About 87% of all U.S. homes are equipped with air conditioners, and air conditioning accounts for 12% of residential energy use. Besides the fossil fuels that power them, many use refrigerants to cool the air, which can be potent greenhouse gasses if released.

But people from Ancient Egypt to the Persian Empire have been beating the heat for millennia without AC. Their solution, the “wind catcher,” could help considerably in the quest for emissions-free cooling.