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Summer in the city can be a cooler experience

While building experts have long known that cities are warmer than surrounding countryside – the urban heat island effect – little evidence existed on what causes it and how to counter it until pioneering work by Professor Maria Kolokotroni.

Her detailed 18-month study across 78 locations in London proved conclusively that poor roof design was the major contributing factor. This leads to increased heating costs in the winter but also much greater use of air conditioning in the summer, which further adds to the heat island effect.

Unnecessary heating and cooling increases energy use, leading to higher carbon emissions and so contributing to global warming. Prof Koloktroni concluded that ‘cool roofs’ technology – materials which reflect solar radiation and release the heat a building absorbs during a summer day, would be the only effective counter measure.

Her studies showed that widespread use of such systems would reduce the temperature in buildings using them by 2.5C – reducing energy demand by as much as six or seven per cent. Such large potential savings in a city’s carbon footprint caught the attention of policy-makers in the UK’s capital governing body – the Greater London Authority.

This in turn fed into the Climate Change Adaption Strategy for London which states that ‘the Mayor will work to….promote cool roof technology in London to reduce the demand for mechanical cooling’.

This rapid acceptance of the professor’s work has been mirrored by policy makers across the EU, informed by the Brunel-led European Cool Roofs Council which brings together policy-makers, industry and building services engineers to promote the technology in large cities, Europe-wide.