How it began
Yakhchals, a name that means "ice pit" in Persian, came into use in Persia around 400 BCE, according to Atlas Obscura and other popular accounts. They met the need for ice all year in a desert climate where summer days can pass 40 degrees Celsius. The structures were used through the Achaemenid, Safavid and Qajar eras. Surviving examples stand at Meybod in Yazd province, at Kerman, at Abarkuh and at Kashan.
Before it existed
Ice houses that store natural ice and snow gathered in winter have existed in many countries, and in Iran ice was also brought down from nearby mountains. What set the Persian ice house apart, according to Archaeology Now, was that the ice was made on the spot in the desert, at air temperatures that could be above freezing.
How it works
Beside the dome lay shallow pools shaded by tall walls so that they stayed cool by day. On clear winter nights they were filled with water, which lost heat by radiation to the night sky and could freeze even when the air was slightly above freezing. The ice was harvested before sunrise and stacked in a deep pit under the dome, in layers separated by straw. Hot air rose to the top of the cone while the coldest air stayed at the bottom. The walls, up to two meters thick at the base, were made of sarooj, a mortar of sand, clay, lime, ash, goat hair and egg whites.
What changed first
Stored ice lasted until the end of summer. It was used to preserve food, to chill drinks such as sharbat and to make faloodeh, a frozen dessert of thin noodles and syrup. Ice was sold in bazaars and delivered to wealthy homes, and large ice houses in cities like Yazd and Kerman were signs of prosperity and patronage. Some stood beside caravanserais for travelers.
Where it stands today
Of the hundreds of yakhchals that once existed, many now lie in ruins. Well-preserved examples include the Moayedi ice house in Kerman and the one near Narin Castle in Meybod. In modern Persian, yakhchal is the ordinary word for a refrigerator. Writers on building design cite the structures as examples of passive cooling without electricity.
