3-2-1 heiss! Citizen Science on Heat Islands

This project won the K3 Climate Communication Award 2023 in the category "Citizen's Prize". 

Previous editions: 

• 2021, 2022, 2023/ Canton of Aargau, Department of Building, Transport and Environment.
• 2024/ City of Zurich, Environmental and Health Protection Zurich (UGZ)
• 2025/ Regional Conference Environment (RKU) Canton of Lucerne

Heat islands in urban areas

Due to climate change, the phenomenon of so-called heat islands in densely built areas is occurring more frequently, for longer periods of time, and with greater intensity. This is not only unpleasant for the population, but also poses a health risk. The '3-2-1 heiss!' citizen science project, initiated by the Canton of Aargau's Department of Building, Transport and Environment, addresses this issue. Residents of various communities and cities measure the temperature of their surroundings while out walking using mobile sensors. 

Participants record temperature values at pre-determined locations using measuring devices from Sensirion. They also record their impressions of the perceived temperature in the '3-2-1 heiss!' app from NOA. 

This project enables hot and cool spots in the settlement area to be identified and compared with participants' subjective perceptions. The results are presented at a closing workshop where ice cream is served, and measures for enhancing the community are discussed. 

Active participation of the population

'3-2-1 heiss!' relies on the active participation of the population at various stages: determining the locations to be measured, taking temperature readings and discussing the results. This makes the data tangible, visible and available for future settlement planning. 

This raises awareness of heat issues and climate change, and strengthens the community by bringing together residents, community officials and politicians. During workshops, participants discuss ways to reduce heat and develop ideas for creating cool public spaces. Additionally, the population selects the most pleasant place in their community. 

Working together to find solutions

The data collected in the '3-2-1 heiss!' project is evaluated and forms the basis of discussions at the final event.

Ideas for improving public spaces that emerge from these discussions, along with the results, are included in the final report. This report is sent to the participating municipalities, who can use it for their future settlement planning. 

Aargau: 

The collected data of the "3-2-1-hot!" project was published on an online map and evaluated by the project team. 

City of Zurich: 

In the Zurich pilot project, seniors from district 4 measured the temperatures of their surroundings on walks with mobile SENSIRION sensors. The findings flow into the future efforts to reduce heat in the city of Zurich. Additionally, the most pleasant place in district 4 was chosen.

Lucerne: 

In eight Lucerne municipalities, 100 private individuals and 12 school classes tracked down the heat in the settlement area. Equipped with sensors, they collected 2699 data points on temperature and temperature perception and documented the data in the 3-2-1 heiss! App. The results were discussed with community representatives to derive measures for cooler places. 

In the media:

• Aargauer Zeitung: "Einwohner sollen Temperaturen messen: Forschungsprojekt geht in die nächste Runde"
• Nau: "Aargauer Gemeinden gehen der Hitze auf die Spur"
• SRF Regionaljournal Aargau: "Aargau – wo sind die Temperatur-Hotspots?"
• Agglo Luzern: Gemeinden suchen heisse Orte

Client: Kanton Aargau, Departement Bau Verkehr und Umwelt, Stadt Zürich, Umwelt- und Gesundheitsschutz Zürich (UGZ), Regionalkonferenz Umweltschutz Luzern (RKU)

Partner: Aargau municipalities; Lucerne municipalities; Naturama Aargau, re:edu, Kanton Aargau, Departement Bau, Verkehr und Umwelt, Sensirion, NOA

Our role: Project Concept and Management, Citizen Science, Climate Communication