An ancient Persian cooling system can lower city heat by as much as 10°C

Can a 1k-year-old Persian cooling system provide relief to our heat-trapped cities? A network of underground water pipes and tubes inspired by Persian-era canals can lower surrounding temperatures by as much as 10°C using just air, water, and solar power, Bloomberg reports. The cooling system, modeled on ancient tunnels dug to bring water to agricultural fields 1k years ago in present-day Iran, is part of the CartujaQanat architectural experiment in Seville, Spain, which houses two auditoriums, green spaces, and a promenade.

How does it work? Water runs through an aqueduct outside overnight, taking it over solar panels on a roof and into giant tanks underground. Contact with the lower temperatures cools the water, and as temperatures rise during the day, solar-powered pumps push the water through small pipes that run in front of fans to generate cold air. Small openings in the floor and steps allow cool air to flow outward.

Special features ensure chillness: The design has features that ensure low temperatures even when the qanat system is not operating such as being built two meters underground, covering the area with a white heat-reflecting roof, and surrounding it by columns and vegetation.