Ancient yakhchals were used to make and preserve ice in the deserts of Persia.
Yakhchals were the ancient ice-making structures used in Persia! Imagine, how difficult it would be to make ice when there is no electricity. These structures were constructed back in 400 BC and the giant conical structures could be used to collect ice. They used to make and collect ice during the colder days and it was used to preserve food or even for the preparation of faloodeh, a famous Persian frozen dessert.
The yakhchals were made up of spiral structures comprising wind towers and vents. While some had holes towards the bottom, the air kept flowing in the underground part of the structure, where ice was prepared and collected. The hot air used to make its way out from the holes present in the top.
It also had walls that kept the water shaded, in a bid to freeze faster. Even if there was ice brought from the mountains nearby, it could be stored here along with the food. The walls were both water and heat-resistant, as it was made using sand, clay, egg whites, goat hair, lime, and ash.
Some of these buildings were built so well that some of them stand even today. One of the yakhchals that still stands today is in Kerman, the capital city of Kerman Province, Iran. It is about eighteen meters high. But it is one of the rare surviving yakhchals. Desert storms eroded a lot of yakhchal buildings, especially the ones that were in the open in the desert regions. Also, ice that was formed in yakhchals was formed in the open and was often contaminated with dust which made it a health risk. Because of all of that, it slowly faded from use and was replaced with modern home and industrial refrigerators.