• • The HDL smart window achieves a solar modulation (ΔTsol) of 63.2% and a luminous transmittance (Tlum) of 88.1%, surpassing typical hydrogel-based thermochromics (ΔTsol < 50%) by over 13 percentage points, directly enhancing daylighting and cooling energy savings in buildings.
• • The formulation remains optically active after 1000 hours at -40 °C and 1000 hours at 80 °C, with no freezing or phase separation, whereas conventional hydrogels fail within 100 hours at -20 °C due to ice crystallization; this extends operational lifetime to >5 years in extreme climates.
• • A 30 cm × 30 cm prototype retains 95% of its initial ΔTsol after 500 bending cycles (radius 5 mm), demonstrating mechanical robustness for roll-to-roll manufacturing, with a projected production cost of $18/m², 40% lower than commercial electrochromic windows.
• • Energy simulations show a 12.3% reduction in cooling energy in tropical climates and a 9.8% reduction in heating energy in cold climates compared to low-E glass, translating to annual HVAC savings of 15–20 kWh/m² in mixed climates.