Quantification of thermal stress abatement by trees, its dependence on morphology and wind: A case study at Patna, Bihar, India

《Quantification of thermal stress abatement by trees, its dependence on morphology and wind: A case study at Patna, Bihar, India》

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作者: Venkatesh Raman;Manoj Kumar;Anjali Sharma;Dominik Froehlich;Andreas Matzarakis

关键字: Mean radiant temperature (TMRT);Physiological equivalent temperature (PET);SkyHelios Pro;Thermal stress;Urban morphology

作者单位: Department of Architecture, National Institute of Technology Patna, Ashok Rajpath, Patna, Bihar, 800005, India;Meteorological Institute, Albert-Ludwigs-University of Freiburg, 79085 Freiburg, Germany;Research Centre, Human Bio-meteorology, Deutscher Wetterdienst, 79104, Freiburg, Germany;Private Researcher, Freiburg, Germany;Department of Architecture, National Institute of Technology Patna, Ashok Rajpath, Patna, Bihar, 800005, India;Meteorological Institute, Albert-Ludwigs-University of Freiburg, 79085 Freiburg, Germany;Research Centre, Human Bio-meteorology, Deutscher Wetterdienst, 79104, Freiburg, Germany;Private Researcher, Freiburg, Germany

摘要: This study attempts to quantify thermal-stress abatement by tress, using the example of Bihar Museum at Patna, Bihar, India, where around 200 trees, though known as great solar heat attenuators, were felled to accommodate the newly-built museum. The study, with a focus on sensitivity analysis, compares two tree scenarios, at two input wind-speeds and seeks to identify the individual/synergetic effects of physical attributes of tree-morphology, background wind, etc., on cooling by trees, through simulations, using freely available model SkyHelios Pro. SkyHelios allows for the spatial/temporal analysis of the thermal changes at a point of time and space. The ‘area-mean’ rise in mean radiant temperature (TMRT) is found 1.9 °C and in physiological equivalent temperature (PET) 1.1 °C, by 28 % trees-removal (area-wise), at noon at 0.5 m/s input wind-speed. TMRT reduction by trees is found directly related to their canopy-size/cluster-density, and inversely to background wind-speed. PET reduction is directly related to the canopy-size/ cluster-density at lower wind-speeds and inversely at higher. The study is limited to daytime (noon) hours. Based on the detailed outputs from SkyHelios simulations, recommendations for passive cooling of urban outdoors in terms of tree size, layout-density, built-up morphology, and background wind-speed are formulated.