Strategic deployment of urban trees to achieve thermal resilience in a Canadian community

Abstract Climate change and urban heat islands are intensifying the frequency and severity of heatwaves, emphasizing the need for resilient and sustainable strategies to cool urban outdoor and indoor spaces. Urban trees are identified as an effective solution, yet limited studies address how different tree deployment strategies enhance building thermal resilience against heatwaves. This study examines the impact of strategic urban tree deployment on building thermal resilience across a neighborhood in London, Canada. Two deployment strategies are assessed: a straightforward strategy based on outdoor temperature hotspots, and a more complex strategy based on building indoor heat stress. The analysis incorporates tree growth and its effect on canopy coverage. A coupled microclimate-building performance simulation evaluates outdoor and indoor thermal conditions, with thermal resilience quantified using a novel method integrating microclimate effects, heat stress intensity, and exposure duration. Results indicated that when canopy coverage increases from 6% to the Nature Canada-recommended 30%, both strategies achieve similar maximum reductions in building surrounding outdoor air temperature (4.0 °C) and Standard Effective Temperature (6.9 °C), as well as comparable reductions in indoor thermal stress. However, at lower canopy coverage levels (≤20%), the indoor based strategy achieves a more uniform resilience distribution and enhances thermal resilience for the majority of buildings with poorer baseline conditions. At 30% canopy coverage and above, the differences between the two strategies become less pronounced, making tree deployment based on outdoor temperature hotspots a straightforward yet effective strategy for improving neighborhood thermal resilience.