Surviving the heat in increasingly “hellish” cities

Can you imagine a new layer in Google Maps, one that indicates the best path to navigate through the shadows on a journey through the city? It’s the idea of ​​urban planning professor at the University of California, Los Angeles, V. Kelly Turner. Will the technological layer be the last in the catalog of solutions to survive the increasingly suffocating heat of cities? At the University of Malaga a few days ago they announced the construction of a center, called Casa Patio, in which a clay lattice manufactured by 3D printing and drip-irrigated has been incorporated into the bioclimatic design.

The technology is added to more natural formulas, such as the replanting of trees, a measure that they are betting on in the town of Castelldefels, where 800 trees have been planted “both in public spaces and in schools, in addition to installing awnings and fans,” comments Manu Reyes, mayor of the municipality.

According to the World Meteorological Organization, Europe is warming twice as fast as the world average and we are seeing it these days across the continent. In the United Kingdom, the red warning due to high temperatures has been activated for the second time in its history; In most of France, temperatures have exceeded 40 degrees and Portugal, Italy, Belgium and Germany have activated heat alerts. In Spain, towns like Andújar, in Jaén, have reached 45.1 ºC and in 28 provinces the number has exceeded 40.

The heat in the cities is becoming unbearable. Since 1975 in Spain there have been 12 heat waves in June, but half of them have occurred in the last ten years. «An indicator that we scientists study is the so-called thermal comfort, which is based on temperatures, but also on humidity. By doing simulations we have seen that, If we continue to rely on a fossil economy, In 2050 we will have intense episodes of heat in summer of between 38 and 40 degrees for many days in a row, but by 2100 we will reach 40-44» says Gara Villalba, professor in the Department of Chemical, Biological and Environmental Engineering at the Autonomous University of Barcelona.

heat island

In addition to mitigating, adapting cities to the intensity of the heat that lies ahead and that we suffer more each summer seems already mandatory. And, despite the fact that cities occupy only 2% of the Earth’s surface, more than half of the population lives in them. If we look at Spain, this figure grows to 80%.

In cities there is the so-called heat island effect. Paved areas, materials such as asphalt and concrete or the lack of shade and vegetation cause heat to be stored during the day and released at night. «Those tropical nights are the ones that worry us the most because they have a great impact on health. Last year there were 4,000 heat-related deaths in Spain. As for studies that measure the heat island effect, there are many, but to give an example, in Madrid temperature differences of up to eight degrees more have been measured in the center compared to the periphery,” comments Isabela León Cesín, architect and head of Projects and Public Policies at the Ecology and Development Foundation (Ecodes).

What are cities doing? These days, the Cáceres City Council restricted work hours on the street. In Córdoba they did something similar and prohibited the circulation of horse-drawn carriages after 2:00 p.m. Fuenlabrada has also modified the operating hours of the clean points. In Zaragoza, for its part, the council has lowered the price of municipal swimming pools and is enabling climate shelters. These air-conditioned spaces, designed so that citizens can find a cool place during the hottest hours, are becoming widespread throughout the Peninsula: Barcelona, ​​one of the pioneers in betting on them, has a network of 500 shelters. But are they sufficient measures? For Manu Reyes, who, in addition to being the mayor of Castelldefels, is the new president of the Spanish Network of Cities for Climate (dependent on the Spanish Federation of Municipalities and Provinces), “municipalism is concerned about climate change and about giving tools to the city councils of the network, even though we do not have all the resources we would like.”

Depave

The city of Portland, in the United States, began a movement in 2008 that has become global: depaving the streets to return the soil to a more natural state. Now they are transforming schoolyards from paved areas to green, shaded spaces. A measure that lowers the temperature up to seven degrees. Paris has copied the idea and has been unpaving schools for some time.

Renaturalize For Friends of the Earth, it is the first of the measures that should be implemented in cities to help us cope with the heat and lower the mercury a little. These days they presented a study in which they relate natural area per inhabitant and income. They have carried it out in collaboration with the Research Group on Architecture, Urbanism and Sustainability (GIAU+S) of the Polytechnic University of Madrid and among their conclusions it stands out that “In lower-income neighborhoods the area of ​​nature per inhabitant is less than in higher-income areas due to the greater housing density.”

The report analyzes the green spaces of ten Spanish cities and is based on the recommendation of the World Health Organization, the 3-30-300 rule: being able to see three trees from the window, 30% vegetation cover in the neighborhood and a park of at least one hectare no more than 300 meters away. After studying the cases of Madrid, Barcelona, ​​Valencia, etc., they conclude that more than half of the citizens do not have green areas, reaching 80% in cities such as Ourense and Valencia.

An interesting part of their study is that they have identified areas of priority action in each city and, for example, for the Puente de Vallecas area, in Madrid, they propose greening the hardest squares due to the presence of asphalt or creating green pedestrian itineraries. “Urban nature is a central element of adaptation to climate change, capable of regulating the impact of heat waves and at the same time contributing to generating spaces for leisure and physical and mental well-being,” they say, and mention the definition given by the RAE of nature as “the physical environment in which living and non-living beings coexist on the margins of urban life.” A concept aligned with the historical way in which urban planning has been planned and that perhaps it is time to change. At least if we look at another study launched by the Ecology and Development Foundation (Ecodes), which addresses “safe and sustainable solutions to reduce both indoor heat and urban overheating as a whole.”

Nature first

In their report they establish a hierarchy in which the first step is “nature.” We have to have many more trees, water and vegetation. It is proven that Trees can lower temperatures by up to eight degrees when there is a heat wave. Then we place the urban design, with depaving, for example, or the commitment to reflective materials on the roofs. In addition, ventilation must be guaranteed in cities. Then we would move to the building level, with passive measures first. Having good insulation is the first thing. The majority of Spanish real estate is old and does not have adequate insulation, which is why houses become ovens. Then it would be interesting to focus on district heat and cold networks in cities, centralized air conditioning in buildings where possible and, finally, there would be efficient individual systems such as heat pumps,” says Isabela León, who insists that air conditioners are in the last line of action because “it is about leaving no one behind” and remembers that, according to the INE, one in three households cannot keep their home at a sufficiently cool temperature.

«Last week the public consultation for the future local heating and cooling plans that come from the Energy Efficiency Directive and that obliges 166 Spanish municipalities to plan between now and 2050 what the heat and cold will be like in cities. The aim is for different departments of each city to sit down and plan what the most critical points of heat and cold will be in the future and be able to act accordingly.

Poor neighborhoods with up to one degree more

►This week the Autonomous University of Barcelona launched a study in which it states that the poorest neighborhoods in large cities suffer more heat, to a degree more than the richest. A pattern that is repeated in Madrid, Valencia, Barcelona or Seville. Urban density and less green are once again behind this extra heat.

The UAB also recently launched a study in which they analyzed different measures to alleviate the temperature and in which they point, in addition to green areas, to white roofs as a cheap and simple measure that can reduce temperatures up to 1.75°C.