熱帶高密度都市地區的植栽降溫效益：以新加坡為例

Vegetation Cooling in Tropical High-Density Urban Areas: Case Studies in Singapore

本研究旨在釐清都市綠化於熱帶高密度都市環境中之降溫效益，並以新加坡為案例進行實證分析。鑒於熱帶地區常面臨都市熱島效應，植栽作為具適應性之緩解策略，具有高度應用潛力。研究選取五個具代表性之場址，依據建築形態與綠化參數進行分類，並透過數值模擬方法評估不同空間配置下植栽的降溫表現。進一步比較各場址之冷卻效益，以探討都市綠化在異質性空間脈絡中的整合策略。
研究結果顯示，都市植栽之降溫效益受場址空間特性與背景氣候條件（如季風風向與微氣候）之交互作用顯著影響。具體設計建議如下：（1）於中密度都市區提升植栽密度與聚集指數，可分別使場址平均氣溫降低至0.3°C與0.4°C，局部點位降溫幅度則可達1.0°C與1.6°C；（2）植栽若配置於迎風面，可有效導入東北季風，進而擴大冷卻區域之範圍，其效益可達原面積之兩倍。
本研究所提出之設計見解，對於提升都市綠化在異質性環境中之現地降溫效能，具重要參考價值，並可作為熱帶都市綠化規劃與設計之實務指引。

This study distinguishes the cooling effect of urban greenery across heterogeneous urban contexts using case studies in Singapore. In well-established tropical regions, introducing vegetation offers an adaptable alternative for mitigating urban heat. Five representative sites were selected based on the building morphology and greenery parameters, exploring how vegetation can be effectively integrated into various contexts. Numerical simulations were conducted to model the cooling effects. A comparative analysis of the cooling effect of urban greenery was conducted across selected sites. Better understandings of where and how to integrate urban vegetation into urban areas to maximize the cooling effect are gained. The results indicate that the cooling effect of urban vegetation is significantly influenced by site context and background climate conditions (i.e., monsoon seasons and local microclimate), as well as the interplay between them. Key design insights include (1) increasing vegetation density and aggregation index in medium-density urban contexts reduces site-averaged air temperature by up to 0.3°C and 0.4°C, and point-based by 1.0°C and 1.6°C, respectively. (2) strategically aggregating vegetation on the windward side to leverage the northeast monsoon wind, potentially doubling the size of effective cooling areas. These insights are crucial to optimize on-site vegetation cooling performance in heterogeneous urban environments.