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<\/div>If London\u2019s roofs were white, it would help keep the city cool in a heatwave<\/p>\n
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Painting rooftops white or covering them with a reflective coating is the best way to reduce air temperature in a city like London during a heatwave. These \u201ccool roofs\u201d should perform better than solar panels, green roofs or adding more trees at ground level.<\/p>\n
Oscar Brousse<\/a> at University College London and his colleagues ran climate simulations to see how London\u2019s temperature during the two hottest days of summer in 2018 would have changed if the city had made widespread use of cooling measures, from cool roofs to air conditioning, along with solar panels, which have a cooling effect. Temperatures that summer peaked at 35.6\u00b0C<\/a> (96.1\u00b0F).<\/p>\n Cool roofs outperformed all other interventions, the team found, lowering average outdoor temperatures in the city over the two-day period by 1.2\u00b0C, and by as much as 2\u00b0C in certain locations. By comparison, additional tree cover only curbed air temperatures by about 0.3\u00b0C, while solar panels lowered temperatures by 0.5\u00b0C.<\/p>\n The study also found that widespread use of air conditioning might keep internal temperatures cool<\/a>, but would boost outdoor air temperatures by up to 1\u00b0C in parts of central London. \u201cFor London, what worked the most for reducing outdoor temperatures at a pedestrian level was the cool roofs,\u201d says Brousse.<\/p>\n <\/p>\n Although the study uses only two days of data for the simulations, Brousse says it is broadly in line with similar published research<\/a>.<\/p>\n Installing reflective coatings, or lightening roof surfaces across the city, would be a relatively easy and low-cost climate adaptation, says Brousse. \u201cI think, actually, this is probably the most easily deployed intervention of all,\u201d he says. \u201cI see barely any reason not to start doing it widely.\u201d<\/p>\n There are reasons beyond cooling to deploy other technologies too, he says. Trees and green roofs<\/a> can boost biodiversity and resident well-being, for example, while solar panels provide clean power.<\/p>\n