Understanding SEER2: Old SEER vs SEER2 (+ Conversion)

Air conditioner energy efficiency ratings are changing. Up till the 31st of December 2022, we using the SEER rating to determine the energy efficiency of air conditioners. From the 1st of January 2023 onward, the SEER rating will be replaced by the SEER2 rating. We are going to look at what SEER2 is and how it impacts the minimum SEER rating in 2023.

Here is what we are dealing with:

  • SEER rating stands for Seasonal Energy Efficiency Ratio. This is the main energy efficiency rating for air conditioners. It tries to most realistically determine how energy-efficient AC units are by dividing cooling BTU/h output by input wattage (BTU/Wh) over the 3 months of summer. Overall, the SEER is a weighted average of an AC running at 25%, 50%, 75%, and 100% output, with a calculated 58% output on average.
  • SEER2 rating stands for Season Energy Efficiency Ratio 2. This is the new main energy efficiency ratio developed in 2016 and introduced by the US Department Of Energy in 2023 and onward. In its essence, SEER2 is the same (equation, calculation) as SEER, but under different test conditions.

The only technical difference between SEER and SEER2 are the harsher test conditions for SEER2 rating measurement pertaining to the external static pressure (we are going to explain this further on).

This difference is small (SEER2 rating is about 4.5% lower than SEER rating) but, in addition to the increase in minimum SEER rating in 2023, is presumed to make a big difference. For a clearer picture of the differences between SEER and SEER2 ratings, you can check this post.

In 2023, we will see two changes that affect the minimum SEER rating:

  1. Increase of minimum SEER rating from 14 SEER to 15 SEER for Southeast and Southwest states.
  2. Replacement of SEER rating by SEER2 rating. Example: 15 SEER unit is now 14.3 SEER unit. This will take some time to get used to in the HVAC community as well.
minimum seer2 and seer rating in 2023
In 2023, we will use a higher minimum SEER rating and a new SEER2 rating for air conditioners and heat pumps.

According to the DOE’s Energy Conservation Program document released in 2016, “the cumulative national net present value (NPV) of total consumer costs and savings for the amended standards for central air conditioners and heat pumps ranges from $2.5 billion (at a 7-percent discount rate) to $12.2 billion (at a 3-percent discount rate).”

This is the presumed economic effect for the 30-year period (from 2023 to 2052) of implementing the SEER2 rating and an increase in the minimum SEER (now SEER2) rating.

We are going to look into what the SEER2 rating is in split-system air conditioners and heat pumps, and what are the minimum SEER ratings in 2023 (state by state for Southeast, Southwest, and the rest of the US):

What Is SEER2 Rating For Air Conditioners And Heat Pumps

Most of us are familiar with the SEER rating. We find it on AC specification sheets and EnergyGuide labels; it is a great metric that enables us to adequately compare the energy efficiency and thereby economic viability of air conditioners and heat pumps.

The goal of every HVAC energy efficiency metric is to most realistically determine real-life energy efficiency and energy expenditure. The first such rating for AC is EER (in 2023, EER is also being replaced by EER) which presumed that an AC would run at 100% cooling output 100% of the time.

We don’t run AC 100% of the time. That’s why, to provide a more realistic metric, DOE introduced Seasonal EER (SEER) in 1987. SEER rating presumes that an AC mostly runs at 50% and 75% output, with a weighted average of 58% output, according to this SEER equation:

how seer vs seer2 rating are calculated

SEER2 rating actually uses the same equation to calculate the energy efficiency; the amount of cooling BTU we get for electricity input (wattage) over a period of 3 summer months (June, July, and August). SEER2 rating presumes, the same as SEER rating, that:

  • We run an AC unit at 100% load for 1% of the time (EER100%).
  • We run an AC unit at 75% load for 42% of the time (EER75%).
  • We run an AC unit at 50% load for 45% of the time (EER50%).
  • We run an AC unit at 25% load for 12% of the time (EER25%).

In short, SEER2 is calculated in the same exact way as SEER. The SEER2 vs SEER difference comes in testing conditions. Namely, we measure how many cooling BTUs we get at 25%, 50%, 75%, and 100% output (these are partial and full power EER ratings). If you change the test conditions, these EER ratings will change and hence the SEER will change, and that’s exactly what the DOE did.

SEER2 rating is measured under harsher test conditions. Specifically, there is a 5-times increase in external static pressure (or pressure at the AC or heat pump vent):

  • SEER rating uses 0.1 inches of water column (in. WC) external pressure test condition.
  • SEER2 rating uses 0.5 inches of water column (in. WC) external pressure test condition. Basically, when measuring the SEER2 rating, the external pressure is 5 times higher external pressure used when measuring the HSPF rating.

Note: According to the Federal Register documents, the DOE also considered 0.3 in. WC pressure for the SEER2 rating.

In short, increasing this pressure aligns the test conditions with realistic conditions better than the up till now used 0.1 in. WC SEER pressure.

The resulting SEER2 rating is thus lower than the SEER rating. This is because the blower motor has to work harder to push the air against 5-times higher external pressure, consuming more watts, and lowering the SEER2 rating.

In addition, the DOE has increased the minimum required SEER rating in 2023, in accordance with the Energy Policy and Conservation Act (EPCA):

Minimum SEER Rating By State (2023)

In 2023, HVAC efficiency standards will increase. Here are the increases, based on the US region (we are also going to look at this state by state):

  • In Southeast states, the minimum SEER rating in 2023 will be increased from 14 SEER to 15 SEER for AC units with below 45,000 BTU cooling output. AC units with 45,000 BTU or higher cooling capacity will have a minimum of 14.5 SEER rating in 2023.
  • In Southwest states, the minimum SEER rating in 2023 will be increased from 14 SEER to 15 SEER. AC units with 45,000 BTU or higher cooling capacity will have a minimum of 14.5 SEER rating in 2023.
  • In the rest of the US, the minimum SEER rating in 2023 will be increased from 13 SEER to 14 SEER for all AC units.

Source: US Energy Information Administration

Here is a minimum SEER rating state-by-state chart for 2023 for below 45,000 BTU AC units (be mindful that this doesn’t yet account for SEER2 rating test conditions, we are going to look at SEER to SEER2 conversion further on):

State: Minimum SEER Rating In 2023:
Alabama 15 SEER
Alaska 14 SEER
Arizona 15 SEER
Arkansas 14 SEER
California 15 SEER
Colorado 14 SEER
Connecticut 14 SEER
Delaware 15 SEER
Florida 15 SEER
Georgia 15 SEER
Hawaii 15 SEER
Idaho 14 SEER
Illinois 14 SEER
Indiana 14 SEER
Iowa 14 SEER
Kansas 14 SEER
Kentucky 15 SEER
Louisiana 15 SEER
Maine 14 SEER
Maryland 15 SEER
Massachusetts 14 SEER
Michigan 14 SEER
Minnesota 14 SEER
Mississippi 15 SEER
Missouri 14 SEER
Montana 14 SEER
Nebraska 14 SEER
Nevada 15 SEER
New Hampshire 14 SEER
New Jersey 14 SEER
New Mexico 15 SEER
New York 14 SEER
North Carolina 15 SEER
North Dakota 14 SEER
Ohio 14 SEER
Oklahoma 15 SEER
Oregan 14 SEER
Pennsylvania 14 SEER
Rhode Island 14 SEER
South Carolina 15 SEER
South Dakota 14 SEER
Tennessee 15 SEER
Texas 15 SEER
Utah 14 SEER
Vermont 14 SEER
Virginia 15 SEER
Washington 15 SEER
West Virginia 14 SEER
Wisconsin 14 SEER
Wyoming 14 SEER

As you can see, the warmer Southeast and Southwest states have a higher minimum required SEER rating (15 SEER vs 14 SEER in the rest of the US). This is a 7% difference; it makes sense for the hot South to have a higher air conditioner energy efficiency because we use AC more in the South than in the North.

Now, we do have to keep in mind that the minimum SEER rating is not the same as the minimum SEER2 rating because SEER is not the same as SEER2.

If you are going to buy a central air conditioner or split-system AC unit (mini split AC or heat pump) that was manufactured in 2023 and onwards, you will likely not see the SEER rating on either the specification sheet or the EnergyGuide label. Instead, the energy efficiency will be expressed as the SEER2 rating.

example of seer rating that is replaced by seer2 rating
Example of SEER rating on AC specs sheet. In 2023, this SEER rating will be replaced by the SEER2 rating.

In order to get a sense of what this SEER2 rating means compared to the SEER rating, it is useful if you convert the SEER2 rating to the SEER rating we are all familiar with.

Converting SEER2 To SEER And SEER To SEER2 Rating

We can figure out the relationship between SEER and SEER2 by comparing two tables, namely:

  • “Table V-30 Amended Energy Conservation Standards for Central Air Conditioners and Heat Pumps as Determined by the November 2016 Test Procedure Final Rule” specifies 2023 HVAC efficiency standards in terms of SEER2 rating.
  • “Table I-1 Amended Energy Conservation Standards for Residential Central Air Conditioners and Heat Pumps Based on the DOE Test Procedure at the Time of the 2015-2016 Negotiations (Recommended TSL)” specifies 2023 HVAC efficiency standards in terms of SEER rating.

From these two tables, we can see that:

  • A 15 SEER rating is now a 14.3 SEER2 rating. SEER2 rating is 4.7% lower than the SEER rating.
  • A 14 SEER rating is now a 13.4 SEER2 rating. SEER2 rating is 4.3% lower than the SEER rating.
  • A 14.5 SEER rating is now a 13.8 SEER2 rating. SEER2 rating is 4.5% lower than the SEER rating.

In short, we can say that the SEER2 rating is roughly 4.5% lower than the SEER rating. Based on this, we can convert SEER to SEER2 rating as well as convert SEER2 to SEER rating. Here are these two conversion charts that will help you understand how the new SEER2 rating relates to the older SEER rating:

SEER To SEER2 Rating

SEER Rating: SEER2 Rating:
12 SEER 11.5 SEER2
13 SEER 12.4 SEER2
14 SEER 13.4 SEER2
15 SEER 14.3 SEER2
16 SEER 15.3 SEER2
17 SEER 16.2 SEER2
18 SEER 17.2 SEER2
19 SEER 18.1 SEER2
20 SEER 19.1 SEER2
21 SEER 20.1 SEER2
22 SEER 21.0 SEER2
23 SEER 22.0 SEER2
24 SEER 22.9 SEER2
25 SEER 23.9 SEER2
26 SEER 24.8 SEER2
27 SEER 25.8 SEER2
28 SEER 26.7 SEER2
29 SEER 27.7 SEER2
30 SEER 28.7 SEER2

Here are some examples of how to think about air conditioner energy efficiency in 2023 and onward:

  • 16 SEER unit is now 15.3 SEER2 unit.
  • 18 SEER unit is now 17.2 SEER2 unit.
  • 20 SEER unit is now 19.1 SEER2 unit.

You can also figure out what the SEER rating is if you see the SEER2 rating of the AC specs sheet using this table:

SEER2 To SEER Rating

SEER2 Rating: SEER Rating:
12 SEER2 12.6 SEER
13 SEER2 13.6 SEER
14 SEER2 14.7 SEER
15 SEER2 15.7 SEER
16 SEER2 16.8 SEER
17 SEER2 17.8 SEER
18 SEER2 18.8 SEER
19 SEER2 19.9 SEER
20 SEER2 20.9 SEER
21 SEER2 22.0 SEER
22 SEER2 23.0 SEER
23 SEER2 24.1 SEER
24 SEER2 25.1 SEER
25 SEER2 26.2 SEER
26 SEER2 27.2 SEER
27 SEER2 28.3 SEER
28 SEER2 29.3 SEER
29 SEER2 30.4 SEER
30 SEER2 31.3 SEER

Here are some examples of how to think about air conditioner energy efficiency in 2023 and onward:

  • 14 SEER2 unit is the old 14.7 SEER unit.
  • 16 SEER2 unit is the old 16.8 SEER unit.
  • 18 SEER2 unit is the old 18.8 SEER unit.

Hopefully, this explains adequately what the new SEER2 rating is and what effect it has on the minimum SEER rating in 2023.

We also have similar changes to these HVAC energy efficiency rating in 2023:

2 thoughts on “Understanding SEER2: Old SEER vs SEER2 (+ Conversion)”

  1. I very much appreciate the clarity and explanation of the article and deciphering the difference of SEER and SEER2. However, the explanation of the static pressure was a little vague.

    Reply

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