Replace any worn out weather stripping around the windows. If the basement windows don't open, this won't be an issue.
Hold a lighted candle or match near the edges of the window to see if the flames flicker. This indicates a draft that needs to be sealed.
Caulk any gaps around the edges of the basement windows. This will ensure a solid seal around the window. Be sure to remove any old caulk first.
Purchase a window insulation kit at a hardware store. Though you can certainly purchase the items individually, a kit is an easy way to get a large enough piece of plastic to cover the window.
Cut the plastic wrap (included in the kit) to the size of your window. You may even want to make it slightly larger and cut it to fit later.
Apply double-sided tape (included in the kit) to the edge of the basement window molding.
Attach the edges of the plastic sheet to the tape, smoothing the sheet down to keep it from wrinkling.
Run a blow dryer back and forth over the plastic sheet so that the heat blows against the plastic sheet and shrinks it, forming a tighter seal.
- Consider adding shutters to the basement windows. They are decorative and can be closed in the evenings to hold the heat in. Packing peanuts can add additional insulation. They also reflect light so as not to cause a total blackout. You can add them between the plastic sheet and the window before you seal all four sides.