A novel liquid flow electrochromic smart window for all-year-round dynamic photothermal regulation†

Abstract

Electrochromic smart windows (ESWs) provide a sustainable solution for energy-efficient buildings. However, they primarily perform dynamic adjustments on the visible and near-infrared bands with a weak control over the mid-infrared (MIR) bands and a limited energy-saving efficiency. Electrolytes are one of the most important parts of ESWs which are predominantly used to provide electronic/ionic transport. Nevertheless, the substantial potential of electrolytes in photothermal regulation is often overlooked. Herein, we developed a novel liquid flow electrochromic smart window (LF-ESW), which could not only realize an efficient solar band regulation via electrochromic materials but also fully switch the MIR emissivity between 0.19 and 0.93 by switching the absence/presence of electrolytes. LF-ESWs could reduce the indoor temperature by 7.1 °C on hot days and increase the indoor temperature by 5.2 °C on cold days compared to commercial low-emissivity (low-E) glass-based windows. Moreover, they could also save building energy consumption up to 86.35 MJ m⁻² compared to common glass-based windows and 49.532 MJ m⁻² compared to low-E glass-based windows. This work provides an innovative strategy for dynamic photothermal regulation in buildings.