Natural air-conditioning in antiquity

Air-coolers and air-conditioning are hot news these days when global temperatures are rising and we seek the comforting relief provided by modern technology. Little do we know about the solutions our ancestors were familiar with. 

Traveling through Iran in April/May, temperatures often rose to 40 degrees Celsius and above. I had heard that many cities managed to keep their houses and streets cool thanks to an efficient system of wind catchers, called badgirs. Today’s examples date back to the 14^th century, but the system existed in Achaemenid times, well before the arrival of Alexander in Persia. 

The city of Yazd on the Central Iranian Plateau is punctuated with some 700 of these strange towers, which, to the untrained eye, look very modern. They fit the city landscape but also seem out of place amidst parked cars and busy traffic. For centuries, the badgirs pull fresh air into buildings and houses, pushing the hot air out through large vertical slots. 

Depending on the prevailing winds and other weather conditions, the towers were designed differently. They could be taller or smaller, have only one opening, and no internal partition if the wind blows constantly from the same direction. When the wind direction is variable, the tower would be divided into vertical sections with openings to the sides pointing in multiple directions. In Yazd, all wind-catchers are four- or eight-sided. 

The Zoroastrian village of Cham near Yazd proudly displays its badgers. Near the Towers of Silence, we also find them surrounding the water cistern. In Zoroastrian belief, earth, fire, and water are holy elements that should not be polluted by their dead. For that reason, they placed their remains on a Tower of Silence where vultures could pick the bodies clean.

Typically, like so many cities in desert areas, houses are built closely together with small windows away from the sun along narrow streets. In Iran, these alleys are called sabats, partially or entirely covered with a series of arches for protection from the sun. 

The wind towers in Iran were also extended to be used as a refrigerating device. That’s why we often see them standing like sentinels around traditional water reservoirs capable of cooling the water to near-freezing temperatures in summer. 

Wind-catchers are not limited to Yazd or Iran but were also present in Egypt and elsewhere in North Africa, the UAE, West Asia, and India.

This makes one wonder why, in today’s world, it is so difficult to develop a free and carbon-zero solution to replace expensive air-conditioners. I agree that our cities are not fit to build these low-tech installations, but beach resorts and countryside settlements could very well profit from our forefathers’ invention.