Composite Film Enables Windows that Switch from Transparent to Color

Commercial buildings in the United States account for nearly 40% of the total energy consumption. Among them, electricity is the largest energy source for buildings. Therefore, the design of new energy-efficient materials and technologies is crucial to meet goals such as the Net-Zero Energy Commercial Building Initiative (CBI) put forward by the U.S. Department of Energy (DOE). Approaches to block or reflect intense sunlight when needed, and to capture the Sun’s light and heat when desirable, remain complex and expensive to fabricate.