Experimental and numerical study on the potential of a new radiative cooling paint boosted by SiO2 microparticles for energy saving

In this study, we prepared a radiative cooling paint by adding polymethylpentene to acrylic resin mixed with SiO2 microparticles. To improve the cooling performance of the radiative cooling paint, it was optimized based on Mie theory and Monte Carlo simulation to determine the optimal volume fraction of SiO2 microparticles, the mass fraction of polymethylpentene, and the thickness of the radiative cooling paint. Then, the cooling potential of the radiative cooling paint was analyzed in detail based on field experiments. Finally, the improvement of the radiative cooling paint over the existing materials was briefly discussed. The results showed that an emissivity in the atmospheric window of 0.91 and a reflectivity in the solar spectrum of 92% (backed with aluminum foil) can be achieved by the optimized radiative cooling paint. The temperature drops/average cooling powers are 1.5 °C/53.3 W/m2 during the nighttime and 5.2 °C/46.8 W/m2 under an average solar irradiance of 639.3 W/m2 during the daytime for the radiative cooling paint covered with a polyethylene film.