College of Urban and Rural Construction, Shanxi Agricultural University, Taigu, 030801, Shanxi, China.
Forestry College of Shanxi Agricultural University, Taigu, Shanxi, China.
Int J Biometeorol. 2024 Oct;68(10):2115-2131. doi: 10.1007/s00484-024-02735-0. Epub 2024 Jul 20.
Increasing heat stress in urban environments due to climate change has a significant adverse impact on human work and daily life. Street canyons as the main component of the underlying surface of the city and the main place of residents' activities, a comprehensive understanding of street morphology and tree planting practices can help to improve thermal comfort. Based on survey data and field experiments, this study designed 30 scenarios and employed ENVI-met model (version 5.0.3) to quantify the effect of street aspect ratio (H/W: H is building height and W is street width) and tree spacing (TS) on pedestrian thermal comfort in two differently oriented streets (north-south and east-west) in Taiyuan, China. Results showed that H/W ratio and TS significantly influenced the street thermal comfort mainly owing to shading. H/W ratio played a pivotal role in reducing mean radiant temperature (Tmrt) and physiological equivalent temperature (PET), and was negatively correlated with Tmrt and PET. Compared to no-tree scenarios, street trees significantly improved thermal comfort (mean reductions of Tmrt and PET were 12.74℃ and 5.66℃, respectively), and PET and Tmrt were significantly negatively correlated with TS. The improvement effect of street trees on Tmrt and PET in east-west oriented street was better than north-south oriented street. H/W = 1.0 and TS = 6 m appeared as the proposed combination to mitigate the summer thermal comfort in the temperate monsoon climate zone. These quantitative results provide new insights into renewal and design strategies for future urban planning.
由于气候变化，城市环境中的热应激不断增加，对人类工作和日常生活产生了重大的不利影响。街道峡谷作为城市下垫面的主要组成部分和居民活动的主要场所，全面了解街道形态和植树实践有助于提高热舒适度。本研究基于调查数据和现场实验，设计了 30 种情景，并采用 ENVI-met 模型（版本 5.0.3）来量化街道纵横比（H/W：H 为建筑物高度，W 为街道宽度）和树木间距（TS）对中国太原两条不同朝向（南北向和东西向）街道行人热舒适度的影响。结果表明，H/W 比和 TS 显著影响街道热舒适度，主要是由于遮阳。H/W 比在降低平均辐射温度（Tmrt）和生理等效温度（PET）方面起着关键作用，与 Tmrt 和 PET 呈负相关。与无树情景相比，街道树木显著改善了热舒适度（Tmrt 和 PET 分别平均降低了 12.74℃和 5.66℃），并且 PET 和 Tmrt 与 TS 呈显著负相关。街道树木对东西向街道 Tmrt 和 PET 的改善效果优于南北向街道。H/W=1.0 和 TS=6 m 似乎是缓解温带季风气候区夏季热舒适度的建议组合。这些定量结果为未来城市规划的更新和设计策略提供了新的见解。
