What is SEER in HVAC? Important for your AC

A SEER rating is an important fact to consider when you want to buy a new AC. It is important when you want your AC to be worth every penny spent on it. It is normal to get confused by looking at the different SEER ratings on different models.

SEER stands for Seasonal Energy Efficiency Ratio. It will help you understand the amount of money and energy an HVAC or AC will use up in a year. The DOE, i.e. the United States Department of Energy has instructed that all AC units should meet the minimum efficiency level marked by the SEER ratings. With a remarkable amount of development in technology, especially around the last 15 years or so, most models have a SEER rating more than the necessary minimum. 


This are theoretical values and it might be hard to reach the same efficiency in real life settings but they can give an indication of what you can expect. Each state has its own weather and a SEER rating doesn’t really take this into account. The way you use your system also affects the performance.

What does SEER mean in an HVAC?

SEER measures the efficiency of an HVAC system’s air conditioning and heat pump cooling. A typical cooling season’s cooling output is divided by the total electric energy input (of the same time). The SEER rating number of an AC tells its maximum efficiency. While buying an AC unit, compare different SEER ratings and buy a more efficient machine. With all the information provided in this blog, you will hopefully be able to select a new AC for your home with confidence.

SEER is a measurement of a central AC’s maximum efficiency in a cooling season. In other words, it is a measurement of an Air Conditioning unit’s energy efficiency. This value pushes manufacturers to design better systems.

SEER is also used for inverters in HVAC. It serves the same purpose and indicates the energy efficiency of the system.

EER versus SEER

EER and SEER both measure how efficient an AC is.

EER focuses on how efficiently an AC cools at 95 degrees Fahrenheit. This is mainly used to check how it performs in warmer climates. According to the Department of Energy, a good EER is 12 for split-systems and 11.5 for packaged air conditioners.

SEER pays more attention to how the system functions over a whole year. So both during cooler and warmer days. This makes sure that manufacturers don’t just optimize for very hot days without paying attention to being efficient during colder days. For this reason, SEER is used more often than EER.

Why is the SEER rating important for an AC?

Homeowners can save money when they install an AC with a high SEER. This is because when the Seasonal Energy Efficiency Ratio is high, it means the AC unit is very efficient. As mentioned earlier, SEER measures heat pump cooling and air-conditioning efficiencies. If you purchase an AC with a rating of 16, you can save nearly five hundred dollars. This is impossible to do with an AC with low SEER. The better the SEER rating, the more efficient is the AC’s operation. 

This is why it can be interesting to replace an older system with a higher SEER rating for one with a lower one. The saving on utility costs and maintenance can be worth it.

How to calculate SEER?

To get the SEER measurement, the amount of heat taken away from the air-conditioned space during a span is divided by the electricity amount the unit consumed in the same timespan. 

SEER uses data to check the performance of an air-conditioning unit for a long period and in various temperatures, or during a cooling season. To be more precise, the SEER ratio is calculated by using a given indoor temperature and a range of outdoor temperatures, starting from 60 to above 100. This is the simulation of a typical season.

It is good to have a higher SEER rating. When an HVAC system has a higher SEER rating, it means it will not need a lot of electricity to cool a space.

Advantages of a high SEER ratio

The R in SEER stands for both ‘ratio’ and ‘rating’. As we explained above, SEER is the ratio of an AC’s cooling output over a cooling season which is divided by the energy used (in Watt-Hours). A Higher SEER rating ensures more comfort for you. 

The two major benefits of a higher SEER rating are:

Greater Energy Efficiency

A higher SEER rating gives higher efficiency in particular conditions. The SEER of most ACs is between 13 and 21. And the minimum SEER that any modern AC must have is 13. Again, you must remember that this indicates the maximum efficiency. Variables like the size of a home or the ductwork affect the HVAC system. Therefore, during the hotter days, you must use other energy-saving ideas in addition to using an AC with a high SEER rating. 

The Department of Energy in the U.S. has decided on the minimum SEER rating that ACs must have, based on the geographical locations. For instance, in the North, it is 13 and in the Southeast or Southwest, the minimum SEER has to be 14. Older AC units had a SEER rating of about eight or nine, but they still worked efficiently. Thus, a unit with 13 or 14 SEER is in no way inefficient. Also, if you are replacing your age-old AC at home with a new one with a minimum SEER ratio, it is still going to be energy-efficient. 

Higher Comfort at Home

Getting an AC unit with a high SEER means more comfortable for you in summer. Especially if you live in warmer regions like the Southwest or Southeast, the AC system will keep you more comfortable. 

Any air-conditioner with a higher SEER has the following two components which help them to function efficiently in providing greater comfort inside the home:’

  • Electric blower with variable speed
  • Two-stage or variable-speed AC compressor

ACs with a lower SEER usually have a single-stage compressor that runs at a fixed speed. These units provide uneven cooling during mild weather. This is because they keep turning off and on. As a result, there might be cold and hot spots too. And the humidity level will be high too, adding to the discomfort. Such air-conditioners can remove the humidity only if they are allowed to run for a long time. 

What is the best SEER rating?

While purchasing an AC, you have to check its SEER rating and decide which would be better for your home. What’s best for one house will not be as ideal in another. A lot of factors play their part. Obviously, you want to get a highly-efficient AC, but there is no one particular SEER which can be called the best. Although, a SEER of 14 or more is undeniably a good rating. Most HVACs now have an average efficiency rating of 16. In some higher-end models, the SEER rating is as high as 23. 

If you are going to replace an old AC which is old having a SEER of 8 or 9, anything over 13 is going to be a significant improvement. Additionally, things like the manufacturer’s rebate and tax credits can lower the cost of the system with high SEER. 

The required SEER depends on your location.

LocationRequired SEER by the Department of Energy
Southwest USA14
Southeast USA14
North USA13
Minimum SEER Required by the Department of Energy for HVAC systems

A system with higher SEER not only reduces the recurring amount of money you will spend to cool your home, but also the need for energy.

To conclude, we can state that the SEER rating is important when you pick a new AC system. There are other factors that are important such as the BTU (or power) of your system and the amount of noise that it produces.