A Fluorescence-Phase-Change Synergistic Radiative Cooler for Adaptive Thermal Management and Energy Savings

Passive radiative coolers leverage outer space as a zero-energy thermodynamic resource to cool objects, including buildings, human bodies, and electronic devices, with the smallest carbon footprint. However, the resulting overcooling aggravates the heating costs of building space during cold nights and winters. To address this long-standing challenge, we introduce a fluorescence-phase-change synergistic radiative cooler (F-PCRC) that achieves smart thermal regulation through the synergistic coupling of phosphor-mediated radiative cooling and a phase-change-triggered energy storage and release mechanism. Under a hot environment, this F-PCRC combines effective radiative cooling capability and PC-activated thermal energy storage to achieve about 4.8 °C below the average subambient temperature in a model building under an average solar irradiance of 803.6 W m –2; under a cold environment, the thermotropic phase-change microcapsules in the coating release the stored thermal energy to achieve a temperature rise of 1.9 °C. Enabled by such dual-mode thermal regulation, this cooler demonstrates significant potential for year-round energy savings and carbon emission reduction when applied to building rooftops, showing an annual electricity saving of 29,291.7 to 69,880.6 kWh per building as confirmed by EnergyPlus-based simulations. Collectively, these findings position the developed F-PCRC coating as a scalable and versatile solution for temperature-adaptive thermal management in sustainable energy-saving applications.