Seasonal energy efficiency ratio (SEER) is commonly used to measure the efficiency of heating, ventilation and cooling (HVAC) equipment. When shopping for a new air conditioning system, you’ll probably notice a SEER rating. The U.S. Department of Energy (DOE), in fact, requires all new air conditioning systems to have a SEER rating. What are SEER ratings exactly?

An Introduction to SEER Ratings

SEER ratings are a measurement of cooling efficiency for HVAC equipment. It takes into account the cooling output of an air conditioning system during a typical cooling season — such as the summer — as well as the air conditioning system’s energy usage.

In the United States, SEER is expressed as a ratio of an air conditioning system’s cooling output during a cooling system over the air conditioning system’s energy usage during that same period. A SEER rating is simply a number that’s derived from this formula. Some air conditioning systems have a SEER rating of 10, whereas others have a SEER rating of 16. Air conditioning systems with a high SEER rating are more energy-efficient than those with a low SEER rating.

Why SEER Ratings Are Important

You can’t ignore the SEER rating when shopping for a new air conditioning system. Since it’s a direct measurement of efficiency, it will reflect the air conditioning system’s operational costs. You’ll spend less money to cool your home by choosing an air conditioning system with a high SEER rating.

Air conditioning systems with a high SEER rating often cost more than those with a low SEER rating, which may discourage some homeowners from choosing them. While more expensive upfront, though, they’ll save you money in the long run. With a high SEER rating, your air conditioning system will consume less energy to achieve a cool and comfortable temperature inside your home.

You may be eligible for a tax credit by choosing an air conditioning system with a high SEER rating. The federal government offers tax credits on certain high-efficiency air conditioning systems, as well as heat pumps, with a high SEER rating.

New air conditioning systems are also required to have a minimum SEER rating of 13 or 14. If your air conditioning system is older than 10 years, chances are it has a lower SEER rating. Older air conditioning systems are less efficient than newer air conditioning systems, so they tend to have a lower SEER rating.