The second most populated city of the United States, Los Angeles, hosts 4 million in its narrower center, and another thirteen in the suburbs. And it would be hard to look for someone who would not complain about annoying heat in the summer. The temperature in the streets normally exceeds forty, and as in one of the few cities in the world, the health workers deal with death from overheating even in winter. The cause does not lie only in the geographical layout of the entire settlement, or that the built-up area is surrounded by warm deserts on three sides. Even in peripheral suburbs the climate is more convenient than in the center. Los Angeles is an example of a large-scale thermal island.
George Spotts, Secretary of the LA Public Affairs Department, has no doubts about the causes of the overheated city. "It may be a dark asphalt that covers all the streets of the city. It attracts the incident sun rays, accumulates heat and radiates it to its surroundings at night. " Buildings and people in the immediate vicinity of roads have to cope with temperatures up to 10 ° C higher than the measured average. "The city works as a perfect thermal trap, and unfortunately people are trapped in this warm trap," says Spotts. Asphalt and the heat problem are solved in a number of other cities around the world, but in Los Angeles, the situation is a bit worse.
It can be a transport infrastructure, a very dense network of regular routes that would otherwise be counted as a pros. Here, however, it functions as a temperature grid that evenly covers the entire city, and loses and distributes the accumulated heat. "We believe that 10% of the entire area of the city practically covers asphalt," Spotts says. "It's an area equivalent to an area of 69,000 urban blocks." What about that? Los Angeles has learned from its past (when it had problems with smoge since the 1950s but solved it up to twenty years later), so it is quick to tackle the problems today.
Spotts still mentions that twenty years ago, the City Hall might have just waved over the superheated streets, recommending people to buy air conditioning. "Fortunately, today no one thinks. Air conditioning is not a good long-term solution and a significant energy burden. And not everyone can afford them. In addition, air conditioning does not protect heat from those outside. "
Eric Garcetti, the mayor of Los Angeles, fortunately does not just want to solve the consequences and the city can preserve it in a certain state, but plans to "go on the attack" . His visions even count towards lowering the average city temperature by 3 ° C over the twenty-year horizon. Because it is expected to increase in temperature, it has to be really creative. As part of the campaign, there is a plan to plant trees in the streets, to lighten roofs or plant them, and also to Spotts' recommendations to color transformation of asphalt on the streets.
"So far, we are not prepared to do this on a flat basis, but we want to test what options would open it," Spotts says. "The white coat has so far been applied to 14 streets in 15 streets, and we will now see what improvements it will make. The first experiment of this type was successfully audited by the Public Transport Department in 2015 in the San Fernando Valley car parks. However, we are a bit worried about how the white roads will be taken by car drivers. " If they know the results, a reflective-cooling gray paint could only be found on a third of the streets of the Cities of the Angels.
CoolSeal is not just a light color. This is a special coating that has only been used by US Air Force Base. It reflects the heat, so there is no thermal footprint on the runways after the take-off or landing of the aircraft. Eventually, spy satellites can not detect whether or not the airport is starting. In civil applications, the benefits of coatings could also benefit those who struggle with the heat in the streets. Complication may be a cost. The coverage of one square kilometer will cost $ 25,000, and the service life will be seven years.
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Author: Radomír Dohnal
Source: Ekolist.cz
