Household air conditioners use electric energy to pump heat out of your home and dump it outside. They distribute cooled air throughout your house and remove moisture form indoor air.
The efficiency of room A/C units is governed by U.S. law and regulated by the U.S. Department of Energy. Every room air conditioner is assigned an efficiency rating known as its energy efficiency ratio (EER). The EER is defined as the cooling output (in Btu per hour) divided by its energy input (Watts) at specified indoor and outdoor temperatures.
The EER is displayed on a yellow label affixed to the A/C or its packaging. Higher EERs are better. The minimum EER allowed by law is between 8 and 9, depending on the capacity and type of unit. The best available EER is about 13.
High-efficiency room air conditioners save money on your utility bills,and result in fewer environmentally harmful emissions.
An average air conditioned home consumes more than 2000 kilowatt-hours of electricity per year for cooling, causing about 3,500 pounds of carbon dioxide and 31 pounds of sulfur dioxide to be emitted by the power plant. At average electricity prices, that costs about $150 as of this writing. A high-efficiency A/C unit can reduce energy consumption (and environmental emissions) by 20 to 50 percent. The most efficient air conditioners on the market are up to 70 percent more efficient than the current average room air conditioner.
Content Provided By the DOE