Your Guide To Energy Efficiency Ratio 2 (EER2)
Carrier defines Energy Efficiency Ratio (EER) as a metric that measures an air conditioner's cooling output in British Thermal Units (BTUs) per hour divided by its power consumption in watts. A higher EER indicates that an air conditioner can provide more cooling for the same amount of electrical energy.
The Energy Efficiency Ratio 2 (EER2) uses the same basic calculation but is based on an updated test procedure designed to better reflect conditions experienced by HVAC systems in the field. The updated procedure uses higher external static pressure, which can result in lower ratings than the original EER test.
Carrier explains that EER2 measures the efficiency of an air conditioner at a specific set of test conditions rather than across an entire cooling season. EER2 is calculated similarly to traditional EER, but under the updated M1 testing procedure, which uses higher external static pressure.
Understanding this rating can help homeowners compare the energy efficiency of different air conditioning systems.
Ashley Davis, owner of Lawson Air Conditioning and Plumbing in Gainesville, Georgia, explains that the EER2 rating can help homeowners better understand how an HVAC system performs during peak operating conditions, when efficiency matters most.
“The EER2 really gives you a sense of how your HVAC system works under extreme conditions,” Davis said. “It provides a clearer picture of efficiency and operating cost when the system is running at its most demanding times.”
She added that this metric is especially useful for evaluating real-world performance during periods of high cooling demand.
“You want to understand what the system is doing in the peak of summer,” she said, noting that it helps homeowners make more informed decisions about long-term energy use and operating costs.
How do you calculate the Energy Efficiency Ratio (EER2)?
EER2 is calculated by dividing the cooling capacity of an air conditioner in British Thermal Units (BTUs) per hour by the power consumption in watts.
EER = Cooling Capacity (BTUs/hour) ÷ Power Consumption (watts)
For example, an air conditioner producing 36,000 BTUs/hour while using 3,000 watts would have an EER of 12.
EER2 uses the same basic ratio, but the rating is determined using the updated DOE/AHRI test procedure. The M1 procedure uses 0.5 inches of water column (in. w.c.) of external static pressure, compared with lower static-pressure conditions used in the previous testing procedure.
Because EER2 uses a different test method than EER, EER2 values can be lower than EER values for the same equipment. The higher the EER2 rating, the more efficient the air conditioner is under the specified EER2 test conditions.
Carrier notes that EER2 can also be relevant when evaluating available rebates: rebates generally start at EER2 ratings of 11.7 or higher for heat pumps and 12 or higher for air conditioners, although specific eligibility requirements vary by rebate program and location.
EER vs. EER2 vs. SEER2
Carrier recommends looking at EER2 alongside SEER2 because the two ratings describe different aspects of cooling efficiency. EER2 is a point-in-time efficiency rating, while SEER2 evaluates efficiency over a simulated cooling season.
| Rating | What it measures | How it is calculated | Primary use |
|---|---|---|---|
| EER | Cooling efficiency under the original test procedure | Cooling output ÷ electrical input | Comparing equipment tested under the older rating procedure |
| EER2 | Cooling efficiency under the updated test procedure | Cooling output ÷ electrical input | Evaluating efficiency under specified peak cooling test conditions |
| SEER2 | Seasonal cooling efficiency | Seasonal cooling output ÷ seasonal energy input | Comparing expected efficiency over a cooling season |
EER2 and SEER2 use the updated M1 testing procedure, which includes higher external static pressure than the previous procedure.
What are the benefits of a high Energy Efficiency Ratio (EER2)?
A high EER2 rating means your HVAC system uses less electricity to cool your home, which can help lower energy bills and reduce your environmental footprint. Opting for a system with a high energy efficiency ratio offers several visionary advantages:
- Lower energy consumption and cost savings: A high EER2 means that your cooling system can provide the same level of cooling with less energy usage. This can help translate to lower energy bills and cost savings over time. With Carrier's range of energy-efficient air conditioners, you can stay comfortable without breaking the bank.
- Reduced environmental impact: Using less electricity for cooling can reduce the amount of energy required to operate your system and may help reduce associated greenhouse gas emissions, depending on how your electricity is generated. Carrier offers air conditioners designed to provide different levels of energy efficiency.
- Improved cooling performance and comfort: EER2 itself measures efficiency, not comfort. However, when evaluating an air conditioner, homeowners can consider EER2 alongside factors such as system capacity, controls, sound levels and humidity management to choose equipment that meets their comfort needs.
What factors affect the EER2 of your HVAC system?
EER2 is primarily a rated characteristic of a specific HVAC equipment combination under standardized test conditions. Actual operating efficiency can also be affected by factors such as equipment sizing, installation, airflow, ductwork, outdoor conditions and maintenance.
- Equipment Size and Capacity: Choosing the right size and capacity of your HVAC system is crucial for achieving optimal energy efficiency. Undersized systems may struggle to cool your home efficiently, while oversized systems can result in short-cycling and energy wastage. Consult with your local Carrier dealer to determine what size air conditioner you need.
- Insulation and Sealing: Proper insulation and sealing play a vital role in maintaining energy efficiency. Well-insulated homes retain conditioned air, reducing the workload on your HVAC system. Additionally, sealing air leaks in windows, doors, and ductwork prevents energy loss, allowing your smart system to operate more seamlessly.
- Maintenance and Regular Servicing: Regular HVAC maintenance and servicing are essential for preserving your HVAC system's energy efficiency. Dirty air filters, clogged coils, and worn-out components can hinder your system's performance and increase energy consumption. Schedule annual AC maintenance and address any issues promptly to keep your reliable system operating optimally.
How can you improve your air conditioner's Energy Efficiency Ratio (EER)?
You cannot change an air conditioner's rated EER2 after it has been tested, but you can improve the system's operating efficiency by selecting efficient equipment, ensuring proper installation and maintaining the system.
- Upgrading to a higher efficiency air conditioner: Consider replacing your outdated unit with an energy efficient air conditioner that features a higher EER rating. When comparing current systems, use EER2 rather than comparing an older EER rating directly with a newer EER2 rating because the test procedures are different.
- Proper installation and sizing: Ensure that your air conditioner is installed correctly and sized appropriately for your home. Improper AC installation or an oversized unit can lead to energy wastage and reduced efficiency. Learn more about air conditioner sizing.
- Tips for optimizing energy efficiency: Implement these simple practices to maximize your air conditioner's energy efficiency: Regularly clean or replace air filters to improve airflow and breathe cleaner air. Keep doors and windows closed to prevent cool air from escaping. Use ceiling fans to enhance air circulation and reduce the workload on your air conditioner. Set your thermostat to a higher temperature when you're away to conserve energy (smart home integrations make this effortless). Seal any air leaks in your home to prevent cool air from seeping out.
How do you choose the right Carrier product based on EER2?
To choose a Carrier AC unit based on EER2, consider the system's rated efficiency alongside your local climate, cooling needs, installation requirements and upfront cost. Carrier currently offers air conditioners with EER2 ratings as high as 12 in the 26VNA1 Infinity® 21 Air Conditioner. Ratings vary by model and system combination.
- Climate: EER2 measures efficiency under specific test conditions, so it can provide useful information when comparing how systems perform under peak cooling conditions. Homeowners in hot climates may also want to consider SEER2 and other system characteristics when evaluating expected seasonal performance.
- Energy Savings vs. Upfront Cost: While initial costs might be higher, a higher EER2 rating indicates greater efficiency under the EER2 test conditions. Actual energy savings depend on factors such as system size, runtime, climate, electricity rates and installation.
- Size and Cooling Needs: Ensure the unit is properly sized for your home. An oversized or undersized unit can lead to inefficiencies despite having a high EER2 rating.
- EER2 Rating: Carrier's Infinity® 21 Air Conditioner (26VNA1) has an EER2 rating of up to 12, along with a SEER2 rating of up to 21.
Work With A Carrier Dealer To Select a High EER2 AC For Your Home
Carrier offers high-EER2 models, specifically the Infinity® Series, which provide optimal efficiency, smart integration, and quiet comfort.. Schedule an appointment with your local Carrier professional for HVAC installation to determine the right HVAC system for your home.
Frequently Asked Questions
SEER2 (Seasonal Energy Efficiency Ratio) measures an air conditioner's efficiency over an entire cooling season with varying temperatures. In contrast, EER2 measures efficiency under a strict, constant peak temperature of 95°F.
Yes, investing in a high-EER2 system is highly recommended for long-term comfort. While the initial investment may be higher, the advanced technology significantly lowers monthly energy bills, meaning the efficiency often pays for itself over the lifespan of the unit.
A good EER2 value depends on the type of split system the homeowner has, with higher ratings indicating superior energy efficiency. Rebates generally start with EER2 greater than or equal to 11.7 for heat pumps and 12 for air conditioners.
To calculate the Energy Efficiency Ratio (EER), divide the cooling capacity of the air conditioning system (in British Thermal Units or BTUs) by its power consumption (in watts). The formula is: EER = Power Consumption (Watts) / Cooling Capacity (BTUs).
The Energy Efficiency Ratio (EER) is important because it measures the efficiency of an air conditioning or heat pump system in converting electrical energy into cooling power. Higher EER values indicate more efficient units, which can help lead to lower energy consumption and reduced heating and cooling bills.
EER (Energy Efficiency Ratio) measures the efficiency of an air conditioning unit by comparing its cooling output (BTUs) to its energy consumption (watts). A higher EER indicates better efficiency, meaning the system uses less energy to cool a space, helping lower energy bills and reduce environmental impact.
About The Author: Travis Baugh is a Digital Brand Marketing Manager for Carrier, where he develops informative, straightforward content to help homeowners better understand heating, cooling, and indoor air quality. His writing is focused on empowering homeowners to make confident, well-informed choices about their home comfort systems.
About The Expert Reviewer: Michelle Notaro is a Product Manager for Residential Air Conditioners at Carrier Corporation, where she helps shape innovative cooling solutions that meet evolving homeowner needs, industry trends, and regulatory requirements.