Originally Posted by t walgamuth

Well, I have not done any infiltration tests. In my experience though, the wood window with a good storm will not match the new quality window on infiltration. In my personal experience though, the windows on my old home and on my old office building were huge by modern standards. over three feet wide and over seven feet tall. Most window manufacturers will not even make a dh window that big and any other style even less so.

The cost of a new quality custom made window that big is just staggering, and you have to get very very precise measurements because ordering the wrong size is a big big hassle.

If you assume that the windows in an old structure are all the same size you will meet with disaster as in many cases they made the opening and then made the windows to fit. They look like the same size but don't try to swap sashes from one to another.

And while the old window properly refurbished and equipped with a good storm may not match a new window for thermal performance, they are pretty good, and that is only one part of the equation in making a selection. Longivity and historical correctness is also a factor. Historic houses that were scorned thirty or forty years ago are now prized.

You really have to look at everything to make an informed decision.