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Personal: Residential


Glazing is the generic term for the transparent material – usually glass – in a window, a door with window insert, or a skylight. These products may be single-glazed (one pane of glass), double-glazed (two panes) or triple-glazed (three panes).

Figure 11

The principal benefit of multiple glazing is that air, which is a good insulator, is trapped and sealed between the layers of glass. In Canada, all homes should have at least double-glazed windows mounted in an insulating glazed unit. In many regions, it may be worth the expense to add a third layer of glazing to existing windows. Reduced heat loss and higher interior glass temperatures will result in increased comfort; in addition, condensation and noise will be decreased.

Most manufacturers now offer the option of a low-emissivity (low-e) coating on their products – a thin, invisible metallic layer applied directly to the surface of the glass. The coating allows heat energy from the sun to enter the home while reflecting heat generated in the home back into the living space. This is an obvious benefit in winter.

Figure 24

In the summer, low-e coatings prevent heat that emanates from objects outside the home, such as pavement and buildings, from entering the living space and help to keep the interior cooler. A double-glazed window with low-e coating has an insulating value roughly equivalent to that of a standard triple-glazed window, but with less weight and often at a lower cost.

Figure 24

Figure 24

Self-Cleaning Glass

This is relatively new to the marketplace. A special coating is added to the exterior glass surface that will actually "shed" anything when it becomes wet. If the glass surface is in a place that doesn't allow it to become wet at all or frequently enough to clean the glass, a fine mist from your garden hose should be enough to start the "shedding" process. You should note, however, that the coating may scratch easily. The use of self-cleaning glass does not affect the energy efficiency of the window.