Switchable Radiative Cooling from Temperature-Responsive Thermal Resistance Modulation

Abstract

Maintaining indoor temperature in a suitable range is necessary for modern buildings. Although radiative cooling is efficient for keeping cool in hot weather, it fails to block heat removal in cold weather. Here, we presented a conceptual design of a switchable radiative cooler (SRC) composed of a radiative cooling coating (RCC) and a temperature responsive part (TRP). Relying on the low thermal resistance state in hot weather, the SRC can conduct internal heat to external RCC for dissipation while automatically switching to a high thermal resistance state in chilly weather, inhibiting the indoor heat removal. Theoretically, we revealed that the SRC can achieve remarkable benefit with a temperature drop of 11 K at warm daytime (ON state) and a temperature rise of 4 K at cold nighttime (OFF state) for a designed building model. The results experimentally demonstrated that the SRC can adaptively regulate the radiative cooling performance of the building model and thus keep the interior thermal comfort. This design may open the pathway for developing switchable radiative cooling systems with zero power input.