cooling homes for decades with increasingly expensive machines. The Persian method has not consumed a single watt for 2,500 years

For decades, air conditioning has been the great response to heat. The more the temperatures rose, the more powerful the machine we installed was. However, more than 2,500 years ago, in a city in the Iranian desert, someone proposed an idea completely different: Maybe the problem was not how to cool a house, but how to build it so that it never got too hot.

The heat has a new enemy. The planet is going through an escalation of unprecedented temperatures and the buildings are starting to pay the bill. Glass facades turn offices and homes into veritable greenhouses, concrete accumulates heat for hours and cities radiate energy at night. absorbed during the day.

The consequence is an increasing dependence on air conditioning. According to the United Nations Environment Programme, cooling systems already consume about 20% of all the world’s electricity, a figure that will continue to grow as heat waves become more frequent.

The Persian redesign. In the heart of the Iranian plateau is Yazda city where summer temperatures easily exceed 40 ºC and where survival was never a question of comfort, but engineering. There appeared one of the most sophisticated passive cooling systems ever conceived: he badgirknown as a wind catcher.

His approach was radically different from the current one. Instead of combating the heat once it had entered the house, the architecture itself took care of it. to capture the fresh airexpel the heat and maintain a habitable interior without consuming electricity.

The “Persian method”: a way of thinking. At first glance, a badgir It looks like a tall, decorative chimney jutting out from the rooftops. In reality, it is a carefully calculated system to take advantage of two natural phenomena.

On the one hand, it captures the air currents that circulate several meters above the ground and channels them towards the interior. On the other hand, even when the wind hardly blows, it acts as a solar chimney: Hot air rises through the tower and, as it escapes, creates a depression that draws cooler air into the building. In many homes, this flow also passed over underground water tanks or connected channels. to the qanatsfurther increasing the cooling effect.

A city designed for the climate. The truly extraordinary thing about Yazd is that the badgir It did not work in isolation. It was part of an architectural ecosystem where each element fulfilled a function. The thick adobe walls slowly absorbed the heat. The inner courtyards they created microclimates protected from the sun.

The qanats They transported groundwater from the mountains and helped cool the air. There were even the yakhchalenormous structures capable of manufacturing and preserving ice for months in the middle of the desert. The result was a city designed to work with the climate, not against it.

And the air conditioning arrived. During the 20th century, much of the Middle East and other warm regions embraced imported architectural models that had little to do with their climatic conditions. Concrete replaced adobe, glass facades replaced solid walls and passive solutions were giving way. to mechanical systems.

Many badgir they were abandoned due to the lack of maintenance, due to the entry of dust or insects and, above all, because the air conditioning offered an immediate response. The problem is that it also moved energy consumption to the center of the equation and made cooling a permanent necessity.

The irony of the West. As many wind towers fell into disuse in Iran, their principles were beginning to reappear discreetly in other parts of the world. Between the end of the seventies and the mid-nineties, thousands of modern versions of wind sensors in British public buildings. Shopping centers, hospitals and schools incorporated ventilation systems inspired by those ancient designs.

In the United States, the Zion National Park visitor center was able to drastically reduce the need for air conditioning thanks to passive cooling strategies based on the same concept. Today architects and engineers they resort to simulations by computer to optimize a technology that was born centuries ago simply by observing how the wind moved.

The future may not be in more efficient machines. Contemporary architecture begins to take on an idea that for decades was relegated to the background: the building is also part of the air conditioning system. Recent regulations in countries like uk They prioritize shade, natural ventilation and reduction of solar gain before resorting to mechanical solutions.

Exterior blinds, slats, vegetal covers, materials with high thermal inertia or patios return to gain prominence. Even those who defend the use of air conditioning agree that these measures can significantly reduce energy consumption.

The big lesson: don’t repeat the same mistake. The history of the Persian method and its badgir It does not prove that we should give up air conditioning. prove something much more uncomfortable: For decades we have tried to solve heat by adding machines to buildings that, in many cases, were designed as if the climate did not matter.

The Persians followed the opposite way more than two millennia ago. Before thinking about how to cool a house, they thought about how to build one that needed to be cooled as little as possible. Perhaps the most revolutionary technology to face the next heat waves is not a new machine, but recover an old idea that had been waiting for centuries on the rooftops of the desert.

Image | Mohammad Hosseini, Diego Delso, Pastaitaken, Dinkun Chen

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