Document Type : Original Article
Department of Architecture, Faculty of Architecture and Urban Planning, Qazvin Branch, Islamic Azad University, Qazvin, Iran
Vegetation moderates a microclimate by casting shadows, increasing light reflection, evaporation and perspiration; and correcting wind patterns. The present study aims to investigate the microclimatic role of vegetated surfaces and bodies in improving thermal comfort in outdoor spaces between buildings. The main research question is which of the green system modes, that is, horizontal vegetation (green floor) and vertical vegetation (green façade) will be more effective in moderating a microclimate and improving thermal comfort in outdoor spaces. To find the answer, an academic building with vertical and horizontal walls facing an outdoor space (yard) was selected as the studied case. Data analysis was performed via numerical modeling (ENVI-met) and RayMan software model. The Indices of PMV (predicted mean vote), PET (physiological equivalent temperature), Tmrt (total mean radiant temperature), and RH (relative humidity) were computed and analyzed to identify and analyze thermal comfort levels in outdoor spaces. The analysis results indicate that vegetation significantly affects thermal comfort in outdoor spaces between buildings in warm seasons by reducing PMV, PET, Tmrt, and increasing RH. In all analytical modes based on the indices of thermal comfort in outdoor spaces, green floor performed better than green façade due to a more extensive tree coverage on horizontal surfaces. The trees planted on horizontal surfaces and the ground improve thermal comfort in outdoor spaces by shading and blocking direct sunlight. Further, the results indicate that compared to vegetation, blocking direct solar radiation and providing shading on surfaces are much more effective in improving thermal comfort in open spaces.