Painting roofs white or covering them with a reflective coating is a more effective way to cool buildings in cities like London compared to vegetation-covered ‘green roofs’, University College London (UCL) researchers have said.

As the climate changes, residents within cities are particularly vulnerable to warming temperatures. Cities generally trap heat, inducing the urban heat island effect that can lead to greater discomfort and mortality for residents during hot spells.

The study used a three-dimensional urban climate model of Greater London to test the thermal effects of different passive and active urban heat management systems, including painted ‘cool roofs’, rooftop solar panels, green roofs, ground-level tree vegetation and air conditioning during the two hottest days of the summer of 2018 – the warmest on record.

Previous research using satellite data has found that rooftop gardens and greenery can help to alleviate severe heat in cities.

But research from the UCL team showed...