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Green roofs

27 October 2007

Cardiff University research has found that buildings green with vegetation can reduce the temperature of cities.

The Welsh School of Architecture research found that leafy walls and roofs could help people turn down the air conditioning on hot days, saving huge amounts of energy.

Head of School, Professor Phil Jones and PhD student Eleftheria Alexandri used computer models to compare the impact of "greening" buildings in nine cities, including London, Mumbai, and Brasília.

Using temperature data from each city's warmest month, the research highlighted in New Scientist, found that the air around every building would be cooler by up to 11 °C with green walls and roofs. The hotter the climate, the greater the cooling effect.

Professor Jones said: "Greening buildings will not only make cities more comfortable to live in, but could also save energy by significantly reducing the demand for air-conditioning on hot days."

The idea is already popular in Switzerland, where roofs covered in alpine plants that require little soil are becoming increasingly common.