What’s The Difference Between SEER and SEER2 Air Conditioner Ratings?

May 9, 2024

In the beginning of 2023, the U.S. Department of Energy (DOE) enacted changes to the primary metric used to describe and compare air conditioner efficiency ratings. Thus began an ongoing transition from the SEER to SEER2 efficiency rating that’s published in AC product literature and spec sheets. In some cases, we currently see both the SEER and the SEER2 rating presented to readers, and in others we may see just one or the other.

In this post, we’ll take a quick look at the background and reasoning behind this revision, as well as the difference between the two types of air conditioner ratings. We’ll also touch base on how the SEER2 rating is embraced in national code for different parts of our country.

family with two daughters opening the front door to come inside.

Lennox condenser corner of house install

Understanding the Traditional SEER Efficiency Rating

The commonly accepted translation of the acronym SEER is “Seasonal Energy Efficiency Ratio.” In brief, the SEER rating represents a numerical calculation that quantifies the BTU cooling output of an air conditioner or a heat pump over the course of an entire, typical cooling season, divided by the electrical energy it uses in Watt-Hours during the season.Energy Star HVAC Products The lower the amount of electricity (watt-hours) that the unit uses, the higher the SEER rating.

What this means for you as a consumer is that the higher the SEER rating, the more efficient the unit and the lower your cooling bills.

What Is the SEER2 Rating?

Lennox Centurion AwardThe new SEER2, or Seasonal Energy Efficiency Ratio 2 rating, is similar to the SEER in many respects – with the noteable exception that the testing standard was revised to incorporate what is known as the new “M1 testing procedure.” The M1 procedure increases static pressure (resistance to airflow) in the forced air test system by a factor of five, a considerable change in the testing conditions. According to the DOE, this update better reflects real life conditions and creates a more accurate measure of the efficiency of an AC unit.

SEER2 Is The More Accurate AC Efficiency Standard

Why would the DOE make this change, especially when there was already a working rating system in place? As mentioned above, the revision is intended to better reflect the actual operating conditions of equipment installed in people’s homes. The DOE concluded that the traditional SEER testing conditions didn’t properly account for the influence of ductwork, as well as commonly used air filters, on static pressure and airflow in a typical system.

The end result is that in the near future we’ll be seeing only SEER2 ratings, which in most cases tend to have slightly lower numbers than the previous standard. National code has already been adjusted to reflect these changes.

Lennox 80+ plus humid. & AC coil case (10)

Comparing SEER and SEER2 Efficiency Ratings

When comparing new air conditioners, it initially seems that all the SEER2 efficiency ratings are slightly lower than their SEER equivalents. This is often the case, but not always. In some instances we have seen testing yield a SEER2 rating slightly higher than the SEER – but this appears to be more of an exception to the pattern we’ve observed. Our team concludes that this result is a function of particular models and manufacturers.

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Do SEER2 Cooling Standards Vary Depending on Where You Live?

For Denver-Boulder metro area homeowners the minimum acceptable SEER2 rating for an air conditioning system differs depending on whether you have a conventional air conditioner (cooling only) or a heat pump (heating and cooling).

We are located in what the DOE defines as the North Region, and in our area a central AC unit must have an efficiency rating of at least 13.4 SEER2 (previously 14 SEER), while a heat pump’s cooling rating must be at least 14.3 SEER2 (previously 15 SEER).

diamond contractor elite logoUnlike AC systems, however, efficiency standards for heat pumps are the same all around the country, which is split into the North, Southeast and Southwestern regions by the DOE. Not surprisingly, the minimum required efficiency for split-system air conditioners in the two southern regions is higher than for cooler Colorado. But enough with the numbers, already!

newly installed condenser in a shaded area

The Impact of SEER2 Air Conditioner Ratings on Our Customers

In all honesty, the impact of the change from SEER to SEER2 air conditioner efficiency ratings on our day-to-day operations and on our customers in the Boulder-Denver area has been relatively minimal. Programs such as Xcel Energy and Lennox rebates, and local code interpretation, have already made adjustments to embrace these changes and our team has been prepared for the new sets of numbers for our customers since they first began entering our realm. The changes have been pretty seamless, other than we often have two sets of similar ratings to explain to our customers.

Not surprisingly, this season we are seeing more equipment with SEER2 numbers than ever before, as inventory levels of equipment tested under the old standard continue to reduce. Of note: While the exact efficiency numbers may have changed – the equipment that we install has not changed one iota to accommodate M1. That translates to peace of mind for our customers.

2024 energy start logoTo learn more about the efficiency ratings of a central or mini-split heat pump or air conditioner that is a good fit for your Denver-Boulder metro area home, please reach out to our friendly team at Save Home Heat Company today to schedule a highly informative, low-pressure, free installation quote.

Please contact me to schedule a cooling system install quote for my home!