Smart Window Shopping

(Money Magazine) -- To hear window salesmen tell it, replacing old single-pane windows with modern double-pane ones will cut your heating and cooling bills in half. Don't believe the hype.
True, today's best windows are twice as energy-efficient as those installed just a decade ago, but because windows make up only a fraction of your home's exterior, your actual energy savings will be no more than 25%, and maybe just 5% or 10%.