If you have leaky double hung windows, instead of replacing them
, why don't you choose to weatherize them? Though new windows maybe more energy efficient, replacement windows will take another 20 years to save enough energy to pay for their costs! Instead, just for a few dollars per window, you could install weather-stripping and keep dust, cold air and even noise out of your home!
There are only about four places where the air leaks in from in double hung windows - where the 2 sashes meet; between the window head and the top of the sash; between the jamb and the sash; and between the sill and the bottom of the sash.
For use between the jamb and the sash, the best weather-stripping to seal it is a V-shaped Polypropylene type. You could find it in the stores under various names like V-Seal, VFlex and V-shaped Fin. This secures to the jamb with a self adhesive strip and the other half presses against the sash. It is thin and smooth and allows the sash to be opened and closed easily.
To begin weathering your double hung windows, first measure the height of the window's sash and add 2 inches when cutting the weather-stripping. Tape the end of it with a scotch tape and insert the tapes end up between the jamb and the sash while keeping the window wide open. Keep the closed end of the V facing toward the exterior.
Now peel the paper off the weather-stripping securing it to the jamb. Repeat this step on the opposite jamb as well taking care that the paper is on the inside of the window. Make your home cleaner and quieter with weathering old hung windows!