[Un article de The Conversation écrit par Ainhoa Arriazu-Ramos – Dra Arquitecta-Investigadora postdoctoral en sostenibilidad medioambiental y adaptación al cambio climático de las ciudades, Universidad de Deusto]
The year 2024 was the warmest ever listed worldwide since the start of the measurements, with an average temperature upper 1.55 ° C to that of the pre -industrial period. Heat waves are no longer isolated events: they are more and more frequent, intense and long.
The impact of global global warming is particularly serious in cities. The phenomenon of urban heat islands (ICU) leads to urban temperatures up to 4 ° C higher than in neighboring rural areas, especially during summer nights.
If we add to this the fact that more and more people live in urban areas (in 2050, more than 70 % of the world's population will be concerned), a question inevitably arises: how to design cities so that they remain habitable despite the high temperatures?
Better design public space
Integrating more nature in our cities is one of the best strategies to adapt them to heat.
But it is not only a question of ensuring a minimum of green space per inhabitant: what is the point of having a large park at an hour's drive, if you do not find a shadow on the way to work or that you do not have a green space in its neighborhood where to take refuge to escape heat?
Nature must be integrated into urban development taking into account the principles of proximity, quality and quantity of green spaces. With this in mind, the “3-30-300” rule is interesting: each person should be able to see at least three trees from their home, living in a neighborhood where at least 30 % of the area is covered with trees and having a park within 300 meters.
Reviewing public spaces and buildings is as urgent as it is to plant trees. Building roofs, for example, can be allies to reduce heat. For this, it may be essential to integrate vegetation or reflective materials. The facades are also important. Choosing their color well (preferably light tones) and the materials that compose them can help reduce the problem of overheating instead of worsening it.
At ground level, it is just as important to rethink the choice of coverings. Avoid the systematic use of asphalt and concrete that absorb heat. Exploring more permeable, cooler materials and integrating more vegetation can make a significant difference.
Housing adapted to heat
But it is not only enough to improve public space: housing also must be able to cope with heat. We spend most of our time there and many of them are unsuitable. For example, a study revealed that 85 % of Pamplona (Spain) housing recorded too high temperatures during the summer of 2022.
The design of buildings is decisive in this regard. Certain aspects linked to the design and construction of these buildings, if they are not taken into account, can worsen the problem of overheating housing.
Thermal insulation is the first point. Insulating a building well is an important measure, especially in winter, but also in summer. However, when well -insulated but too hermetic accommodation warms, it becomes difficult to evacuate heat. The key therefore lies in the design: the distribution of parts (and any mechanical ventilation systems, such as VMC, editor's note) must allow adequate ventilation.
The large windows are another point that can be a problem. They are now appreciated for natural light and the view they offer, but if they are not properly protected from the sun, they contribute to the warming of the accommodation. It is important that solar protections are an integral part of the design of the building and are no longer just accessory elements. It is possible to alleviate solar radiation without completely darkening the house: stresses, adjustable shutters, awnings or strips, etc.
It should also be noted that housing that has only one exposure are more at risk, while those with double exposure make the refreshment easier.
Given current housing needs, new houses tend to be smaller. Many apartments in the city center are also divided into smaller apartments. This trend is problematic because it leads to an increase in the number of single-oriented housing. In addition to compliance with the minimum surface, it would therefore be interesting to demand that they guarantee minimum thermal comfort conditions.
In addition, it has been shown that the dwellings located on the top floors will suffer between 3.4 % and 5.4 % more hours of overheating than those located on the intermediate floors. Improving roof insulation is not enough, as insulation has an efficiency limit. It is therefore also necessary to innovate to improve the construction of buildings at this level.
It does not only depend on town planning or architecture. Citizens must also learn to adapt to urban heat and know how to manage their accommodation during the hottest days: understand the influence of the orientation of the accommodation, ventilate at the right time depending on the difference between the interior and exterior temperature or even properly use solar protections.
What prospects?
If we want to adapt the cities to heat, we must not elude the social dimension of the problem.
Extreme heat does not affect the whole population in the same way: the elderly, children and those who live in poor quality housing or in unattractive neighborhoods are more exposed.
Finally, we must be aware that thermal comfort cannot only depend on air conditioning or other mechanical systems. It is necessary to rethink our cities and accommodation so that they can adapt to heat by their very design.
In an increasingly hot world, the most suitable cities will be those which will be able to maintain thermal comfort while minimizing dependence on energy consumption.
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
