Cool roofs could have saved c250 heatwave deaths, claims UCL/Exeter study
1 Oct 2024
Nearly 250 lives could have been prevented during London’s record 2018 hot summer if the capital had made wide use of reflective colour roofs, claims joint research from UCL and the University of Exeter.
Using 3D computer modelling, the scientists assessed the technology’s likely impact for the period from June to August of that year.
Writing in Nature Cities, they calculated the average urban temperatures for the period, cross-checking this with actual measurements from the time. The teams then modelled the difference expected given three alternative scenarios.
These included models in which all London roofs had been coated in reflective colours, all had rooftop solar panels and a hypothetical, non-urbanised London.
Their data analysis suggested that, if light-coloured roofs been widely installed throughout London, it could have cooled the city by about 0.8°C on average. The researchers claimed this could have prevented the heat-related deaths of an estimated 249 people – almost a third (32%) of the 786 heat-related deaths that occurred in the period studied.
By comparison, rooftop photovoltaic solar panels would have cooled the city by about 0.3°C preventing an estimated 96 people across the city, or 12% of the heat-related deaths during that summer.
From June through August, the average temperature around London was 19.2°C, about 1.6°C warmer than average for that time of year.
The researchers also extrapolated the estimated economic impact of the heat deaths: Saving 96 lives using rooftop solar panels would have reduced the economic burden on the city by about £237 million; saving 249 people through use of cool roofs would have saved £615 million, stated the researchers.
Rooftop solar panel adoption would have an additional economic benefit, they asserted, producing 20 terawatt-hours (TWh) of electricity, more than half the energy usage of London during the entire year for 2018.
Lead author, Dr Charles Simpson (UCL Bartlett School Environment, Energy & Resources) said: “If widely adopted, cool roofs can significantly reduce the ground-level air temperature of a city. The resulting cooling effect across the city would save lives and improve the quality of life for residents throughout the urban area.”
Given that hot summers are expected to become more frequent due to climate change and the fact that around 83% of the UK population is urban based, the need to mitigate these effects will become more important, suggested Simpson’s co-author professor Tim Taylor of the University of Exeter.
He said: “The need for our cities to adapt to climate change is clear. Changing our roof spaces offers one potential solution. We need to encourage action like this, to reduce the burden of excess heat on people living in urban areas and capture potential co-benefits, including energy generation.”
The research developed as part of the HEROIC: Health and Economic impacts of Reducing Overheating in Cities project based at UCL and Exeter, and supported by Wellcome Trust and NERC.
Pic: Shutterstock (John Panella)
