A 3D shading simulation tool to support local climate adaption actions

Enhancing green infrastructure plays a critical role in urban climate adaptation to mitigate heat stress. Recent studies show that the cooling function of green space is more strongly correlated to its shading effect than its vegetation density. The local governments of Dortmund, Germany, have started to enhance green space and shaded places as part of the heat mitigation strategy, yet they lack practical tools for implementation. To support these actions in practice, we developed a 3D shade simulation tool at the city scale to visualise the shading effect in real-time, quantify shaded hours and simulate tree planting scenarios.

We first identify the surface temperature hotspots using satellite data, then integrate the 3D building model with Level of Detail 2, combine the tree cadastre data and LiDAR point cloud to create the 3D tree model, and finally, transform the 3D building and tree model into an open-access web application.

This web-based tool lets users visualise the shading effect from trees and buildings in real time or at any time. At any given location, users can quantify the accumulated shade hours over any time span at this specific place. The additional interactive tree planting tool allows users to simulate the scenarios after tree planting to simulate the improved shading effect.

This tool has been used for two heat mitigation action projects in the city. Firstly, the senior office used this tool to identify the best-shaded places as cooling spaces and resting places for elderly people. Secondly, the Green Connects project plans to plant 100 trees near Mosselde and Rohdesdiek Street, 50 of which will be on public land and 50 others on private land. With our shading simulation tool, urban planners and citizens can quickly identify areas that lack shading, particularly these temperature hotspots, and then simulate tree planting scenarios for optimised heat mitigation.