What is the Difference between Seer and Seer2?

The primary difference between SEER (Seasonal Energy Efficiency Ratio) and SEER2 is the way the systems are tested and rated. While both measure seasonal cooling efficiency, SEER2 is the modern standard introduced by the Department of Energy (DOE) in 2023 to provide a more accurate representation of real-world performance.

Key differences include:

• Testing Conditions: The traditional SEER rating was measured at a low static pressure of 0.1 inches of water column (in. w.c.), which represented ideal laboratory conditions. In contrast, SEER2 uses the M1 testing procedure, which tests at a higher pressure of 0.5 in. w.c. to better simulate the resistance found in typical residential ductwork.
• Accuracy: Because SEER2 accounts for realistic airflow restrictions—such as tight bends in ducts and restrictive filters—it provides a more honest efficiency figure than the older SEER metric.
• Rating Values: Because the SEER2 test is more difficult to pass, the numerical rating is typically lower even if the equipment hasn’t changed. For example, a unit previously labeled as 16 or 17 SEER might be rated as 15 SEER2 under the new testing standards.
• Regulatory Status: SEER governed systems manufactured before 2023, whereas SEER2 is the mandatory standard for all new equipment installed from 2023 onward.

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