連棟住宅之街廊比對街谷內風環境之影響－－以臺南市氣象資料為例

The Impact of Length to Width Ratio on Wind Environment for Row Houses in Street Canyons – A Case Study of Weather Data in Tainan

近年來，都市中街道通風程度、風道等被規劃領域廣為討論。都市風環境的不佳係為導致局部溫度增加的主因之一。然而，風道與微風發生機率的相關規範，在規劃過程中缺乏適切建立與評估。基於上述，本研究設定街廓長寬比1:1 至4:1 等4 個案例，探討風環境分佈。關於微風之定義，本研究以1.5m/s 做為微風之基準。在氣象資料方面，採用台南市5 年夏季之氣象資料分析8 個主要風向的韋伯分佈，並考量風速剖面與高度關係的指數率，再利用經過驗證後之計算流體動力學模型，模擬不同案例的都市街廓對於該8 個風向的受風情形，於後配合韋伯分配，推估該區域內平均風速與微風發生機率。焦點區域則針對地表高1.5m 之行人受風尺度與5m 高之居家生活場域。由模擬結果能得知都市街道中隨著街廓長寬比的增加，風速減緩的現象越趨明顯。

Recently, the ventilation levels of streets and wind path have been widely discussed in planning field. Poor wind environment in urban area results in the rise of air temperature in street canyons. According to the reasons above, the length to width ratio of 1:1 to 4:1 row houses were chosen as simulation cases, in which the width is 40 meters and the height is 12 meters. The weather from June to September, year 2003 to 2007 in Tainan was analyzed to estimate the Weibull distribution. The wind profile and surface roughness were considered to calculated air flow. The verified CFD were carried out to observe the wind environment for wind coming from 8 directions. Base on the CFD results, the parameters of Weibull were substituted into the analysis of the wind distributions. It was found in the simulations that the wind speed decelerated obviously in larger L/W row houses.