Thursday, September 28, 2023
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Increasing the proportion of green spaces, building with permeable materials, or promoting urban climate shelters are some of the measures that can help combat the 'extra degrees' that visit our cities each summer.
By Santi Lozano
Who hasn't spent more than one summer night tossing and turning in bed because of the excessive heat? What few people know is that this phenomenon has a name and a scientific explanation behind it, which is known as the 'heat island effect.' This is due to the increase in nighttime temperatures in urban areas compared to the outskirts or nearby rural areas.
"Central districts of cities in particular tend to overheat a lot during the day, and when night falls and temperatures drop, that accumulated heat goes back into the atmosphere, producing a scorching hot microclimate that can be harmful to health," explains Rubén del Campo, spokesman for the State Meteorological Agency (AEMET). One of the causes of this overheating, according to experts, is found in the construction materials used in cities, such as asphalt or concrete, which have a high capacity to absorb heat during the day; or the reduction of natural spaces, which help to provide shaded areas and cool down neighborhoods by evaporating water. In addition, the U.S. Environmental Protection Agency points at that narrow streets and tall buildings, which are very common in large cities, reduce wind flow by heating the air trapped in them. An effect that is further enhanced by residual heat from vehicles, factories, and air conditioners.
That’s why, as del Campo puts it, "it is essential to increase tree coverage in cities and replace asphalt with other more permeable materials that can trap moisture from rainwater or morning dew."
New architecture must be based on the architecture of yesteryear
In this regard, the Eduardo Torroja Institute of Construction Sciences at CSIC is working on designing innovative materials that are environmentally friendly and adapted to phenomena such as heat islands. "Large cities need to renew their urban planning policies so that green and shaded areas such as parks, fountains, or tree façades can play a more important role," states Teresa Cuerdo, architect and researcher at the scientific organization. "New architecture should look to the architecture of yesteryear and incorporate light-colored, reflective elements with higher albedo, as it is these types of building materials that prevent the heat island effect."
On the other hand, cities must also push for the creation of climate shelters. By this, we mean public spaces such as libraries, marquees, shopping malls, or even churches. Buildings that provide the population with the opportunity to cool off during mid-day temperatures or heat waves. "The solutions have to be adapted to the characteristics of each city and its residents, paying special attention to the most vulnerable groups," explains Cuerdo.
Examples of cities adapted to the heat island effect
Spain, precisely because it is the second country in Europe - just behind Italy - to suffer most from the effects of heat waves, has cities that are benchmarks in terms of sustainable architecture. A well-known example is the city of Vitoria, where construction, innovation, and respect for the environment go hand in hand in its streets. There, new buildings and urban furniture contain modern materials capable of repelling solar overheating and the heat island effect. In addition, there are a multitude of green spaces and areas.
Other municipalities that are improving in this area are Seville, with the installation of sunshades in central streets and the remodeling of its parks and rivers; Barcelona, which has set up 200 municipal spaces as climate shelters; or Zaragoza, which has reduced the entrance fee of its municipal swimming pools.
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