Chromogenic materials in building energy efficiency: application trends, suitability assessment and future prospects

With the continuous development of urbanization, building energy consumption is escalating, and the strategy of using chromogenic materials to optimize surface colors in buildings provides more possibilities for energy savings. Currently, most related research focuses on the performance and applications of chromogenic materials without considering their applicability. This paper first investigates three types of chromogenic materials in buildings (photochromic, thermochromic, and electrochromic materials), categorizes them, and explores their color-changing mechanisms. It elaborates on their current applications in building envelope structures. Secondly, based on weather conditions and temperature variations in 100 typical cities in China, this study introduces the weather scaling index (WSI) and diurnal temperature index (DTI) to quantitatively assess the suitability of chromogenic materials in different regions of China. Finally, using WSI and DTI, a chromogenic material applicability (CMA) model is developed to provide scientific guidance for regions and climatic zones globally suitable for adopting chromogenic materials. The research results indicate that regions characterized by low latitude, high altitude, and significant daily temperature differences are more suitable for deploying chromogenic materials. By comprehensively considering the characteristics, mechanisms, solar radiation intensity, and temperature distribution of chromogenic materials, this paper quantitatively analyzes the application prospects of these materials in different regions, providing a theoretical basis for evaluating building energy consumption and promoting the widespread application of chromogenic materials in building energy conservation.