In the same city, the possibility of taking refuge from the heat is bidirectional: there are those who sleep with the air conditioning on and those who take shelter among centennial trees -as long as the parks are not closed.
Madrid, in the midst of a heat wave, may seem like a uniform metropolis, but a study published last year reveals a much more nuanced truth: temperatures in neighborhoods like Malasaña and areas like Casa de Campo differ by up to 8.5 degrees. It is not just a question of climate: it is a question of urban planning, nature and inequality.
The consulting firm Arup, with its UHeat tool, mapped the heat island effect in cities around the world, and Madrid leads the way with the greatest thermal difference between urban areas. The analysis, based on satellite data and climate modeling, identified Plaza Juan Pujol as the hottest spot (with 3% vegetation) versus the north of Casa de Campo, where greenery covers 89% of the surrounding area. But beyond statistics, this phenomenon raises fundamental questions about how people build, live and survive in the city.
What is the urban heat island?
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The urban heat island (UHI) effect refers to the increase in temperature in densely urbanized areas relative to their rural or more vegetated surroundings. Materials such as asphalt or concrete absorb and retain heat during the day and release it at night, preventing temperatures from dropping. Cities literally overheat. As a result, temperature differences of up to 15ºC can be seen between the city and towns in the Sierra, such as Rascafría.
Madrid is a paradigmatic example. According to Arup’s Urban Heat Snapshot, during a critical day in the summer of 2022, the greatest thermal difference between neighborhoods of all the cities analyzed was recorded, above that of Bombay, London or New York. But this difference is not distributed randomly: neighborhoods with less green areas, more asphalt and higher building density are the hottest, and usually coincide with lower income districts and worse thermal insulation in housing.
Areas such as Puente de Vallecas, Usera or Carabanchel are among the most vulnerable, not only because of the ambient temperature, but also because of the impossibility of having access to a thermally comfortable environment without increasing the energy bill. This conclusion was reached by a group of researchers at the Polytechnic University of Madrid (UPM) in a study that echoes El Confidencial in a report entitled The heat in Madrid, street to street: “We are prisoners of the interiors with air conditioning.
How to combat the heat island
The good news is that urban heat has a solution. And it’s not science fiction. Arup and other experts agree that urban design is key: more vegetation, permeable surfaces, water and natural shade can significantly lower the temperature of a street or neighborhood.
Green roofs and walls, clear pavements, fountains and foggers are other tools already in use in different cities. London has developed a plan for reflective roofs and solar panels to reduce thermal emissions at night. In Madrid, however, some recent reforms, such as the Puerta del Sol or the felling of the Plaza de Santa Ana, have been criticized for going in the opposite direction.
Architect Eugenia del Río emphasized in an interview on Telemadrid’s Buenos Días program that urban climate shelters, such as air-conditioned libraries or senior centers open to the vulnerable population, will be increasingly necessary. Even some, such as the one in the Círculo de Bellas Artes, promoted last summer and continued this year. Be that as it may, extreme heat is no longer an anomaly: it is a constant in Madrid’s calendar.