In Largo de São Domingos, in the neighborhood of Santa Maria Maior, one of the few trees in the downtown area serves as shelter from the sun. Photo: Orlando Almeida

Where can we go to escape the heat? – this is the question many of us are asking these days, especially in poorly protected and poorly cooled homes. A Climate Shelter is exactly that, a place where one can seek relief and coolness during an intense heatwave – such as the one we are experiencing these days, out of season. These are important places for Lisbon residents to face climate change and the increasingly frequent episodes of intense and persistent heat.

This is particularly important because, in addition to discomfort, heat is also associated with increased mortality. In August 2003, for example, a heatwave killed about two thousand people in Portugal. Ten years later, excess mortality attributed to high temperatures was estimated at over 1600. In 2018, Lisbon’s thermometers marked 44ºC and, according to IPMA’s climatological summary, the average maximum air temperature value in the country in August was the highest since 1931.

To get away from the heat, Lisbon has a vast network of climate shelters, but they are hidden. They can be found in gardens, squares, viewpoints, waterfront areas, lakes, water fountains, or even libraries and shopping centers. And they depend on various factors, such as the penetration of breezes, the existence of shade or green spaces, and trees.

Despite existing throughout the city, these points have not yet been adequately identified and publicized. And there are several areas of the city that have no cool island – at least within a proximity radius that allows for easy access and relief for local populations.

In July 2022, a recommendation was approved in the Lisbon Municipal Assembly (AML), presented by the Livre municipal deputies’ group, calling for the identification of these places in Lisbon. Livre asked for the identification of these places during last year’s summer, but it did not happen.

This week, Manuel Banza, a Lisbon resident with a taste for data, has taken the lead and published a work of “identification and prioritization” of locations where conditions should be created for the creation of climate shelters.

The conclusions: there are six locations in the city particularly exposed to heat and far from heat shelters.

1- Downtown

2- Alto de São João e Rua Morais Soares

3- Chelas

4- Rego neighborhood

5- Parque das Nações

6- Ajuda

According to Manuel Banza’s study these are the areas with the most problems finding a shelter from the heat.

Where else do you feel the heat in Lisbon and what is the effect of the breeze?

In February of last year, we talked about how the city should prepare itself to face the heat and how Lisbon needs more trees so that we don’t “roast in the sun”.

The density of the city and its materials lead to an increase in temperature in the urban space, compared to rural areas. This is the Urban Heat Island effect. In Lisbon, the differences in temperature caused by the Urban Heat Island effect range from 2°C to 3°C.

With the help of the work that has been developed by researchers at Zephyrus, the climate change research unit of the University of Lisbon, we have learned that the areas of Lisbon that suffer the most from the intensity of the heat are in the Downtown and Parque das Nações.

“These are parts of the city that, due to the high urban density, lack of vegetation, and ventilation, end up being warmer than areas outside the city,” explained António Lopes, an associate professor at the Institute of Geography and Spatial Planning of the University of Lisbon (IGOT) and coordinator of Zephyrus.

In the case of the Downtown, it is difficult to find shade, there are virtually no trees, and “the breeze hardly enters” – a dangerous combination of factors.

Santa Maria Maior baixa Lisboa
In downtown Lisbon, there are almost no trees in public space. Shade exists particularly associated with consumption spaces, such as esplanades or bars, leaving little space for shade in public space. Photo: Nuno Costa Gomes

Cláudia Reis, a researcher at Zephyrus, has been studying the potential effect of breezes on the cooling of the city through wind modeling.

“We already knew a little bit about the breezes, but we didn’t have much data. We have the wind coming from the northeast, the breezes. Normally, in the early morning, we have a north wind, which is our regional wind, then the wind is interrupted and turns to the northeast-east.”

In the downtown, for example, the wind does not enter.

“There is no wind, the breeze tries to enter and does not enter, so there our penetration of the breeze is almost zero and that is a problem – because of the buildings, because of the city’s topography.”

Cláudia Reis

In Lisbon, the most important breezes come from the Tagus River and the Atlantic Ocean. They enter the city from the west and “are much more frequent in the summer,” which, she says, “is an advantage” for the city.

But it doesn’t reach everywhere.

This study is still trying to understand to what extent the breeze can penetrate the city and what its effect is on thermal comfort, that is, “how many degrees we can lower the temperature with the penetration of the breeze,” but it is already certain that it has the potential to help cool the urban space.

Wind and shade are the two key factors for cooling down public spaces in the city

In addition to their cooling potential, wind – in the case of Lisbon, the northerly winds – is “one of the most important systems in Lisbon for removing pollutants.”

As the breeze does not enter the downtown area, according to Cláudia Reis, shade should be prioritized. When it is not possible to plant trees in the downtown area, she suggests installing removable awnings for shade after the summer.

Vegetation density helps cool down the city, and green spaces play a central role in cooling the city. Therefore, they are potentially interesting places for creating and identifying Climate Shelters in Lisbon.

However, the existence of green cover alone does not guarantee cooling or relief from heat. A striking example of this is provided by Manuel Banza – the Alameda D. Afonso Henriques garden. There are no trees along its large lawns, and therefore, there is no shade or cooling.

Mapping the city locations that need shelters

It is difficult to find climate shelters in the city, Photo: António Brito Guterres

When he began planning the analysis that he published this week, Manuel Banza had just returned from a walk in great discomfort in the city, with heat and no trees nearby. In the street where he lives, in the Arroios neighborhood, “there is not a single tree,” says the data analyst.

Manuel Banza then went in search of the city points where it is most necessary to create climate shelters. “It was a process that took a long time,” he says, because he did not have shadow data to work with when he started this project.

He took the data that shows the intensity of the Heat Islands in Lisbon and combined it with proximity to green spaces and libraries, the existence of trees, and the number of inhabitants per block (BGRI, according to data from the 2021 Census, the portuguese demographic statistics).

Among the six areas identified by Manuel Banza as a priority for the creation of climate shelters, two of them coincide exactly with the areas in Lisbon where the urban heat island effect is most strongly felt: Parque das Nações and the Dowtown.

This means that not only is the heat felt more intensely in these areas of the city, but it is also particularly difficult to find relief from the heat there.

The Chelas area described as “one of the most historically forgotten areas of the city,” is another critical point in the analysis, as well as the most densely populated area of the city – Morais Soares Street.

Here, despite the population density, it is difficult to find shelter from the heat.

To help Lisbon residents understand where they can seek refuge on hot days, Manuel Banza created an interactive map that shows the intensity of the urban heat island effect at dusk, as well as the location of water fountains, green spaces, lakes, libraries, or municipal pools.

Shelters as spaces for socializing, showers, and temporary shadow

Manuel Banza sees climate shelters as “spaces for socializing”, capable not only of cooling down on hot days but also of bringing people together.

“A shelter can help with the heat, but it can also simultaneously help create spaces to rest and experience the city. We might be walking and see a shaded spot that invites us to stay there to rest, talk or just watch the city happening.”

Manuel Banza

For Manuel Banza, “a lively city needs spaces that provide and foster community.”

For the creation of climate shelters, the data scientist proposes “a co-creation and ethnographic research process”, involving the active participation of local communities in a collaborative manner and avoiding the “imposition of solutions” from the start.

Where it is not possible to plant trees, it is still possible to create shade and experiment with other infrastructure that provides refreshment and cooling.

In Seville, the streets have a kind of curtains between the buildings to mitigate the heat.

In Vienna, according to Cláudia Reis, they are planning to experiment with installing showers, and Isabel Mendes Lopes, a municipal deputy elected by Livre in Lisbon, proposes a similar solution for Lisbon: sprinklers, and creating shade through planting trees “wherever possible.”

In the interactive map below, it is possible to see the absence of trees in the Dowtown area.

Lisbon’s plans to cool down the streets

In Paris, there are around 1100 “Islands of Freshness” identified, activated on days of intense heat and which include gardens, cemeteries, museums, churches, swimming pools, places with sprinklers, and pools where Parisians and visitors can find refuge.

The plans to cool down Paris include planting trees in places where there are none, such as the Opera Garnier. Photo: Ville de Paris.

Barcelona also has a network of more than 200 spaces that guarantee a maximum temperature of 27 degrees throughout the summer – and has a network that seeks to replicate Climate Shelters in less privileged areas.

In its recommendation for the identification and creation of climate shelters in Lisbon, the Livre party requested in a second phase the “densification” of the identified network, as well as the construction of a “contingency plan for days of higher heat.”

Isabel Mendes Lopes, member of the Municipal Assembly, regrets that after the approval of the recommendation, it did not have an immediate effect. “There was no disclosure of spaces where people could go during those heat waves, there was no sense of urgency in the summer of 2022,” she says.

Although the Livre party’s recommendation was not immediately followed, the Lisbon City Council is reportedly following up on the proposal.

According to the latest “Written Information from the President” report, which provides an update on the progress of the city’s projects and programs, the Department of Environment, Energy and Climate Change of the Lisbon City Council reports the existence of a municipal project for a “Climate Shelter Network.” At the moment, according to the document, the project is in the phase of researching information related to the implementation of similar initiatives “in cities in the USA, Paris and Barcelona.”

Work is also underway to “prepare information on city cooling initiatives in 2022” under the C40 Cool Cities program, part of the global C40 network of cities (which Lisbon is part of) aimed at supporting local initiatives to reduce the impact of the urban heat island effect.

In this line, Lisbon has recently presented a program aimed at combating the effects of heat on the population.

This is the “Cooling the City” program, which is expected to result in “the transformation of urban squares into cooler, greener squares and an increase in the presence of trees in the streets,” according to information presented by the municipality.

Mensagem tried to obtain an update on the development status of the Cooling the City program, for which it contacted the Lisbon City Council and the team coordinating the Ruas Verdes+ project. As of the publication date, no response has been given.

The Ruas Verdes+ project, recently presented, is part of this municipal program and initially envisages the planting of 20 trees on a stretch of Carlos Mardel Street, between Alameda and Arroios Market. Subsequently, the planting of more trees in other nearby streets is also planned under the project.

Manuel Banza has published several other analyses based on data from Lisbon – such as the application of the 15-minute city concept in the city, or the impact of the proliferation of local accommodation units in the city.

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