The traditional single sheet of clear glass offers little insulation against cold winters and hot summers. Energy conservation is an important issue, so here are some window efficiency features to consider:
DOUBLE OR TRIPLE GLAZING – Double-glazed windows have a sealed space between the two panes of glass, and the air in the space provides an added layer of insulation. Compared with a single pane, double glazing can cut heat loss nearly in half. The insulating value of triple-glazed windows is higher still, but the extra layer adds to the weight and cost.
LOW-E COATING – Clear glass allows large amounts of radiant energy to pass through – heat in from the sun in summer, heat out from your house in winter. A low-E, or low emissivity, coating is a microscopically thin metallic film that acts something like a two-way mirror, reflecting heat back into the house in winter and blocking heat from the sun in summer. Some coatings may darken the glass, so review samples to help you choose.
GAS FILLED – Instead of air in the sealed space between glass panes, these windows use argon, krypton, or other inert gas. These gases are denser than air, so they provide better insulation.
CLADDING – This is the vinyl or aluminum that covers the exterior of a wood window so that it doesn’t have to be painted.
TILT-IN SASHES – On windows with this feature, the sash (moving part of a window) can be tilted for easy cleaning.