According to the U.S. Department of Energy, the average family shells out $1,500 annually for utilities. Air conditioning can account for as much as 70% of summer energy costs. To put this in everyday context, let's hear from Mr. Electricity: He says that running central A/C uses 10 times more energy than leaving the refrigerator door open 24 hours a day for an entire year. (I'm not willing to sacrifice my Fudgesicle stash to fact-check that theory.)

To twist a timeless cliche: An ounce of prevention is worth a pound of sweat. Small things (like changing the filter and cleaning the coil) can reduce your unit's original efficiency anywhere from 5% to 20% each year. Here are some additional tips that will help you beat the heat wave and keep your (financial) cool this summer:

Get audited: Many utility companies perform energy audits for free or a small fee. They'll identify trouble spots and make remedy recommendations.

Give your HVAC an annual physical: Regular maintenance (which you're going to schedule right now, right?) will prevent a minor HVAC problem from turning into a major one.

During an annual checkup, your heating/cooling pro can also look for buildup on the outdoor A/C and heating coils and clean them. Ask them how to check and clean the indoor coil, too. Because the coil is moist during summertime, it attracts a lot of dust. According to the Air Conditioning Contractors of America (ACCA), dirt buildup on the indoor coil is the most common cause of poor efficiency.

Keep your coolant: A system that's 10% low on coolant (also called freon or the "refrigerant charge") costs about 20% more to operate than a system that's fully loaded, says the ACCA. (Leave the topping off to the pros, since freon is a hazardous substance.) Additionally, low freon can cause the compressor to overheat and die early. That can result in a big-ticket repair bill if you have to replace the compressor or condensing unit.

Go with the flow: All A/C operation manuals recommend cleaning or replacing your air filter about once a month. (Easier said than done in my place, where doing so requires moving a bookcase. Is that bad feng shui?) Most filters cost less than a cappuccino, and a clean one can lower your A/C's energy suck by 5% to 15%.

Keep a lid on it: Grandma was right about drafts being dangerous. Worn-out (or nonexistent) weatherproofing can result in serious air leaks that can contribute to more than one-third of cooling costs. (Looks like plastic sheeting and duct tape are handy to have around.) About 30% of the heat in your house is absorbed through the roof. Vents and attic fans can help keep things circulating and prevent your bills from going through the ... well, you get it.

Do planetary good and save big: Switching to a high-efficiency air conditioner (see energystar.gov for more), though costly, will probably put the most money back in your pocket over time. According to the Air-Conditioning and Refrigeration Institute (ARI), a homeowner replacing a 10-year-old unit could improve energy efficiency by as much as 55% by upgrading to a system with a more efficient SEER. Not only that, but the karmic bonus points are immeasurable. Two-thirds of all homes have A/C, releasing about 100 million tons of carbon dioxide into the air each year. (That's two tons for each home with an air conditioner.)

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Dayana Yochim keeps her cool in the D.C. heat by drinking plenty of fluids, using a defrizzing hair balm, and programming her thermostat. The Fool has a disclosure policy.