Nature-based cool pavements for urban overheating mitigation: Experimental proof of concept

Global warming is leading to more frequent and intense heat waves, transforming urban areas into inhospitable environments, particularly during the summer, due to the exacerbation of the urban overheating effect. Outdoor pavements, which account for 20–40 % of urban surfaces, play a crucial role in this phenomenon due to their dark colour and low albedo, resulting in high surface temperatures and the accumulation of thermal energy released into the environment. This study introduces a nature-based solution to mitigate the impact of urban overheating by cooling outdoor pavements using water from existing fountains or ponds in cities. The water functions as a coolant, significantly reducing the surface temperature of the pavement by up to 25 °C compared to dry samples exposed to the sun. The innovative aspect of this concept lies in the fact that the pavements do not exhibit capillarity, thereby achieving sensible cooling without evaporation and subsequent water consumption. The concept's impact is examined by considering pavements of varying thicknesses and albedos. In the conducted experiments, water-cooled pavements 100 % eliminated the risk of overheating compared to air temperature. This strategy offers an effective and sustainable approach to counteract the adverse effects of urban overheating in cities.