Increased solar energy and daylight utilisation using anti-reflective coatings in energy-efficient windows

For a double-glazed window with one low-e hard coating, light transmittance was found to increase by as much as 15 percentage points, from 74 to 89% transmittance, if both panes were AR-treated, while the emissivity of the low-e coated pane was virtually unaffected. Compared to clear double glazing, the visual transmittance was increased by 7 percentage points. The simulations show that the monthly average solar factor (g-value) increased by 7 percentage points compared to the low-e double-glazed window without AR-coatings. The annual heating demand decreased by 4% due to the higher solar transmittance of the window. The AR-coating increased the daylight factor by 21% according to the simulation. The study has shown that the main benefit of using AR coatings in a low-e window is the improvement of visual transmittance and the resulting increase in the daylight factor.