Single-pane double-hung windows from the 19th century don’t have the best of reputations. They can be notoriously drafty, full of rattles, loose in the joints, or can simply refuse to budge. But as a number of studies have shown, when these windows are properly weatherstripped and paired with good storm windows, they can match the performance of new double-pane units for much less than the new ones cost.
With new putty, paint, and weatherstripping, the sash are ready to face the cold and last through the 21st century as good as new.