It should be the simplest job in the world: Keep the cold air out of your house and keep the warm air in. However, almost every house has at least one gaping hole in its defenses that allows a veritable hurricane of increasingly expensive heated air to cascade into the great outdoors.

If you've found gangs of squirrels huddled around various spots around your house warming their paws in the flow of hot air, some simple steps can send those pesky rodents elsewhere.

According to Scott Warrick, a general contractor in the Charlotte, N.C., area who advises his clients frequently on energy conservation, most of the biggest money-saving projects can be handled by the average homeowner, and all of them will pay for themselves in very short order.

Block The Door

"Close the door! You're heating the neighborhood!" How many times did you hear that from your dad? It may have been hyperbole, but the exterior doors of your house are a major source of heat loss, and it's usually not the front door that's the major culprit.

"People forget about their back and side doors," said Warrick. "They're often not as high-quality as the front doors and can be a major source of heat loss."

Weather-stripping kits, available at any hardware store or home center, are an inexpensive way to seal up a door and prevent the worst of the air leaks. If it's a door that's no longer in use, consider using silicone sealant around the edges for a more permanent fix, but bear in mind this will render the door unusable.

For those toe-freezing under-door drafts, get a draft dodger, a tubular pad filled with beans or sand that will sit at the base of the door and block the air passage. You can find them online, and they're also a regular fixture at craft shows in the colder states.

Don't forget to caulk any gaps around doorknobs and locks, also.

One final note on doors: If you have a storm door, make sure the windows are closed. This sounds silly, but Warrick said he's seen dozens of houses with storm door windows left open in mid-winter, nearly negating their insulating potential.

Check The Windows

Windows are huge heat-emitters, although newer homes should have double- or triple-paned windows that largely fix the problem. If you're in an older house, however, you're not out of luck.

The first thing to do is check for gaps or cracks around the window frame. Caulk the small ones. If you find larger gaps, there are foam sealant products that you can use to fill the gap which can be smoothed and painted to match the surrounding surface.

On the interior, as long as you don't mind a bit of a trailer-park charm, plastic window sealing film can transform even the coldest well-windowed room into a warm enclave. It seals around the edge of the window and forms an insulating air cushion between the glass and the interior of the house. The sheets come in sliding-glass door and window sizes, and usually come complete with double-sided tape for installation. Beware, as the tape can be a bear to remove come springtime.

Drapes and blinds also help with heat retention, but be sure to open them when the sun is full on the window to allow the sun's warmth to help out with the heating chores.

Check The Heat

You hopefully had this done before the season started, but if you haven't had your heating system inspected by a trained professional, do so as soon as possible! Not only can leaks or faults in the system rob you of full cooling potential, things like cracked heat exchangers can allow carbon monoxide into your house.

If you have a newer heating unit, often a yearly inspection is built into the cost of the package. The best plan is to find a reputable technician with a good track record and simply make a yearly appointment for a system check. That way, you won't have to remember to call and book your service.

If you use a fireplace, be sure that you close the flue when the fire is cold. Left open, that flue makes your chimney a giant wind tunnel that can shoot hot air out of your house as fast as the furnace can pump it in.

The water heater is another potential money loser. While all water heaters do have internal insulation, if you've ever laid your hand against the side of yours you'll know that a substantial amount of heat still escapes. Water heater blankets, basically fiberglass insulation sealed on both faces with plastic sheeting, are available at most hardware and home center stores year-round in the plumbing department. Look for one that comes with a top piece that forms a "hat" and insulates the top with cutouts for the various pipes.

Take A Walk

Nobody knows your house better than you do, which is why it's a good idea to have someone who isn't as familiar with it walk around the exterior with you. That crack around the hose bib you've seen a thousand times might escape your attention, but it will stand out like a sore thumb to anyone else.

Check carefully around hose bibs, dryer vents, circuit breaker boxes and anywhere anything penetrates the shell of the home, such as the spot where your TV cable goes in. You may not find a single gaping hole, but plugging the dozen or so small ones you do find will add up to substantial savings in the long run.

Look Upstairs

Finally, it's time to go up to the attic. You would be amazed how many homeowners have never pulled down that attic trapdoor and checked out their insulation. Do you have enough? Is it in good shape? Are there cold winds whipping in around attic vents or vent pipes? There is no way to know any of this without a visual check, and that means you (or someone lighter than you, if you've been packing in too many holiday snacks) needs to go up that shaky ladder into the Great Beyond.

While any one of these tips can save you substantial money in the long run, taking care of all of them should not require more than a weekend's work. You'll get to know your house better, and you'll hopefully stop dreading that oil, gas or electric bill quite so much in February.