According to a study, painting London's rooftops white or other reflective colors could prevent hundreds of deaths during the city's sweltering summers.According to the research, covering the capital's roofs with solar panels could potentially help reduce heat-related deaths, albeit somewhat. It would also produce a significant amount of clean energy for the city. Using computer modeling, researchers from the Universities of Exeter and College College London (UCL) examined the effects of "cool roofs," or roofs painted white or other reflective colors, on London's temperatures during the city's warmest summer ever in 2018.These light-coloured roofs, commonly found in hot countries, absorb less radiant energy from the sun than traditional dark roofs.

The researchers examined their cooling effects in summer 2018, when there were an estimated 786 deaths in Greater London in June, July and August attributable to the heat, as temperatures averaged around 19.2C, or 1.6C above average for the time of year.

They found that if all London’s rooftops were cool roofs it would lower average outside air temperatures by 0.8C, and if all of them were covered in solar photovoltaic (PV) panels, which absorb some of the heat to convert to electricity, temperatures would be down 0.3C.They estimated that 249 deaths could have been avoided with full coverage of cool roofs, around a third of those who died from the heat in 2018.

And if all roofs carried solar panels, 96 deaths could have been avoided, and the solar PV could generate up to 20 terawatt hours of electricity, more than half of the total London used in the whole of 2018.The lives saved by the cool roofs would have reduced the city’s economic burden by around £615 million, and those saved by the solar PV would have reduced it by around £237 million, the researchers said.

They also said that if 2% of buildings had solar PV and the rest were cool roofs it would have saved 248 lives and generated up to £146 million worth of clean electricity.

Lead author Dr Charles Simpson, from UCL, 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.”

He added: “Solar panels have great benefits as a source of renewable power, so it’s good to see they won’t make the city hotter.”

The need for our cities to adapt to climate change is clear. Changing our roof spaces offers one potential solution.

Co-author Professor Tim Taylor, of the University of Exeter, said: “The need for our cities to adapt to climate change is clear.

“Changing our roof spaces offers one potential solution.