福州东西向深街谷内树致行人夏季热环境差异  

Difference of Pedestrian Thermal Environment in Summer Caused by Trees in the Deep East-West Street Canyon in Fuzhou

作　　者：林定[1] 吴俊[1] 刘亚敏 邓卓 韩朝帅 LIN Ding;WU Jun;LIU Yamin;DENG Zhuo;HAN Chaoshuai

机构地区：[1]福州大学数字中国研究院(福建),福州350108 [2]国民核生化灾害防护国家重点实验室,北京102205

出　　处：《中国园林》2023年第2期120-126,共7页Chinese Landscape Architecture

基　　金：福建省科技计划引导性项目“树木对城市街谷内局地微环境的影响和应用”(编号2019Y0005)资助。

摘　　要：夏季东西走向的街道因长时间暴露于日照形成最不舒适的行人环境,树木可提供树荫降低气温但也阻碍了局地通风,然而,植树对行人热环境的综合影响尚不清楚。针对城市高密度街区(LCZ 2类型)中东西走向的街道,开展行道树绿化差异对行人热环境综合影响的定量计算与分析。结果表明:1)树木对行人热环境的影响是非线性的,且在夏季白天不同时段呈不同规律,街道树木覆盖率与树致平均行人气温差异值之间存在如下关系:上下午非线性关系强烈,中午则接近线性关系;2)当树木覆盖率小于50%时,树致行人气温降低的梯度大,每增加10%树木覆盖率,行人高度平均气温最高约降低0.26℃;树木覆盖率超过50%以后,植树带来的热效益改善值减小,而且影响的时间窗口趋于中午附近(11:00—14:30);3)东西向街道内的各种植树方案都对行人热环境产生正面影响,当树冠相互接触形成连续树荫时,树致改善效应接近饱和,继续提高种植密度反而会产生负面影响。考虑城市用地紧张,建议东西走向的街道,采用可形成连续树荫的50%左右覆盖率的行道树绿化,以获得舒适的行人小气候。East-west streets are exposed to the longest sunshine during summer, which leads to the most uncomfortable pedestrian environment.Trees can provide shade to reduce the temperature, but hinder the local ventilation. However, the comprehensive effects of tree planting on the pedestrian thermal environment are unclear. In this paper, the quantitative calculation and analysis of the comprehensive impact of street tree greening differences on the pedestrian thermal environment are carried out for the east-west street in high-density blocks(LCZ 2).The results show that: 1) The influence of trees on the pedestrian thermal environment is nonlinear, and there are different laws during different periods of the day. The relationship between street tree coverage ratio and the tree-induced average pedestrian temperature variation is as follows:the nonlinear relationship is stronger in the morning and afternoon, but it approximates linearity at noon;2) When the tree coverage ratio is less than 50%, the gradient of pedestrian temperature reduction caused by trees is large. For every 10% increase in tree coverage, the average temperature of pedestrian height will decrease by about 0.26℃;while it exceeds 50%, the thermal-benefit improvement value brought by tree planting decreases, and its time window of influence tends to be near noon(11:00-14:30);3) Various tree planting schemes in the east-west street have a positive impact on the pedestrian thermal environment.When the tree crowns contact each other to form a continuous shade, the tree induced thermal benefits is close to saturation, and the go-on increase of planting density has a negative impact. Thinking over the shortage of urban land, it is suggested that street trees with a coverage rate of about 50% that can form continuous shade should be greening the east-west streets to obtain a comfortable pedestrian microclimate.

关 键 词：风景园林 行人热环境 树木覆盖率 天空可视因子 树木绿化 数值模拟 

分 类 号：TU986[建筑科学—城市规划与设计]