Micrometeorological simulations to predict the impacts of heat mitigation strategies on pedestrian thermal comfort in a Los Angeles neighborhood
Micrometeorological simulations to predict the impacts of heat mitigation strategies on pedestrian thermal comfort in a Los Angeles neighborhood
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DOI：
10.1088/1748-9326/11/2/024003
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发表时间：
2016-02
影响因子：
6.7
通讯作者：
M. Taleghani;D. Sailor;G. Ban-Weiss
中科院分区：
文献类型：
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作者：
M. Taleghani;D. Sailor;G. Ban-Weiss
城市热岛效应影响着城市行人的热舒适性。本文以洛杉矶县东部的一个社区为例，模拟了四种热缓解策略对微气象和行人热舒适的影响。调查的策略包括太阳能反射“凉爽屋顶”，植被“绿色屋顶”，太阳能反射“凉爽路面”，并增加街道树木。一系列的微气象模拟极端炎热的一天进行了假设广泛采用的每一种缓解策略。比较每个模拟控制模拟假设当前的土地覆盖的邻居表明，额外的行道树和凉爽的路面减少了1.5米的空气温度，而凉爽和绿色屋顶主要提供冷却的高度以上的行人水平。然而，凉爽的路面增加了从地面反射到行人在一组无阴影的受体位置的阳光。这种反射的辐射增强了平均辐射温度，从而使白天的生理等效温度（PET）增加了2.2 °C，降低了行人的热舒适度。在另一组距离道路平均5米的受体位置和预先存在的树木覆盖下，凉爽的路面导致白天表面空气温度显著降低，平均辐射温度变化较小，导致PET降低1.1 °C，从而改善热舒适性。对于改善行人的热舒适性在下午在无阴影的位置，增加行道树被认为是最有效的策略。然而，下午的热舒适性的改善，在已经阴影的位置附近的街道是最显着的凉爽的路面。绿色和凉爽的屋顶对行人的热舒适性的影响最小，因为它们修改了屋顶水平的能量平衡，高于行人的高度。
The urban heat island impacts the thermal comfort of pedestrians in cities. In this paper, the effects of four heat mitigation strategies on micrometeorology and the thermal comfort of pedestrians were simulated for a neighborhood in eastern Los Angeles County. The strategies investigated include solar reflective ‘cool roofs’, vegetative ‘green roofs’, solar reflective ‘cool pavements’, and increased street-level trees. A series of micrometeorological simulations for an extreme heat day were carried out assuming widespread adoption of each mitigation strategy. Comparing each simulation to the control simulation assuming current land cover for the neighborhood showed that additional street-trees and cool pavements reduced 1.5 m air temperature, while cool and green roofs mostly provided cooling at heights above pedestrian level. However, cool pavements increased reflected sunlight from the ground to pedestrians at a set of unshaded receptor locations. This reflected radiation intensified the mean radiant temperature and consequently increased physiological equivalent temperature (PET) by 2.2 °C during the day, reducing the thermal comfort of pedestrians. At another set of receptor locations that were on average 5 m from roadways and underneath preexisting tree cover, cool pavements caused significant reductions in surface air temperatures and small changes in mean radiant temperature during the day, leading to decreases in PET of 1.1 °C, and consequent improvements in thermal comfort. For improving thermal comfort of pedestrians during the afternoon in unshaded locations, adding street trees was found to be the most effective strategy. However, afternoon thermal comfort improvements in already shaded locations adjacent to streets were most significant for cool pavements. Green and cool roofs showed the lowest impact on the thermal comfort of pedestrians since they modify the energy balance at roof level, above the height of pedestrians.