Development and evaluation of the energy-saving effect of photothermal cooperative composite hydrogel smart window

Thermal responsive hydrogel smart windows have attracted wide attention due to their design flexibility and excellent thermal responsive optical properties. Only relying on temperature control, sometimes the phase transition speed is not fast to meet the needs of rapid thermal response rate in practical applications. Here, a hydrogel with excellent photothermal response characteristics was prepared through combining the photothermal conversion efficiency of graphene nanoparticles and the thermal response effect of hydroxypropyl cellulose. The photothermal cooperative hydrogel (PCH) smart window has integrated high solar modulation ability (ΔT sol  = 61.2 %), excellent infrared isolation ability (ΔT IR = 48.6 %) and fast response speed (within 2 min) successfully. In outdoor demonstrations, the PCH window can reduce 13.1 °C compared to the ordinary window, showing promising energy-saving performance in summer daytime. Simulations suggested that PCH window can cut off 13.1 % heating, ventilation, and air-conditioning (HVAC) energy consumption compared with the Low-E window in Singapore. The PCH window can dynamically adjust solar radiation through light and heat, which provides a new strategy for intelligently reducing the energy consumption of buildings.