Shopping for AC

The energy efficiency of air conditioners has improved a great deal in recent years. Replacing an old air conditioner with a modern, efficient one can reduce your air-conditioning cost by up to half.

The Energy Guide® label is placed on all new air conditioners and must remain there, by law, until the unit is sold. It includes an EER (Energy Efficiency Rating) for portable room air conditioners, and a SEER (Seasonal Energy Efficiency Rating) for central air conditioners.

The higher EER or SEER ratings indicate more efficient appliances. Older portable air conditioners may have an EER of only 5 or 6. If you replace it with a unit rated at EER 10, you will save up to half on your electrical cost for cooling.

If you live in a moderate cooling climate, select a room air conditioner with an EER 10 or higher. Central air conditioners should have a rating of at least SEER 13.

Don’t buy air conditioning equipment that is over-sized. You’ll get the best efficiency from a small air conditioner that runs full-time on the hottest day of the year. Over-sized equipment cycles on and off frequently, wasting energy and shortening the life of motors and compressors. It may be tempting to purchase a larger air conditioner because it’s only slightly more expensive than a smaller unit, but you’ll spend more on electricity in the long run.

Install your portable air conditioner in a window that doesn’t receive direct sunlight during the heat of the day. This will allow it to deliver cooler air to the home. The north or east side of the home is often a good location. Better yet, install it in a window shaded by a tree.

For more information on air conditioning see The Homeowners Handbook to Energy Efficiency Your Home Cooling Energy Guide, Chapter 8 of Residential Energy: Cost Savings and Comfort for Existing Buildings or for specific information about servicing air conditioners for energy efficiency, see Saturn Hydronic Systems Field Guide.