城市設計對城市微氣候與宜居性的影響

Abstract

本研究探討都市設計參數對台北市微氣候及人體感知的影響，旨在為都市規劃者及建築師提供建議，協助打造更健康且永續的都市環境。透過將都市微氣候知識融入設計中，期望能透過氣候敏感型都市設計來提升人類在都市空間的福祉。 為達成此目的，本研究設定三大目標：(1) 開發一個計算框架，透過Computational Fluid Dynamics（CFD）模擬，研究建築環境與微氣候之間的關係；(2) 分析特定都市設計參數如何影響當地微氣候；(3) 提供設計參考指引，將模擬數據融入設計過程，讓設計更具可實踐性。 研究框架聚焦於台北市的亞熱帶氣候，透過CFD模擬，檢視不同都市配置對環境熱舒適度的影響，並評估了兩款模擬工具：ENVI-met 與 ANSYS Fluent。雖然 ANSYS Fluent 提供詳細的建模設定，但其複雜的操作及對綠化模擬的局限性，使 ENVI-met 成為本研究模擬分析的首選，ENVI-met具備強大的數據庫及效益，儘管其對植栽降溫效果可能存在高估。 本研究成果發現，牆面反射率、地面反照率及土壤濕度等材料特性對空氣與輻射溫度具有顯著影響。尤其是建築牆面與地面之間的交互作用，導致日間複雜的熱舒適結果。針對都市設計參數（包括容積率 FAR、建蔽率 BCR 和綠覆率 GCR）的詳細分析顯示：在27種情境下，較高的 FAR 提升了遮陰效果並改善熱舒適性，而 BCR 的影響則受到建築面積、建築高度、太陽照射及氣流互動而異。適當的 GCR 水準能有效降低溫度，但過度綠化會造成反效果，因此需平衡綠化配置。 針對不同街區形式（如獨立型、線型、開放型及半開放型）之研究發現，開放型及半開放型建築街區型式有助於提升熱舒適度，而線型建築佈局可促進自然通風，降低熱壓力。同時，公園類型亦影響熱舒適性：分散型小公園只能提供局部降溫效果，而中心型大公園則帶來更寬廣的降溫效益。 透過將理論模型轉化為實用框架，本研究結果證實，都市設計參數在理論與實際應用中對微氣候及熱舒適度的影響具有一致性，並適用於台灣多樣化的氣候條件。研究進一步揭示了微氣候在多種都市佈局下的複雜性，並提出未來應優化設計策略，以應對不同環境需求。 最後，本研究拓展了都市設計對其他宜居性因素（如聲學及視覺感知）的重要性，提出未來都市設計應採用整合方法，平衡都市建築配置與其他感官體驗。通過關注居民活動、聲學與視覺舒適性及熱環境條件，都市規劃者可打造宜居、有活力且永續的都市活動空間，提升整體宜居環境。 基於研究框架，本研究的所有發現已總結為設計參考指引，供建築師與規劃者在未來設計時參考。

This study examines the impact of key urban design parameters on microclimate and human perception in Taipei City, aiming to provide urban planners and architects with actionable insights for creating healthier, more sustainable urban environments. By integrating urban microclimate knowledge into design, this research supports the development of urban spaces that enhance human well-being through climate-sensitive designs. To achieve this aim, we pursued four objectives: (1) developing a computational framework to study the interactions between built environments and microclimate via CFD simulations, (2) analyzing how specific urban design parameters shape local microclimate conditions, (3) exploring adaptive urban design strategies to improve urban livability, and (4) creating guiding design references for integrating simulation data into design practices for more accessible insights. The research framework, applied in Taipei's subtropical climate, uses scenario-based simulations to assess how different urban configurations influence environmental comfort. Two simulation tools, ENVI-met and ANSYS Fluent, were evaluated for this purpose. While ANSYS Fluent offers detailed modeling capabilities, its complexity and limitations in greenery modeling led to the choice of ENVI-met for general trend analysis, given its robust databases and efficiency, despite some tendencies to overestimate vegetation's cooling effects. Key findings reveal that material properties such as wall reflectivity, ground albedo, and soil moisture significantly influence air and radiant temperatures. Albedo effects, especially the dynamic interactions between building walls and ground, contribute to complex thermal comfort outcomes throughout the day. Detailed analysis of urban design parameters—Floor Area Ratio (FAR), Building Coverage Ratio (BCR), and Green Coverage Ratio (GCR)—across 27 scenarios shows that higher FAR enhances shading and thermal comfort, while the effects of BCR vary due to building footprint and height interactions with solar and airflow dynamics. Strategic GCR levels effectively reduce temperature, though excessive greenery yields diminishing returns, indicating the need for balanced greenery planning. Exploring different city block forms, such as Detached, Linear, Open, and Semi-Open types, we found that Open and Semi-Open forms improve comfort, while Linear layouts facilitate natural ventilation, reducing thermal stress. Park types also play a role in comfort: Pocket parks provide localized cooling, while Center parks offer wider cooling benefits. By translating theoretical models into a practical framework, this study demonstrated consistent effects of urban design parameters on microclimate and comfort across Taiwan's varied climates. The findings highlight the complexities of microclimate within diverse urban layouts and suggest future research directions for refining design strategies. Lastly, the study extends to visual perception, proposing that designs balancing natural and built elements improve view quality, especially with greater building spacing. Effective strategies include adjusting Height-to-Width ratios, implementing setbacks, and integrating layered greenery, enhancing both thermal and visual comfort in urban spaces. Based on the proposed framework, all the findings of this study are summarized as design guiding references for architects and planners to reference when implementing future projects.