Performance effects and analysis of passive daytime radiative cooling coatings under environmental aging conditions

Passive daytime radiative cooling (PDRC), as a cooling technology requiring no additional energy consumption, plays a significant importance for achieving building energy efficiency. In practical applications, PDRC materials are inevitably exposed to complex outdoor environments for extended periods, and the long-term stability of their spectrally selective properties ultimately determines their practical viability. In this study, a commonly used and industrially scalable PDRC coating was selected, and its performance evolution was systematically evaluated from multiple perspectives through a series of carefully designed accelerated aging tests corresponding to approximately one to five years of outdoor service. Furthermore, the long-term energy-saving performance of the aged PDRC coating was quantitatively assessed using building energy consumption simulations. The results indicated that the aged PDRC coating exhibited no structural damage such as cracking or substrate decomposition. Its emissivity in the atmospheric transparent spectral window (ε _ATSW) remains essentially unchanged, while the annual average decay rate of solar reflectivity R _sol) is limited to 2.73 %, resulting in a performance retention exceeding 82.91 % after five years, far superior to commercial white coatings. Simulations results indicate that coating aging leads to an 18.87 % increase in cooling energy demand in temperate regions of China, whereas the increase is limited to only 9.85 % in low-latitude hot climates. These results confirm that PDRC coatings offer long-lasting radiative cooling performance and meet the core requirements for large-scale manufacturing and engineering applications, while also providing an important reference for the lifecycle assessment of PDRC materials.