基于ENVI-met软件对热环境模拟及人体热舒适性研究: 以安徽省建科院绿色屋顶为例

Study on thermal environment and human thermal comfort of green roof based on ENVI-met simulation-Green roofs of Anhui Institute of Building Research and Design as an example

  • 摘要:
    背景 在全球气候变化背景下,随着城市热岛效应加剧,对城市热环境及人体热舒适性研究日益得到重视。夏热冬冷地区绿色屋顶在夏季有着显著的降温增湿效应。
    目的 探索绿色屋顶在降低城市热岛效应,提升人体热舒适性等方面的机制,为城市绿色屋顶的规划设计提供科学依据。
    方法 以安徽省建筑科学研究设计院(后简称:建科院)绿色屋顶为研究对象,选取晴朗无风的典型天气条件下对花园式绿色屋顶进行实地监测,在验证模型精度可靠性的基础上运用ENVI-met 4.4.5软件模拟花园式与草坪式两种不同类型绿色屋顶,随机式、组团式与围合式三种不同植被布局形式,从"面"的角度测量绿色屋顶降温增湿效应以及用生理等效温度(PET)对人体热舒适性进行评价。
    结果 结果表明:(1)绿色屋顶在夏季有着明显的降温增湿效应,降温效应呈现白天弱夜间强,增湿效应呈现白天强夜间弱的总体分布特征。(2)草坪式与花园式绿色屋顶类型呈现的降温和增湿的变化趋势较为一致;降温幅度分别在0.002~0.068℃与0.001~0.141℃之间,增湿幅度分别在0.367%~1.952%与0.555%~2.305%之间;花园式略强。(3)在19:00至次日6:00时间段,此时空气温度处于26.462~28.436℃之间,相对湿度处于54.192%~66.608%之间,PET处于18~23℃,为人体热舒适性水平最佳的时段;在11:00-16:00时间段,此时空气温度处于28.557~30.349℃之间,相对湿度处于49.646%~57.636%之间,PET>41℃,人体热舒适性处于一天中最差水平;在6:00-11:00以及16:00-19:00时间段,PET处于23~41℃,人体热舒适性处于一般水平。(4)在植被配置比例相同,植被布局不同的情境中,地块平均温度依次为随机式布局 < 组团式布局 < 围合式布局,且温度的高低与风速大小呈正相关,与相对湿度大小呈负相关的关系,相同时间点三种不同植被布局形式呈现相同的热应激水平。
    结论 在夏热冬冷地区,草坪式与花园式绿色屋顶在夏季都具有一定的降温增湿效果,一天中不同时间段的人体热舒适水平也会表现不同,所以增加绿色空间和城市绿量,对于改善城市微气候和提高人体热舒适性具有重要意义。

     

    Abstract:
    Background In the context of global climate change, with the intensification of urban heat island effect, research on urban thermal environment and human thermal comfort is gaining increasing attention. Green roofs in the hot summer-cold winter regions have significant cooling and humidifying effects in summer.
    Objective The study is designed to explore the mechanism of green roofs in reducing urban heat island effect and improving human thermal comfort, and provide a scientific basis for the design of urban green roofs.
    Methods The garden green roofs of Anhui Institute of Building Research and Design were monitored under a clear and windless weather condition. The ENVI-met 4.4.5 software was used to simulate two different types of roof greening (garden and ground-cover) and three different vegetation layout forms (random, group, and enclosed) based on verifying the accuracy and reliability of the model. The cooling and humidifying effects of green roofs were measured from a "surface" perspective, and the physiological equivalent temperature (PET) was used to evaluate human thermal comfort.
    Results (1) Green roofs had significant cooling and humidifying effects in summer, with a stronger cooling effect during the day than at night and a stronger humidifying effect at night than during the day. (2) Ground-cover and garden roof greening showed similar trends in cooling and humidifying effects. The daily temperature decline of ground-cover and garden green roofs ranged from 0.002℃ to 0.068℃ and from 0.001℃ to 0.141℃, respectively; the humidity increase ranged from 0.367% to 1.952% and from 0.555% to 2.305%, respectively; garden roof greening showed steeper changes. (3) During 19:00-6:00 the next day, i.e., when the air temperature was between 26.462℃ and 28.436℃, the relative humidity was between 54.192% and 66.608%, and PET was between 18-23℃, the human thermal comfort was at its highest level. During 11:00-16:00, i.e., when the air temperature was between 28.557℃ and 30.349℃, the relative humidity was between 49.646% and 57.636%, and PET was >41℃, the human thermal comfort was at its lowest level. During 6:00-11:00 and 16:00-19:00, i.e., when PET was between 23-41℃, the human thermal comfort was at an average level. (4) In the context of same vegetation configuration proportions and different vegetation layouts, the average temperature of the plot from low to high was random layout < group layout < enclosed layout; the temperature was positively correlated with the wind speed and negatively correlated with the relative humidity; the three vegetation layouts showed same heat stress levels at same time points.
    Conclusion In the hot summer-cold winter zones, both ground-cover and garden roof greening have certain cooling and humidifying effects in summer. Associated human thermal comfort levels change in a day. Therefore, increasing green space and urban green volume is important to improve urban microclimate and enhance human thermal comfort.

     

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