A temperature-adaptive radiative cooling coating enabled by thermochromic powders for all-season building energy savings

The present study proposes a novel temperature-adaptive radiative cooling (TARC) coating enhanced with thermochromic powders. The optical properties were determined using four-parameter semi-quantum (FPSQ) model, and the proposed TARC coating was then prepared according to the derived composition. The thermal response characteristics of the proposed TARC coating to ambient temperatures were experimentally investigated. In addition, the cooling/heating capacity of the proposed TARC coating and its energy savings potential for building applications were detailed discussed by comparing with a traditional passive daytime radiative cooling (PDRC) coating. The results showed that the mid-infrared emissivity and solar reflectivity increase from 0.89 to 0.94 and 0.62 to 0.76, respectively, as the TARC temperature changes from 24 °C to 32 °C at a critical temperature of 25 °C. Furthermore, a daily average supra-ambient temperature of 7.4 °C and a daily average heating power of 43.8 W/m 2 were achieved by the proposed TARC coating during a day with heating demand even though the cooling energy was still produced during the nighttime. This study demonstrated that the proposed TARC coating can better meet the annual energy-saving demand than the PDRC can.