GB/T 25261-2018 "Reflective Thermal Insulation Coatings for Buildings" applies to reflective thermal insulation coatings used on the internal and external surfaces of buildings, specifying their technical requirements, test methods, and other aspects. It clearly defines core performance indicators such as solar reflectance and hemispherical emittance, and covers conventional performance requirements such as weather resistance and alkali resistance. Corresponding testing methods are used to determine various performance characteristics, providing a unified basis for product quality control, engineering applications, and acceptance, thereby contributing to building energy efficiency.