Self-Cleaning BaSO₄/TiO₂/HGM/Epoxy Diffuse Reflection Composite Coating for Improving the Lighting Level

The quality of lighting in enclosed environments has always been a concern, and in many cases, it even causes a game between comfort (even safety) and energy consumption. How to durably improve the lighting level under the same energy consumption is an important way to solve the problem of lighting quality in closed environments. In this paper, we design a high-reflectance composite coating with diffuse reflection and self-cleaning properties (named DRCC). Its reflectance can maintain more than 85% in visible light with heat treatment at 100 °C for 24 h, immersing in pH = 1–13 or 3.5 wt % NaCl solution for 14 days, and even a salt spray test for 14 days. It enables DRCC to maintain a high total illumination (2496 lx) after nine pollution cycles with a retention rate of 93.0%. In contrast, the total illuminance values of the glazed tile and the DRCC primer are only retained to 1510 and 1903 lx, with retention rates of 77.7 and 71.1%, respectively. Moreover, we also inspect the energy consumption under the tunnel environment by DIALux software, revealing that the DRCC will conserve energy by about 14.4% in contrast to the glazed tile. These key properties that have been integrated into the DRCC are expected to provide unique advantages for a wide range of applications in enclosed environments, such as tunnels, basement stores, auditoriums, and so on.