As early as 400 BC, Persia built an ancient architectural style called Yakhchal to store ice in the desert. Yakhchal, “Yakh” means “ice” and “chal” means “pit”. It literally means ice pit.

These dome roof refrigerators are generally widely used in central and eastern Northern Iran. The ice pit serves not only the upper class society, but also the public. The weather here is very H๏τ during the day, and the ice from Yakhchal helps Persians to alleviate the heat in summer.

Yakhchal consists of several parts. First of all, the vent at the top of Yakhchal allows cold air to enter, all the way down to the bottom of the underground storage room, and also exhausts relatively warm air(Figure 2). The exterior of Yakhchal will also be equipped with wind catchers and wind towers to keep the temperature cool

Then, from east to west is the shading wall(Figure 3). Normally, the maximum height of the wall is 10 meters, and the length is 5-12 meters. The walls have to be 2 meters thick to keep the inside temperature as extremely low as possible. Inside Yakhchal, a storage space will be dug underground to store ice and food.

And there is a basin next to the shading wall(Figure 3). Water is led up by qanats (underground aqueducts), which will guide the water(melted snow) from the mountain to the basin (40-50 centimeters depth) and the underground storage area in Yakhchal (6 meters depth) .

The water that is channeled into the underground storage area of Yakhchal will be frozen by the low temperature at night. For the water in the basin, water will also freeze at night. The villagers gathered together in the morning to break the ice from the basin and take the ice to Yakhchal for storage. This process usually lasts eight days and nights, and villagers should do this because it is a traditional ceremony.

In the last step, ice was covered with straws and brushwood, and the entrances was closed with sea sedge. In summer, there will be a ceremony to open the entrance, and then everyone can benefit from the ice pit.

Also,Yakhchal was able to store ice because it had special walls. The walls are made of a unique material called Sarooj. Sarooj is made of sand, clay, egg whites, lime, goat hair and ashes. The ash acts like an insulator.

There are 2 entrances to enter the Yakhchal. One is used for transporting ice, and there will be a slope leading to the bottom to transport the ice to Yakhchal in winter. This entrance is almost used in winter. The other entrance is used in summer. This one has a staircase for people to take ice. Villagers will take ice from Yakhchal to keep their food, fruit, sherbets and faloodeh cold.

In addition, villagers will take large pieces of ice from Yakhchal and transport them to the province by donkey for sale. However, Yakhchals’ ice is not clean as the ice we eat today. Ice is formed in the desert, so it is often polluted by dust and soil.

Moreover, the vent at the top of Yakhchal will be damaged due to rain and solar radiation, so the Persians will use a material called adobe to repair the vent every year(Figure 5). Before the 1960s, Yakhchal was still in use, and since then, Yakhchal has been phased out.

Yakhchal’s magic is to keep the temperature low throughout the H๏τ summer to prevent the ice from melting. As we have seen in the cities of Kerman and Orumie, some Yakhchals have been restored to show visitors the creativity and smartness of Persia thousands of years ago .

Persian engineers at that time have shown us their magic and great creation. However, it is mentioned here that not only Persians but also Chinese can store ice. As early as 700 BC, during the Tang Dynasty and Qing Dynasty, ice was put into copper boxes to refrigerate fruits. The copper box can keep the food cold. And holes are designed on the copper box to allow some cold air in the box to be emitted and keep the room cool.

Finally, based on the above understanding, the ancient method of making ice was difficult and the ice was not clean. Nowadays, with the progress of the times, it is relatively easy for us to get the ice. We can buy sonic ice in convenience stores, or there are ice makers in the market. Ice makers can let us enjoy clean and fresh ice at any time.