Loose glass or a void in the area around the window casing can contribute to a draft around the window. Eliminate cold airflow, using a variety of possibilities. Start the process by moving a lit candle or lighter around the window and glass edges to see where the draft is originating.
Check your windows to see if there is missing caulk around the window glass and outside casing of the window. Also, check the glass for tightness by pressing on the glass to see if it moves. Remove all the old caulk, using a putty knife. If glazer points are present, remove and replace them prior to starting the caulking process. To caulk, place the caulking tube in a caulking gun. Cut the pointed end to a 45-degree angle. Press the nose of the caulking tube to the area and squeeze the trigger. Move the tube along the glass or window casing so you travel approximately 1 inch each second. The angle of the tube will create a triangular shape of caulking against the area. The caulking will take up to 24 hours to dry completely.
Window Insulation Film
Window insulation film is a thin sheet of plastic to use inside the house over the entire window. Place double-sided tape next to the window casing on the trim. Place the tape all the way around the window. Cut a piece of window insulation film 4 inches larger than the dimension of the taped area. Carefully center and stick the cut film to the window. Heat-shrink the plastic with a hair dryer. Start at the top and work your way downward. Exact instructions are available on the window insulation film package.
Window Drafter, also known as a Draft Snake
If your window is leeking along the bottom edge, place a window drafter on top of the trim across the bottom of the window. Slide the window drafter snugly to the window. A window drafter is a long tube filled with such things as sand, rice or plastic beads
Shades and Curtains
Chose a cellular shade to hang next to the window. Cellular shades are made from a glued fiber process which holds the cold next to the window and allows light to pass through. Hang the cellular shade along the top edge of the window. Home improvement centers will cut the shades to fit, so take along window measurements. Cold air also can be blocked by insulated, heavy or layered curtains. The heaviness of the curtains holds the window draft at bay behind the fabric. Advantages of curtains include a variety of shades, styles and light-blocking capability. There are a few disadvantages to the insulated window treatments, though. They can block light and are a bit pricey.