Ice in a desert summer had a winter supply chain. Iranian icehouses, called yakhchals, stored ice collected from shallow outdoor pools after cold winter nights. Straw and thick walls slowed heat reaching the ice through the warmer months.

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• ✓iranicaonline.org
• ✓jfa.arch.metu.edu.tr

In Iran’s desert, a mud-brick dome kept ice through summers that could climb above a hundred degrees Fahrenheit. But the ice wasn’t made inside the building. Workers filled a shallow pool beside it. On clear winter nights, the water lost heat to the sky and froze. A tall wall shaded the pool from the morning sun. They broke the ice into pieces and carried it into an icehouse called a yakhchal, storing it in a deep pit beneath the dome. Straw separated the layers. Thick adobe walls and insulation slowed the heat reaching the stored ice as winter turned into summer. Engineers modelled the Meybod icehouse and found that, with a full store in January, about eighty percent of the ice could remain by September. That surviving ice had customers. In Isfahan, sellers carried blocks to the bazaar. Shops used ice to chill drinks and fruit. Travelers reported that ordinary people could afford it, too. They were selling winter by the block—in the middle of summer.