Energy Efficient Replacement Windows: How What You Don't See Can Help You

Window manufacturers are always looking for ways to improve the energy efficiency of their home replacement windows. This is true for replacement windows of every type: vinyl replacement windows, fiberglass replacement windows, and even wood replacement windows — there’s a constant focus on product improvement, helping the homeowner keep warm air in and chilly air outside.

They’ve found pockets of opportunity between the panes of glass in double-pane or triple-pane windows. These narrow spaces are so small they often escape the homeowner’s notice, yet they can have a major impact on the home’s energy efficiency.

The first point to consider is the integrity of the chambers created by multiple panes of glass. The spacers — small hardware pieces integral to the window — used can make a huge difference in this. Older windows used aluminum spacers — which could conduct heat and subsequently create condensation. Now, warm-edge technology and other replacement window advances have dramatically minimized this problem. Additionally, the new spacer technology is far superior to the older plastic pieces that would buckle and warp over time, creating opportunities for air penetration.

Next, think about what’s between those panes of gas. It’s not just dead air in there, although you’ll hear the phrase bandied about now and again. Instead, these chambers are often filled with an inert, insulating gas. The most common choices are argon and krypton.

Argon is generally the default choice — the option that comes standard on most home replacement windows. Argon is an extremely dense, slow moving gas. Argon conducts heat far less efficiently than plain air — the difference is almost 30%! — which means that the gas acts as an invisible insulating chamber.

Argon is a naturally occurring gas: the air we breathe in, every day, all day, is about 1% argon. There is no health risk associated with argon in home replacement windows. Some homeowners are concerned about the argon gas leaking out of their windows — after all, you can’t see argon, so how will you know if it’s gone? However, top replacement window manufacturers tell us that argon gas loss in the best replacement windows is 1% or less annually: you’ll have your windows for decades before argon loss becomes an issue.

The other option is Krypton gas. Like argon, krypton is invisible, odorless, and naturally occurring. However, krypton is far, far denser than argon. Due to this increased density, krypton is a far more effective insulator. In fact, krypton is three times more effective as an insulator than argon, much less plain air.

Krypton glass is generally available as an option on home replacement windows. It does not come standard. However, the upgrade may be well worth it, especially in heating dominated environments such as ours. Keeping warm air in while winter winds whip outside is always a good idea!

Vinyl home replacement windows are available filled with argon gas, krypton gas, or, occasionally, a mixture of the two. The same options are available in fiberglass home replacement windows and some wood replacement windows.