In times of climate change a strong effort should be made to enhance thermal conditions within cities to create livable environments. Shading in urban open spaces has been recognized as an important parameter in modifying microclimatic conditions and enhancing thermal comfort particularly in hot regions. When designed appropriately, shading can mitigate the Urban Heat Island (UHI), enhance pedestrian thermal comfort and affect outdoor activities.

A decision support tool (DST) was developed for evaluating the minimum shading coverage required, by trees or other shading devices, to improve thermal comfort in streets during the most critical hours of the day. The presented DST accounts for the density of tree-canopies or the albedo of various materials used for shading devices. To develop the index, a set of climatic simulations was run using the Green CTTC model and thermal comfort was determined by the PET index. Based on the simulations Open-space Shading Coefficients (OSC) were computed and used to develop an Open-space Shading Index (OSI). The city of Tel-Aviv, characterized by a hot-humid climate, was selected as a case study. Results demonstrate the viability of the index as a DST for assessing the extent of shading required to achieve thermal comfort in urban streets.

在气候变化时期，应大力改善城市中的热条件，以创造宜居的环境。城市开放空间中的阴影已被认为是改变微气候条件和增强热舒适性的重要参数，特别是在炎热地区。如果设计得当，遮阳可以减轻城市热岛（UHI），增强行人的热舒适度并影响户外活动。

开发了决策支持工具（DST），用于评估树木或其他遮阳设备所需的最小遮阳覆盖率，以改善一天中最关键时刻的街道热舒适性。提出的DST考虑了树冠或用于遮光设备的各种材料的反射率的密度。为了开发该指数，使用Green CTTC模型运行了一组气候模拟，并通过PET指数确定了热舒适度。基于仿真，计算了开放空间阴影系数（OSC），并将其用于开发开放空间阴影指数（OSI）。案例研究选择了以湿热气候为特征的特拉维夫市。结果表明，该指数作为DST的可行性，可用来评估在城市街道上实现热舒适所需的阴影程度。