Add up all those overlooked cracks, gaps, and openings around your windows, doors, plumbing, and wiring, and you may find your house has a hole the size of a Mack truck. Seal it up, and you'll save more than 10 percent on your heating bills. Start by caulking or weatherstripping around windows. For added comfort, pick up a product such as the 3M Indoor Window Kit at the hardware store. Resembling Saran wrap, the plastic sheet costs about $20 and can be discreetly stretched over windows using double-sided tape, blow-dried for a tight fit, and peeled off come springtime. It can increase a single-paned window's R-value by up to 90 percent. Fill in cracks around door frames with caulk, and while you're at it, install a screw-on or adhesive-backed door sweep. Use expanding-foam sealants to fill in larger gaps around plumbing and electrical work, especially where pipes enter your house through exterior walls. Tackle energy suckers in overlooked places, too—like exterior wall sockets and switches. You can block them up using fitted insulation pads. Just unscrew the switch plates and pop the pads into place.
Learn how an energy audit can help you
detect where fuel costs are flying out the windows and walls.