How to Find the EER for an HVAC Unit

EER

• The Energy Efficiency Ratio (EER) indicates how efficiently an air conditioning unit uses energy. The Air Conditioning and Refrigeration Institute developed this method of assessment in 1975 to measure all cooling elements of HVAC systems. However, the United States Congress implemented a more complex means of assessing HVAC cooling system efficiency, SEER, in 1978. As of 2011, EER only applies to air conditioners used in single rooms. The higher an EER rating, the more efficiently a unit uses energy. According to the United States Department Of Energy, national appliance standards require air conditioners to have an EER of 8 to 9.8 or higher.

Calculating EER

• Calculating your air conditioner's EER requires little more than simple division. Simply divide the cooling capacity of the unit, expressed in British Thermal Units (BTUs), by the unit’s power input in watts. Information on the cooling capacity of an air conditioner and its power input in watts generally appears on the unit's packaging or in the owner's manual. You can also ask the air conditioner's vendor or manufacturer for EER information before purchasing the unit.

SEER

• The Seasonal Energy Efficiency Ratio (SEER) is a method of measuring the energy efficiency of the cooling element in an HVAC unit. This measurement takes into account climate and calculates energy efficiency levels during the times of highest use. You can determine the unit's SEER rating by dividing its cooling output in BTUs by the total electric energy input in watts-hours during the course of the season when it's used most. The HVAC unit's manufacturer or installer can also tell you the unit’s SEER rating.

Energy Star Ratings

• The federal government certifies numerous commercial products through its Energy Star program. To qualify for an Energy Star rating, the HVAC unit must have a SEER rating of at least 14 to 14.5; and if the system also has a single air conditioning unit, an EER rating of at least 11 to 12 as of 2011. Energy Star-certified HVAC systems must also have a Heating Seasonal Performance Factor (HSPF) of 8 to 8.2. HSPF measures heating performance, just as SEER measures cooling performance. According to the California Energy Commission, systems with high SEER and EER ratings often cost more but save consumers money in the long term by using less energy.