What is Double Glazing?
Double glazing is the process by which a window is formed with two panes of glass with a space between those two panes. That space is usually some standard thickness, normally several millimeters. Air is trapped between the two panes and acts as an insulator. In some double glazed windows, argon or krypton is used in place of air because of their great insulating properties. Before the unit is sealed, a drying agent is used to make sure that no moisture gets trapped between the panes. Windows that are double glazed can be certified as such by the AAMA.
The seal is very important to keep moisture out and to allow the air or gas between the panes to do its job and insulate against the outside weather. If any condensation appears between the panes, it means that the window seal has failed and the window is not airtight. This is clear evidence of a performance issue with an old window, or a manufacture or installation problem with a new one. If such a problem exists, the window seal cannot be properly repaired. To correct the problem, the unit needs to be replaced.
Why Double Glazing is Important
In single pane windows, over half of a home's heat loss goes through the window openings. Double glazed or double pane windows cut down substantially in heat loss. The cost of this added feature in new windows can pay for itself over time as home heating and cooling systems do not have to run as often to keep a home at temperature, meaning substantially lower heating and cooling bills.
Double glazed windows also help homes emit reduced carbon dioxide emissions, helping the environment; and, they cut down on outside noise pollution in the home. And these windows are also more secure, and more difficult to break into than single pane units.