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SEER Rating Energy Savings Calculation

SEER: How to Calculate The Energy Savings of Different SEER Ratings in Air Conditioners

The SEER rating of your air conditioner will determine how energy efficient it is.

What is SEER? Simply put, SEER stands for Seasonal Energy Efficiency Ratio. The resulting number that is applied to an air conditioner is called it's SEER rating. The higher the SEER rating the more energy efficient a given air conditioner is.

What SEER is right for me? Good question that everyone should ask themselves before purchasing a new AC system. The highest SEER is not always best. It all depends on the individual's circumstances.

Let's run through a comparison calculation on a 3.5 Ton 14 and 16 SEER...

  1. Step 1: Use this equation to determine each air conditioner’s estimated annual energy use:

    [(Size of A/C system x 12,000) / SEER] x 2100 = amount of Watt-hours used annually

    To better understand what’s happening here, let’s breakdown each step of this equation:

    Size of A/C system x 12,000

    The first part of the equation is calculating the amount of cooling your air conditioner provides. 1 ton of cooling = 12,000 BTUs. (2 tons = 24,000, 3 tons = 36,000 etc)

    This is the capacity of your A/C system, much the same way the horsepower of a car tells you the capacity of the engine.


    Next, we need to calculate how efficiently your A/C system provides that capacity...

    Dividing the capacity by the air conditioner’s SEER gives you the approximate number of Watts the air conditioner uses per hour.

    You’ll now have the amount of energy your A/C uses per hour, which is similar to how the MPG of your car tells you how many miles you can go on one gallon of gas.

    x 2100

    Next multiply by the number of hours you’ll use your A/C. An excel spreadsheet showing The Life Cycle Cost Estimate of a Qualified Central Air Conditioner indicates the average Phoenix-area home uses their air conditioner for about 2100 hours per year.

    The result is

    = amount of Watt-hours used annually

    You’ll now have the estimated amount of energy (measured in Watt-hours) that the A/C will use in a year.

    So for our 3.5-ton example air conditioners, we get:

    For a 14 SEER

    [(3.5x12,000)/14]x2100=6,300,000 Watt-hours (rounded to nearest thousand)

    For a 16 SEER

    [(3.5x12,000)/16]x2100=5,512,500 Watt-hours
  2. Step 2: Find the energy use difference between the 2 A/C options

    Now that we know approximately how much energy each of our air conditioners will use, we need to find the difference between them. This is simple subtraction:

    Energy use of 14 SEER - Energy use of 16 SEER = Energy savings of higher unit

    In our example, the difference is 787,500 Watt-hours, annually.

  3. Step 3: Convert to $$$ saved

    Now we simply need to calculate the actual amount of money this number equates to. Your electric company (either APS or SRP) charges you per kWh, or kilowatt-hour.

    To convert the Watt-hours to kWh, you divide by 1000.

    So our example is 787,500 Watts/hour / 1000 = 787.5 kWh.

    Now to get the estimated annual energy savings, you just multiply by the rate your utility company charges. The average electrical rate in Phoenix is 0.12 per kWh.

    So a 3.5-ton, 16 SEER unit in Phoenix saves you about $94.50/year (787.5 x $0.12) in electricity costs over a 14 SEER unit.

    • The difference between a 14 SEER and 15 SEER is $50.40/yr
    • The difference between a 15 SEER and 16 SEER is $44.10/yr

So, is a higher SEER air conditioner worth it?

Well, it will depend on two things:

  1. The price difference between the two air conditioners
  2. How long you plan on being in your home

In our example the 16-SEER air conditioner was going to cost close to $1,000 more. If you only plan on being in your home 5 more years, you likely won’t see the payoff ($94.50 x 5 years = $472.50).

But if you plan on living in your home for the full 15 years of the air conditioner’s life, you will see some overall savings ($94.50 x 15 = $1417.50).

And don’t forget: when calculating the difference between the SEERs, a 16-SEER+ air conditioner can qualify for rebates. Check our website for details.

Still not sure? Give us a call at 480-458-7287 and we will be happy to walk you through the equation and help make a decision.

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