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Short Abstract

Cròniques de la Calor engaged 439 residents across five Barcelona neighbourhoods to study urban heat. Through 48 thermal walks with sensors and surveys, participants generated a unique dataset linking microclimatic data and thermal perceptions, informing urban planning and climate adaptation.

Abstract

Cròniques de la Calor (Heat Chronicles) is a citizen science project that investigates urban heat and thermal perception across five neighbourhoods in the Barcelona metropolitan area. In collaboration with 14 non-academic partner organizations, we engaged 439 residents as co-researchers across all stages of the research process. Participants—living in areas classified as highly climate-vulnerable—identified 210 public outdoor sites of relevance in their daily activity. Sites were characterized using spatial and environmental indicators linked to climate resilience. Over the course of 48 thermal walks, residents carried portable low-cost sensors that continuously recorded air temperature, relative humidity, and geolocation, generating 296,286 processed microclimatic data points. At pre-defined sites, participants also completed surveys reporting their Thermal Sensation Votes and Thermal Comfort Votes, producing 5,169 self-reported entries. Sociodemographic data provided further context to these subjective responses. The resulting dataset enabled point-by-point analysis of thermal experience within the urban fabric. With particular attention to children and adolescents, the project identified age- and gender-dependent trends in thermal perception. Additional insights revealed significant patterns between subjective heat perception and the vegetation index and the sky view factor and highlighted key public outdoor sites—including primary care centres, public transport hubs, sports facilities, and parks—especially vulnerable to extreme heat. Thermal walks have had the capacity to deliver informed evidence-based recommendations for urban planning, public health, and climate adaptation. It demonstrates how citizen science can support multi-level decision-making, from municipalities to neighbourhood associations and schools, while amplifying the voices of those most affected by climate vulnerability.