Smarter Living: Energy

photo: Jasleen Kaur/Flickr

An air conditioner is the kind of thing that you don't get around to purchasing until you really need it. But the wrong model could end up costing you too much in energy bills without effectively cooling your space. So before you rush out and grab the only one left at your local hardware store, read our recommendations for buying the best AC for your needs and your budget.

• Already have a unit? Check the year. If it's eight years old (or older), it's time for a new model. The energy savings from the upgrade will likely pay for the purchase in little time.
• Know your BTUs. AC cooling capacity is measured in BTUs, or British Thermal Units. But more BTUs does not necessarily mean cooler and therefore better. BTUs are like shoe sizes. The wrong size will be uncomfortable. If the unit is too small, you'll be running it constantly. If it's too big, you'll be cold before the room is dehumidified and your space will feel clammy. To get it right, determine the square footage of the space you want to cool and find a unit that will blast out 20 BTUs for every square foot. The Energy Star Web site has a guide to help calculate your BTU needs. For a more detailed approach that considers the climate where you live, the number of windows and even the heat from appliances and people in the room, use the Association of Home Appliance Manufacturers Cooling Calculator.
• Look for the Energy Star seal, which guarantees that the model uses at least 10 percent less energy than the typical AC. If an Energy Star certified model isn't available, look for the energy efficiency ratio (EER) of the units you are considering. Extremely efficient appliances have an EER of 11 or 12. Avoid any model with a ratio below 10, which could hike your electricity bill.
• If you have calculated your BTUs, checked for the Energy Star seal, noted EERs and you still can't decide between models, compare the yellow-and-black Energy Guide labels on the AC boxes. The label gives you an estimate of energy costs per year.
• Once you've covered the basics, look for models with "smart" features, such as an energy-saver setting that shuts the unit off once the room reaches the desired temperature, a digital thermostat display for accurate temperature readings, and filters that are easily removed for cleaning or replacement.
• If you're replacing an older unit that's no longer up to snuff (and if yours is eight years old or more, it isn't), ask your public utility if it offers rebates, or check out the rebates page at Energy Star. You could end up saving $75 or more on your purchase.
• Dispose of your old unit responsibly. Air conditioners contain ozone-depleting refrigerants that can be removed only by an authorized handler. Contact your waste-management authority or an appliance retailer to learn the proper disposal method and site in your area, or search www.earth911.org.

Once you have your unit in place, follow these tips to maximize efficiency and comfort:

• Keep the unit set to the highest temperature that is still comfortable.
• On especially hot days, switch the unit to the recirculate setting, which continues to cool the already cool air in the room rather than pulling in hot air from outside.
• Use a ceiling fan or box fan, which will do some of the cooling work. You'll be able to turn up the setting on the AC, saving energy without sacrificing comfort.
• Keep lamps and appliances, which produce heat, away from the AC unit and its thermostat.
• Close all curtains, windows and doors and turn off any lamps that aren't needed.
• Clean removable filters and check disposable filters once a month. Keep the unit vacuumed and free of dust, which can restrict airflow and make the it less efficient.
• Turn up the temperature a few degrees before you go to bed, and shut off the unit before you leave the house.

Learn More

Low-Cost Cooling

last revised 8/16/2011