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How to Tell If You Have IGU Windows

A Glass Doctor Sepcialist in front of a window

I-G-Who? The world of windows can be anything but transparent for newbies. The obscure terminology alone can be enough to make your poor brain shatter. Whether you’re living in an older home, or on the lookout for a great buy, here’s how to tell if you’ve hit the window jackpot with IGUs – otherwise known as insulated glass units…

What the heck is an IGU?

“IGU” is an acronym for “insulated glass units,” which refers to double and triple-pane windows: Windows with multiple panes of glass from 1/8 inch to 3/8 inch thick, separated by a spacer and sealed to prevent condensation buildup. Invented and patented in 1865 by Thomas Stetson, insulated glass saw little use the 1930s, when C.D. Haven made it commercially available as “Thermopane,” and building architects began replacing the single-glazed windows of skyscrapers with double-glazed IGUs and incorporating green-tinted, iron-rich glass for occupant comfort. The energy crisis of the 70s later pushed the U.S. government into further research to combat the loss of energy dollars leaking from the nation’s windows… And the rest, as they say, is history.

What is meant by “insulated” glass?

Since glass, by its nature, is a poor insulator, thickness doesn’t matter – but spacing in-between panes does. Seemingly innocuous, the air pockets between triple and double pane glass panels boosts insulating power, inhibiting heat transfer. Add a low-E coating, and your packing some serious insulating punch. And heat insulation isn’t the only benefit of these energy efficient windows.

Bang for your window box

In addition to guarding against heat loss/gain, IGUs also…

  • Increase comfort
    Making winter window drafts and air leakage a thing of the past.
  • Reduce sound transmission
    A boon in homes near busy streets or with noisy neighbors.
  • Boost window brawn
    Standing up against gale-force windows (and overzealous children).
  • Lower heating and cooling bills
    By upholding the thermal envelope of your home to keep air and heat where it’s supposed to be – and preventing your heating and cooling system from working overtime.

How can you tell if you have double pane windows in your home?

While in some cases it can be easy to see at a glance if windows in your home are double or triple pane, an easy test can confirm this. Simply light a match and hold it against the glass (but not too close)… Then you’ll see the reflection of the match flame in the glass. With single paned glass you’ll see a single reflection. With double paned glass, you’ll see 2 flames reflected. Triple pane will indeed show three panes. For the pyrophobic, a flashlight should also work.

With their customizable shapes, sizes and thicknesses, insulating glass units offer a greener, cleaner window solution for every application from industrial to commercial and residential. IG-Who? IG-You! Discover how the addition of affordable IGUs can put your home in a new light. Contact Glass Doctor today.


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