Effect of greening vacant houses on improvement in thermal environment using ENVI-met simulation: A case study on Busan metropolitan city

This study aimed to analyze the improvement in outdoor thermal environment by greening of persistently vacant housing and open areas in a densely built old downtown area of Busan Metropolitan City using ENVI-met. Simulation was performed for a summer day by constructing four scenarios for four areas considering the building density and slope direction. The results indicate that compared to the current scenario, the concrete scenario had the worst thermal environment, where the average temperature, mean radiant temperature (MRT), and physiological equivalent temperature (PET) increased by 0.04°C, 1.49°C, and 0.51°C, respectively. In contrast, the tree scenario exhibited the most significant improvement. The average temperature, MRT, and PET decreased by 0.03°C, 1.66°C, and 0.65°C, respectively. Moreover, the removal of vacant houses in dense residential areas improved ventilation, and PET decreased by approximately 8°C locally. Planting trees higher than the demolished vacant houses mitigated the thermal environment considerably. The effect of greening was the strongest in the residential areas located on the south-facing slope with the worst thermal environment. This study provides essential data for implementing greening as a smart reduction strategy in the sustainable management of vacant houses.