Highly reflective “cool materials” are commonly used to reduce temperatures in the urban environment. Recently developed “super cool” materials feature an even higher albedo and emissivity (both above 0.95) than traditional cool materials. To examine the impacts of super cool roofing materials on outdoor air temperature compared to traditional cool roofs and green roofs, we conduct a sensitivity study with the microclimate model ENVI-met. Simulated surface temperature of super cool roofs remained around 6 K below ambient air temperature during high solar irradiation, which is consistent with observations. Super cool roofs – with an averaged street-level air temperature cooling of around 0.85 K in times of high solar radiation – provided 0.1 to 0.15 K more cooling than commonly used cool roofs and green roofs. Results also showed that super cool roofs could lower pedestrian-level air temperatures in some areas by up to 2.4 K. However, spatial analysis demonstrated that cooler air from roof level blocks the vertical air exchange of street canyons. Finally, the street-level cooling performance of all three roof types is predicted to decrease non-linearly with increasing building height by around 0.003 K per meter and to cease at building heights of around 100 m.

高反射性“凉爽材料”通常用于降低城市环境中的温度。最近开发的“超酷”材料比传统的酷材料具有更高的反照率和发射率（均高于 0.95）。为了检查与传统凉爽屋顶和绿色屋顶相比，超凉爽屋顶材料对室外空气温度的影响，我们使用微气候模型 ENVI-met 进行了敏感性研究。在高太阳辐射期间，模拟的超冷屋顶的表面温度保持在环境空气温度以下 6 K 左右，这与观察结果一致。超级凉爽的屋顶——在高太阳辐射时平均街道空气温度冷却约为 0.85 K——比常用的凉爽屋顶和绿色屋顶提供 0.1 到 0.15 K 的冷却效果。结果还表明，超冷屋顶可以将某些地区的行人空气温度降低多达 2.4 K。然而，空间分析表明，来自屋顶的较冷空气阻碍了街道峡谷的垂直空气交换。最后，预计所有三种屋顶类型的街道级冷却性能将随着建筑高度每米增加约 0.003 K 呈非线性下降，并在建筑高度约 100 m 时停止。