A numerical assessment of microclimate and cooling effects of a modular street parklet for urban heat mitigation

Street parklets are gaining popularity among urban planners as an effective strategy to green our cities due to their high portability and adaptability. Beyond social and aesthetic benefits, parklets also have the potential to mitigate urban heat on the local scale. However, their cooling potential has been rarely explored, highlighting the need for research into their cooling mechanisms and the optimal use of their portability in real-world deployment. This study investigates the cooling effect of a modular parklet in a real-world urban environment using a comprehensive computational fluid dynamics (CFD) model that incorporates the key cooling processes of vegetation, including aerodynamic, shading and transpiration effects. Empirical measurements are used for CFD model setup and validation. The results indicate that the parklet effectively modifies near-ground and pedestrian-level airflow and thermal fields, achieving a maximum air temperature reduction of 0.66 °C at 2 p.m. and 0.70 °C at 6 p.m., with cooling extending downwind beyond the parklet geometry. Further, the parklet reduces the physiological equivalent temperature (PET), with a maximum reduction of 1.5 °C at noon and 1.3 °C in the evening. ... mehrThe PET reduction footprint can be up to 14 m in the evening. However, aerodynamic drag from vegetation reduces airflow speeds, leading to increases of PET in some areas. These findings highlight the importance of location-specific designs of parklets to maximise their cooling benefits, and provide a basis for strategically leveraging their portability in real-world deployment.