A Fresh Take on Urban Cooling: Rainwater Harvesting Shows Promise in New Study

Extreme Heat: Researchers Find New Way to Cool Urban Areas

According to НВ — Техно: As heat waves become more intense in many parts of the world, cities are searching for affordable cooling strategies. On August 6 at 19:00, University of Manchester scientists presented findings on a method that collects rainwater from rooftops and then uses it to spray buildings during hot periods. The approach, modeled in Tokyo, showed meaningful drops in urban temperatures, less pressure on electricity systems, and lower heat output from air conditioners.

The results were published in the journal Earth's Future. To assess the system-which stores rainwater and automatically irrigates roofs-the research team used numerical modeling and AI, with Tokyo as the test case. According to lead author Dr. Zhonghua Zheng:

"What matters most is not the size of the water tanks or how much water is used; the crucial factor is when the sprinklers are activated."Dr. Zhonghua Zheng

Cooler roofs mean less heat reaches interiors, reducing reliance on air conditioning. That, in turn, lowers the total heat released in large cities, especially during the hottest years. The study also found that excessively large water storage tanks offer only slight extra gains, since leftover water tends to sit on the roof surface rather than evaporate.

The Benefits: Why Rainwater Cooling Matters

The same rainwater harvesting technique can also lessen the chance of extreme urban flooding during heavy storms, an important issue as the climate changes. The findings suggest that using harvested rainwater to cool cities could be a valuable response to global warming.

For cities dealing with higher temperatures and rising energy demand, this approach offers a practical option. It supports both temperature control and water resource management, particularly in urban environments where flooding is becoming more common. Given climate projections, creative solutions like this one may become essential for building future-ready cities.