ThermaGuard Energy Star Glass Option Package

We’ve all heard of ENERGY STAR? and know that energy-efficient windows save on heating and cooling costs. But do you know how your choice of options affects a window’s energy efficiency? Here are some of the elements of your window that help make it energy efficient. For more on understanding the thermal performance metrics that make a product ENERGY STAR?? rated view our Understanding Window Energy Ratings post.


Companies use a variety of framing materials to reach energy efficiency, including vinyl and wood. Harvey vinyl windows have a low maintenance vinyl frame, and the way it’s constructed helps the overall window provide excellent thermal insulation. But remember, not all vinyl is equal – thicker vinyl walls with multiple air chambers improve thermal performance.


Harvey Majesty wood windows have wood frames that provide excellent thermal insulation values and are the right choice for homes that have historical features. Our wood windows are clad with aluminum to reduce maintenance on the exterior.


Weatherstripping is another element that adds to energy efficiency by protecting against air leakage. The lower the air leakage, the better the energy efficiency.

Air Leakage Rating

The average vinyl window has an air leakage rating of .3 cubic feet per minute (cfm). The Harvey vinyl window averages an air leakage rating of .03 cfm.


Low-E refers to a special coating applied to a pane of glass. By reflecting infrared light, Low-E helps stop temperature transference. In addition to its energy-saving properties, Low-E glass helps reflect UV rays that lead to fading color on interior furnishings. For more details on how this works see our 3 Main Benefits of Low E Windows article.


The glass itself is a terrible insulator. Older windows with only one pane of glass allow heated or cooled air to escape more rapidly. Two panes of glass insulate much better than a single pane because of the air space between the two panes. Triple pane adds another air pocket, enhancing the insulation value even more.?Adding gas between the panes improves the energy efficiency dramatically (see gas fills below).


The air, between the glass panes, works as an insulator because air is a poor conductor of heat. Some energy-efficient windows go one step further and have argon or krypton gas injected between the panes of glass. Still wholly transparent to the eye, these gasses are heavier than air and provide even better insulation. In the case of seal failure causing leakage, both argon and krypton are odorless, transparent, and non-toxic, so there is no worry.


Harvey’s spacer system is located inside the window where the glass seals to the window frame. Our u-channel spacer bar is one continuous piece, providing both structural integrity and increased thermal performance. The spacer system offers insulation to the edges of the glass, the area that is most vulnerable to temperature transference.

Browse our windows?for information about our vinyl and wood windows and the energy-efficient options available.

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