Here are a few tips for making your windows more efficient this winter: First of all, lock your windows. This will force them to fit as tightly as possible at the top, middle, and bottom of your double-hung windows, and all around your crank-out windows. Second, ensure that your storm windows are closed, with all the glass panels in the winter position. Third, check for a flexible-edge sealing strip at the top, middle and bottom of double-hung windows, and add V-seal if needed. Ask about V-seal at Ashfield Hardware. Fourth, feel free to seal all around the window sashes with good old rope caulk putty. It is easy to remove in spring. Fifth, be sure to have at least two layers between you and the outside. You can add interior plastic film as a second or third layer, and the plastic is perfectly transparent Finally, be sure that air is not leaking around the entire window assembly. Fill gaps around the casings and at corners. Another note about windows is to consider closing draperies or curtains at night, especially if you are sitting near the window. Ordinary non-insulated curtains can reduce the radiant heat transfer from you to the cold, dark outdoors.