Trap 'Water' between Glasses

Abstract

Buildings account for 40% of global energy consumption, while windows are the least energy-efficient part of buildings. Conventional smart windows only regulate solar transmission. For the first time, we developed high thermal energy storage thermochromic smart window (HTEST smart window) by trapping the liquid hydrogel within triple-glazed glass. The outstanding specific heat capacity in liquid hydrogel together with excellent thermochromic property (90% of luminous transmittance and 68.1% solar modulation) and good thermal insulation gives the HTEST smart window excellent energy storage and conservation performance. Simulations suggested that HTEST window can save 15.3% more energy than the double-glazed low-E glass. In outdoor demonstrations, the HTEST smart window significantly lowered the room temperature ~30°C in summer compared with the double-glazed glass. Compared with conventional energy-saving glasses which need expensive equipment, the “water” trapped structure offers a disruptive strategy of easy fabrication and scale-up, which opens an avenue for energy-saving buildings and greenhouses.

Keywords: Thermal energy storage, Liquid hydrogel, Smart window, Thermochromic, Energy saving