How much R-value is lost when a seal breaks on a double-paned glass window? A friend says it is still dead air

I've read there isn't much insulating difference between a single pane and a double-pane window,-- it maybe amounts to $5 per window per year in heating oil. Search for "R U Warm yet" on this website: http://blog.tomevslin.com

So it seems the main reason to fix a double pane with condensation between the panes is aesthetic. Does everyone agree?

4 Answers

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  • Big D
    Lv 5
    1 decade ago
    Favorite Answer

    If the seal is broken the vacuum between the pains is lost.

    R-Value is gone.

  • Nancy
    Lv 4
    4 years ago

    The thermal seal has failed. The manufacturers create a thermal seal between the panes of glass so air (or argon gas) is trapped between the panes. This provides better insulation for heat and cold as well as sound. Condensation is a sure sign that the seal has failed. There is no easy way to fix the seal, other than replace the window. You may find a company that will just replace the double paned glass with a factory seal, but it's nearly impossible to repair the existing glass.

  • 1 decade ago

    You are right...mostly....because the dead air space is the insulating factor. Thermo panes don't hold a vacuum, they are filled with an inert gas, like Argon...which doesn't transfer heat as well as regular air...but the difference between the inert gas and regular air is very small.

    While the difference between single and double panes in R-value is not tremendous (although $5 per window per year Xs the number of windows = a nice dinner for two) there is a comfort factor involved here.

    Heat travels from hotter areas to colder areas. People are almost 100 degrees, so they radiate that heat away towards anything that is colder than that. The greater the difference in temperature between things, the more heat it "pulls", so if the surface of the windows is colder, they "feel" colder to you.

    The surface of a thermopane window is several degrees warmer than a single pane, so they are more comfortable to sit near.

    Source(s): 50 plus years of living in Northern Wisconsin....
  • 1 decade ago

    why not take the window out, frame the opening and insulate the space? you can't see out of either, right? aside from the fact that the condensation could freeze and break the glass when it gets extremely cold some night. then what would you do? 3 am and not a window guy around. likely cost 5 times what fixing it would, right? good luck and happy holidays!

    Source(s): been called!
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