行道樹對都市街谷微氣候影響之研究

Research on the Influence of Street Trees on the Microclimate of Urban Street Valleys

龔宇彥(Yu-Yen Kung)

指導教授 ： 黃國倉

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102977

摘要

全世界的人口約有50%居住於都市，而根據預估，在2030年前會達到80%。另根據統計(Sanaieian, Tenpierik et al. 2014)，居住在都市的人口排放的溫室氣體佔了全球溫室氣體的70%以上。隨著都市規模的擴張，都市建築的空調耗能逐年增加，使得都市熱島效應日益加劇，都市所致的溫室氣體排放逐年上升。本研究以改善都市微氣候為目標，將都市街谷型態之幾何組成拆解成三要素：道路寬度、座向以及高寬比，利用直交表組合成16種之街谷型態，以單一樹種、單一種植間距的行道樹作為改善都市微氣候的調適策略手段，共計有32組模擬，利用微氣候模擬軟體ENVI-met模擬最熱日與最冷日下多種街谷型態下種植行道樹前後之微氣候差異，再透過本研究提出之模式，包含：（1）利用冷房度時（Cooling Degree Hour）推估一年中逐日的最大溫度修正量，以及（2）利用儒略日（Julian Day）推估相對於最大溫度修正量之逐時修正係數γ，並對相對溼度、風速以及風向如法炮製，藉此產製一年逐時氣象資料，將單日的微氣候模擬結果延伸至可供建築能源模擬使用的氣象資料，以利未來將微氣候調適效益轉換為建築節能與減碳效益。在既有建築之節能策略近乎枯竭的情形下，透過行道樹的種植改善都市微氣候，進而降低建築用電量與溫室氣體排放，希冀能協助住商部門達成國家《溫室氣體管理法》的減碳目標。
根據本研究之成果顯示，在僅考量街谷型態下的氣象資料，與過去建築能源模擬所使用的TMY氣象資料有很大的差異，夏季白天月均溫最高可以相差3.68°C，故若是用TMY進行模擬，與建築實際面臨的氣候環境有所落差。另外，在僅考量街谷型態的對微氣候的影響條件下，在街道座向為N-S向、深街谷的幾何組成下有較好的降溫效益；若考量行道樹的調適效益，則應優先以街道座向為E-W向、淺街谷且道路寬度較窄的街道為優先規劃對象。

關鍵字

都市微氣候 ； 行道樹 ； 微氣候調適 ； ENVI-met ； 街谷幾何型態

並列摘要

Approximately 50% of the world’s population lives in cities, and according to estimates, it will reach 80% by 2030. According to the research (Sanaieian, Tenpierik et al. 2014), people living in cities emit more than 70% of global greenhouse gases. With the expansion of the scale of cities, the energy consumption of air-conditioning in urban buildings has increased year by year, making the urban heat island effect increasingly intensified, and greenhouse gas emissions caused by cities have increased year by year. With the goal of improving the urban microclimate, this research disassembled the geometric composition of urban street canyons into three elements: road width, orientation, and height-to-width ratio, and used orthogonal tables to combine them into 16 street canyon types. One species and street trees with a single planting distance are used as an adjustment strategy to improve the urban microclimate, and there are 32 sets of simulations in the study. The microclimate simulation software ENVI-met is used to simulate the microclimate difference after planting street trees in a variety of valley types on the hottest and coldest days. Based on the model proposed in this study, includes: (1) using Cooling Degree Hour to estimate the maximum temperature correction amount for each day of the year, and (2) using Julian Day to estimate the hourly correction coefficient γ relative to the maximum temperature correction amount, and process the relative humidity, wind speed and wind direction in the same way, so as to produce one-year hourly meteorological data, and extend the single-day microclimate simulation results to the weather data which is available to building energy simulation. The generated weather data is used to facilitate the conversion of micro-climate adjustment benefits into building energy-saving and carbon-reduction benefits in the future. When the energy-saving strategies of existing buildings are almost exhausted, the planting of street trees can improve the urban micro-climate, thereby reducing building electricity consumption and greenhouse gas emissions, hoping to assist the residential and commercial sector to achieve the national carbon reduction goals.
According to the results of this research, the meteorological data under only the street-valley pattern is very different from the TMY meteorological data used in the building energy simulation in the past. The maximum difference between the average temperature during the day and the month in summer can be 3.68°C, so if it is the simulation with TMY is different from the actual climate environment faced by the building. In addition, under the condition of only considering the influence of street canyons on the microclimate, the street orientation is N-S and the geometric composition of deep street canyons has better cooling benefits; if the mitigation benefits of street trees are considered, priority should be given to streets with E-W orientation, shallow valleys and narrow road widths.

並列關鍵字

urban microclimate ； street trees ； microclimate mitigation strategies ； ENVI-met ； geometric composition of urban street canyons

參考文獻

Baker, N. and K. Steemers (2003). Energy and environment in architecture: a technical design guide, Taylor Francis.

Brown, G. and M. DeKay "Book Review–Sun Wind and Light: Architectural Design Strategies."

Bruse, M. (2010). "ENVI-met 3.1 manual contents." from https://envi-met.info/documents/onlinehelpv3/cnt.htm.

Castaldo, V. L., A. L. Pisello, C. Piselli, C. Fabiani, F. Cotana and M. Santamouris (2018). "How outdoor microclimate mitigation affects building thermal-energy performance: A new design-stage method for energy saving in residential near-zero energy settlements in Italy." Renewable Energy 127: 920-935.

Chatzinikolaou, E., C. Chalkias and E. Dimopoulou (2018). "URBAN MICROCLIMATE IMPROVEMENT USING ENVI-MET CLIMATE MODEL." International Archives of the Photogrammetry, Remote Sensing Spatial Information Sciences 42(4).