Identifying Double Glazed Windows

Glass Spacers and Window Edges

One way to identify if a window is double glazed or single glazed is by examining the area where the glass meets the window frame. For double glazed windows, you will notice a thin spacer - usually made of silver, bronze or black material - that separates the two panes of glass. This indicates an insulated, double glazed window. Single glazed windows do not have any type of spacer between the panes of glass.

Window Age as an Indicator

The age of a window can also provide clues. Windows built before 1980 are nearly always single glazed without insulation. After this period, double glazed windows became more common for their improved energy efficiency. So if a window looks quite old, it likely has only a single pane of glass.

Seeing the Gap Between Panes

One clear sign of double glazing is seeing the gap between the two panes of glass. You can observe this space by looking at the edge of the window. There will usually be about a half-inch wide separation filled with air or argon gas. An aluminum foil spacer runs around the perimeter to keep the panes precisely spaced. This interior gap is not present with single glazed windows.

Difference in Sound Insulation

Another difference between single and double glazing relates to sound insulation. The multiple airspaces in a double glazed unit help block outside noise significantly better. If you put your ear up to a window, single glazing tends to let through more ambient street noises and other sounds from the exterior. The additional pane and gaps in double glazing provide superior sound dampening properties.

Identifying Double Glazed Window Frames

Window frames can provide clues too. Double glazed frames have a deeper, hollow design to accommodate the extra thickness from two panes rather than one. There may be drainage holes or weep holes at the bottom for any condensation to escape. Meanwhile, single glazed frames will appear simpler and more narrow without these additional design elements.

Using a Thermal Imaging Camera

One high-tech method is to use an infrared thermal imaging camera. These devices can detect the slight temperature differences between the interior and exterior surfaces of single glazed versus double glazed windows. The multiple glazing of a double pane unit helps insulate and the camera will clearly show the insulation difference compared to single glazing. However, a thermal camera is certainly not necessary - the naked eye clues above work very well too.

Summary

In summary, look for glass spacers or gaps, consider the age of the window, listen for sound differences, and examine window frames. Catching glimpses of multiple glazed panes from the sides provides a surefire way to distinguish single glazed from better insulated and sound dampening double glazed options. Understanding these identifying characteristics helps properly diagnose window types.