PAINTING ROOFS PROTECTS FROM HEAT

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 the Sun can keep buildings significantly cooler, scientists found. The Oxford University study said the ‘heat island’ effect is caused partly by a lack of moisture and vegetation in cities compared with rural landscapes.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 suggested that introducing cool roofs across the city could reduce peak daytime temperatures 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 during a heatwave, claimed the researchers. Applied worldwide, it may lead to thousands of deaths being avoided.

The urban heat island effect is most pronounced at night because buildings slowly release stored heat at that time. However, the biggest benefits of cool roofs were seen during the hottest part of the day where sunlight was reflected away.

Study co-author Dr Clare Heaviside said: ‘Climate change and increasing urbanisation mean that future populations are likely to be at increased risk of overheating in cities. Building interventions have the potential to reduce this risk.