During a heatwave, many of us repeatedly inspect weather forecasts, in an effort to anticipate how hot we will feel, and for how long. It’s often a matter of single numbers: perhaps 25°C in the early hours, with a 35°C peak in the afternoon.
But according to SWICE researcher Marlyne Sahakian, these figures, while they feel unequivocal, may be hiding a deeper truth: “Heat does not affect everyone equally.” She has just released a report on thermal justice in the city of Geneva, together with Alice Guilbert, Sharayu Shejale and Julien Forbat, based on an extensive survey on thermal comfort conducted in the summer of 2025.
The report highlights the necessity to adapt to heat and its consequences. Because human-related climate change is increasing both the frequency and length of heatwaves to disastrous consequences, reinforcing the resilience of people, institutions and governments appears urgent.
In this context, the team at the University of Geneva highlights the role of thermal justice, which takes into account how people are affected by heat based on their socio-economic status: gender, income, type of accommodation, and whether they own their accommodation or rent it. Their first finding is that women and minorities are more affected by excessive heat, which may be explained by them taking on a larger share of care duties or having less flexibility in how they use their time.
Other parameters contribute to an individual’s thermal comfort, which can be understood as one’s physical, mental and emotional wellbeing, combined with their autonomy and participation. People that categorize their salary as high, and people that see themselves as healthy, tend to be less affected by heat. Having more space per person also decreases the perceived impact of heat.
The report also highlights a discrepancy in available solutions to owners and renters, respectively. The first group has access to structural solutions, such as installation of heat pumps, better insulation or shutters, while the second group is left to focus on cooling bodies or using small-scale technological solutions. Income also factors in the increased ability that more wealthy households have to escape the city.
The authors provide a set of recommendations including prioritizing structural or technological thermal improvements for unsuitable accommodations and low-revenue inhabitants, increasing the flexibility of workers, normalizing different behaviors during heatwaves, and increasing access to cool spots in public spaces.
Marlyne Sahakian was also invited to discuss her team’s findings in the media, including in an interview with France3 Occitanie, where she explains how sufficiency, thermal justice and city transformation are the keys to maintaining our wellbeing within planetary boundaries.