SEER measures how efficiently an air conditioner or heat pump cools your home over an entire cooling season. The higher the SEER ratio, the less energy the unit needs to deliver the desired cooling. In other words, a higher SEER rating means the system is more efficient at cooling your home.
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SEER vs SEER2
On January 1, 2023, the US Department of Energy (DOE) introduced new energy efficiency standards for newly manufactured HVAC systems under the M1 appendix. This update introduced revised testing procedures to better reflect how systems perform in real-world conditions, including higher external static pressure and adjusted fan power calculations. As part of these updated regulations, the SEER rating was replaced with SEER2.
Previously, SEER energy standards used a lower external static pressure of 0.1 inches of water column, which didn’t fully reflect real-world duct conditions. However, for SEER2, this pressure requirement has been increased to 0.5 inches of water column to match the actual environmental conditions. While both SEER and SEER2 indicate how efficiently an HVAC system cools over a season, SEER2 generally provides a more accurate reflection of real-world performance.
Calculating SEER2 Ratings
To determine this SEER2 rating, air conditioners are tested in a controlled lab environment that simulates real-world summer conditions. The indoor and outdoor temperatures are set just slightly apart, similar to how a home would actually feel during that season. The system’s cooling performance and energy use are measured at several different operating points. These results are then combined to represent the unit’s performance across an entire season, not just a single moment under ideal conditions.
Mathematically, it’s calculated by dividing the total cooling output (in BTUs) by the total electricity consumption (in watt-hours).
SEER2 = Total Cooling Output (BTU) / Total Electrical Energy Input(Watt-hours)
Because of this, SEER2 reflects typical everyday efficiency rather than maximum output. A higher SEER rating means the system can provide the same amount of cooling while using less electricity throughout the season.
What Is a Good SEER2 Rating?
As of 2025, all new residential AC systems in the US must meet the Department of Energy’s regional SEER2 minimum standards, which vary by region to account for local climates and ensure efficiency.
Central Air Conditioners & Heat Pumps
- In the North, all air conditioners must have a minimum SEER of 13.4.
- In the Southeast and Southwest, requirements vary by system size. Air conditioners below 45,000 BTU must have 14.3 SEER2 or higher, while those 45,000 BTU or above must meet 13.8 SEER2 or higher.
- For split-system heat pumps, the nationwide minimum standard is 14.3 SEER2 or higher in all regions.
Ductless Mini-Split Systems
A good SEER2 rating to look for is 16 or higher. Some high-performance models can reach a SEER2 rating of up to 32.2.
Do Higher SEER2 Ratings Affect Energy Use?
Higher SEER2 ratings indicate better cooling efficiency, meaning the system uses less electricity to deliver the same amount of cooling. This leads to lower energy bills and more consistent comfort, especially when paired with a smart thermostat that helps reduce unnecessary runtime.