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Iranian Ice Houses Were Early Refrigerators

Credits: ©2013 Solaripedia

A Persian ice house, or yakhchal, is an ancient passive refrigerator allowing the storage of ice in the deserts of Iran. Ice was collected in winter and stored in the ice house where it was kept cool in summer by the domed shape and thick walls made from a special mud called srooj, composed of sand, clay, egg whites, lime, goat hair, and ash, which was resistant to heat transfer. Ice-houses are believed to have been used in Iran as early as two thousand years ago (although textual archaeological evidence dates only to the 17th century) and have been employed as recently as 50 years ago.


Ancient Ice House of Iran 17th Century

During the winter, ice and snow would be stored in an Iranian ice house and packed with insulation, often straw or sawdust. It would remain frozen for many months, often until the following winter, and could be used as a source of ice during summer months. ©2007 Basheem

The traditional yakhchal were built at villages on the perimeter of the large deserts on the Central Plateau. Their cone-shaped domes, up to 20 meters high, cover a large open pit for ice storage. The dome is constructed of mud and mud bricks from the excavation of the deep ice pits. An opening at the apex of the dome allows any heat or moisture to escape, and the deep pit uses the ground to moderate the temperature. The ice was either hauled in from nearby mountains or lakes, or produced in open basins at the ice house site.

Such local ice production plants were typically supplied with fresh water from qanats, the ingenious water supply tunnels that brought water for human settlements and irrigation from the distant mountains. A qanat is a series of well-like vertical shafts, connected by gently sloping tunnels to create reliable delivery of water for human settlements and irrigation in hot, arid and semi-arid climates.

For local ice production, the qanat feeds a long, shallow channel dug on the north side of the ice house; an east-west wall shades the channel to make the ice form more quickly. During winter, water would fill the channel and freeze during the night. Before the sun rose, the ice that had formed would be broken and collected and moved to the ice house. This was repeated each night until there was enough ice to last the next summer. Then the ice was stored and packed with insulation such as straw or sawdust in the naturally cooled yakhchals. It would remain frozen for many months, often until the following winter, and could be used as a source of ice during summer months.

In many ice houses, the large underground spaces with thick insulated walls were also cooled via wind towers that draw cool subterranean air up from the qanat to maintain lower temperatures inside, even during hot summer days. As a result, the ice melted slowly and was available year-round.

The ice houses have gradually become obsolete with the advent of electricity and the introduction of the electric refrigerators. Because they were made of perishable materials, most of the ice houses have disappeared and the rest are facing a grim future.

More than a hundred ice houses can be found all over Iran, but they are disappearing. Engineer Hemming Jorgensen researched and catalogued Iranian ice houses in 2010 and found, registered and mapped 129 ice house sites, including domed (111 examples), walled (6) and underground ice houses (12). They were situated at villages (104), at towns (13), and at caravansaries or forts (12). Of the total of 129 ice houses, 71 have or had an associated open-air ice-making plant, and 58 were simply storage facilities.