I’m thinking of upgrading my old windows in order to make them more energy efficient. What are some of the main features that are available in new windows, and what are the costs for these features?
The following is a summary of several key features available in new windows:
Double or Triple-Glazed Glass (Thermopanes)
These are two or three panes of glass manufactured as one window with a very thin separation between the panes. This separation width provides less convective heat loss than the typical separation width of 2-4 inches, which is often observed on standard thermopane or single-pane windows equipped with a storm window.
A low-E (emissivity) coating is merely a thin, invisible metallic layer. It is only several atoms thick, and is applied directly to a window’s surface. Standard window glass easily allows solar heat and radiant heat (heat from objects, such as furniture and trees) to pass through it. However, a low-E window at night will be heavily reduced. In the winter, heat from room objects will be reflected back into the home rather than being wasted through the window to the exterior. In the summer, heat from objects on the exterior will be reflected back to the exterior, thus reducing nighttime air conditioning requirements. Low-E coatings also allow few ultraviolet rays through, which can mean less fading of carpets and fabrics.
Inert Gas Fills
Another big advancement in window technology has been the introduction of inert gas fills into the space between the glazings. Argon and krypton are the usual choices, with argon being the most common. Filling the space between the glazing with these heavier gases reduces heat loss due to convection and conduction.
Low Conductivity Spacers
The spacer between the glazing at the perimeter of the window has historically been made out of aluminium, which is not only lightweight and durable, but also provides considerable heat loss. Newer non-metallic spacers are now available to reduce heat loss at this location.
The cost for the inclusion of the energy efficiency features described above varies, but can be 10-15 percent more than standard double-glazed units. However, many window manufacturers are converting their production lines to produce only high-performance units.
Some super high-performance windows that are using cutting-edge technology for even more energy savings than those described above are available, but at considerably higher costs.
Proper installation is especially important with high-performance windows because poor installation techniques can negate their performance. Installation should be completed in accordance with manufacturer’s recommendations and should reflect current industry standards, such as CSA-A440.4 “Window and Door Installation Standard,” In addition, other installer certification programs, such as “Window Wise,” or those developed by the Siding and Window Dealers Association of Canada (SAWDAC) are available. Be sure to check out your contractor’s qualifications to ensure proper installation.
Completion of an energy efficiency assessment, such as the EnerGuide for Houses program, is recommended prior to upgrading in order to determine the feasibility of upgrading windows.
Visit the home inspection experts at AmeriSpec of Canada for more tips and valuable home improvement information.