Storm Windows: More than Just Weather Stripping
A variation on the weather-stripping of windows would be the installation of storm windows. Storm windows are simply extra window panes that are installed on the outside of the window frame in the fall to add an extra layer of glazing to your window. This effectively creates a temporary double paned window where a single pane window existed before. The heat loss from a single pane window can be reduced by 50% to 75% by adding a storm window to it. When you install a storm window over a window in your home, you need to caulk it well on all sides while taking care to leave weep holes free at the bottom. The weep holes will allow any moisture that accumulates between the regular window and the storm window to escape.
Storm windows add to the effectiveness of a window's weatherstripping in lowering convective heat losses in the same way that caulking will do. Then there is the additional benefit of the storm windows in the reduction in the conductive heat losses that would have been taking place at the surface of the window's glass prior to the installation of the storm window.
As an alternative to storm windows but in a similar spirit you might install clear vinyl shades which can be rolled up into a box. The box is installed at the top of the window on the inside of the pane. The sides and bottom of the shades are fastened tightly to the window frame with magnets or with special tracks. Whenever you need to open the window, you can release the sides and bottom of the shade and roll it up and out of the way.
Anderson, Bruce and Malcolm Wells. Passive Solar Energy Second Edition, The Homeowner's Guide to Natural heating and Cooling. Brick House Publishing Company, Amherst, New Hampshire, 1994
Bossong, Ken and Jan Pilarski. Passive Solar Retrofit for Homeowners and Apartment Dwellers. Citizens' Energy Project, Wash D.C. 1982. report series no.137" Home owner's Guide to Passive Solar: An Overview"