“To me, the strangest problem is how many old-house owners have been persuaded to throw away all their fine old windows and replace them with plastic counterparts that will last only 5 to 20 years. A well-built old window can be maintained and repaired to last for centuries and can also be upgraded to meet current energy-saving goals with simple, low-cost treatments like exterior storms, interior air panels, or even ordinary roller shades.”

http://www.oldhouseonline.com/window-repair-tips-from-john-leeke/