Saving Energy While Staying Cool
Greentips: June 2004
As temperatures rise, many people turn to energy-hungry air conditioning systems for relief. To cool your home in the most efficient manner-and save money in the long run-consider the following factors when choosing an air conditioner.
Size: Air conditioners are rated according to the amount of heat (measured in British thermal units, or BTUs) they remove from the air per hour. Select a unit that removes an average of 20 BTUs per square foot of living space or higher, depending on how much sunlight the space receives, how many large appliances are located within it, and how many people occupy it.
Buying a larger unit than you need will cool your living space too quickly, resulting in frequent on/off cycles that waste energy and money. Brief running times also fail to properly dehumidify the air, leaving it cool but clammy.
Refrigerant: Ozone-damaging hydrochlorofluorocarbons are no longer used in air conditioners. A list of alternative refrigerants is available on the Environmental Protection Agency website (see the link below). Be sure your dealer is able to install and/or service units using these alternatives.
Efficiency: Room air conditioners are rated by their energy efficiency ratio (EER), the amount of BTUs removed per watt of electricity used. Central air conditioners use a similar system known as seasonal energy efficiency ratio (SEER). Choose a unit with the highest EER or SEER possible within your budget-the higher the number, the more efficient the unit. Energy Star-rated units are the most efficient.
Location: Room air conditioners should be installed in a shaded area, away from trees and shrubs. Direct sunlight on the unit and shrubbery that blocks ventilation force the air conditioner to work harder than necessary. Also, do not place heat-generating appliances such as televisions and lamps near the unit's thermostat.
Installation: To ensure energy efficiency, room/wall units should fit snugly in place and be airtight. Central air conditioning systems should have insulated ducts and unobstructed vents.
Maintenance and operation:
- Set the air conditioner's thermostat as high as you can comfortably tolerate.
- To have a cool home when you return from work or a trip, install a programmable thermostat that can turn on a central air system 30 minutes before your arrival.
- Check the air filter often, cleaning or replacing it when necessary.
- For room/wall units, unplug and vacuum clean the interior heat exchanger. Hose off the exterior heat exchanger. Run a stiff wire through the drain channel to remove clogs, and use a fin comb to straighten bent coil fins.
- Central air systems should be serviced by a professional.
Disposal: If you decide to replace an old air conditioner with a new, more efficient model, hire a certified technician to safely recover refrigerant from your old unit.
Many states offer rebates for purchases of energy-efficient appliances. Check with your state energy office or local utilities, or use Energy Star's Rebate Locator.
