Why painting roofs white can save lives in heatwaves

THOUSANDS of deaths in heatwaves each year could be prevented by painting roofs white, research has suggested.

Cities can heat up by an extra nine degrees centigrade compared to rural areas in an effect called the ‘urban heat island’.

But painting roofs in colours that reflect light can keep buildings significantly cooler.

Experts calculated how many people lose their lives during long, hot spells compared with how many would die normally. The 2003 heatwave is thought to have caused 2,000 deaths in England while a four-day spell of heat in July 2009 killed 300.

The Oxford University study said the ‘heat island’ effect is caused partly by a lack of moisture and vegetation in cities compared with rural areas.

Materials used in urban buildings also store up more heat.

The scientists calculated how much it would be possible to cut temperatures in Birmingham with white roofs after simulating heat levels seen in the summers of 2003 and 2006.

The study, published in the journal Environment International, suggested peak daytime temperatures could be cut by up to 3C during a heatwave.

Around half of the commercial and industrial buildings in the city would have to paint their roofs white to achieve this reduction.

It could potentially offset around 25 per cent of temperature-related deaths, say the researchers. Applied worldwide, it may lead to thousands of deaths being avoided.

Study co-author Dr Clare Heaviside, of Oxford’s Environmental Change Institute, said: ‘Climate change and increasing urbanisation mean that populations are likely to be at increased risk of overheating.’

‘Increasing urbanisation’