When installing a new central air conditioning system or replacing your existing AC unit, one of the first things you should always consider is the Seasonal Energy Efficiency Ratio or SEER rating. SEER ratings are important as they tell you exactly how energy efficient a central AC unit is, and SEER is also used to measure the energy efficiency of ductless mini-split ACs as well as the efficiency of heat pumps when cooling. Knowing what SEER rating is best for your new AC can be difficult, which is why we’ve produced this guide to help you understand SEER ratings so you can more easily decide which new unit is right for your home and for your budget.

What Do SEER Ratings Actually Mean?

The SEER rating system was originally developed to better estimate the energy usage of air conditioners and more accurately measure their energy efficiency. Measuring energy usage and efficiency can be tricky simply because both can fluctuate quite a lot depending on outdoor temperature and humidity. SEER ratings are designed to help overcome this problem by estimating how much total energy an AC unit would use in an average year instead of just looking at the hourly or daily usage.

Any AC unit will use less energy when the outdoor temperature is cooler, and the humidity is lower simply because it will work more effectively in these conditions and not need to run as frequently or for as long of a time. On the other hand, an AC unit will have to work much harder and be less efficient whenever the outdoor temperature is in the 90s or above or if the outdoor humidity level is much higher. This can again make it extremely difficult to estimate average energy usage since temperature and humidity can fluctuate greatly from late spring to early fall when an AC is typically in use.

To calculate the SEER rating of any AC, the unit is first tested by running it at various temperatures and humidity levels to see how much energy it uses under different conditions. This test is designed to simulate the different weather conditions the AC may operate in over the course of a normal cooling season to gauge total yearly energy consumption more accurately.

After estimating the energy usage in these different conditions, the test can then determine how much total electricity the unit would use in a normal season. The SEER rating can then be calculated by taking the number of BTUs of cooling the unit produces and dividing it by the total number of kilowatt-hours of electricity the unit would use per season. Essentially, SEER is just an expression of how many BTUs of heat energy an AC unit can remove per each unit of electricity it consumes. The higher the SEER rating is, the more efficiently the unit works and the less energy it will use.

How SEER Can Help to Estimate Energy Usage and Potential Savings

Understanding the exact science behind SEER ratings isn’t necessary. Nonetheless, SEER ratings are extremely useful as they allow you to directly compare various AC units by estimating how much total energy each one would use per year and how much your total yearly cooling costs would be for each different unit. Each higher SEER rating equals an approximately 7% increase in energy efficiency, i.e., a 16 SEER unit would use around 7% less energy than a unit of the same size with a 15 SEER rating.

The SEER rating for your current AC unit should be listed on the manufacturer’s information label, which is usually found on the back of the unit. You can use this information to also estimate how much you could save on your total yearly cooling costs with a new AC.

Let’s say that you currently have a 3-ton AC with a 10 SEER rating. In the Tacoma area, the unit would normally run for an average of just under 300 hours a year and normally cost around $100 a year to run. If you were to replace it with the same size of unit with a 14 SEER rating, your total yearly energy costs would typically decrease by at least 28% saving you nearly $30 a year. The reason we say at least 28% is that there is very little chance an old 10 SEER unit still works as efficiently as it did when it was brand new, which means your energy savings with the new unit would likely be quite a bit higher.

If you’re unsure of exactly how much energy your current AC uses and how much it costs to run each year, you can find numerous tools online from the US Department of Energy and other organizations that allow you to quickly estimate this based on the size and SEER rating of your current AC unit. These tools also estimate the overall usage based on where you live, which is obviously important since an AC in Washington won’t run as much or use as much energy as it would if you lived somewhere further south.

Comparing Energy Savings to Increased Cost

Determining which SEER rating is the best choice for your new AC can be difficult as it depends in large part on what your total budget is. If money is no object and you have an unlimited budget, you’re obviously best to go with the highest SEER unit available. Since this typically isn’t the case for most people, it always helps to look at how much total money a higher SEER unit could save you and compare this to the total cost of the unit. This way, you can more easily determine whether the added energy savings are worth the increased cost of the higher SEER unit.

As of January 2023, the Department of Energy requires that any new air conditioner installed in Washington and the northern US must be at least 14 SEER which is an increase of 1 SEER from the previous minimum. That said, you can technically still install a 13 SEER unit until the start of 2024 if it was manufactured before the end of 2022.

In Tacoma, a 3-ton 14 SEER AC would use around $70 to $80 worth of electricity per year on average, whereas a 3-ton 18 SEER unit would only use around $50 of electricity. Any new air conditioner will usually last for about 15 years, which means that the 18 SEER unit would save you somewhere around $300-$450 in energy costs over the life of the unit compared to the 14 SEER unit. If you’re on a limited budget and the difference in price between the 14 SEER and 18 SEER units is greater than the estimated savings you’d get from the higher SEER unit, it’s probably better to stick with the 14 SEER unit.

Choosing a unit with a much higher SEER rating can make sense in much hotter places where the AC would run for far more hours each year and cost much more money to use. In the Pacific Northwest, however, a higher SEER unit is often not worth it simply because the total energy savings will almost never offset the higher cost of the unit. The only thing you may still want to consider is that a higher SEER unit will lessen the environmental impact of your air conditioning and lower your carbon footprint.

Expert HVAC Services and Support

If you’re looking to install a new central AC unit or a ductless mini-split AC or heat pump, Hunt’s Services is ready to help. Our technicians can not only determine what size and type of unit will work best for your home, but we can also help you decide which SEER rating is best based on your budget. For more information or to schedule any air conditioning or heating service in the Tacoma area, contact us today.

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