Windows

When saving energy and tightening up the house envelope, windows are important.  When we moved to our house 30 years ago, the windows were the double hung with a separate double hung storm window and screen.
About 15 years ago, we replaced the windows with double hung double pane windows, with a gas in between the panes.  A drawback of these windows is that when they are broken, it is not just a simple window pane replacement.  We needed to take the window in to Solvay Glass to have the proper double glazing and sealing.  I added a plastic storm window over the inside of the windows last winter.  When the wind blew hard, you could see the plastic "ballooning".  Bottom line, if you have a window, no matter how well sealed, you have air infiltration through the cracks.

This year we are replacing the basement windows with Block Glass windows.  Over the years, the basement windows have been broken and replaced with a combination of boards, glass and plastic.  This will tighten up our basement, having already eliminated gravity flue connections to the chimney in our earlier renovations, we are now eliminating a lot of cracks that wind can blow into.