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KMID : 1024520150240060819
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Journal of the Environmental Sciences
2015 Volume.24 No. 6 p.819 ~ p.826
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Impacts of Different Urban Surfaces on Summer Thermal Performance
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Jo Hyun-Kil
Wu Qiang
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Abstract
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This study measured temperatures and albedos of urban surfaces for different colors and materials during summer, and
calculated the energy budget over different urban surfaces to find out the thermal performance affecting the heat built-up. The study selected six surface colors and 13 materials common in urban landscape. Their surface temperatures (Ts) and albedos were measured at a given time interval in the daytime from June to August. Average Ts over summer season for
asphalt-colored brick was 4.0℃ higher than that for light red-colored one and 9.7℃ higher than that for white-colored one. The Ts for artificial surface materials of asphalt paving, brown brick wall, and green concrete wall was 6.0℃ higher than that for natural and semi-natural ones of grass, grassy block, and planted concrete wall. There was the greatest difference of 16.3℃ at midafternoon in the Ts between asphalt paving and planted concrete wall. Average albedo over summer season of surface materials ranged from 0.08 for asphalt paving to 0.67 for white concrete wall. This difference in the albedo was associated with a maximum of 15.7℃ difference at midafternoon in the Ts. Increasing the albedo by 0.1 (from 0.22 to 0.32) reduced the Ts by about 1.3℃. Average storage heat at midday by natural and semi-natural surfaces of grass and grassy block was about 10% lower than that by artificial ones of asphalt, light-red brick, and concrete. Reflected radiation, which ultimately contributes to heating the urban atmosphere, was 3.7 times greater for light-red brick and concrete surfaces than for asphalt surface. Thus, surfaces with in-between tone and color are more effective than dark- or white-colored ones, and natural or semi-natural surfaces are much greater than artificial ones in improving the urban thermal environment. This study provides new information on correlation between Ts and air temperature, relationship between albedo and Ts, and the energy budget.
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KEYWORD
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Material, Color, Surface temperature, Albedo, Energy budget
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