White roofs: The simple trick cities and homeowners are using to beat the heat

Cities and homeowners are increasingly turning to "cool roofing," a centuries-old technique of painting rooftops white, to combat the escalating heat of summer.

This method, which involves applying a layer of white paint, is gaining traction due to its low cost and straightforward principle: lighter surfaces reflect more heat. As urban heat islands intensify with climate change, this strategy offers a tangible way to lower ambient temperatures. A study published in July 2024, led by Oscar Brousse of University College London, found that white roofs could "reduce outdoor temperatures by an average of 1.2 degrees Celsius" in urban areas.

“

With climate change, big cities are facing a major public health challenge: how to break the "heat island" effect whereby thermal energy accumulates in roofs, walls, roads, making life impossible?

Brousse, a researcher, highlighted the critical challenge cities face in mitigating the "urban heat island effect," where heat accumulates in buildings and infrastructure, making city life unbearable during heatwaves. The "cool roofing" technique directly addresses this by reflecting solar radiation instead of absorbing it, thereby lowering surface and air temperatures. This approach is being adopted by various entities, from large commercial buildings to individual homes, as a practical response to increasingly severe heat events.

“

reduce the outdoor temperature by an average of 1.2 degrees Celsius