Yakhchals (lit., "ice pit") are structures used throughout Iran for storing ice, particularly in the hot arid region of the central plateau where their monumental mud-brick domes dominated the skyline of many towns and villages. As public buildings, yakchals provided insulated spaces for preserving the ice produced in winter to be used over the hot summer.
Although several historical yakhchals remain, none can be dated to before the Safavid period. However, historical sources attest to the extensive use of ice for conserving food and cooling drinks (water, sherbet or wine), indicating that it was a long established practice in Persia. Ice storing, Elisabeth Beazley suggests, might have been introduced by the Mongols from China, where ice houses operated since the eighth century BCE.
Although snow was occasionally stored in yakhchals, most ice was made by freezing water in nearby shallow pits filled with water from qanats (subterranean water channels) or streams. Water froze in the tanks when the temperature dropped to freezing over winter nights. In morning, the ice was broken and stacked in the ice tank, where it was insulated and kept dry.
A typical yakhchal consists of three main components: an ice-making pool (yakhband), a shade wall, and an ice tank. The ice-making pools were long rectangular shallow pits thirty to fifty centimeters deep and lined with baked bricks which rendered them waterproof. Along the south side of the pool was a tall tapering wall, up to ten meters high and stretching from east to west in order to provide shade from the sun during the day, thus accelerating the freezing process in night. The wall further protected the tank from wind, which can also hinder the freezing process. Most yakhchals, such as the one at Abarqu, comprised several parallel walls and pools. In order to provide further protection, some shade walls were curved or had walls attached to their east and west.
Two major types of ice tanks existed, each found in regions with specific climatic conditions; in the colder regions of the north and northwest, tunnel-shaped underground tanks are prevalent, while in the hot arid regions of the central plateau the circular domed ice-pit is the dominant form. The latter consist of deep pits, vaulted with conical domes (gunbad-i rok), measuring up to ten meters in diameter and fifteen meters in height. At the crown of some of the domes was a hole for ventilation (havakesh). The depth of the pit varied, depending on the amount of ice needed as well as the level of humidity and coldness required for preserving the ice. Some yakhchals were as deep as ten meters, such as the Khalili Yakhchal in Tehran. The pits were built with stone or mud mixed with straw, with a layer of an insulating material added. For the drainage of the melted ice, a narrow vessel or a well was built on the bottom of the storage area.
Yakhchals typically have two doors, one on the north side and one on the south. The north door was used in winter for stacking the ice into the tank, and then the doors were sealed when the tank was filled with ice. The bottom of the yakchal was accessed via a spiral stair. Yakhchals are chiefly built of unbaked mud-brick, or baked brick coated with mud plaster, which is the best available material and acts as a strong insulation. In the region of Yazd, shade walls are articulated with a series of shallow arched niches, which also helped the wall structurally. In some cases the interior walls are decorated with bands of brickwork.
Yakhchals were responses to the climatic condition of the settlements located on the fringe of the central desert of Iran, where water is scarce. No yakhhals can be found in the southern coastal region of Iran, where the temperature rarely drops below the freezing point. Most yakhchals are now derelict and in ruins, with the exception of those that have been renovated for tourism.
Beazley, Elizabeth. "Some Vernacular Buildings of the Iranian Plateau." Iran 15 (1977): 89-102.
Beazley, Elisabeth and Micheal Harverson. Living with the Desert: Working Buildings of the Iranian Plateau, 49-56. Warminster: Aris & Phillips, 1982.