A yakh-chāl is an ancient natural refrigerator.

The subterranean domed structure often stored ice in it, but sometimes was known to keep food material in it as well.

Ice from nearby mountains was brought in during the cold seasons, and stored there for use during the summer months. This ice was from the ancient times used for the making of the traditional Persian ice cream.

The subterranean space coupled with the thick heat resistant constructing material kept the outside heat from reaching the interior space year round.

These stuctures were mainly built and used in Iran. Many remain standing that were built hundreds of years ago.

In 400 BC Iran, Persian engineers had already mastered the technique of storing ice in the middle of summer in the desert. The ice was brought in during the winters from nearby mountains in bulk amounts, and stored in specially designed, naturally cooled refrigerators, called yakhchal (meaning ice storage). This was a large underground space (up to 5000 m³) that had thick walls (at least two meters at the base) made out of a special mortar called sārooj, composed of sand, clay, egg whites, lime, goat hair, and ash in specific proportions, and which was resistant to heat transfer. This mixture was thought to be completely water impenetrable. The space often had access to a Qanat, and often contained a system of windcatchers that could easily bring temperatures inside the space down to frigid levels in summer days. The ice was then used to chill treats for royalty during hot summer days.

See also

• Iranian architecture
• Ice house
• Traditional water sources of Persian antiquity
• Qanat
• Kariz

Cooling technology | Iranian architecture

Yakhchal