Citizen science dataset on residents' urban heat perception in outdoor public spaces of climate-vulnerable neighborhoods

Abstract

We present a dataset generated to investigate urban heat and thermal perception across five neighborhoods in the Barcelona metropolitan area. In collaboration with 14 non-academic partner organizations, we conducted a series of citizen science campaigns involving 439 residents as co-researchers engaged throughout all stages of the research process. Participants, residents of areas classified as highly or very highly climate-vulnerable, identified 210 public outdoor sites relevant to their daily lives. These locations were subsequently characterized using a range of spatial and environmental indicators pertinent to urban heat island effects, urban health, and climate resilience. Over the course of 48 thermal walks, participants carried portable, low-cost sensors that continuously recorded air temperature, relative humidity, and geolocation, resulting in 296,286 processed microclimatic data points. At pre-defined sites, individuals completed standardized surveys to report their Thermal Sensation Votes and Thermal Comfort Votes, yielding 5,169 self-reported entries. Sociodemographic data were also collected to further contextualize participants' responses. The resulting dataset integrates objective environmental measurements with subjective perceptions of heat, enabling point-by-point analysis of thermal experience within the urban fabric. It offers a novel, multi-dimensional resource to support research on heat, thermal inequality, and the experiential dimensions of climate vulnerability, and is intended to inform evidence-based decision-making in urban planning, public health, and climate adaptation.

Figures (11)

• Figure 1: Contents and activities of the three working sessions with participants. (a) Introduction and public spaces mapping (Session 1); (b) Collective thermal data collection (Session 2); (c) Results discussion and dissemination (Session 3). Images illustrate the activities developed during these sessions.
• Figure 2: Thermal walk routes in one location. Simultaneous thermal walks conducted on May 30, 2024, in Collblanc-La Torrassa (CT, L'Hospitalet de Llobregat). Each participant group was assigned a different color to distinguish their route. Routes were designed to cover 31 outdoor public sites (red marks) prioritized by the community--including the starting/ending point (white star)--which were identified and labeled using predefined alphanumeric codes. A total of 67 participants were involved, divided into 6 groups corresponding to 6 different routes. Along these routes, thermal surveys collected a total of 959 self-reported entries (TSVs, TCVs and wTCVs).
• Figure 3: Mobile equipment for the thermal walks. (a) Modified shopping cart with custom panels and two sensors mounted consistently oriented to the direction of movement. (b) Ballot box and individual ballots used to capture participants’ subjective perceptions of heat. (c) Sensors connected via the MeteoTracker app to tablets inside the cart, enabling continuous recording of geolocated microclimatic data.
• Figure 4: Paper ballots used for voting in the thermal surveys (in Catalan). (a) Example of the back of a ballot, displaying a unique design for easy identification. (b) Sociodemographic form completed by participants before the walk (see Table \ref{['tab:sociodem_english']} for the English translation). (c) Survey on thermal comfort, thermal sensation, wind, and sun exposure from Ballot 1, completed before starting (see Table \ref{['tab:vote1_english']}). (d) From Ballot 2 onwards, the questions are the same as in (c) with an additional question on thermal comfort experienced while walking from the previous site (see Table \ref{['tab:vote2_english']}).
• Figure 5: Schematic diagram of data processing. We provide both raw and processed individual trajectories, with geolocated microclimatic sensor data. Participants' heat perceptions at each site, along with their sociodemographic profiles, were digitized. This information was used to build a dataset for each thermal walk, containing data at each site. We enriched the dataset with urban contextual indicators for each site (e.g., NDVI, SVF, IVAC). Finally, we compiled three aggregated files: one with data for all 210 sites, another with all 1 867 unique responses, and a third with the 439 complete response sets by participant ID.