Increasingly individual crafts people and companies are appearing that specialize in window restoration.
Fans of historic preservation and the boards that enforce preservation decrees are more and more making the argument that window restoration is less costly and better for the planet than window replacement. Though they do not compare the costs of replacing wood framed windows with modern metal, plastic and fiberglass framed windows, repair is certainly less expensive up front than installing a modern wood framed window.
The argument can also be made that the pollution caused by excessive energy consumption due to historic windows is made up for by the aesthetic appeal of such windows.
Below is a collection of embeddable presentations on the subject.
Here is a slide show of a powerpoint from the New England Window Restorers Alliance:
The Old House Web has a video "Old Windows are Green". The presenter notes that with storm windows installed the restored windows will be much more comfortable. Of course you'd have to check to see if your historic board allows exterior storm windows.
This video from Austin's Red River Restorations touts the higher quality materials in historic windows and suggests that the charm of historic windows make not replacing them a green decision.
Fine Homebuilding Magazine posted their March 11, 2010 illustrated guide "Should Your Old Wood Windows Be Saved?" online. It provides fairly authoritative information and suggestions.
Restoration Works Inc in Chicago makes their case for window restoration being green in this web page. The arguments they make are generally applicable to any window restorer.