First, test your home for airtightness. On a windy day, hold a lit incense stick next to your windows, doors, electrical boxes, plumbing fixtures, electrical outlets, ceiling fixtures, attic hatches and other locations where there is a possible air path to the outside. If the smoke stream travels horizontally, you have located an air leak that may need caulking, sealing or weather stripping. Caulk and weather strip doors and windows that leak air. Caulk and seal air leaks where plumbing, ducting or electrical wiring penetrates through exterior walls, floors, ceilings and soffits over cabinets.
Install rubber gaskets behind outlet and switch plates on exterior walls.
Look for dirty spots in your insulation. These often indicate holes where air leaks into and out of your house. You can seal the holes by stapling sheets of plastic over the holes and caulking the edges of the plastic. As a less costly and less permanent alternative, you can use a heavy-duty clear plastic sheet on a frame or tape clear plastic film to the inside of your window frames during the cold winter months. Remember, the plastic must be sealed tightly to the frame to help reduce infiltration.