On the development of super cool paints for cooling purposes

Urban heat island effect is an increasingly pressing environmental issue globally, driving more energy consumption for cooling in buildings and cities. Super cool paint is the paint-type super cool material characterized by high solar reflectance and infrared emittance values in the atmospheric window, enabling sub-ambient cooling under direct sunlight. As the research progresses, super cool paints have been successfully developed for large-scale implementation for real-world building applications due to their relatively low cost, flexibility, and straightforward fabrication process. Herein, this study reviews and summarizes the super cool paints for building cooling purposes. It begins with an overview of the polymer-particle and porous super cool paints, offering insights into their current research and recent advancements, mainly focusing on their optical properties and the key challenges that limit their practical implementation. Subsequently, fluorescent-based super cool paint, which incorporates phosphors and quantum dots to provide diverse colors and enable ultraviolet conversion, is summarized. Furthermore, we critically discuss the recent advances of these super cool paints, highlighting their remaining limitations and proposing potential solutions for future development. This review aims to deliver comprehensive and critical insights into super cool paints with a particular focus on their applicability in buildings.