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libcarp
R value of window

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

MLB Construction
Re: R value of window

probably about an R-1 or R-2

it's less than a 1x piece of wood

Mastercarpentry
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

keith3267
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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