Photograph of older side-vent combination hot air furnace and central air conditioning system. The evaporator coil or A-coil is
visible in the top of the unit. Air Conditioning & Heat Pump SEER Ratings
History of the DOE Air Conditioner and Heat Pump Efficiency Standard

  • SEER RATING HISTORY - CONTENTS: definition of SEER & history of & reasoning behind the development of SEER ratings. New DOE standard and history of air conditioning system ratings and refrigerants. Notes on the1987 Ban on ozone depleting gases.
  • POST a QUESTION or READ FAQs about the definition & interpretation of SEER ratings on air conditioners or heat pumps
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History of SEER Ratings:

This article defines and explains the SEER energy efficiency rating found on air conditioners, heat pumps, and other mechanical systems. SEER stands for "Seasonal Energy Efficiency Ratio. This is a measure of the energy efficiency of the air conditioning system. SEER ratings permit consumers to compare operating costs of various cooling systems and products.

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New DOE Air Conditioner and Heat Pump Efficiency Standard to Take Effect January 1, 2006

SEER = [Total Cooling Output Over the Cooling Season] / [Total Electrical Energy Input Over the Cooling Season]

Older air conditioning systems are likely to have a lower SEER (perhaps 5 or 6) than a newer more efficient system (perhaps SEER=10). But beyond comparing SEER ratings, a look at the building insulation, air leakage, and the layout, insulation, and adequacy of the air conditioning duct system are likely to have a very large, usually determining effect, on the operating cost of air conditioning systems in buildings.

Details about SEER and other important air conditioner system measurements, terms, and definitions can be read at SEER RATINGS & OTHER DEFINITIONS. Readers should also see APPLIANCE EFFICIENCY RATINGS.

US EPA: All heating and air conditioning equipment is supplied with a manufacture's rating of the energy efficiency. The current minimum standard for air conditioners and heat pumps is a 10 Seasonal Energy Efficiency Rating (SEER).

This has been the standard for many years, and equipment with this rating represents the vast majority of residential air conditioning installed in the United States. Starting January 1st of 2006 the Department of Energy has ruled that any new equipment installed must meet a new minimum efficiency of 13 SEER.

According to DOE studies the change from a 10 SEER to 13 SEER represents a 30% increase in air conditioning or heat pump energy efficiency. This is good news for your electric bill!

However, to achieve this new standard requires changes to the equipment. Generally speaking the new efficiency standard is going to be achieved in two ways. The first change is going to be in compressors. New technology compressors run quiet and provide excellent efficiency and durability. The second way to increase the equipment's efficiency is to increase the size of the evaporator and condenser coils in the system. The new compressors and larger coils will mean an increase in the cost of the equipment.

Another factor in the cost of installation is size of the line set in the equipment. In many cases involving a retrofit, the old size line set may be inadequate for the larger coils and refrigerant charge of new equipment. Finally, another factor involving the cost of the installation could be the thermostat. Many new systems come with diagnostic control boards. A new digital thermostat can take advantage of the diagnostics and cut down on maintenance calls or diagnostic time. This means savings for the consumer and peace of mind to know their equipment is running properly.

As more manufactures change from production of 10 SEER equipment to 13 SEER equipment the consumer should see some savings in the price, but the overall cost of all heat and air equipment will rise beginning this year. The price of metal continues to impact the cost of equipment and as stated in the paragraph above, the 13 SEER equipment is normally larger than the comparable 10 SEER equipment (i.e. more metal in manufacturing).

So, in conclusion there is going to be a trade off facing builders, homeowners and heat and air contractors in the near future. The technology to save 30% on energy consumption will be the standard as mandated by the Department of Energy. But, to achieve that energy savings will impact the up front cost of installation. If you have any questions on the standard you can give us a call or type in "13 SEER" on the search section of the DOE's web site at

Its not just the equipment compatibility, and getting the best efficiency, but also the need to take into effect the changeover from R-22 refrigerant to R-410a. Right now [January 2007-Ed.] you have a choice. January of 2010 (just 3 years away), the manufacturers have been mandated to stop making all R-22 equipment, and reduce importing and production of R-22 refrigerant.

As far as the efficiency and refrigerant changes, check out the DOE and EPA web sites. What You Should Know about Refrigerants When Purchasing or Repairing a Residential A/C System or Heat Pump DISCLAIMER: EPA seeks to promote energy efficiency and the safe use of ozone- friendly substances, and does not endorse any particular company or its products.

SEER Energy Rating Articles


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