| Summary: | 碩士 === 中國科技大學 === 建築研究所 === 102 === Due to urban rapid expansion and huge amount building constructions, the city area a large number of trees were removed away and became grass lot, that decreases the sun shading area of the ground and facades dramatically and results to more strong urban heat island effect. According to researches, a cluster of trees in a city is able to reduce site temperature 3.8℃ in the summer season, and canopy shade cooling potential among different kinds of tree is varied. The planting design in the Taiwan Green Building Evaluation System EEWH only takes account the tree CO2 fixation to the earth rather than the tree shading and cooling effect to the site, as a result to choose better shading tree in a green building design is usually ignored. This research the experiment and investigation of different kinds of popular tree in Taiwan will be conducted, and a site cooling island coefficiency of tree planting as a bonus tool for building envelope energy saving evaluation will be formulated.
This research results show that in the shaded area of different trees the cooling effect of temperature measured in site is range from 0.27℃ to 1.62℃, the sun radiation reduction is range from 733.6 W/m2 to 939.1 W/m2, the temperature of ground surface is lower from 10.62℃ to 26.78℃, and the temperature of building façade tiled solid wall surface is lower from 2.47℃ to 4.47℃. The Study finds out the tree canopy leaf dense is the first major factor and the canopy coverage size is the second factor for the cooling of ground surface, and the tree canopy height is the only main factor for the cooling of vertical solid wall. Following the study results, a cooling island coefficiency calculation formula of tree planting for evaluation cooling effect is proposed. There are three factors involved in this calculation formula, i.e., tree canopy original cooling potential, tree canopy growing integrity, and tree planting effective location for wall shading. The cooling island coefficiency γ is proposed as a bonus factor for evaluating the energy efficiency of envelop, EEV, and the highest value of γ is below or equal to 1.2 .
Keywords：green building, urban cool island, tree canopy shading, tree planting
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