When we think about how the refrigerators, which are indispensable for preserving food, invade our homes today, the origin of the freezers is actually quite recent. The first domestic refrigerator was invented in 1813. However, when we put aside the mechanical mechanisms, these modern devices that involve using electrical power and focus on the fact that food needs to be stored for a long time, we can see that low temperatures or cold environments were known thousands of years ago to prevent food from spoiling.
The structures called Yakçallar, built during the Persian Empire and still standing today, are a shining example of this legacy of wisdom. Built around 400 BC, these structures were used to prevent melting ice and to preserve food in the hot Persian deserts, thousands of years before the discovery of electricity.
Characteristics of Yakcallar and Cooling Process
Reaching a height of approximately 18-20 meters, Yakçallar gives the impression of a gigantic dome. The walls of Yakçallar, which was built using mud produced with a special mixture, were also built with very thick bricks made of the same material. In addition, these structures have underground areas with a capacity of 5 thousand cubic meters, and the walls of these areas have a thicker structure than the walls on the surface. This thickness of the mud walls can reach the bottom of Yakçal.
We call the special mixture used in the construction of yakcals “sarooj”. It is known that the sarooj mortar, which is unique to the Persian culture, contains sand, clay, egg white, lime, goat hair and ash. Sarooj, which is obtained by combining these materials, is resistant to water while keeping the heat inside out. For gigantic refrigerators, a better option could not be imagined.
Yakçallar can be considered to have a complex structure due to the basic principles underlying them to offer an effective solution against desert heat. However, the working principles are quite simple. Ice plays an important role in the cooling process. Ice can be obtained from storage tanks where rainwater is collected, or through underground tunnels where it is frozen at night.
In addition to the cooling process, the yakcals also have the task of providing air circulation inside. This cycle is carried out with a structure similar to the system of the Persian windbreaks. Basically, it is based on the logic of evacuating the hot air inside the building and thus ensuring circulation, keeping the inside cool.
Some of these structures, which were built thousands of years ago, are still standing and untouched. In Iran, Afghanistan, and Tajikistan from the lands ruled by the Persian Empire, you can see such huge cold storage structures called “yakchal”.
