Electroreflective window with up to 8 °C reduction in indoor temperature for energy saving in buildings

Smart windows, capable of dynamically adjusting solar radiation blockage, offer a promising solution for managing indoor lighting and temperature in buildings, thereby reducing heating, ventilation and air conditioning energy consumption. While reflective smart windows outperform transmissive ones in solar thermal management, creating high-contrast, user-controllable, and rapidly tinting reflective smart windows remains a challenge. In our study, we developed an electroreflective device (ERD) utilizing a reversible silver electrodeposition method. By employing NiO as a counter electrode, we reduced the tinting voltage from −2.015 V to −1.645 V, achieving a remarkable tinting response time of only 7.6 s at a −2.5 V operating voltage. The ERD boasts transmittance and reflectance contrasts of 81.1 % and 74.1 %, respectively, and impressive modulations in solar heat gain coefficient (ΔSHGC) and solar reflectance (ΔRsol) of 0.553 and 0.571. In outdoor solar irradiation tests, the ERD's solar radiation modulation capabilities led to a temperature reduction of 8 °C compared to clear glass. Global climate zone simulations further illustrate the ERD's energy-saving potential, with up to 38.35 % and 29.74 % energy savings in cooling, heating and lighting for Singapore and Changchun (a representative mid-latitude city in the north temperate zone), respectively.