We are in the process of dramatically upgrading the insulation of our 120 year old farm house and adding on a mudroom/laundry room, new bathroom and replacing the sunporch. We are in northern Michigan (zone 6a). Our original plans had Andersen 400 windows with a U-factor of 0.26 but our builder inadvertently ordered, purchased and installed an older version of the same window that is 0.30 for 12 windows. Everything else about the window is the same — the difference is a coating on the glass.
Our builder is telling us that there isn’t much difference between 0.26 and 0.30 and the work and cost involved would not be worth the gains in U-factor. I don’t know anything about windows and wanted a non-biased opinion. Should I push the issue and ask him to replace the sash with what was originally planned? Or is he correct in saying there really won’t be much of a difference between 0.30 and 0.26?
Thanks for your opinion,
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