2,400-year-old refrigerator stores ice in hot summer

Ancient Persian engineers created a refrigerator that used no electricity and could preserve ice and food in the scorching desert all summer long.

A yakhchāl structure in Yazd, Iran. Photo: Wikipedia.

In the arid deserts of the Persian Empire, ancient engineers developed sustainable technology that could store ice throughout the scorching summers as early as 400 BC, long before the advent of electricity, according to Vintage News.

The yakhchāl is an ancient cooling device that is tall and hollow, and the space inside the yakhchāl was used to store ice, food, and other perishables. This method of keeping cool in the extreme desert temperatures was simple enough that even poor families at the time could use it.

Ice was collected from nearby mountains during the winter and stored in yakhchāls. Most of these "refrigerators" had their own underground water channels underneath to bring water from nearby rivers and streams.

The space inside the yakhchāl has a capacity of 5,000 m3. Photo: Wikipedia.

Standing an average of 18 metres high, the yakhchāl is a dome-shaped structure made of mud that soars high above the ground. Inside the structure is a space that can hold up to 5,000 cubic metres, with walls at least two metres thick. The walls are built from a mortar called sarooj, a mixture of sand, clay, egg whites, lemon, goat hair and ash. All the ingredients are mixed together in certain proportions to create a mortar that acts as an insulator and is even completely waterproof.

This outdoor refrigerator has its own ventilation system to keep the interior cool in the summer. Some yakhchāls built hundreds of years ago are still standing. Today, in Iran, Afghanistan, and Tajikistan, the term “yakhchāl” is still used to refer to modern household refrigerators.

According to VNE