Cities worldwide are piloting the use of solar reflective coatings on roads to mitigate the Urban Heat Island (UHI). Solar reflective pavement has been praised as simple, low-cost solution with a demonstrated ability to reduce surface temperature and, potentially, energy use. Less well understood is the effect of solar reflective coatings on radiant heat, which influences human thermal exposure and comfort. We present the first biometeorological observations of solar reflective coating to investigate its thermal performance from a pedestrian perspective. Hourly transects were conducted in two Los Angeles neighborhoods with MaRTy, a mobile platform that measures air, surface, and mean radiant temperature. Transects were performed on July 30, 2019, a typical summer day with low wind speeds and maximum air temperature of 31°C. The surface temperature of the coated asphalt concrete was 4°C to 6°C lower than that of the regular asphalt concrete, but coated surfaces reflected 118 Wm-2 more shortwave radiation on average and up to 168 Wm-2 more at noon. In the evening, MaRTy observed 20 to 30 Wm-2 of added reflected shortwave radiation on sidewalks next to the reflective pavement. Mean radiant temperature over reflective pavement was 4°C higher during midday. Although air temperature was reduced by 0.5°C in the afternoon, after-sunset cooling was negligible. Findings illustrate the benefits and disadvantages of reflective pavement with respect to various thermal performance metrics. Cities should weigh the tradeoffs of UHI mitigation, thermal exposure, implementation and maintenance costs, lifecycle, and other competing priorities in the context of space use.

中文翻译：

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太阳能反射路面——缓解热量的政策灵丹妙药？

世界各地的城市都在试行在道路上使用太阳能反射涂层，以减轻城市热岛 (UHI)。太阳能反射路面被誉为简单、低成本的解决方案，具有降低表面温度和潜在能源使用的能力。不太了解的是太阳反射涂层对辐射热的影响，这会影响人体的热暴露和舒适度。我们首次对太阳反射涂层进行生物气象学观察，以从行人的角度研究其热性能。每小时横断面是在洛杉矶的两个社区使用 MaRTy 进行的，这是一个测量空气、地表和平均辐射温度的移动平台。横断面于 2019 年 7 月 30 日进行，这是一个典型的夏日，风速较低，最高气温为 31°C。涂层沥青混凝土的表面温度比普通沥青混凝土的表面温度低 4°C 至 6°C，但涂层表面平均多反射 118 Wm-2 的短波辐射，中午时反射高达 168 Wm-2。晚上，MaRTy 在反射人行道旁边的人行道上观察到 20 到 30 Wm-2 的附加反射短波辐射。中午时分，反射路面上的平均辐射温度高出 4°C。虽然下午气温下降了 0.5°C，但日落后的降温可以忽略不计。调查结果说明了反射路面在各种热性能指标方面的优缺点。城市应权衡 UHI 缓解、热暴露、实施和维护成本、生命周期以及空间使用背景下的其他竞争优先事项。