Presents the results of a study investigating the energy performance of evacuated glazings or glazings that maintain a vacuum between two panes of glass. Determines their performance by comparing results to prototype highly insulated superwindows as well a more conventional insulating glass unit with a low e-coating and argon gas fill. The DOE-21E energy analysis simulation program was used to analyse the annual and hourly heating energy use to windows of a prototypical house in Madison, Wisconsin. Cooling energy performance was also investigated. The results show that for highly insulating windows the solar heat gain coefficient is as important as the window's U-factor in determining heating performance for west, south and east orientations. For orientations with little direct solar radiation the U-factor primarily governs performance, The vacuum glazings had lower heating requirements than the superwindows for most orientations.

KEYWORDS: year 1996, Windows, glazing, performance, comparing, vacuum, housing, USA