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Livechat summary: Murcia's experience in cooling down cities with a new type of asphalt

Updated: Oct 18, 2018

Summary of the livechat led on Convercities by Jaime Ruiz Huescar, e-mobility manager of Murcia (Spain) and Ignacio Garcia Legaz from the Building Technological Center of the Murcia region on July 6th, 2018.

The “urban heat island effect” refers to the pockets of intense heat captured by the concrete, asphalt, dark roofs and the dearth of foliage. It will worsen in the future: climate models suggest that some cities could see roughly three times as many extreme heat days by 2050, which is a bit of a problem.

To lower the temperature and reduce energy consumption from cooling equipment, cities can of course plant trees, but some city officials are exploring innovative ways to cool down their atmosphere. A new type of asphalt tested in Los Angeles has been proved to lower the road temperature by as much as 5.5°C (10F) compared to black asphalt, drawing the attention of cities in China, Australia, Saudi Arabia and Israël. Murcia, Spain, is the European lab for a similar new kind of solar/heat reflective pavement.

Ignacio Garcia Legaz is the coordinator of the EU funded project "Heatland" which develops a new type of pavement with an albedo (reflecting power) of 0.46, vs. 0.05 for traditional ones. This 3-year project has been financed by the European LIFE Call - Life Climate Change Adaptation, a 2014-2020 €3.4 billion program.

Reflecting solar rays thanks to a slightly white material should enable to reach an air temperature decrease of 1.5ºC and a temperature decrease of 10ºC on the surface of the road. The expected energy savings for refrigeration devices amount to 7%. The higher reflective power should also enable cities to lower street lighting electricity consumption by 5%. Another advantage of this “cool” technology is that it’s less noisy than regular pavement.

The technology developed by the Building Technological Center of the Murcia region and a local company is different from CoolSeal, the one used in Los Angeles with the same purpose: CoolSeal is spread on the surface of regular pavement like painting whereas the material used in Murcia is a new bitumen binder. Of course, pavement emissions have been tested and no toxic substance is generated. The clear color may darken with time due to pollution, thus harming its efficiency, but the first tests show that solar rays also cause it to get clearer during the first year. Currently this new technology is more expensive than regular pavement: 224 k€/24,000 m².

Once Murcia gathers enough data from the ongoing test, it will develop a mathematical model enabling any city to forecast the effect of this technology on its streets. The two projects leaders will keep Convercities members posted regarding these pilot test results.