Seasonal energy efficiency ratio (SEER) is a metric that measures the cooling efficiency of HVAC systems. It represents the cooling or heating output of air conditioners, heat pumps and similar devices. A SEER-compliant air conditioner is designed to operate more efficiently, providing cost savings and improved comfort for a home’s occupants.

The SEER rating was introduced as a testing and rating standard in 1979, requiring manufacturers to disclose their systems’ energy efficiency ratings. Over the years, the minimum requirements for HVAC systems have been updated periodically. These adjustments were used by regulating bodies to encourage manufacturers to produce more energy-efficient products.

Beginning in January of 2023, the Department of Energy (DOE) has taken steps to change how HVAC systems should be tested. The agency has established new M1 testing procedures that demand better efficiency ratings. This new cooling efficiency rating is known as SEER2. The goal behind these changes is to pave the way for more sustainability.

Below, we’ll cover the details of the new SEER rating and compare it to the former. The discussion will also answer the question: “What is SEER,” and how will the new SEER interactive ratings impact AC suppliers, manufacturers and homeowners?

What is SEER?

As mentioned earlier, according to the standard SEER definition, this metric measures the efficiency of cooling and heating equipment. Your AC is considered more energy efficient when it has a higher SEER rating. 

However, unlike other efficiency ratings, such as the Energy Efficiency Ratio (EER), SEER measures the efficiency of a system throughout an entire cooling season. The average energy efficiency is measured across varying outdoor temperatures, humidity levels and indoor temperatures, simulating the run of a whole season.

How is SEER Calculated?

In the computation of the efficiency ratio of AC units, the total cooling output of a system is divided by the total energy it consumes throughout a cooling season. Manufacturers conduct standardized tests under controlled conditions in a laboratory to measure these outputs based on the standard SEER definition. During these tests, usual operating conditions are simulated that mimic conditions experienced during a typical cooling season.

The cooling output of an AC unit is calculated by measuring the amount of heat removed from indoor air. This is determined by measuring various temperature differentials and typical airflow rates.

At the same time, manufacturers monitor the electrical input to an AC system to measure its total energy consumption. Auxiliary components, fan power, compressor power and other factors are also considered.

After all tests and measurements are complete, the figures for the total energy consumption and cooling output are used to calculate the SEER rating of an appliance.

Limitations of SEER as a Ratings Standard

Even though the SEER interactive rating system is beneficial for evaluating the energy efficiency of an HVAC system, it also has several limitations:

  • Climate Dependency: The test conditions used in this rating system are climate dependent, which may not represent the actual efficiency of an AC in different climate conditions.
  • Limited Comparison Across System Types: SEER ratings are best suited for comparing systems of the same type. Compared to central air conditioning systems, you can’t use them to compare the efficiency of various systems, such as ductless mini-split systems.
  • Non-Energy Related Factors: This rating system focuses solely on energy efficiency but ignores other significant factors that may impact an AC system’s performance. System reliability, noise levels and indoor air quality aren’t used as factors, even though they contribute to the overall efficiency of a unit.
  • Single Point Measurement: This rating system measures a specific humidity level and outdoor temperature. You can’t determine an AC system’s performance measurements under different operating conditions. As such, a higher SEER rating can’t tell you the optimal efficiency of your system in all scenarios.

Raising the Bar with SEER2

The new efficiency rating system, SEER2, was developed in 2016. However, the companies in the HVAC industry were able to delay its implementation. It was only in 2019 that these manufacturers agreed to begin compliance with SEER2 on January 1, 2023. It can better determine how well an HVAC can use electricity and efficiently cool the air in a room.

External Pressure Testing

One way to determine a unit’s efficiency is via external pressure testing, which is measured in inches of water in a column (in. WC). It measures the external pressure force to make the water rise inside a column.

Under SEER, the required external pressure is only 0.1 in. WC, while under SEER2, the tests use 0.5 in. WC. In effect, the new rating standards use tests that require five times the external pressure than the old system. Experts see this as a more accurate measurement of an equipment’s efficiency.

A Drop in Efficiency Ratings

It is important to note that SEER2 also uses the same calculations as the old SEER. However, the test conditions for SEER2 are more stringent, which will cause a drop in the efficiency ratings for all equipment previously tested.

Experts estimate that all previously built and designed HVAC systems will have an 8.5% variance in their ratings under the new efficiency standard. Under a controlled testing environment, it’s been observed that AC units would experience a 4.5% drop in their ratings under the new 2023 standard. However, since AC equipment is built differently, some models may experience a 7% drop in the ratings instead.

Some models that previously had a 15 SEER rating can now have 13.8 to 14.3 under SEER2. Those with 28 SEER ratings can get a drop of 25.8 to 26.7 rating.

Factoring Variances in Output Capacity

Another advantage of the SEER2 over the old SEER rating system is that it accounts for how hard an AC unit works at various cooling season stages. Some months will be warmer than others during an entire season, impacting the performance and efficiency of an AC system.

AC units will be tested at varying operating capacities: 20, 50, 75 and 100 percent. The usage will be adjusted depending on the capacity level of each unit, as follows:

  • 1% total usage at 100% capacity.
  • 42% total usage at 75% capacity.
  • 45% total usage at 50% capacity.
  • 25% total usage at 25% capacity.

Accounting for Regional Climate Differences

Apart from implementing changes in the testing and computation methods, the DOE also implemented different compliance levels based on the region where one is located. Some regions experience colder climates, while others have warmer weather.

In addition, the compliance levels will vary depending on the unit type. For example, central and packaged HVAC systems installed in the northern regions of the U.S. will be required to meet 13.4 SEER2 testing standards, while central ACs installed in the South are required to meet a 14.3 SEER2 rating. The higher requirement for southern regions accounts for those states’ hotter and more humid weather conditions.

Installation Date vs. Manufacturing Date

In the past, HVAC equipment used manufacturing dates to determine compliance with SEER ratings. This means technicians can still install subpar AC units as long as equipment pieces were manufactured before new ratings took effect.

However, under SEER2, any HVAC system manufactured before 2023 that doesn’t meet the new rating standards may only be installed once modified to meet current standards. This rule applies to states in the southern regions but not to the states in the northern regions. In the northern states, compliance will be based on the manufacturing date, while in the southern states, compliance is based on the installation date.

The Impact of SEER2

The impact of SEER2 will be more significant for people living in the South than in the North. The minimum will increase by 1 SEER for all regions in the U.S. AC units installed starting in January 2023 will be more energy efficient and perform better. However, these stricter regulations also mean the prices of newer AC units will become more expensive since manufacturers will have to upgrade their products to meet these new standards.

Trust SEER2 Compliance Experts

Homeowners must ensure that their HVAC systems remain in tip-top shape and comply with current ratings and standards. At HomeFront Heating and Air, we provide reliable and efficient repair and maintenance services to ensure your comfort. Contact us today, and our specialists will gladly answer your questions.

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