By Anne Fonda
EER stands for energy efficiency ratio. It’s a rating the United States Department of Energy (DOE) requires that measures the energy efficiency of an air conditioner or heat pump at the outdoor cooling temperature of 95°F.
EER2 is an updated version of EER that all cooling systems put into use starting on January. 1, 2023. A new testing procedure is used that is more accurate than previously.
The higher the number, the more energy efficient the cooling unit is. An energy-efficient AC or heat pump can save you money on your utility bills and leave a smaller carbon footprint in the process.
EER2 ratings are always calculated with the unit working at an outdoor temperature of 95°F, an indoor temperature of 80°F, and at 50% humidity.
EER2 and SEER2 both evaluate an air conditioner’s energy efficiency, but they’re concerned with two different types of temperature conditions:
Think about SEER2 as being an average of cooling efficiency, while EER2 is one specific data point. Trane’s product descriptions may both ratings. For new units, you should be able to find the efficiency information on the yellow Energy Guide card.
The following table from the DOE shows the regional standards for both EER2 and SEER2.
| North | Southeast | Southwest | ||
| Units with cooling capacity less than 45,000 Btu/hr | Seasonal energy efficiency ratio 2 (SEER2) | 13.4 | 14.3 | 14.3 |
| Energy efficiency ratio 2 (EER2) | 11.7/9.8* | |||
| Units with cooling capacity equal to or greater than 45,000 Btu/hr | Seasonal energy efficiency ratio 2 (SEER2) | 13.4 | 13.8 | 13.8 |
| Energy efficiency ratio 2 (EER2) | 11.2/9.8** | |||
| Single-package units – air conditioners | Energy efficiency ratio 2 (EER2) | 10.6 |
* The 11.7 EER2 standard applies to products with a certified SEER2 less than 15.2. The 9.8 EER2 standard applies to products with a certified SEER2 greater than or equal to 15.2.
** The 11.2 EER2 standard applies to products with a certified SEER2 less than 15.2. The 9.8 EER2 standard applies to products with a certified SEER2 greater than or equal to 15.2.
Yes. ENERGY STAR® has specific energy rating minimums for HVAC equipment to be listed as ENERGY STAR®-certified or qualified. Outdoor units must also be paired with compatible indoor coils to earn the designation.
| Heat Pump Equipment (HP) | ≥ 7.8 HSPF2/ ≥15.2 SEER2/ ≥11 EER2 for split systems ≥ 7.2 HSPF2 ≥15.2 SEER2/ ≥10 EER2 for single package equipment including gas/electric package units. |
| Central Air Conditioners (CAC) | ≥15.2 SEER2/ ≥12.0 EER2 for split systems ≥15.2 SEER2/ ≥11.5 EER2 for single package equipment including gas/electric package units. |
While understanding EER2 is important for all AC unit or heat pump owners to get the full picture of their unit’s efficiency, it’s especially important if you live in the Southern United States where high, humid or dry temperatures are the norm.
EER2 ratings are typically more important for those living in the Southern U.S. because this HVAC efficiency metric is calculated by using one temperature — 95°F. In the South, it’s standard for summer days to reach and exceed this high temperature, so a unit’s EER2 rating will help indicate how well a cooling system will hold up during hot days.
If a unit has a high SEER2, but a low EER2, it means it’s very efficient in mild and cool conditions but may have poor efficiency when it’s really hot. This is very important for homeowners who live in extreme temperatures to understand, so you can get a unit that maximizes comfort.
A highly energy-efficient air conditioner or heat pump could save you money on your utility bills and help the environment in the process. If you’re looking to purchase or upgrade your HVAC system, a Trane Comfort Specialist™ can help.
Anne Fonda, Content Writer at Trane Technologies
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: Mark Woodruff, Sr. Product Manager – Ducted Outdoor Products
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.
Seasonal Energy Efficiency Rating (SEER) measures the efficiency of the cooling process in air conditioners and heat pumps. The higher the SEER, the more energy efficient the system.
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