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  1. #1
    Join Date
    Oct 2007
    Posts
    175

    Default R value of window

    Single pane casement style, from 1940s - any idea?

  2. #2
    Join Date
    Sep 2012
    Location
    Boston
    Posts
    820

    Default Re: R value of window

    probably about an R-1 or R-2

    it's less than a 1x piece of wood

  3. #3
    Join Date
    Jan 2008
    Posts
    1,096

    Default Re: R value of window

    Probably closer to zero.

    1 "R" equals one inch of dead air space and glass is a very good conductor of heat. The glazing isn't where most of the heat loss occurs in old windows, rather the worst is found in air infiltration around them. If they seal well and the frames do too, then I'd consider replacement more optional than mandatory. An IR scan and smoke test will point out where your insulation dollars are best spent at.

    Just because something is getting old does not mean it's no good anymore!
    (I hope that's true because it applies to me as well!)

    Phil

  4. #4
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,381

    Default Re: R value of window

    The R-value of a single pane of clear glass is about R-0.75. You can increase the r-value by adding a reflective film to the glass that will bring it up to about R-1.5.

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