A Colorful Electrochromic Infrared Emissivity Regulator for All‐Season Intelligent Thermal Management in Buildings

Radiative cooling is a technology that utilizes the high emissivity of materials in the atmospheric window to achieve cooling, showing great application prospects in building energy-saving. However, traditional static passive radiative cooling materials with broad-spectrum high emissivity can lead to increased heating energy consumption in winter due to overcooling and a weakened cooling effect in summer due to the urban heat island effect. In this study, a colorful, intelligent infrared emissivity regulator is well designed based on a multi film ultrathin electrochromic device for all-season thermal management in buildings. The infrared emissivity of the regulator can vary in real time in response to seasonal or temperature variations, allowing for the switching between radiative cooling and insulation. Guided by nano-photonics theory for multilayer optical films, the regulator achieves multi-modal dynamic infrared emissivity regulation in the atmospheric window <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mi>Δ</mml:mi> <mml:mspace></mml:mspace> <mml:mover><mml:mi>ε</mml:mi> <mml:mo>¯</mml:mo></mml:mover> </mml:mrow> <mml:annotation>$\Delta \ \bar{\varepsilon }$</mml:annotation></mml:semantics> </mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mi>Δ</mml:mi> <mml:mspace></mml:mspace> <mml:mover><mml:mi>ε</mml:mi> <mml:mo>¯</mml:mo></mml:mover> </mml:mrow> <mml:annotation>$\Delta \ \bar{\varepsilon }$</mml:annotation></mml:semantics> </mml:math> , and the high reflectance in the non-atmospheric window inhibits heat gains from the external environment. The regulator demonstrates excellent environmental adaptivity with an acceptable response time, a long cycle life, and good bending resistance. The regulator can achieve ≈2 °C/3 °C (nighttime/daytime) temperature adjustment. The simulation results indicate that the regulator can achieve an annual building energy saving of 3.46 MJ m^- ².