Recycled materials could help pave the way to urban cooling

Crumbled rubber and recycled aggregates could be used to produce pavements that help reduce heat absorption as part of a plan to stop temperatures going through the roof in our sweltering summer cities.

Speaking about plans to tackle London’s urban heat island effect, the city’s Mayor Ken Livingstone compared the capital to a storage heater that sucked up heat during the day and released it at night.

During heat waves this not only makes life sticky an uncomfortable as people do not get a chance to cool down, but also poses a serious health risk and a noticeable spike in death rates among the elderly and infants.

Research funded by the Greater London Authority which sought to monitor the problem and suggest possible solutions found that at the peak of the 2003 summer heatwave the temperature in the city centre was a staggering nine degree celcius higher than in the rural greenbelt outside the capital.

Previous estimates had put the figure nearer four of five degrees.

Mr Livingstone told edie there was no quick fix for this problem but action needed to be taken now to reduce the future impact of the problem as the effects of climate change intensify.

“I suspect there isn’t a great deal that can be done in the short term and we need long term solutions,” he said.

“[But] the reason we’re in this situation now is because nobody was thinking about it ten years ago.”

He added that there was a particular urgency as previous climate change models had assumed the UK was essentially rural and had failed to take into account the additional warming effect experienced by cities.

Recommendations made by the research team – made up of academics from a number of universities as well as professional environmental consultants – included an extensive tree planting programme, the promotion of ‘green roofs’ and paving that could help to cool the city rather than turn it into an oven.

Alex Nickson, a policy officer for the Greater London Authority, told edie that laying new pavements and replacing those that needed repairs with alternative materials could have substantial environmental benefits as well as boosting the market for recycled materials.

“You have three big wins,” he said.

“Using crumbled rubber and building aggregate not only puts recycled materials to better use but also reflects the heat rather than absorbing it as traditional materials do and it is more permeable which means less run off when it rains, helping to conserve water.”

Professor Glen McGregor, the King’s College academic leading the project, told edie: “The different institutions have different expertise so [the consultancy] ARUP has been doing some modelling on the causes of the urban heat island and looked at some of the aspects of climate change while King’s College has been looking more generally at the nature of heat islands and at who might be vulnerable in terms of health impacts.

“Brunel University and the University of Arizona have been mapping urban heat islands with a mixture of traditional observations and satellite imagery and the London School of Hygiene & Tropical Medicine has been looking at the health factors.

The research will be used to shape policy in a number of areas, said Mr Livingstone, and is an important first step in understanding the relationship between London’s microclimate, development and perdicted changes to our climate.

Sam Bond

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