“A yakhchāl is an ancient type of evaporative cooler. Above ground, the structure had a domed shape, but had a subterranean storage space. It was often used to store ice, but sometimes was used to store food as well. The subterranean space coupled with the thick heat-resistant construction material insulated the storage space year round.” Wikipedia
“In most yakhchāls, the ice is created by itself during the cold seasons of the year; the water is channeled from the qanat (Iranian aqueduct) to the yakhchāl and it freezes upon resting inside the structure.”
“Sometimes equipped with a system of bâdgirs (ancient design of windcatchers or wind towers) that could easily bring temperatures inside the space down to frigid levels even in summer days… Bâdgirs catch the slightest breeze by the vents at the top and funnel the cooling air down through internal, vertically-placed wooded slats to the water or structure below. Alternately, the bâdgir can function as a chimney, expelling warm air upward to pull cool air in from a base opening…”