Date

2022-7-4

Author

Başçıl Erkaya, Dilara

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As a result of the urbanization in the last few centuries, green and permeable surface areas have decreased, and surfaces covered with materials with high heat holding capacity have increased. An increase in the environmental temperature caused by excessive heat above the urban areas is called Urban Heat Island (UHI) effect. This study primarily aims to find a correlation between the microclimate change of Ankara and the change in the building and urban surface materials due to expansion of urban areas. Within the scope of the study, 16 urban blocks with different structural and environmental characteristics were selected within the borders of Ankara. The buildings in the selected blocks and the surrounding urban elements were photographed with both digital and thermal cameras, and the albedo values of the relevant surfaces were calculated. Later, microclimate simulations of three-dimensional modeled areas were made in ENVI-met software and maps showing surface temperature, potential air temperature, wind speed and reflected shortwave radiation values were produced. vi The data obtained from the simulation results were compared with the measurements made in the physical environment and it was observed that they showed consistency. According to the results, building and urban characteristics such as building heights, surface albedo values, window to wall ratio, urban layouts and environmental elements affect the microclimatic conditions. In two blocks with very similar structural features, the different urban layout of the buildings primarily changes the wind passage pattern and the wind speed. Building heights also change the wind passage pattern and the area of shadows on the ground, causing changes in sensible temperature. As the albedo value of a material increases, the surface temperature decreases, and the use of low albedo materials reduce the ambient temperature. On the other hand, materials with low albedo value and high surface temperature have higher radiation energy to their surroundings. In addition, the presence of vegetation and water bodies reduces the potential air temperature by evaporation and absorbing the SW radiation. This effect helps to reduce the air temperature and increase the thermal comfort level of the people.

Subject Keywords

Urban Heat Island, surface albedo, thermal imagery, ENVI-met, thermal comfort level

URI

https://hdl.handle.net/11511/99779

Collections

Graduate School of Natural and Applied Sciences, Thesis