Building energy consumption constitutes a significant portion (~40%) of global energy usage, with windows representing a major pathway for unwanted heat exchange. This study introduces a novel approach using silica hydrogel windows that achieve thermal management through dynamic control of solar energy transmittance based on their hydration state (wet/dry). A coupled Mie theory and Monte Carlo radiative transfer model was developed to systematically investigate the influence of hydrogel thickness, porosity, and particle diameter on optical properties. Results demonstrate that the hydrogel exhibits effective window functionality with significant solar modulation (250 W) and visible transmittance variation (35% ΔT_v) between wet and dry states. Dry hydrogel windows substantially reduced heating loads, achieving a heating energy saving rate of up to 72.2% compared to single-pane windows. Conversely, wet hydrogel windows offered superior visual clarity during cooling periods, with 82.5% visible transmittance and a 0.38 reduction in haze compared to the dry state. A proposed "Cooling Wet/Heating Dry" (CWHD) operational strategy demonstrated annual energy savings exceeding 30.0% across multiple climate zones compared to conventional windows. This system presents a promising pathway for developing intelligent, energy-efficient building envelopes.
 

hydergel,energy-saving windows,radiation transfer