Daytime radiative cooling technology can cool objects to sub-ambient temperatures under direct sunlight without energy consumption. The technology relies on high reflectance of solar irradiation and high emissivity in the atmospheric window (infrared emission with 8 to 13 μm wavelengths). We report a bilayer structured coating for passive daytime sub-ambient radiative cooling. The bilayer radiative cooling coating has high solar reflectance (0.94), and high infrared emissivity (0.96) in the atmospheric window. The bilayer coating achieved a sub-ambient temperature of 3.6°C under solar irradiance of 990 W / m2 at an ambient temperature of 26.6°C, and the averaged sub-ambient cooling temperature of ∼8 ° C during the night. A test with two model rooms shows that the indoor air temperature reached a maximum difference of 9.7°C between the one with the bilayer coating and that with normal white coating.

中文翻译：

---

用于辐射冷却应用的双层结构涂层

日间辐射冷却技术可以在阳光直射下将物体冷却至低于环境温度而无需消耗能源。该技术依赖于太阳辐射的高反射率和大气窗口的高发射率（8 至 13 微米波长的红外发射）。我们报告了一种用于被动白天亚环境辐射冷却的双层结构涂层。双层辐射冷却涂层在大气窗口中具有高太阳反射率 (0.94) 和高红外发射率 (0.96)。在环境温度为 26.6°C 的情况下，双层涂层在 990 W/m2 的太阳辐照度下实现了 3.6°C 的亚环境温度，夜间平均低于 8°C 的亚环境冷却温度。对两个样板房进行的测试表明，室内空气温度的最大差异达到了 9。