As climate change pushes temperatures higher year after year, European cities are facing more frequent and more intense bouts of extreme heat. But not everyone in a city feels the heat the same way. Even within the same neighbourhood, some buildings and streets are far more vulnerable than others, according to a study published in the journal Cities. The team from the University of the Basque Country (EHU) argue that knowing exactly where those hotspots are could save lives.
Mapping Where the Heat Hurts Most
The team from the SAREN (Sustainable And Resilient built ENvironment) group at EHU developed a new methodology to measure the vulnerability of buildings and open public spaces to heatwaves, and tested it in three Spanish cities with very different climates: Bilbao, Madrid and Cáceres. The results show that heatwave risk is far more complicated than just the temperature on a weather forecast.
More Than Just the Thermometer
Researcher Irantzu Álvarez explained the thinking behind the project: “We are looking at how to conduct a multi-dimensional and multi-scale assessment of the risk posed by heatwaves in urban areas. The risk posed by heatwaves is not measured solely by temperature; it has multiple dimensions.”
To get a real sense of how much a given area suffers in a heatwave, you need to look at three things: how the city is built (its buildings and public spaces), where the hottest spots are, and who lives there (how many people might be affected and how vulnerable they are).
“In this study, we have measured the vulnerability of each of the city’s buildings and open spaces in Bilbao, Madrid and Cáceres (all three located in different climate zones),” added researcher Laura Quesada.
A Tool Any City Can Use
The outcome is a set of urban vulnerability maps that show, in clear detail, where to focus action first. The team believes this is the key to making climate adaptation efforts actually work on the ground. “Adaptation measures can be implemented much more effectively with this type of study,” they said.
Having tried the methodology in three very different cities, the team is confident it can be applied anywhere. “The methodology is fully replicable; it can be used anywhere. This makes the methodology more robust. It is a genuinely useful tool for municipalities and cities.”
Inequality Shows Up in the Heat Too
One of the clearest patterns to emerge was that lower-income areas tend to be more vulnerable to heatwaves. Older residents, people on low incomes, and those living in poorly adapted buildings all face greater risk.
“The importance of socioeconomic variables when measuring vulnerability. People on low incomes, older people, etc. are far re vulnerable,” the research group said. “Vulnerability is not the same throughout a city. It is therefore not enough to say that one city is more vulnerable than another, because there are different hotspots within the city. There may also be different situations within the same neighbourhood, which is why this type of detailed research is necessary.”
In other words, two neighbours just a few streets apart can face very different risks when the temperature rises.
Buildings, People, and the Street Outside
The research pulled together a huge amount of data, combining three types of information: socioeconomic data (such as income and age), building characteristics (such as construction type and insulation), and environmental factors (such as nearby green space or shade).
Importantly, the researchers took the single building as the smallest unit of analysis. That matters because it allows adaptation measures to be targeted much more precisely. “This methodology shows which buildings or types of buildings should be renovated or adapted first,” said Álvarez and Quesada.
The team also looked at how a building’s surroundings affect its risk. A building might be structurally vulnerable to heat but sit next to a well-shaded park, which eases the pressure. Another might be more modern but surrounded by concrete that soaks up and radiates heat long after sunset. “A building may be sensitive to heat, but its residents may have the financial means to protect their home from it,” they explained. “Buildings may be highly vulnerable but have plenty of green areas and shade around them. Taking all of this into account means that adaptation measures can be implemented in different ways.”
Climate-Smart Cities Need Street-Level Knowledge
As summers continue to warm, this kind of fine-grained mapping could become essential for city planners. Blanket climate adaptation policies may miss the mark if they ignore how much variation exists even within one neighbourhood. The EHU team’s approach offers municipalities a practical way to spot the most at-risk corners of their cities and act where the need is greatest.
Quesada-Ganuza, L., Álvarez González, I., Villaverde García, A., & Garmendia Arrieta, L. (2026). Assessing urban heatwave vulnerability through a multiscale and multicriteria GIS-based approach: Evidence from three Spanish cities. Cities. DOI: 10.1016/j.cities.2026.107514