SEER stands for Seasonal Energy Efficiency Ratio. SEER2 is an updated version of the previous SEER rating system for air conditioners and heat pumps. The Department of Energy (DOE) mandated that the changes go into effect on January 1, 2023.
SEER2 measures air conditioner and heat pump cooling efficiency. It’s the ratio of total heat removed during the cooling season divided by the total electric energy used by the cooling unit during the same time frame.
By Anne Fonda
When it comes to SEER vs SEER2, SEER2 is a higher efficiency standard. The new SEER2 metric utilizes a new M1 blower testing procedure. The updated testing procedure more accurately reflects real-world conditions for HVAC systems by changing the static pressure used in the testing lab from 0.1” w.g to 0.5” w.g. by up to 5 times. New testing procedures change the minimum energy efficiency required for cooling and heating systems.
EER2 is another measure of an air conditioner or heat pump’s cooling efficiency. The two metrics use different temperature conditions.
If you live in a hot and dry climate such as the desert Southwest, or a hot and humid climate like parts of the Southeast, a unit’s EER2 rating might be more important to you than the SEER2 rating.
Learn more about HVAC system efficiency metrics.
That depends on where you live and your climate. A higher SEER2 rating means greater energy efficiency. And since an AC unit or heat pump also dehumidifies while it cools, a more efficient unit also means greater comfort.
The minimum standard SEER2 requirements for air conditioners vary by region in the United States. In the North, all types of air conditioners must have a rating of 13.4 or higher.
In the Southeast and Southwest, SEER2 ratings depend on the type of air conditioner and capacity. Split system air conditioners throughout the Southeast and Southwest must have a SEER2 rating of 14.3 or higher if they have a capacity less than 45k BTU, and 13.8 or higher if they have a capacity greater than or equal to 45k BTU.
Split system heat pumps must have a SEER2 of 14.3 or higher in all regions.
Your actual HVAC system cooling efficiency will also depend on the size of your home, your current ductwork, and other variables.
Single-packaged air conditioners and heat pumps in all regions must have a SEER2 of 13.4 or higher. Again, the higher the rating, the more efficient the unit is. Talk with your Trane dealer about the best rating for your home and your comfort.
Ductless mini-split systems typically have a higher cooling efficiency rating than traditional split systems due to advanced technology designed to maximize efficiency. Look for a rating of at least 16. Some Trane single-zone mini-split heat pumps have a SEER2 rating of up to 33.1.
If a mini-split is a 1 to 1 matchup (meaning 1 outdoor unit with 1 indoor unit) then it follows the same minimums as the normal residential split system: Which is 14.3 for South and Southwest AC units and all nationwide heat pumps. And 13.4 for AC units in the North.
It’s tough to give a quick answer because a good cooling efficiency rating depends on several factors unique to each home including location, size, the length of the typical cooling season, and what you’re looking for in a heating and cooling system. Since ratings vary, it’s important to talk to your local Trane dealer and discuss what efficiency ratings you need to get the comfort and energy savings you want.
A higher SEER2 rating will mean a higher level of comfort and long-term savings on your energy bills, especially if you use a smart thermostat to maximize efficient energy usage.
In truth, the upfront cost of the unit will likely be higher. High-efficiency AC units and heat pumps tend to come with features like variable-speed cooling, which means the unit will stay on longer at lower speeds instead of starting and stopping.
If you live somewhere with high humidity, or if some rooms in your house are cold while others are hot, a higher SEER2 unit with this feature will make you much more comfortable.
If you live in a mild climate where humidity isn’t an issue, you may consider a lower SEER2 unit a better option as it will save you money at the time of installation. Visit our Pricing Guide for an idea of the cost difference or contact your local Trane dealer directly. The number in a model name for air conditioners and heat pumps references the SEER2 rating.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Kimberly Sexton, Senior Systems Engineer
Energy Efficiency Ratio (EER2) measures the energy efficiency of your air conditioner or heat pump as it cools at the outdoor temperature of 95°F. The higher the EER2, the more efficient the system.
HSPF2, or Heating Seasonal Performance Factor, measures a heat pump’s overall energy efficiency throughout the entire heating season (fall and winter). The higher the HSPF2 rating, the more efficient the heat pump.
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