Energy efficient thermochromic smart windows based on polymers and metal oxides

Thermochromic energy efficient windows dynamically regulate building energy exchange by changing their optical transmittance. Recently, thermochromic materials with different chromic mechanisms are developed to fulfill smart window demands. Advanced fabrication technologies for smart windows also lead to building energy efficiency optimization. In this Perspective, representative mechanisms and performances of promising thermochromic systems, including vanadium dioxide, hydrogels, perovskites, ionic liquids, and liquid crystals, are discussed. Furthermore, the emerging technology of radiative cooling is emphasized for future building energy saving. Building temperature regulation and energy saving based on smart windows will make great impacts on the global low carbon economy.