Scalable epoxy-based radiative cooling coatings with ternary filler synergy for efficiency and low-cost building thermal management

Radiative cooling (RC) has garnered significant attention due to its potential to reduce energy consumption without external power input. However, RC technology hinders by its high cost of raw material and challenge in large-scale production. In this study, a cost-effective and well-performance RC coating was fabricated by employing epoxy resin and a ternary particle system composed of barium sulfate (BaSO4), silicon dioxide (SiO2), and hexagonal boron nitride (h-BN). Systematic optimization of the filler ratios and particle loading significantly enhanced the optical and thermal properties. The resulting coating exhibits a high mid-infrared emissivity of 95.9% within the atmospheric window (8–13 μm). Outdoor testing under a solar irradiance of 926 W/m2 revealed a peak temperature drop of 12.8 °C, outperforming commercial coating by 9.38%. Moreover, the coating demonstrates strong adhesion to substrates such as bricks and maintains stable cooling performance under prolonged outdoor exposure. Notably, the fabrication cost in laboratory is only 145 CNY/m2, highlighting the economic viability of this approach. This study presents a scalable and cost-effective manufacturing strategy for RC coatings with both well cooling efficiency and environmental adaptability, offering great promise for applications in building energy conservation, smart exteriors, and climate-resilient infrastructure.