The Relationship between Urban Geometry Patterns, Air Flow and Thermal Comfort: A Case Study of Chiang Mai Municipality
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Abstract
Environmentally friendly cities need to relate to nature. The research aims to study on the effect of urban geometry patterns on airflow and thermal comfort in Chiang Mai municipality. The study applied the proportion between building height and road width or height-to-width ratio (H/W ratio) as the urban geometry. The Computational Fluid Dynamics or CFD simulation was used as a tool in order to simulate airflow patterns through buildings and test the efficiency of airflow in various building patterns based on 6 urban density levels, between 10% to 60%, It was found that the temperature in the areas at density levels of 40-60% having high relativity to the H/W ratio. Hence, the wind current in the area with dense high-rise buildings and narrow streets is obstructed by the buildings itself. Thus, the airflow is restricted causing low ventilation rate and temperature increase in some areas where the air could not reach. Furthermore, when a whirlwind occurred after a strong wind current hits the high-rise building, it raises some safety concerns to the residents and the building structures. Despite the dense high-rise buildings, a good urban planning which considered the position and design of the building that is not obstructing the wind direction could generate the airflow direction and promote ventilation. The results from the satellite imagery for vegetation indices show negative correlations with the local temperature. The research studied the temperature comfort condition by collecting the meteorological data in the studied area. The comparison between temperatures, relative humidity and wind speed according to the Psychrometric Chart found that in areas with a density of 30% or more, the temperature was higher than the temperature comfort ranges. Accordingly, the results recommend a suitable management by increasing green areas, consideration of building openings and vertical ventilation methods for buildings in that area. Further suggestion in the future in on adjusting the building's height relative to the width of the street for future urban areas.
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The articles published are the opinion of the author only. The author is responsible for any legal consequences. That may arise from that article.
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