Glazing

Window glass, called glazing, has come a long way since the days when windows had only a single pane between you and the elements. Today's energy-efficient windows come with glazing "systems" that incorporate multiple panes of glass, gas fillings, and high-tech, heat-sensitive coatings. Sorting through the options takes a bit of effort, but it more than pays off in increased comfort and reduced energy costs

Double-Pane Insulated Glass
Most new windows sold today are dual-pane glass (sometimes called insulated glass or by the formerly trademarked name Thermopane), in which a layer of inert gas — typically argon or krypton — is sealed between inner and outer panes. The gas is a poor thermal conductor, so it slows the passage of heat through the glass, eliminating the need for storm windows.