Passive cooling design options to ameliorate thermal comfort in urban streets of a Mediterranean climate (Athens) under hot summer conditions
Passive cooling design options to ameliorate thermal comfort in urban streets of a Mediterranean climate (Athens) under hot summer conditions
复制标题
DOI：
10.1016/j.buildenv.2012.04.019
复制
发表时间：
2012-11
影响因子：
7.4
通讯作者：
L. Shashua-Bar;I. Tsiros;M. E. Hoffman
中科院分区：
文献类型：
--
作者：
L. Shashua-Bar;I. Tsiros;M. E. Hoffman
本研究旨在探讨如何透过适当的城市设计，降低街道空气温度，改善夏季行人的热环境。案例研究是雅典的一条街道，具有低纵横比H/W（H：建筑物高度; W：街道宽度）、低树冠覆盖水平和高交通量。城市设计变量为树木覆盖率、交通荷载、墙面覆盖率、高宽比。它们的热效应是单独和共同估计的小气候绿色CTTC模型，而热应力的评估使用生理等效温度（PET）指数。研究的一天是相对炎热的（中午36.5 °C），在街道上有8小时的热应激（分别为2小时和6小时的极端和强烈热应激）。可接受的近不适限制当地行人被认为是PET分类热应力水平调整到当地条件下，通过应用校正方程获得的PET值。结果表明，所研究的方案与空气温度下降和改善热舒适的阴凉处，特别是在一天中最热的时间。树木的热效应是主要的影响因素，其次是高湿比的增加和墙体表面粗糙度的增加。所有研究的设计方案被发现能够减少热应力小时数，但树木树冠覆盖面积比增加的情况下，被发现本身只能与当地行人的中度热应力。还讨论了替代的热舒适性局部智能控制（SCAT）选项。
This work investigates how to reduce, by appropriate urban design, air temperature at the street level and to improve pedestrian thermal conditions in summer. The case study is a street in Athens with low aspect ratio H/W (H: building height; W: street width), low trees canopy coverage level, and high traffic. Urban variables for design are trees canopy coverage area ratio, traffic load, walls surfaces albedo, and H/W. Their thermal effect is separately and altogether estimated by applying the microclimatic Green-CTTC model whereas thermal stress is assessed using the Physiological Equivalent Temperature (PET) index. The studied day is relatively hot (36.5 °C at midday) with eight hours of heat stress (two and six hours of extreme and strong heat stress, respectively) at street level. Acceptable near-to-discomfort limits for local pedestrians are considered whereas PET classification heat stress levels are adjusted to local conditions by applying a correction equation to obtained PET values. Results show that the examined scenarios are associated with air temperature decrease and improvement of thermal comfort in the shade, especially during the day's hottest hours. The trees thermal effect is the dominant factor followed by the increase of H/W and of the walls surfaces albedo. All the studied design scenarios are found able to reduce the number of heat stress hours but the trees canopy coverage area ratio increase scenario was found by itself able to be associated only with moderate heat stress for local pedestrians. Alternative local smart controls for thermal comfort (SCAT) options are also discussed.