How to Use an Air Conditioner Efficiently

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There are several steps you can take to use your air conditioner more efficiently.
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Air conditioning is an essential in many areas where summer temperatures rise above 90 and 100 degrees Fahrenheit for days and weeks at a time. Excessive heat can affect your overall health and can result in death during extreme heat events. Adding an air conditioner to cool one room or the entire house can literally save a life. To use an air conditioner efficiently, implement cost-saving measures to reduce the load on the unit without driving the power bill to unaffordable levels.


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Window Air Conditioner

A window air conditioner should be sized to fit the square footage of the room or space. An undersized unit runs longer while cooling the space, and an oversized unit will cycle on and off frequently, which reduces its efficiency as well as its life span.

Determine the square footage of the space by multiplying the length of the room by the width. Then, check the manufacturer's size chart or multiply the square footage by 30 or by 40 in the case of a kitchen to find the necessary Btu (British thermal unit) rating for the air conditioner. Also, check the ENERGY STAR rating on the unit; if it costs less to run, the long-term savings make a more expensive and efficient unit a better buy.


If you're cooling only one room in your home, close the door to keep the cool air inside the desired space. Avoid cooking during the heat of the day or use small appliances like slow cookers rather than the oven to avoid adding additional heat and moisture to the room.

Central Air Conditioner

While a central air conditioner is already sized for your home, maintain its efficiency by keeping the interior air registers open. Closing vents in a room actually reduces efficiency and produces "hot spots" in the home.


Add a smart thermostat to keep the home at a comfortable level of 78 degrees Fahrenheit during the day and slightly lower at night to improve your sleep. During work hours, set the thermostat at 82 degrees until 30 to 60 minutes before you return home. A smart thermostat will lower the temperature automatically so that when you get home, the house will be a comfortable temperature.

Ways to Improve Overall Efficiency

In addition to using your air conditioner efficiently, you can further improve its cooling effects by closing the curtains so the sun doesn't beat into the room. Window films reflect the ultraviolet rays and subsequent heat away from the home. Seal around windows and window air conditioners to reduce hot and cold air infiltration in summer and winter. If you live in a mobile home, consider cleaning the roof and painting it with a white elastomeric "cool roof" coating to reflect heat as well as improve its watertightness.


Direct the airflow from the air conditioner to the center of the space. Add fans and ceiling fans to move the cool air around. Improving air circulation in the home allows you to raise the thermostat setting by approximately 4 degrees and still stay comfortable. Use the fan over the stove when cooking and the bathroom fan when showering to remove excess heat and moisture from the house.

Add shade over the air conditioner with a trellis, awning, sun sail, shrubbery or a shade tree. The shade from a tree can reduce temperatures by 10 degrees or more. However, leave at least 12 to 24 inches of clearance over and around the unit so that it has good air circulation and so that if it needs maintenance, you or an HVAC technician can get to the unit.


To improve efficiency, change or clean the air conditioner filters every four to eight weeks depending on the manufacturer's directions. Remove any debris around outdoor units and rinse the coils with mild dishwashing liquid and a hose equipped with a hand-held nozzle and then allow them to air dry. Don't use a power washer because the pressure can damage the fins and bend the coils.



Ruth de Jauregui is the author of 50 Fabulous Tomatoes for Your Garden. She writes numerous home and garden articles for a variety of online publications. She got her start as a book and cover designer in San Francisco for William (Bill) Yenne at American Graphic Systems. In addition to designing books, she wrote her first book, Ghost Towns. With several nonfiction books under her belt, de Jauregui recently published her first novel, Bitter.