Thermal performance prediction of street trees inside isolated open spaces – evaluations from real scale retrofitting project

Climate change and the urban heat island (UHI) effects are increasing heat stress and adversely impacting outdoor thermal comfort in urban areas. The study demonstrates that thermal comfort conditions can be improved by reducing air temperature and surface temperature with the integration of street trees into the urban environment. In this work, computational fluid dynamics (CFD) simulations using unsteady Reynolds-averaged Navier–Stokes (URANS) equations have been performed to analyze the cooling effect of street trees for heatwave period (18–22 June 2015) in a hot-humid urban environment. The results are then compared in-term-of air/surface temperature, flow-velocity and apparent temperature for the vegetation case, open-space case, and built case. The analysis shows that the vegetation can effectively decrease surrounding temperature (a reduction of 1.2 K), thereby reducing energy consumption and effectively promote thermal comfort conditions. The study findings will encourage city planners and citizens to take action for urban greening.