Yakhchāl were ancient evaporation coolers with a dome shape above ground and subterranean storage space for ice, food, and other perishables. This effective method of storing ice in the middle of the desert may seem complex, but in reality, it was a simple technique that even the poorest could afford.
Exterior and interior (dome) of the yakhchal in Meybod
Exterior and interior (dome) of the yakhchal in Meybod, Iran.
Ice was collected during winters from the nearby mountains and brought to the yakhchāl, and most also had qanats (underground channels) to carry water from nearby sources
Rising to about 60 feet in height, the structure of the yakhchāl above the ground was a massive mud brick dome. Bellow the ground there was an empty space up to 5000 cubic meters with very thick walls, measuring at least 2 meters at the base. The walls were made out of a type of mortar called sarooj; a mixture composed of sand, clay, egg whites, lime, goat hair, and ash in very specific proportions. This mortar was resistant to heat transfer and it was also thought to be completely waterproof.
The structure often contained a system of windcatchers, which helped in bringing temperatures inside down to frigid levels during the summer.
Yakhchal near Kerman, Iran
Nishapur – Omar Khayyam MausoleumBy
Some of the yakhchāls that were built hundreds of years ago still remain intact. In present-day Iran, Afghanistan, and Tajikistan, the term yakhchāl is also used to refer to modern household refrigerators.