都市型態及綠色基礎設施對重劃區戶外熱環境之影響

Abstract

全球正面臨都市化造成熱島效應、夏日極端高溫等環境惡化現象，影響人們在戶外活動的熱舒適性。都市重劃區具有建築錯落分佈且高樓層的特性，提供通風與調節氣溫的潛力。而許多研究指出綠色基礎設施(green infrastructure, GI)如：公園綠地、街道綠帶等，能改善都市熱環境。故本研究目的為探討重劃區內的都市型態與綠色基礎設施配置形成的空間組合方案，將如何影響行人戶外熱舒適度。 本研究歸納臺灣雙北地區五處焦點重劃區的都市街廓大小、平均樓高及道路寬度等空間資訊，作為建置模擬方案的基礎配置參考。以重劃區的都市型態與綠色基礎設施組成為自變項，環境氣溫與生理等效溫度為應變項。應用ENVI-met作為研究工具，提出共14個模擬方案，分階段探討都市型態和綠色基礎設施對重劃區降溫的影響。在都市型態方面，將重劃區內的建築樓高、建築配置方式作為探討變項，形成4種都市型態方案，篩選出具最佳熱舒適表現的都市型態作為下階段模擬的基礎方案；在GI組成方面，比較不同GI類型（住宅街廓綠化、公園綠化、街道綠化及聯合三種綠化）和4種不同喬木覆蓋率方案，在重劃區都市型態下的熱環境情形；最後，綜合比較第一階段4種都市型態方案在相同綠化程度下的熱環境表現與降溫效益，提出具較佳熱舒適表現的都市型態與GI配置方案。 研究結果顯示不同方案在不同時段的氣溫與熱舒適度表現各異。在都市型態方面，高樓方案之熱舒適優於低樓方案；建築分散配置方案優於集中配置方案。在綠色基礎設施組成方面，相同喬木覆蓋率下，以平均配置的聯合綠化方案最優，其次為住宅街廓綠化和公園綠化；中午時段的喬木覆蓋率降溫效益最佳，越高的喬木覆蓋率方案，環境較為涼爽舒適，每增加10%喬木覆蓋率，可以降低氣溫0.17℃、PET 0.86℃。研究結果可提供都市規劃人員作為優化戶外熱環境的建築及綠色基礎設施空間配置參考。

The world is currently facing environmental deterioration such as urban heat islands and extreme summer temperatures caused by urbanization, which impact the thermal comfort of outdoor activities for people. Urban redevelopment zones feature scattered high-rise buildings, offering the potential for ventilation and temperature regulation. Many studies indicate that green infrastructure (GI) such as parks and green belts can improve the urban heat environment. Therefore, this study aims to explore how the spatial configuration formed by urban morphology and GI in redevelopment zones affects pedestrians' outdoor thermal comfort. This study synthesized spatial information on urban street sizes, average building heights, and road widths from five focal redevelopment zones in the Taipei Metro Area as the basis for configuring simulation scenarios. Taking the urban morphology and green infrastructure configuration of redevelopment zones as independent variables, with air temperature and physiological equivalent temperature (PET) as dependent variables. Using ENVI-met as the research tool, a total of 14 simulation scenarios were proposed to investigate the impact of urban morphology and green infrastructure on cooling in redevelopment zones. Regarding urban morphology, building heights and configurations within the redevelopment zones were varied to form four urban morphology scenarios. The urban morphology scenario demonstrating the best thermal comfort performance was selected as the basis for subsequent simulations. In terms of GI composition, different types of GI (greenery around the building, park greening, street greening, and a combination of these) and four different tree canopy coverage rates were compared under the urban morphology scenarios to assess their impact on the thermal environment. Finally, the study comprehensively compared the thermal performance and cooling benefits of the four urban morphology scenarios in the first phase under the same level of greening, proposing urban morphology and GI configuration scenarios that offer superior thermal comfort. The research results indicate that different strategies exhibit varying temperature and thermal comfort performances at different times of the day. In terms of urban morphology, the high-rise scenario shows better thermal comfort compared to the low-rise scenario, and dispersed building configurations outperformed concentrated ones. Regarding GI composition, under similar tree canopy coverage rates, the combined greening with average distribution showed optimal results, followed by greenery around the building and park greening. The cooling benefits of tree canopy coverage are most effective at noon, with higher canopy coverage leading to a cooler and more comfortable environment. For every 10% increase in tree canopy coverage, the temperature can be reduced by 0.17°C and PET by 0.86°C. The research findings can serve as a reference for urban planners to optimize the spatial configuration of buildings and green infrastructure to enhance outdoor thermal environments.