If you’re looking to add central air conditioning to your home or need to replace your existing AC or heat pump, energy efficiency is one of the most important factors to consider. Looking at energy efficiency ratings is important since it will directly impact how much energy your AC uses and how much it costs to keep your home cool. The energy efficiency of any type of central cooling unit or ductless mini-split is expressed as a SEER rating. This guide will help you understand what SEER ratings mean, how they’re calculated, and why they’re important.

What Are SEER Ratings?

Seasonal energy efficiency ratio or SEER is used to show approximately how many total kilowatts of electricity any type of air conditioning unit would use in an average year. SEER ratings are simply a ratio of the total energy input (how many kilowatt-hours of electricity the unit uses) to the total cooling output (how many BTUs of heat the unit removes from the home) throughout an entire cooling season from late spring to early fall.

The reason SEER ratings are important is that the energy usage of an air conditioning system fluctuates based on how hot and humid it is outside. The effectiveness of an AC system decreases with an increase in heat and humidity. This, in turn, leads to increased energy usage since the system will need to run for longer to fully cool the home. This is why it’s necessary to focus on the total energy usage across the entire cooling season since how much electricity an AC uses can go up or down from day to day or even hour to hour.

A unit with a higher SEER rating will use less energy than a unit that is the same size but has a lower SEER rating. As SEER ratings increase, energy usage decreases by approximately 7%. In other words, a 15 SEER AC is around 7% more energy efficient than a 14 SEER AC.

As of the start of 2023, any new central AC, heat pump, or ductless mini-split AC installed in Idaho must be at least 14 SEER. If your existing AC unit was installed before 2006, there is a decent chance that it’s only 10 SEER. In this case, any new unit you choose would reduce your annual cooling costs by approximately 28% compared to what you’re currently paying.

How Is SEER Calculated?

The only way to know the total amount of energy an AC unit will use over one season is to test it and see how well it performs in varying conditions. Specifically, the unit is tested by running it at temperatures ranging from 65 to 104 degrees Fahrenheit to see how effectively it works and how long it will take it to fully cool a home at different temperatures. These tests are important as they simulate the different conditions the unit may operate under from late spring to late summer or early fall. After determining the total kilowatt-hours of electricity the unit would likely use in one season, SEER can then be calculated by dividing the total electricity usage by the unit’s BTU rating.

Understanding the New SEER2 Ratings

Traditional SEER ratings are no longer used, as the US Department of Energy mandated that the HVAC industry switch to the new SEER2 rating system at the start of 2023. SEER2 ratings are more accurate, and the reason is that the testing requirements were updated to represent real-world operating conditions.

SEER2 ratings are between 4.3% and 4.8% lower than SEER ratings. This means that 14 SEER equals approximately 13.4 SEER2, which again is the minimum required rating in Idaho.

How SEER Can Help You Estimate Cooling Costs and Energy Savings

The main point of SEER and SEER2 ratings is that they allow you to estimate how much money you can potentially save with a more energy-efficient AC unit. Let’s say that your existing AC is a 3-ton, 10-SEER unit. If you replace it with a 3-ton, 18 SEER2 unit, your annual cooling costs would drop by approximately 88%. In the Boise area, this means that the new unit would usually save you just under $150 a year. If you, instead, just went with the minimum of 13.4 SEER2, your annual cooling costs would only decrease by around $80 per year on average.

When comparing SEER ratings and trying to determine which new AC unit is the best choice, it is more useful to look at approximately how much you can expect to save over the entire life of the unit instead of just in one year. The average lifespan for a new central AC or heat pump is around 15 years.

If you chose a 3-ton 13.4 SEER2 AC, your total cooling costs over the 15-year life of the new unit would likely be somewhere around $3,200 based on current average electricity rates in our area. If you instead installed a 16 SEER2 unit, you’d end up saving somewhere around $550 over 15 years.

The reason that we recommend comparing lifetime energy costs and savings is that it makes it much easier to determine whether or not it’s worth it to spend more money on a higher SEER unit. Let’s say that you’re looking at a 16 SEER2 unit, and it costs $1,000 more than the 13.4 SEER2 unit you’re considering. In this case, the lower SEER2 unit would be more cost-effective in the long term.

If you don’t have a specific budget you have to stick to and are mainly concerned about energy usage and the environmental impact of your AC system, it is always best to choose whatever available unit has the highest SEER rating. If you do have a more limited budget, you’ll want to find the unit in your price range that will be most cost-effective in the long run. If the energy savings for a higher SEER unit are equal to or greater than the cost difference between it and a lower SEER unit, it’s always best to choose the higher-rated unit even though it costs more upfront.

In hotter, more humid climates, choosing a unit with a much higher SEER rating will usually end up paying off over time. In places like Idaho, where your AC won’t run nearly as much per year and your cooling costs are lower, it’s usually better to try and find a balance between energy efficiency and upfront costs.

With more than 40 years of experience, Perfect, Plumbing Heating & Air is the top choice for all of your air conditioning and heating needs in Boise and the Treasure Valley area. Our certified technicians specialize in HVAC installation as well as repairs and maintenance, and our team can also take care of your indoor air quality and plumbing needs. If you have any questions about SEER ratings or need any HVAC service, give us a call today, and we’ll be happy to schedule an appointment for you.

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