Difference Between EER and SEER

EER or energy efficiency ratio and SEER or seasonal energy efficiency ratio are both ratings related to the energy efficiency of a home cooling appliance, typically an air conditioner, during a change of the Temperature outside. They are typical in every appliance. Thus, knowing the correct combination is important to select the right appliance suitably. 


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The difference between the energy efficiency ratio or EER and seasonal energy efficiency ratio or SEER is that SEER typically measures how efficiently the cooling system works over a regular cooling season, whereas EER is a standardized measurement of the energy efficiency of an air conditioner during a specific outdoor temperature.


The higher the ratio of EER in an appliance (with the given and constant factors), the more efficient the air conditioner is, as it typically measures the efficiency at a specific outdoor temperature that is 95 degrees Fahrenheit. It is the efficiency of the air conditioner at the peak of the cooling time. 

SEER is the most common way to measure the energy efficiency of an air conditioner as it can operate over an entire season. It is unique in itself because of the ‘S’ in SEER that stands for ‘seasonal.’ Thus, it can operate in a variety of temperatures ranging from 65 to 104 degrees Fahrenheit. 

Comparison Table

Parameters of ComparisonEERSEER
Full form Energy Efficiency RatioSeasonal Energy Efficiency Ratio
UsageEER typically measures efficiency at a particular temperature which is at the peak cooling time.SEER measures efficiency over a range of temperatures at a particular season.
Preferred type of applianceEER is preferred for room air conditioners.SEER is preferred for central air conditioners. 
Specific TemperatureThe specific outdoor temperature at which EER measures efficiency is 95 degrees Fahrenheit.The range of temperature at which SEER rating tests ranges from 65- 104 degrees Fahrenheit.
Suitability according to locationHigh ratings of EER must be preferred when the location is usually 95 degrees F or above. Good ratings of SSR must be considered for areas with moderate climates. 

What is EER?

EER or energy efficiency ratio is a standardized measurement of the energy efficiency of an air conditioner at a particular temperature. The Temperature is usually at the peak cooling time, in peak Temperature, i.e., 95 degrees Fahrenheit. These are mostly suitable for room air conditioners like a window, through-the-wall ACs, ductless mini-split, portable AC, etc. High energy efficiency ratings of EER in an air conditioner are most appropriate for areas with high outdoor Temperature, usually 95 degrees F or above. 

Air conditioners with high energy efficiency ratings are more efficient. Their purchase price is slightly higher than the rest, but they consume lesser electricity and last longer, which compensates for the higher price in the long run. Ratings differ from appliance to appliance, depending upon their capacity. The ratings should be a minimum of 6, ranging from 9.4 to 10.7 for the bests in the present market. 

The calculation of EER is a simplified process and is much less complicated than that of the SEER. It is calculated by dividing the cooling capacity measured in British Thermal Units (BTU) by maximum cooling wattage hours. The equation can be framed as below- 

EER = Cooling Capacity (Maximum BTU) by Maximum Cooling Watt-Hours

What is SEER?

SEER or seasonal energy efficiency ratio is the most common way to measure the overall energy efficiency of an air conditioner over a range of temperatures in a particular season. The SEER rating tests and calculates efficiency at various temperatures, usually ranging from 65- 104 degrees Fahrenheit. Unlike EER, it can calculate efficiency at both high and low cooling hours.

Appliances with higher SEER ratings make it better as compared to others with lower SEER ratings. It is calculated by the ratio of cooling efficiency measured in British Thermal Units (BTU) and total energy consumed in watt-hours. At present, a variety of SEER-rated air conditioners are available in the market. Most outdated SEER models that are functional can be replaced either by replacing a piece of the equipment or by specifying new installations. Because of their wide and easy availability, replacement is also cost-efficient. However, because of such replacements and installations, the quality of the appliance and the effect of cooling might degrade. 

Presently, the highest rating of SEER is that of Residential split system air conditioners, at 20 SEER or above. Appliances with higher SEERs are a little above others as they have larger coils, multiple compressors. Some of them are even designed with refrigerant flow and variable supply airflow. 

Main Differences Between EER and SEER

  1. EER stands for Energy efficiency ratio, whereas SEER stands for seasonal energy efficiency ratio. The ‘S’ in SEER makes all the difference between the two.
  2. EER is a rating of an air conditioner that typically measures the energy efficiency when the outside temperature is at its peak. SEER ratings of air cooling systems are capable of measuring the energy efficiency of a range of temperatures of an overall season. 
  3. The highest peak of outside Temperature set for EER is typically 95 degrees Fahrenheit. The range of Temperature that a SEER typically follows is 65 degrees F to 104 degrees F. 
  4. EER is most suitable for room air conditioners like potable ACs, mini-split ACs, windows, etc. SEER is only suitable for central air cooling systems. 
  5. EER is preferred in areas that have high temperatures, typically 95 degrees F or above. SEER is preferred for areas having a moderate climate.


  1. https://en.cnki.com.cn/Article_en/CJFDTotal-TJDX200609014.htm
  2. https://en.cnki.com.cn/Article_en/CJFDTotal-LTJX200709020.htm
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