本研究主旨為探討都市街道綠化與鋪面設置之蒸散作用產生的現象與溫度及空氣中熱含量變化之影響,期望探討植栽設置和鋪面材質的改善,達到良好之通風及降溫效果。 本研究利用Penman-Monteith equation推算植物蒸散作用時所需之熱量,並藉由計算流體力學(Computational Fluid Dynamics,簡稱CFD)之模擬方式,在無風和有風的都市環境中,針對街道不同的鋪面材質與綠帶設置的變化形成之風場特性及溫度和空氣中熱含量變化影響之情況,以了解植栽的蒸散作用對都市高溫環境中降溫的成效。 藉由模擬結果得知,種植植栽對於都市降溫具有顯著的影響且植栽的蒸散作用可緩解都市高溫現象:有風環境下草地鋪面的溫度相較無風之柏油鋪面溫度下降溫6°C;種植植栽的也使溫度下降約7.04°C。此外,在無風的環境下因風場呈現滯留狀態,使熱量散失不易,反之在有風的環境中則有較明顯的降溫效果。就建物群而言,建築物受風面與背風面皆容易因渦流產生使熱量堆積,因此在未來制定都市設計準則時應考量植栽導風與行人風場的通風性,才能減緩高溫現象,以達到永續之生態都市目標。
Purpose of this study is to explore the influence of transpiration appearance and temperature of urban street planting and pavement on enthalpy change in air, expecting to explore the improvement of planting setting and pavement materials to achieve good ventilation and cooling effect. This study takes advantage of Penman-Monteith equation to figure out the heat required for plant transpiration, and by means of simulation method of Computational Fluid Dynamics (referred as CFD), under wind and no wind urban environment, aims at the influence of wind field characteristics and temperature, formed by different pavement materials and changes of planting setting, on enthalpy change in air, to realize the cooling effect of planting transpiration on urban high temperature environment. By simulation results learn that planting has remarkable influence on urban cooling, and planting transpiration can ease urban high temperature phenomenon: compared with no wind asphalt pavement, temperature of grass pavement under the wind drops about 6°C; temperature of planting also drops 7.04°C. In addition, under no wind, wind field presents detention state, so that heat loss is not easy, whereas windy environment has obvious temperature decrease. For building group, both windward side and leeward side are easy to cause heat accumulation by eddy, therefore, planting leads the wind and ventilation of pedestrian wind field should be considered into future development of urban design guidelines, so that to reduce high temperatures, to achieve sustainable ecological city goals.