MicroBUS: PALM-related simulations and wind-tunnel measurements of street trees in urban traffic hotspots

Abstrakt

The MicroBUS project focuses on scenario-based simulations of traffic-related urban hotspots to improve understanding of the interactions between airflow, thermal comfort, and air quality. The outcomes are intended to support evidence-based urban planning and decision-making in the city of Prague, particularly in relation to future emission-reduction requirements imposed by the European Union. Initial work has included wind-tunnel measurements for domains comprising streets with heavy traffic loads. Complementary simulations using the PALM model serve as a bridge between wind-tunnel experiments and real-world sensor observations and will have real application potential. The investigated scenarios consider tree planting in streets as a potential measure to improve thermal comfort. Our previous results indicate that street trees can substantially modify local ventilation and the urban energy balance, leading to measurable changes in thermal comfort, as quantified by the Universal Thermal Climate Index (UTCI). However, trees increase PM10 concentrations, and their impact is dependent on tree-coverage configurations. The findings suggest that a reduced number of trees may represent a more effective compromise, offering comparable improvements in UTCI while limiting increases in PM10 concentrations. Furthermore, trees in wider, main streets appear to be more beneficial than those in narrow street canyons.