Outdoor thermal comfort in open transitional spaces with limited greenery in hot summer/cold winter climates

Regarding the constant use of transitional spaces, there is an intense interest in studies on the outdoor thermal comfort in transitional spaces, especially in regions with hot summers. This study aims to analyze the outdoor thermal comfort conditions of a transitional space focusing on vegetation cover change to distill findings into a set of design guidelines for landscape architects and urban planners to enhance the thermal comfort in open transitional spaces, especially in airport terminals with hot summer, and cold winter climate. The case study for this research is an open transitional area at the Mehr-Abad airport. Mehr-Abad airport experiences blistering summers and freezing winters. The environmental situation is analyzed using ENVI-met software. Subsequently, without-grass and without-tree scenarios were simulated to study the impact of greenery on transitional thermal comfort. The results were validated using the on-site collected data. In this study, results demonstrate that the average PET in the current situation is 39.81 ℃ in summer (hot sensation) and 5 ℃ in winter (cold sensation). Based on the results, removing the grass cover is the most suitable scenario for both summer with 35.80 ℃, and winter with 6.68 ℃. The best scenario consists of adding more deciduous trees to open transitional spaces to reduce solar shading in winter. This study provided a better understanding of the effects of vegetation in transient-oriented limited spaces on outdoor thermal comfort and looked deeper into vegetation characteristics concerning the transitional space requirements in hot summer/cold winter climates.