So many names for the same kind of product! Double or triple-paned insulated windows are windows manufactured with 2 or 3 pieces of glass with an air space between them.The air space provides a temperature shield to reduce heat being transferred through the glass. Insulated or double-paned windows are also useful for sound dampening when noise is a concern. Insulated glass may be laminated or tempered for further energy efficiency or strength.
Insulated windows using the double-pane process were invented in the 1930s. In the 1950s, the Thermopane brand name was the most popular. The manufacturing process is well established and now the innovation comes through improving the energy efficiency of the windows.
The best insulating comes from having the correct thickness of the air space in between the double panes. Too little space and the heat is transferred through the glass and too much space allows convection currents between the glass to transfer heat between the The thickness of the insulated glass unit is also impacted by the strength of the frame.
Generally the thickness of a double-paned window works well in commercial and residential uses. Triple-paned windows further reduce heat loss but are often too heavy for most residential and commercial applications.