Apparent temperature data from thermal walks organized by the City of Amersfoort to be able to evaluate how people perceive temperature at certain locations. The subjective opinions of the participants of the thermal walk are complemented by measurements from a sensor measuring air temperature, wind speed and humidity.

Method and approach

Usually city designers use maps, calculations and models to find solutions for urban heat stress. In this project, we explored the use of a different method: thermal walks. Thermal walks focus on involving citizens by asking them how they perceive heat stress. As such, it tries to incorporate data on their experience of heat ‘in real life’. In Amersfoort we planned ten thermal walks for inhabitants in the summer of 2022. The city is, amongst others, designed for inhabitants, so our focus was to experience heat with inhabitants themselves. An additional benefit is that by doing so, awareness on heat stress and the negative effect it can have on health is enhanced.

During the thermal walks, groups of participants walked through predesigned routes throughout the city. They were accompanied by one or more representatives from COA. During the walks, participants were asked to fill out short surveys on predefined locations. The surveys had to be filled in digitally, so a smartphone with internet was required. To lower barriers to participate citizens who did not have a smartphone available were provided with a model owned by COA.

The walk focused on gathering data on subjective heat experience. Examples of questions that were included are: are the thermal conditions on this location pleasant for you? If not, would you prefer colder or warmer temperatures? And which circumstances on this location influence your thermal experience here?

The guided walks followed three routes and started on three predefined locations: near the Central Railway area, in the neighborhood called Schothorst and in the city centre (see figure 4). There were five to seven stops during each route. At each stop the survey was filled out on two locations: one in the sun and one in a shadow spot.

Besides the subjective heat stress, a sensor was used to measure objective heat stress. The sensor used was a JDC Skywatch BL 500. It includes measurements of wind, air pressure, UV index, humidity and temperature. The sensor connects via Bluetooth with a smartphone to read the measurements. In the app a route can be tracked, saved and published online. At each location a waiting time of one minute was used to allow the sensor and participants to acclimatize.