Yakhchal: The Indigenous Fridge of Middle-East

Yakhchāl in a desert, Iran. (Jeanne Menjoulet / Flickr)

Around 400 BC, Persians had invented a cooler that enabled them to store ice year-round. This cooler goes by the name of yakhchāl, which is a Persian word comprising of two words, ‘yakh’ meaning ice, and ‘chāl’ meaning pit.

The structure of yakhchāl is divided into two parts, one above the surface and one below. Above the surface, the yakhchāls could rise up to a height of 18 meters. From a distance, Yakhchāl looks like a mud-brick, domed-shaped structure. The storage space is situated beneath the surface.

As far as the volume is concerned, the yakhchāl provided an ample storage space of about 5000 cubic meters. People used this for storing ice, water, and even perishable items including vegetables and fruits. Once the water was added to the yakhchāl, it froze due to the low temperature inside.

How does Yakhchāl work?

Inside yakhchāl. (Jeanne Menjoulet / Flickr)

The main reason why yakhchāl worked so effectively lies in its design, which is based on aerodynamics. The yakhchāl is designed to be conical in structure with a hole at the top. This hole allows the cold air to enter the yakhchāl and pave its path all the way down to the bottom. The conical architecture of the yakhchāl allows the hot air to rise up to the top and exit, maintaining a cooler environment inside. 

The materials used for the construction of yakhchāl also plays a major role. The walls of the ‘desert cooler’ were made up of insulating materials. A traditional mortar called sarooj, prominently used in Iranian construction, was used in these coolers. Sarooj is made by mixing clay, sand, lime, egg whites, ash and goat hair in a fixed proportion. This special mortar provided ultimate insulation to the cooler.

In some cases, a wind catching towers were used to direct the wind inside the yakhchāl. Moreover, the storage space was surrounded by walls as thick as 2 meters and was cleverly located below the surface.

Wind catching tower. (Diego Delso / Wikimedia Commons)

During winter, people gathered snow from the nearby mountains and bought them to the yakhchāl. In case this was not a feasible option, water was directed to it through nearby groundwater pools or springs via ‘qanāts’. 

Qanāt refers to a system of transporting water from underground water sources through a gradually sloped channel.

The inventors of this marvel understood the importance of water. As a consequence, trenches were made at the bottom to capture the ice that might have melted into the water during the day. At night, this captured water froze again due to the drop in temperature. This created a cycle that maximised efficiency while minimising the environmental impact.

But, perhaps, the most distinctive feature of the yakhchāl doesn’t lie in its capabilities, but, in its accessibility. It is said that the yakhchāl didn’t only cater to the needs and luxuries of royals but was accessible to everyone.

It is kind of disappointing to see this incredible structure in such a deplorable state. While most of the yakhchāls have not been able to withstand the ravages of time, some of them are still very well preserved and can be found across middle-eastern countries.

While the use of yakhchāl has seized in modern times, the legacy still carries on, yakhchāl is now used to refer to modern day refrigerators.

Fact Analysis:
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• Ancient Technology
• Qanat
• Windcatcher
• Yakhchāl