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Understanding HVAC Efficiency Ratings

What is a SEER rating?

The minimum energy efficiency level for central air conditioning systems made and sold in the United States is regulated by the U.S. Department of Energy (DOE). The efficiency level of a central air conditioner is determined by its "seasonal energy efficiency ratio" (SEER). This SEER rating is technically defined as the cooling output provided by the unit during its normal annual usage period divided by its total energy consumption. More simply, the SEER rating is similar to the miles-per-gallon rating for automobiles. The more energy efficient the air conditioning equipment is, the higher the SEER rating - because less electricity is needed to cool your home.

What is the minimum SEER standard today?

Since 1992, the minimum efficiency standard for central air conditioners and heat pumps has been set at 10 SEER. That's about to change. Beginning in January 2006, the minimum efficiency level for all new central air conditioners manufactured must be at least 13 SEER.

What does the 13 SEER standard mean for homeowners?

The 13 SEER regulation does not affect a homeowner's current air conditioner. But the 13 SEER transition will affect homeowners and builders looking to purchase a new central air conditioner this year or next in several ways, including:

  • Farewell to 10 to 12 SEER systems: Beginning January 23, 2006, central air conditioners rated at 10 to 12 SEER will no longer be manufactured. However, 10 and 12 SEER systems can continue to be sold and installed until inventory of these products is exhausted.
  • Lower operating costs: An air conditioner rated at 13 SEER uses 30 percent less electricity than a 10 SEER system.
  • More advanced technology: New central air conditioners use more advanced technology and have more features to enhance efficiency, comfort, reliability and convenience.
  • Bigger systems: Air conditioners usually get larger in size as the SEER rating is increased. That's because to achieve a higher efficiency, manufacturers need to install more coil (i.e. copper or aluminum tubing) to more efficiently transfer heat.
  • Expect to pay more: In general, the higher the SEER rating, the more it will cost to purchase a new air conditioner. Higher efficiency systems tend to be larger and use more materials like steel, aluminum and copper; they are also more costly to manufacture, transport and install.

How should homeowners use SEER ratings?

When buying an air conditioner, it's generally recommended to select the highest SEER system you can afford. You may want to ask your contractor to calculate the payback period in which the new system will "pay for itself" in terms of lower utility bills. Sometimes the savings are enough to partially or fully offset the cost of the new system within a few years. This is an individual calculation provided by the contractor that factors in your home's size and the typical energy costs for your geographic area.