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SEER2

SEER2 is the updated efficiency testing standard for air conditioners and heat pumps that took effect on January 1, 2023. Mandated by the U.S. Department of Energy, SEER2 uses a revised testing procedure (M1) that adds external static pressure to simulate real-world installation conditions with connected ductwork. Because this added resistance makes the test more realistic but more demanding, SEER2 values are approximately 4.7% lower than the old SEER values for the same equipment. For example, a unit previously rated at 15 SEER would test at roughly 14.3 SEER2. All new residential HVAC equipment manufactured after January 2023 is rated and labeled using SEER2.

💡 Key Takeaways

  • ✓SEER2 is the updated efficiency testing standard for air conditioners and heat pumps that took effect on January 1, 2023. Mandated by the U.S. Department of Energy, SEER2 uses a revised testing procedure (M1) that adds external static pressure to simulate real-world installation conditions with connected ductwork. Because this added resistance makes the test more realistic but more demanding, SEER2 values are approximately 4.7% lower than the old SEER values for the same equipment. For example, a unit previously rated at 15 SEER would test at roughly 14.3 SEER2. All new residential HVAC equipment manufactured after January 2023 is rated and labeled using SEER2.
  • ✓SEER2 numbers are about 4.7% lower than old SEER numbers for the same equipment, the equipment did not get less efficient, the test got harder.
  • ✓Federal minimum efficiency requirements were updated to SEER2 values. In the Southwest, the minimum is approximately 14.3 SEER2 for split systems.
  • ✓All new residential AC equipment manufactured after January 1, 2023 is rated using SEER2.

SEER2

/sɪər tuː/

Definition

SEER2 is the updated efficiency testing standard for air conditioners and heat pumps that took effect on January 1, 2023. Mandated by the U.S. Department of Energy, SEER2 uses a revised testing procedure (M1) that adds external static pressure to simulate real-world installation conditions with connected ductwork. Because this added resistance makes the test more realistic but more demanding, SEER2 values are approximately 4.7% lower than the old SEER values for the same equipment. For example, a unit previously rated at 15 SEER would test at roughly 14.3 SEER2. All new residential HVAC equipment manufactured after January 2023 is rated and labeled using SEER2.

What is the difference between SEER and SEER2?

SEER2 uses updated testing that simulates real ductwork resistance, producing numbers about 4.7% lower than old SEER. It is more accurate to real-world performance but represents the same equipment efficiency.

Source: The Cooling Company

SEER2 efficiency rating badge

Quick Facts

January 1, 2023Effective date
Added static pressure in testKey change
~4.7% lowerNumbers vs SEER
~14.3 SEER2 (split)Southwest minimum

How SEER2 Works

Infographic comparing SEER and SEER2 testing methodology differences

SEER2 testing adds duct resistance for more realistic efficiency numbers.

Real-World Application

When shopping for a new AC in Las Vegas, you will see SEER2 ratings on all current equipment. The numbers look lower than the old SEER you may be used to, but this does not mean the equipment is less efficient, the test is just more rigorous. A 15.2 SEER2 system performs comparably to what was previously labeled 16 SEER.

Pro Tip

When comparing a new system's SEER2 rating to your old system's SEER rating, multiply the SEER2 number by 1.047 to get the approximate old SEER equivalent. This helps you accurately compare efficiency improvements.

“When comparing a new system's SEER2 rating to your old system's SEER rating, multiply the SEER2 number by 1.047 to get the approximate old SEER equivalent. This helps you accurately compare efficiency improvements.”

TCC HVAC Team (Licensed • EPA-Certified)
The Cooling Company • 2026-09-26T22:07:43.711Z

Important Things to Keep in Mind

  1. SEER2 numbers are about 4.7% lower than old SEER numbers for the same equipment, the equipment did not get less efficient, the test got harder.
  2. Federal minimum efficiency requirements were updated to SEER2 values. In the Southwest, the minimum is approximately 14.3 SEER2 for split systems.
  3. All new residential AC equipment manufactured after January 1, 2023 is rated using SEER2.

Did You Know?

The switch to SEER2 was driven by research showing that the original SEER test (with zero external static pressure) overstated real-world efficiency by not accounting for the resistance of actual ductwork installations.

FAQ

Is SEER2 better than SEER?

SEER2 is not better or worse, it is a more accurate testing method. The equipment is the same; the test now reflects real-world conditions with ductwork resistance.

Do I need to replace my old SEER-rated system?

No. SEER2 applies only to new equipment. Your existing system continues operating exactly as it always has.

How do I convert SEER to SEER2?

Divide the old SEER number by 1.047 to get the approximate SEER2 equivalent. For example, 16 SEER is approximately 15.3 SEER2.

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