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Some good reasons to buy a new high-efficiency central AC unit

6/2/2016 2:24:23 PM

If your central air conditioner is old (15-20 years) and showing wear, it may be time to shop for a new one—before it breaks down on a 90-degree day. Some good reasons to buy a new high-efficiency AC unit: save energy and money, enhance comfort, and reduce carbon emissions.

You can reduce air conditioning energy use by 20 to 50 percent by switching to a high-efficiency air conditioner and taking other actions to lower home cooling costs, according to the U.S. Department of Energy.

The Minnesota Commerce Department offers the following tips to consider when shopping for a new central AC unit:

Proper sizing. Over-sizing an air conditioner is the most common mistake made by consumers, thinking that “bigger is better.” Buying too large of a unit is not only expensive, it can increase discomfort by not removing enough humidity from the air.

The primary tasks of an air conditioner are to cool and dehumidify. A system that is too large often achieves the desired temperature before the humidity is adequately removed. If a system is too small, it may dehumidify well but not cool the air sufficiently. 

A properly sized unit needs an operating cycle long enough to balance the removal of both heat and humidity. Make sure that your contractor does a heat-gain calculation to ensure the proper sizing of the unit.

Efficiency ratings. Since 2006, all residential central air conditioners sold in the United States must have a seasonal energy efficiency ratio (SEER) rating of at least 13. The higher the SEER rating, the more efficient it is for cooling. 

ENERGY STAR®-qualified units must have a SEER rating of at least 14; SEER ratings go up to 20. ENERGY STAR-qualified central units use 8% less energy than conventional new models. 

The Center for Energy and Environment (CEE) provides an HVAC Calculator to estimate operational costs, fuel consumption, and carbon dioxide emissions for new heating and cooling systems compared to your current system.

How to pay for it. To offset the cost of a new AC unit, many utilities offer rebates for high-efficiency central AC units. For instance, Xcel Energy offers a rebate of $150-$450. Also, there is a federal Residential Energy Efficiency Tax Credit of up to $500 (good thru Dec. 31, 2016) for AC units and other equipment that meet efficiency criteria. 

Loan programs, such as the Home Energy Loan Program from CEE, offer low-interest loans to homeowners who want to make energy improvements to their properties.  See the Database of State Incentives for Renewables and Efficiency at for information on utility rebates, tax credits, loans, and other incentives.

Resources. To learn more about air conditioning, check out the Home Cooling section of the Minnesota Commerce Department's Home Energy Guide (pdf). Some tips on selecting a contractor are covered in a previous energy tip.

Minnesota Energy Tips is provided twice a month by the Minnesota Department of Commerce, Division of Energy Resources. Contact the division’s Energy Information Center at or 800-657-3710 with energy questions.


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