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研究成果

綠建築對都市熱島緩和及舒適度提升之量化效益評估研究

計畫主持人: 王安強
協同主持人: 黃國倉
執行單位:
執行期程:
GPN:
ISBN:
MOIS:
組別: 環境控制組
執行方式: 協同研究
關鍵詞: 都市熱島效應、都市微氣候、戶外熱舒適、熱島降溫
參考文獻:

中文摘要


一、研究緣起

近年來在氣候變遷之影響下都市環境愈趨炎熱,推行綠建築有助於改善基地周遭之熱環境。我國自1999年起綠建築標章制度上路,其中影響都市熱環境之相關指標包括綠化量指標與基地保水指標。本研究目的在於量化這些綠建築設計因子對於緩和都市熱環境與戶外熱舒適提升之量化效果,期能量化確立綠建築在改善都市微氣候上之貢獻,以供未來擬定都市降溫策略之參考。有鑑於此,本研究透過電腦數值模擬解析之技術,嘗試建構綠建築設計因子與實際減緩都市熱島與提升戶外熱舒適之量化效益,作為未來綠建築設計、綠建築政策成果對於都市環境改善之效益預測,並藉由量化之因子敏感度分析提出提升都市環境品質之關鍵策略。

二、研究方法及過程

研究首先透過國內外文獻回顧,同時蒐集國際上綠建築評估系統相關文件,進行比較國際上綠建築評估系統內有關都市熱島減緩與戶外熱舒適相關之評估指標規定。針對各綠建築技術(如各種基地保水手法、綠化改善、建築群體之配置、不同建材之應用等)對於戶外熱環境之量化效益,本研究以電腦流體力學數值模擬(Computational fluid dynamics, CFD)之方式進行系統性模擬,藉由模擬結果與小規模實測比對驗證無誤後,輔以統計學變異數分析(ANOVA)方法,建立各因子對(1)都市熱環境緩和與(2)改善戶外熱舒適,之貢獻度分析同時建立量化之預測模式。本研究搭配戶外熱環境實測進行模擬之驗證。此外,由於數值模擬方法受限於當今電腦運算能力之限制,難以進行全年長期之模擬。因此必須挑選能夠代表當地氣候之代表日氣象資料以為模擬之外界氣候標準,進行夏季代表日之挑選,以氣候較為嚴苛之日探討各基地因子對熱環境之緩和效果。

在確立影響都市熱島與戶外熱舒適之關鍵影響因子後,為了有效率並系統性的以數值模擬實驗確立各因子之敏感度,建立各因子之量化貢獻量,在模擬實驗之規劃上採用田口實驗計畫法之直交實驗,以減少實驗所需之時間。透過有限次數之模擬實驗對各相異的建成環境配置案例模擬後,進行各案例之微氣候熱環境輸出以為分析,並嘗試建立綠建築設計因子對熱環境之預測式。最後,嘗試研訂「綠建築指標對戶外降溫及舒適效益換算式」草案,同時提出提升環境品質之關鍵策略,分析熱島緩和及舒適提升導入或修正現有綠建築評估項目之可行性,以作為未來評估綠建築推行下對於都市熱環境之改善量化效益評估。

三、重要發現

1.完成國內外有關都市熱島成因與國際上綠建築評估內容內有關都市熱島之評估方法回顧。

2.完成都市微氣候模擬工具與實測之比對,確立電腦模擬之輸入參數。

3.完成擬定都市熱島降溫與提升熱舒適模擬之環境因子與熱季外界氣候條件選定。

4.以實驗計畫法之直交表規劃模擬實驗與建模之工作,建立量化之都市熱島降溫與戶外熱舒適(以過熱嚴重度表示)之預測模型:

(1)在對日間降溫效益方面,以「平均建築高度」、「空地喬木覆蓋率」、「人工鋪面區平均反射率」與「建蔽率」為影響較顯著之因子。

(2)在對夜間降溫效益方面,以「平均建築高度」、「空地喬木覆蓋率」與「建蔽率」為影響較顯著之因子。

(3)在對戶外日間過熱嚴重度方面,以「平均建築高度」、「空地喬木覆蓋率」與「空地的綠覆面積比」為影響較顯著之因子。

5.提出「綠建築指標對戶外降溫及舒適效益換算式」,使得綠建築評估系統內之綠化量指標與基地保水指標評估內容得以與本研究所開發之熱環境預測模式接軌以利模式之評估應用。

6.完成實際綠建築標章申請案例共12例之試算演示,應用本研究所開發之預測模式評估其開發前後對基地日夜間降溫之效果,以及進行基地過熱嚴重度之評估,以確立預測模式應用之可行性。

四、主要建議事項

根據本研究成果發現,提出下列建議:

建議一

建議應用本研究所建立之環境降溫與熱舒適評估預測模型,可將過去之綠建築案例進行評估,嘗試量化綠建築對環境降溫與提升熱舒適上之量化效益,彰顯我國綠建築政策在改善都市微氣候上之成效:立即可行建議。

主辦機關:內政部建築研究所

協辦機關:財團法人台灣建築中心

建議二

本研究為了探討在熱季中最嚴苛時綠建築設計對基地內降溫與熱舒適提升之效益,因此以幾近無風之狀態下進行探討。然而,都市風廊之創造以及基地內建築群之配置以提升通風品質與風速,與戶外熱舒適之提升有密切關係。建議後續可針對都市建築群之配置如何影響基地內通風以利降溫與提升熱舒適進行量化之研究:立即可行建議。

主辦機關:內政部建築研究所

協辦機關:無



英文摘要


1.Introduction

Urban thermal environment is exacerbating due to the influence of climate change in recent years. Thermal environment could be improved by implementing green building design. The Taiwanese green building labeling system is launched in 1999, in which system, the greenery and water retention indices are related to the urban thermal environment. The objective of this study is to quantify the effect of implementing these indices on the alleviation of the urban thermal environment and the improvement of the outdoor thermal comfort. The research results could be provide as a reference for formulating urban heat island mitigation strategies. To this end, computational numerical simulation was adopted to construct the quantitative appraisal models between the green building design and its inducing effect. 

2.Methodology

Literature reviews were firstly conducted to identify crucial factors that affects the urban thermal environment as well as outdoor thermal comfort. Furthermore, international green building labeling systems were also collected, the evaluating methods regarding the urban environment were compared. This study adopted computational fluid dynamic (CFD) technique to study the effects on the thermal environment of green building designs such as strategies of water retention, greenery, material of the pavement etc. Concerning the numerous environmental designing factors to be considered with and due to the fact that the process of CFD analysis is time-consuming, the design of experiment method was employed to facilitate the research efficiency by limiting the simulation runs to 27 cases. The ANOVA was adopted to analyze the relative contributions of each design factors and to construct the predicting models of the ambient temperature mitigation and the outdoor thermal comfort improvement.

3.Major findings

(1)This study accomplished the comparisons of the evaluation methods of urban heat island existing in green building labeling systems worldwide.

(2)A field measurement campaign was conducted for validation against the CFD simulation software.

(3)Identification of Taipei’s extreme meteorological data for simulation was performed to study the urban environmental thermal condition on the extremely hot date.

(4)Green building design factors that affected the thermal environment were identified:

i.The influential factors against the diurnal temperature mitigation are the average building height, tree’s canopy coverage ratio, albedo of the pavement material, and the building coverage ratio.

ii.The influential factors against the nocturnal temperature mitigation are the average building height, tree’s canopy coverage ratio, and the building coverage ratio.

iii.The influential factors against the severity of outdoor overheating are the average building height, tree’s canopy coverage ratio, and the greenery coverage ratio.

(5)The predicting models of both urban heat island mitigation potential and the outdoor thermal comfort improving effect were established.

(6)The application of the established models were demonstrated by 12 actual green building cases and the feasibility of the models were confirmed.

4.Recommendations

As the quantitative models for appraising the green building design against the urban thermal environment have been established, it is suggested that to gradually evaluate the urban heat mitigation and thermal comfort improving potentials of every green building labeled cases.