Outside air comes in and warmed air escapes through leaky frames, accounting for 10 to 25 percent of your heating costs.How to spot it:
On a blustery day, close all windows and exterior doors and the chimney-flue damper. Light a stick of incense, move it around the perimeter of each window, and watch for air that interrupts the delicate rise of smoke. How to stop it:
First check the window from the outside, paying close attention to where its casing meets your home's siding. "This is an area that often doesn't get the kind of attention it needs," says Ted Kidd, an energy consultant in Rochester, New York. Scrape out any cracked or dried caulk, and apply a fresh bead of paintable acrylic latex, such as DAP's Alex Plus. On the inside, add new weatherstripping. For a few hours' work, you can make an old wood double-hung airtight using a kit like the Easy-Stop Weather-Stripping System ($74 per window; advancedrepair.com
). The kit contains a silicone flap for the bottom rail of the lower sash and a pile strip for its top meeting rail. Also included are new paintable cellular PVC parting beads (narrow bands that separate the upper and lower sashes) with built-in insulation.The payoff:
Shave up to $20 off your annual energy bill for each window you weatherize.