Any homeowner who is looking for a new air conditioner will most likely come across both SEER ratings and EER ratings for different AC makes and models. These two ratings are similar in that they both measure an AC’s energy efficiency. However, they are also different and understanding them can help homeowners make a more informed decision.
EER Ratings
EER, energy efficiency ratio, is a measure of the efficiency of a cooling system when the indoor temperature is 80 degrees Fahrenheit and outdoor temperature is at 95 degrees Fahrenheit with 50% humidity. The higher the number, the more efficient the cooling system is. EER is one of the first attempts by the Air Conditioning and Refrigeration Institute to standardize the method of calculating the energy efficiency of air conditioning units.
The energy efficiency ratio of a cooling system is calculated by dividing the total energy input, measured in watts, by the cooling output, measured in BTU’s or British thermal units, under a specific set of conditions. Introduced in 1975, the EER rating did not take seasonality into consideration. In 1978, the United States Congress passed a law requiring classification of certain cooling systems with an efficiency rating that took seasonality into consideration, thus, SEER was introduced. However, EER ratings are still used today, particularly on commercial cooling units above 6 tons.
SEER Ratings
The difference between SEER, seasonal energy efficiency ratio, and EER is the use of seasonal conditions in the calculation of system efficiency. The higher the SEER, the more efficient the unit is. This rating measures how efficiently a central air conditioner or heat pump will operate over an entire season. In technical terms, it is a measure of the total cooling output of a heat pump or central air conditioner, measured in BTU’s, during the normal cooling season versus the total energy consumption during the same period.
As of 2006, the mandated SEER ratings for new cooling units must be at least SEER–13; however, modern cooling equipment have ratings as high as SEER–23. SEER is a better alternative to EER as it offers a better approximation of the actual cooling costs of operating an air conditioner based on the installed climate zone.
Homeowners looking for new cooling systems should always compare efficiency levels using the SEER rating. It is a contractor’s job to provide homeowners with clear, concise information that will help them make an informed, confident choice. Call us to learn more about efficient heating and air conditioning options.