Keep it cool: how to save on air conditioning this summer

Summer 2015 may not be sweltering yet, but it will be soon enough, and that means one thing for millions of people: air conditioning. And while we may take air conditioning for granted, it's generally an expensive luxury. Americans spend more than $22 billion a year on electricity to cool their homes with air conditioning — and use a whopping 183 billion kilowatt-hours, according to recent statistics from the U.S. Department of Energy. That accounts for at least 15 percent of all energy used in some homes, and in warmer climates can represent up to 70 percent of a summer electric bill.

If you're shopping for a new air conditioner, you'll notice quite a few different sizes and models. But one thing's for sure: Savings are always chill. Here's a quick primer to staying cool and keeping your wallet from overheating when picking out an A/C unit.

What's a BTU and How Many Do I Need?

Chances are you already know that BTU stands for British Thermal Unit, and that the more BTUs an air conditioner cranks out, the stronger its cooling power. But here's the problem: Most American consumers aren't sure how to translate BTUs into the square footage of a room. (No disrespect to the Brits, but maybe we need an American Thermal Unit, where 1 AMU corresponds to 1 square foot?)

Lobbying for the AMU aside, you don't have to guess how much BTU power you'll need to cool your space. Instead, download this Energy Star document and turn to page three. There you'll find a handy chart that simply correlates the area you want to cool into BTUs per hour. So for example, an air conditioner with a rating of 8,000 BTUs can cool a room that's 300 to 350 sq. ft., aka one that measures about 18 ft. x 18 ft. Of course, you still have to measure your room, but we trust you can work a tape measure and apply this formula: Area equals length times width. For irregularly sized rooms, you can always estimate.

Air Conditioner + Ceiling Fan = Savings

It's one thing to run an air conditioner in your room. But combine its power with a simple ceiling fan, and you can have the best of both worlds. Costing less than a penny an hour to run, ceiling fans have an immediate impact on your domestic comfort once you buy and install them. They generally start at about $40 a piece. The nice thing about a ceiling fan is that it can make you feel anywhere from 3 to 8 degrees cooler.

Calculate Your Yearly Costs Before You Buy

When you buy any air conditioner these days, it should come with one of those bright yellow Energy Guide stickers on the box that tells you exactly how much that unit will cost to run. Take this into account, as that's part of your total cost for both buying and operating the unit. Most folks think bigger is always better, but not so. According to the Energy Star folks, "Air conditioners remove both heat and humidity from the air. If the unit is too large, it will cool the room quickly, but only remove some of the humidity. This leaves the room with a damp, clammy feeling. A properly sized unit will remove humidity effectively as it cools." Damp and clammy isn't much better than sweltering.

Why a New Window Unit Could Pay for Itself

If your air conditioner is more than 10 years old, seriously consider replacing it. Many new air conditioners are so efficient that, according to U.S. Department of Energy estimates, you will use about 10 percent less energy with a new Energy Star appliance than one without that designation. Depending on how long you hold onto that new unit, you could save $60 or more over its lifetime in energy costs alone — a de facto rebate just for upgrading to an Energy Star model.

The key number to look for is the Energy Efficiency Rating (or EER): The higher the EER, the more efficient the unit. So if you replace an old EER 5 unit with a new EER 10 unit, you'll cut your cooling costs in half. You should also look for the "Energy Star" and "Energy Guide" labels when purchasing a window unit. An energy-efficient unit will cycle the compressor on and off so that it doesn't operate continuously. And Energy Star central air units are on average 14 percent more efficient than standard models. Speaking of which ...

The Great Central Air Debate

If you're thinking about upgrading to central air, it's easy to beat yourself up for being an energy hog, or to get intimidated by the sticker price. Yes, it's true that central units will use a lot more power than, say, a single window unit on each floor of a 2-story dwelling. But if you have more than two rooms to cool, then your best bet is to go with a central unit, which also provides long term resale value for a home. Well-designed central systems also win out in terms of being able to filter the air for allergens and pollutants, and for controlling humidity.

Again: Keep in mind that window units aren't necessarily more energy efficient than central air units. A window unit that is too small to cool a room may run continuously, wasting energy. When shopping for a central air conditioning system, make sure the SEER number (seasonal energy efficiency ratio) is 13 or better (14 in warmer climates). A less efficient system will cost you more to run.

Help Your New Air Conditioner Do Its Job More Efficiently

It's easy to think that buying a new air conditioner or two will solve all of your summer cooling problems. But your AC could use a little help. With central units, for example, a programmable timer or thermostat can save you about $180 every year in energy costs by regulating the temperature when you're out of the house, and by turning on only when you return home.

With window units, air filters get dirty, and fast. Clean your AC filter at least every month, as a dirty filter makes your AC work harder and use more electricity. Regardless of the type or age of the unit, you should change your filters after every 90 days of use. What's more, you'll use less energy cooling down a room by keeping direct sunlight out during the day. Sunlight can raise room temperature by 10 to 20 degrees. The less heat gets into your home, the less you have to pay to remove it. It just so happens that drapes block sunlight and heat better than blinds.

Do Some Careful Deal Shopping for Your A/C

We've got an ever-updated list of air conditioning deals for you to peruse and compare. This time of year, sales are as plentiful as backyard barbecues, and the worst thing to do is feel a heat wave hit you in the face, rush to the first store you can find, and buy the first unit you see. Chill out, if you will, and do some comparison shopping, checking out multiple units for price, efficiency, reliability, and features.

The few minutes you spend comparing notes and using your shopping smarts will do more than show off how cool you are. It will help you make a prudent choice with your money that will keep your living space comfy all summer long, and for many summers to come.

This article first appeared on DealNews.com.