Quantitative assessment of green coverage changes under the human-biometeorological perspective: A simulation case study in Jeju, Republic of Korea

Abstract

To prove the promotion of urban green to mitigate the regionally predetermined heat stress on the local urban scale, comprehensive numerical simulations using ENVI-met v5.0.2 were carried out in an E-W street canyon considering the representative urban structure in Jeju, Republic of Korea, on the heatwave day of August 15, 2020. The simulations consisted of 10 combinations of urban green infrastructure: street trees, grass, façade, and roof greening. Compared to the bare condition, combined green infrastructure led to the maximum reduction in mean air temperature (ΔTa) by 2.1 K, mean radiant temperature (ΔTmrt) to 25.3 K, and physiological equivalent temperature (ΔPET) to 16.1 K. Street trees exhibited the greatest effect on the ΔTmrt and ΔPET as a measure of human thermal comfort. The combination of various green infrastructures has a larger impact on ΔTmrt on the S-facing sidewalk compared to the N-facing sidewalk, with a mean ΔTmrt of 21.2 K for the S-facing sidewalk and 8.0 K for the N-facing sidewalk. Green infrastructure brings about indoor ΔTa by 1.5 K at the N-bordering building. As relevant design guideline to reduce human heat stress in urban areas, the simulation results provide urban/landscape planners the quantitative effect of combinations of green infrastructure.