Aiming to help its residents cope with rising temperatures, the city of Madrid is testing a new type of bus stop shelter. In addition to providing shade, the 'Natural Cooling' bus shelter can actually lower ambient air temperature for waiting passengers by up to 9°C (16°F). Developed and patented by JCDecaux, the units aren't equipped with energy-intensive air conditioning. Instead, they use an age-old technique evaporative cooling. As water evaporates, it absorbs heat from its surroundings and cools the air around it.In the bus shelter, hot air passes through a wet, honeycombed panel. The cooled air is then directed toward people seated on its bench. The self-contained system runs on solar power and harvests rainwater, which is stored in a tank. It only switches on when temperatures exceed 25°C (77°F), and someone pushes a button on the cooling panel. No mist is produced, avoiding health risks associated with inhaling microscopic water droplets.Madrid's municipal transport company, EMT Madrid, recently installed two of the shelters in Pavones and Villaverde Cruce. While JCDecaux announced the product in 2020, this is the first time it's being trialed in a public setting. The pilot project will allow JCDecaux and EMT Madrid, which operates 4,565 shelters throughout the city, to evaluate the concept's real-world performance. If successful, cooling shelters could be widely implemented, offering a tangible solution to urban heat challenges and providing residents with a bit of relief on sweltering days.