Cooling a home on hot, humid days can be an energy-intensive process—in fact, cooling generally becomes the largest energy expense homeowners face during the summer. A room air conditioner may seem like an easy-to-install, low-cost way to add comfort to a home, but it’s easy to waste energy and money in the process. 

A room air conditioner is an encased assembly—a self-contained box, basically—designed to be mounted in a window, through a wall, or as a console. These units deliver conditioned air to an enclosed space, room or zone. Costing between $100 and $1,000, they can be purchased at home improvement centers, big box retailers—even yard sales and flea markets. They tend to last a long time with minimal maintenance, so selecting the right unit can save significant amounts of energy.

Room air conditioners rated by Energy Star, an energy efficiency program under the U.S. Environmental Protection Agency and U.S. Department of Energy, are at least 10 percent more efficient than the federal standard. An energy efficiency ratio (EER)—the ratio of the cooling capacity in British thermal units (Btu) per hour to the power input (in watts)—measures each units’ efficiency. The higher the EER rating, the more efficient the air conditioner will be. National appliance standards require room air conditioners built after January 1, 1990, to have a minimum EER of 8.0 or greater.

Energy Star–qualified units have advanced compressors, drawing more heat efficiently from the air than conventional compressors. The high-efficiency motors in these units use less energy to circulate air and run more quietly. However, they do cost slightly more. Energy savings depends on how often the unit operates.
Nationally, an average consumer saves approximately 76 kWh per year—about $8—with an Energy Star-rated room unit. Residents in hot and humid states could save up to $30 per year, while residents in cooler states may only save $4. Over the life of the unit a consumer could save between $50 and $250, depending on the model and climate. Regions with hotter and more humid climates have the greatest energy-savings potential since they require more cooling.

Consumers should look for models with timers and programmable thermostats. These features offer better temperature control, allowing users to cool spaces according to their preferences. For example, a homeowner can program the air conditioner to turn on 20 minutes before bedtime to make the bedroom comfortable.
Installing a room air conditioner is typically an easy job. Most units fit in a window. A homeowner who can lift the unit into place can install it in a matter of minutes. Another option is to create a custom opening in the wall. Large-capacity units often require a dedicated electrical circuit or may have specific wiring and breaker requirements. These units may need to be installed by a professional.

Room air conditioners come in a variety of sizes. Many people buy the largest unit they can afford, assuming more power is better. While that may be true in racing, it’s not necessarily the case when buying an air conditioner. A unit that is too large will cool the room too quickly to properly remove all of the humidity, leaving the room feeling cool, but also wet and clammy.

Most room air conditioner purchases are “impulse buys”— purchased during hot weather by consumers who have conducted little research. Most retail displays do not promote the benefits of Energy Star–qualified models. Purchase the unit from a knowledgeable retailer who will help you select the right size unit for your room. 

Consumers replacing an existing unit with a more efficient unit should not throw the old unit away. Air conditioners
contain refrigerant that should be removed by a trained technician before the unit is recycled or thrown away. Contact a local solid waste organization for information on how to properly dispose of old air conditioners.

Air conditioning will raise your monthly electric bill—your purchase decisions, climate, and length of use determine how much of an impact there will be. An energy-efficient room air conditioner uses less energy and costs less to operate than a cheaper, inefficient model. Making smart energy choices will leave you happier, cooler, and with a couple extra bucks in your pocket.

SIDEBAR: Before You Buy
Before buying a room air conditioner, take some easy and inexpensive energy-saving measures in your home. Any of these measures will maximize the cooling power of your air conditioner.
• Add caulk and weather stripping around doors and windows
• Add insulation to attics and exposed walls
• Move furniture or obstacles away from room air conditioners
• Close blinds or curtains during the day