As global temperatures rise, cities like London are facing a growing problem: the urban heat island effect. Concrete buildings, asphalt roads, and underground infrastructure trap heat, creating a microclimate significantly warmer than surrounding rural areas. This trend is expected to worsen, with average summer temperatures in London projected to increase by 5.4 degrees Fahrenheit by 2050.
But there might be a simple solution: painting rooftops white. According to a new study published in the journal Geophysical Research Letters, widely adopting “cool roofs” – either painted white or covered with a reflective coating – could reduce London’s outdoor temperature by an average of 2 degrees Fahrenheit, reaching up to 3.6 degrees Fahrenheit in some areas.
The study, conducted by researchers at University College London, compared the effectiveness of various cooling strategies, including rooftop solar panels, green roofs, extensive street vegetation, and even air conditioning. While other interventions like solar panels and street vegetation did provide some cooling, they weren’t nearly as effective as cool roofs. Surprisingly, air conditioning, though effective in keeping dwellings cool, actually increased outdoor temperatures in central London by up to 1.8 degrees Fahrenheit.
The researchers, using a 3D computer model of London, ran climate simulations for the hottest days of summer 2018, finding that cool roofs provided the most significant cooling effect. While the study acknowledged limitations, such as focusing only on outdoor temperatures and not factoring in the costs and benefits of other interventions, they emphasized the potential of cool roofs to alleviate the urban heat island effect in London.
This research highlights the importance of innovative solutions to combat the growing threat of climate change, particularly in urban areas. Painting rooftops white could be a simple yet effective way to cool cities and mitigate the negative impacts of rising temperatures.
