Ice Storage

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"In 400 BC 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 large quantities, and stored in specially designed, naturally cooled refrigerators called yakhchal (meaning ice pits). A large underground space with thick insulated walls was connected to a qanat, and a system of windcatchers was used to draw cool subterranean air up from the qanat to maintain temperatures inside the space at low levels, even during hot summer days. As a result, the ice melted slowly and ice was available year-round."