Double glazing is better than single glazing windows because it helps with house insulation, helps with noise reduction and reduces the condensation that builds up on windows. Double glazing is when windows are constructed with two panes of glass, usually separated by a small space that is either filled with air or other gases.
One of the primary purposes of double glazing windows is for insulation purposes. Although double-glazed windows let in just as much light as single glazed windows, they hold in the heat much more efficiently, halving the loss of heat through the windows, according to the Energy Efficiency and Conservation Authority. This helps to reduce heating and cooling costs for homeowners. In addition, using argon in the space between the glass panes or using low-e glass helps with insulation.
Double glazing windows can help with noise reduction in the medium to high frequencies of sound. This works particularly well for voices, but does not work for louder or lower-pitched sounds, such as traffic noise. Using thicker glass or leaving a bigger gap between the panes is also best for noise reduction, although leaving a bigger gap between the panes does not help with insulation.
If a house already has a single-pane window, a process called secondary glazing can be performed in order to add in a second pane.