Homeowners have a wide berth of choices in replacement windows and one factor – filled windows – leaves some homeowners scratching their heads. When a window salesperson touts filled windows as a perk, what exactly are you getting? Well, it depends on who is doing the selling.
There are two types of windows that fall under the general ‘filled windows’ description. First, there are vinyl windows, which may have insulating foam that fills in the vinyl chambers of the window frame. Then, there are the replacement windows, which have insulated glass. Within the two panes of glass, double pane glass, an inert gas fills the space between the panes. Let’s take a look at the differences and the impact each one will have on your replacement window investment.
Filled Windows – Insulating Foam and the Vinyl Window FrameVinyl windows expand in the heat and contract and become brittle in the cold. To counteract the natural properties of the material and to make it more stable for window use, vinyl windows are constructed with a network of chambers inside the frame. These chambers provide more structural integrity for the frame.
Higher end vinyl windows add a second layer of structural integrity with additional chambers that actually contain metal rods to increase the window frame’s strength. Often this network of chambers contains an insulating foam. The foam is inserted into the chamber of the vinyl frame, to increase its energy efficiency and help protect the home against the heat gain in summer and the bite of cold in winter. This can be referred to as a filled window.
One issue with the energy efficiency claims of a filled frame is that the Department of Energy (DOE) doesn’t support them. The industry acknowledges foam insulation is better than no insulation, but the DOE’s EREC Brief Report on Window Frames stated “…Data shows that the difference between filled and hollow vinyl frames is small. Generally, vinyl frames of all types are slightly less of a thermal insulator than wood.”
Additionally, while the chambers provide strength, they also provide additional girth. The larger, chambered frames decrease the amount of space available for the glass portion of the window. As a result, the homeowner is left with less window for viewing and more frame to support the smaller window.
Filled Window – Insulated Window Glass filled with Argon Gas
Another common use of the term ‘filled window’ is referring to the argon gas filling the space between the two panes of window glass, boosting the window’s energy efficiency. The gas is installed in a vacuum to boost its reliability. Then sealed tightly.
Energy efficient windows perform by keeping heat from passing through the window — keeping the heat from escaping in the winter and from entering in the summer. Argon gas is an invisible, nontoxic and odorless gas that is denser than air. When injected into the space between the window panes, the weight of the gas dramatically reduces the amount of heat that can pass through the glass panes.
The Energy Efficiency Equation combines Argon Gas and Low E
The other important factor in this energy equation is the low E coating applied to the window glass before it is filled and sealed. You can read more about low E coatings here.
Argon gas not only increases the energy efficiency of the glass, it adds to the soundproofing qualities of the window and will not corrode the window material like oxygen will.
The insulating qualities of argon gas are convincing, but what if the argon gas suddenly, or slowly begins to leak? No worries! Only a minimal amount of argon is needed to fill the glass frame and if it’s discharged suddenly, it will dissipate quickly. It is a non-volatile gas found naturally occurring in the atmosphere – it’s not man made.
Many homeowners don’t worry about the safety, but worry about the investment – how do companies keep the gas from slowly leaking their dollars away?
Seal Failure and What to Expect
A SIGMA study reported the seal failure rate for replacement windows with argon gas fill. A window like Renewal by Andersen has a seal failure rate of one third of one percent over a 20 year period, while the industry average is three to five percent over the same time period. If the seal does fail and gas leaks out, there are a few ways to tell:
-moisture will develop between the panes of glass
-the moisture will calcify into white powder often seen in between window panes
While vinyl windows can come with argon gas fill, customers may not have much protection against seal failures. Between 1990 – 1999, 400 vinyl window manufacturers have gone out of business. When the window is no longer in production and the contractor who installed the window is no longer in business, not only is the warranty useless, but the whole window must be replaced because the parts are no longer available.
Seal failure is one of the typical problems with windows and it occurs over time. Vinyl windows are particularly prone to seal failure, although anything is possible. An ill-fitting window and a poorly installed window will also fail, regardless of the frame material.
Problems such as these are what led me to offer homeowners a substantial guarantee. I guarantee that your new window will perform as good as the day it was installed for as long as you own your home. Doesn’t that make sense? If you invest in replacement windows, you ought to be able to rely on them no matter what. And with an unconditional guarantee like that, I also chose what brand of windows I could depend on to deliver that promise. For my business that brand was Renewal by Andersen.
“Andersen is more concerned about the long-term reliability of the window, than considering what they can do to cut costs and compete with the low cost vinyl companies,” Ashley Hamrick, a Design Consultant at Mr. Rogers Windows said. “They have maximized the energy efficiency of the window, which is why they use three coats of low-E on the window. Ninety-five percent of the UV rays are eliminated with 100 percent argon gas installed in a vacuum, so the window is as energy efficient as possible.”
Filled windows can be a perplexing option for homeowners, however, the best way to know what kind the salesperson is showing you is by asking the right questions. Windows are a big investment and can affect your resale value. You have the right to know whether the glass is argon-filled glass or if it’s the frame with additional insulation. You also have the right to know the seal fail rates for that particular brand or style of window. Don’t be afraid to ask the tough and technical questions.