Assessing Thermal Comfort in Outdoor Public Spaces: Evaluating Mitigation Strategies for Extreme Heat

Most outdoor public spaces are underutilized during extremely hot weather. In the absence of adequate shading, these areas become high-risk zones, posing significant health risks, particularly for vulnerable populations such as the elderly and children. Some cities aim to retrofit public spaces as part of their heat action plans to make them more useable and thermally safe during extreme heat events. However, cities lack the relevant scientific data to inform such plans and often have no means of evaluating and quantifying the likely benefits from specific redesign strategies. To address this challenge, we evaluated the outdoor thermal regime in Mesa, Arizona, on a human scale. We generated high-resolution Mean Radiant Temperature (MRT) data using surface models developed using LiDAR point clouds and meteorological forcing data from a local weather station. We modified the surface models to reflect future scenarios and exposure settings following the plans for modifying vacant lots in the city. MRT in most vacant lots without shading reaches values as high as 80 °C during the day. We observed that the heat burden was reduced by about half at locations with shading from existing trees. Future work will investigate how the redesign strategies improve the useability of the spaces under different exposure settings.