How to Prevent Heat From Leaving Your Window in the Winter

Caulking, Indoors and Out

• There's a simple test to determine if there are air leaks around your window. On a windy day, move a lighted stick of incense near the edges of the window indoors. If the smoke blows away from the window frame, that's evidence that there are cracks or crevices that should be sealed. The cracks can be sealed by applying a silicon caulk to the window frame outside and using a paintable latex caulk indoors. The U.S. Department of Energy estimates that when warm air is allowed to leak through gaps around window frames, it can increase your heating bill by as much as 10 percent.

Add Another Barrier With Plastic Wrap

• Much of the insulating action of double- and triple-pane windows takes place in the space between the glass, rather than the glass itself. Installing a window insulation film during the winter is an easy and inexpensive way to create another insulating air space, and it also prevents warm air from leaking outdoors through any small cracks. Window films are installed by taping the material to the window frame and using a hair drier to shrink the film tightly into place.

Interior Storm Windows

• In historic homes with single-pane windows, interior window inserts let you approach double-pane performance without the need to replace the house's architecturally matched original wood or metal frame windows. These lightweight inserts can be clipped into the window frame during cold weather and -- unlike plastic wraps -- do not affect the appearance of the existing glass. Much easier to work with than old-fashioned outdoor storm windows, interior window inserts can reduce heat loss by 50 percent.

Insulating Curtains Add Elegance

• When you close a set of insulating curtains at night, you're preventing heat loss during the coldest hours of the day. Insulating curtains can look as stylish as an ordinary window treatment. The insulating material can consist of an inner core of fabric or foam lining within the curtain. Some varieties are waterproof for use in bathroom or shower areas. Most insulating curtains are heavier than conventional models, so they may require stronger curtain rods and fittings.