Under the hot Middle Eastern sun, an Egyptian slave fills a clay pot with cold water from the River Nile and brings it into his mistress’ home. He plucks up his reed fan and swiftly fans the air above the fresh waters. The vapor-infused breeze offers some sweet relief from the intense midday heat. This scene, depicted on wall paintings dating back to 2,500 BC, offers a glimpse into the enduring history of evaporative cooling. Other archaeological artifacts illustrate how the ancient Egyptians would hang reeds or wet cloths in their doorways and windows. As the wind blew across the damp fabric, the air temperature entering into their homes would become markedly cooler.
In fact, once you understand the principles of evaporative cooling, then you can look at ancient history with increased clarity. Evaporative cooling works on the principle that air flowing across water will gain water vapor and become cooler, providing relief to those on the other side. The peoples of antiquity obviously did not have electric cooling technologies, but they used architecture and design to channel the elements of evaporative cooling – air and water – to control the climate of their homes.
Ancient Architecture is Super Cool!
When we think of Arabia or ancient Persia, we conjure up a skyline of domes and turrets silhouetted against a burnt-sienna sky. This architectural style was not haphazard but an elegant system to channel the sweeping winds into the home. These turrets were called windcatchers, or bâdgir in Persian. They were tall, capped towers with a large opening on one side. This open side would face the prevailing wind, thus “catching” it, and bring it down the tower into the heart of the building to maintain air flow, thus cooling the building interior.
In another windcatcher system, the open turret would face away from the prevailing wind, and using principles of air pressure, the hot air would get sucked down an underground chute and then sweep across an underground canal, or qanat. The contact with water would cool the air, which would then be drawn up and out the house through the windcatcher. The effect of this constant flow of cool air was a decrease in the structure’s overall temperature. Evaporative cooling working its magic.
A similar cooling system operated in the Roman Empire. Wealthy aristocrats would divert aqueducts into their homes, using water and wind’s cooling powers to provide some means of air conditioning.
Meanwhile, in the Far East, an inventor living during the Han Dynasty in China nearly 2,000 years ago, constructed a three meter wide human-powered rotary fan with seven wheels to refresh members of the Emperor’s court. Five hundred years later the Emperor Xuanzong of the Tang Dynasty had a “Cool Hall” built in his palace. This adapted technology combined rotary fans, this time water-driven, with the effects of the spray from huge water-spewing fountains, producing the first air conditioning system with evaporative cooling.
Feeling the Winds of History
Evaporative cooling truly bears the weight of history. But at Quilo, it’s packaged into a nimble apparatus. Sleek and simple to use, you do not need to build turrets or engineer reservoirs and aqueducts. Just fill up the tank of the Quilo 3in1 with water, press a button, and feel the cool winds of history waft over you.