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Heat island: causes and solutions


If you live in an asphalt jungle in the heart of the city, you will surely have heard of the concept ofheat island. Urban centers are more "hot "compared to the rest of the hinterland, so, if you live in the city center you have to resign yourself to the fact that the mercury column will mark a few degrees higher than the outskirts.

Theheat island phenomenonit has several negative impacts that can be reflected directly and indirectly on human health. The effects of the heat island can be summarized in the following points:

  • Increase in the use of energy to cool summer environments (air conditioners, air conditioning systems, ventilation ...)
  • Consequent high emission of pollutants and greenhouse gases, even tropospheric ozone
  • pollutants transported by urban runoff waters and consequent increase in surface water temperatures

Heat island, the causes

What causes the heat island phenomenon?
The causes are two and they intensify each other!

#1
In urban centers, solar radiation is more absorbed due to materials such as asphalt and concrete which increase the accumulation of heat. Due to the strong overbuilding and the lack of green spaces, urban islands lack evaporating / evapotranspiring surfaces.

#2
Use of equipment that releases heat: cars, appliances, air conditioners… anything that uses energy that releases heat. If an air conditioner cools your home, the outdoor unit releases heat which increases the phenomenon ofurban heat island.

Isola di Calore - the solutions

The question becomes more difficult: How can we save ourselves from this chaos we have made?
As is clear, theurban heat islandit is a direct consequence of human activity. Very little could have been enough: to cushion the effect ofheat island it would have been enough to better manage urban spaces. Careful planning of urban centers would have allowed to maintain more green spaces in proportion to the concrete surfaces. Unfortunately, human urbanization has always moved and continues to move in the direction of overbuilding: land consumption is a disconcerting reality that is killing the environment and not only in our country. The advance ofconcreteit represents a European problem that requires Community directives. Every year, over 1,000 square kilometers of new land are used for human activity and then cemented.

That ofheat islandis only one of the consequences of the wild overbuilding, other dramatic implications are found with the problem strongly felt in Italy of thehydrogeological instability.

In order to demolish the overbuilding, contributions have been created to promote the reuse of areas already concreted but left to decay: how many abandoned warehouses have you noticed in your city? In this context, thetax incentives for land reuse.

Environmental problems only rarely have immediate solutions. To mitigate the problem ofheat islandin some cities around the globe they are looking for asphalt replacement materials. The asphalt has a dark color so it is characterized by a low reflection coefficient: the asphalt absorbs heat. A NASA test is exploitingwhite roofsto counteract theurban heat island; white is a reflective color. Even more effective could be the use of green roofs and green walls.

An "improved" version of the classic asphalt has already been developed for the roads, lighter and less prone to absorb heat. The light asphalt is not harmless to the environment but at least it does not absorb a lot of heat and reflects the light better so as to make the roads safer. Bio asphalt (bioasphalt) made with nano materials of organic origin is more low-impact, but the high production costs still make it prohibitive.

To get an idea of ​​the gap between green space and asphalt, just think that a square meter of asphalt surface absorbs 6 times more thermal energy than the same lawn surface. If you are interested in countering the heat island phenomenon (much felt in the cities of Bologna, Milan, Trento, Ancona, Turin ...) you can set up, in your own small way, a movement to support the implementation of green roofs and to increase green spaces in the city. If you intend to leave from your home, here is a guide onhow to make a green roof. Do not exclude the possibility of organizing an urban garden or proposing to the administration of your municipality of residence, the use of smart urban furnishings such as the plant Tillandsia.

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You may also be interested in the article on "Ozone hole



Video: The urban heat island effect (October 2021).