If you have been shopping for a new air conditioner or heat pump, you have probably seen numbers such as 16 SEER, 17 SEER2, or 21 SEER2 listed in the product specifications.
But what do those numbers actually mean?
SEER and SEER2 are energy efficiency ratings used to help homeowners understand how efficiently an air conditioner or heat pump can cool their home. In simple terms, the higher the SEER or SEER2 rating, the more efficiently the system can provide cooling.
However, there is a little more to the story, especially now that many newer HVAC systems are rated using SEER2 instead of the traditional SEER rating.
In this guide, you can see the difference between SEER and SEER2, what these ratings tell you about an HVAC system, and what you should consider when choosing a new air conditioner or heat pump.
What Does SEER Mean?
SEER stands for Seasonal Energy Efficiency Ratio.
It measures the cooling efficiency of an air conditioner or heat pump over an entire cooling season rather than measuring efficiency at only one specific outdoor temperature.
Think of SEER a little like the fuel-efficiency rating of a vehicle.
Two cars may both get you to the same destination, but one may use less fuel to get there. Similarly, two air conditioners may both cool your home to the same temperature, but the system with the higher efficiency rating may use less electricity to do it.
In general:
- A higher SEER rating means greater cooling efficiency
- A more efficient system may use less electricity to provide the same amount of cooling
- Higher-efficiency equipment can potentially help reduce cooling-related energy consumption
This is why you will often see SEER prominently displayed when comparing air conditioners and heat pumps.
What Is SEER2?
SEER2 is the newer version of the SEER efficiency rating.
The basic idea is the same: SEER2 measures how efficiently an air conditioner or heat pump provides cooling over a typical cooling season.
The important difference is how the equipment is tested.
SEER2 uses an updated testing procedure designed to better represent the conditions an HVAC system may experience when installed in a real home.
One of the major changes involves testing equipment against greater external static pressure. In simple terms, the new testing method makes the equipment work under conditions that more closely represent the resistance created by real-world ductwork and HVAC installations.
So while SEER and SEER2 both measure seasonal cooling efficiency, SEER2 uses a different and more demanding testing procedure.
SEER vs. SEER2: What Is the Difference?
Here is an easy way to think about it:
SEER = the previous efficiency testing standard
SEER2 = the newer efficiency testing standard using updated testing conditions
Both numbers describe cooling efficiency, but because the testing procedures are different, a SEER rating and SEER2 rating should not automatically be compared number-for-number.
For example, seeing a system rated at a lower SEER2 number than the SEER rating of another system does not necessarily mean that the first system is less efficient. You need to make sure you are comparing equipment using the same rating standard.
When comparing new HVAC systems, it is best to compare:
SEER2 to SEER2
rather than:
SEER to SEER2
This will give you a much more accurate comparison between systems.
Why Was SEER2 Introduced?
HVAC systems do not operate in laboratory perfect conditions once they are installed inside a home.
Your home’s ductwork, airflow, filter, indoor coil, equipment configuration and other factors can all affect how hard the system needs to work.
The updated SEER2 testing procedure was developed to better represent some of these real-world operating conditions.
This makes SEER2 a useful measurement when comparing the efficiency of newer air conditioners and heat pumps.
For homeowners, the important takeaway is simple:
SEER2 is not an entirely different type of efficiency it is an updated way of measuring seasonal cooling efficiency.
Is a Higher SEER2 Rating Better?
From an energy efficiency perspective, yes.
A higher SEER2 rating generally means the system can provide more cooling for the electricity it consumes.
For example, when comparing two properly sized and properly installed systems under similar conditions, a higher SEER2 system will generally be more energy efficient.
However, the highest SEER2 rating is not automatically the best choice for every home.
There are several other factors to consider, including:
- The size of your home
- Your home’s insulation
- The condition and design of your ductwork
- Your cooling needs
- How frequently you use air conditioning
- The type of HVAC system
- Equipment features and technology
- Your budget
- Installation quality
The goal should be to choose an HVAC system that provides the right balance of efficiency, comfort, performance and cost for your home.
Does a Higher SEER2 Rating Mean Lower Electricity Bills?
Potentially, but SEER2 should not be viewed as a guarantee of a specific utility bill.
A more efficient air conditioner or heat pump generally requires less electricity to provide the same amount of cooling than a less-efficient system under comparable conditions.
However, your actual energy use depends on many factors.
For example, your electricity consumption can be affected by:
- Outdoor temperatures
- Thermostat settings
- Hours of operation
- Home insulation and air sealing
- Window size and orientation
- Duct leakage
- Equipment sizing
- HVAC maintenance
- Indoor airflow
This is why choosing efficient equipment is only one part of creating an energy-efficient home.
Installation Matters Just as Much as the Rating
A high SEER2 number looks impressive on a specification sheet, but an HVAC system can only perform properly when it is correctly selected and installed.
An improperly sized system, poor airflow or problems with the ductwork can reduce comfort and affect system performance regardless of the equipment’s efficiency rating.
Proper HVAC installation should take into consideration factors such as the home’s size, layout, insulation, windows and overall heating and cooling requirements.
This is also why simply replacing an old air conditioner with another unit of the same tonnage is not always the best approach.
A professional HVAC assessment can help determine which system is appropriate for your particular home.
Where Will I See the SEER2 Rating?
When researching a new air conditioner or heat pump, you may find the SEER2 rating in several places, including:
- Manufacturer product pages
- Product specifications
- HVAC brochures
- Equipment documentation
- Efficiency certification information
- Quotes provided by HVAC contractors
You may also see wording such as “up to 18 SEER2” or “up to 21 SEER2.”
The words “up to” are important.
An outdoor unit may be capable of achieving a certain maximum SEER2 rating only when paired with specific compatible indoor equipment and components.
In other words, the efficiency of your HVAC system is based on the complete matched system, not simply the outdoor air conditioner or heat pump by itself.
When comparing quotes, ask your HVAC contractor about the efficiency rating of the actual equipment combination being proposed for your home.
What About HSPF2 and EER2?
When researching heat pumps and air conditioners, you may also come across terms such as EER2 and HSPF2.
They measure different aspects of HVAC efficiency.
EER2
EER2 measures cooling efficiency under specific operating conditions.
While SEER2 represents efficiency across an entire cooling season, EER2 provides another way of evaluating cooling performance.
HSPF2
HSPF2 stands for Heating Seasonal Performance Factor 2.
It is particularly important when evaluating a heat pump because it measures the system’s seasonal heating efficiency.
A heat pump provides both heating and cooling, so SEER2 tells only part of the story.
When comparing heat pumps, homeowners should consider several specifications together, including:
- SEER2 for cooling efficiency
- HSPF2 for heating efficiency
- Heating capacity
- Cold climate performance
- Equipment features
- Sound levels
For homeowners in Ontario, heating performance can be especially important because our HVAC systems operate through long and sometimes very cold winters.
What Is a Good SEER2 Rating?
There is no single SEER2 number that is perfect for every homeowner.
Today’s HVAC market includes everything from dependable standard-efficiency equipment to advanced variable-capacity systems with very high efficiency ratings.
Rather than focusing only on finding the highest number available, consider what you are trying to accomplish.
If your priority is reducing upfront cost, a reliable standard-efficiency system may make sense.
If you plan to stay in your home for many years and prioritize energy efficiency, quieter operation and advanced comfort features, a higher efficiency system may be worth considering.
The best HVAC system is ultimately the one that is properly sized, professionally installed and suited to your home’s needs.
The Bottom Line: SEER and SEER2 Made Simple
If you remember only a few things about SEER and SEER2, remember these:
- SEER measures seasonal cooling efficiency.
- SEER2 is the newer version of the efficiency measurement using updated testing conditions.
- Higher ratings generally indicate greater cooling efficiency.
- SEER and SEER2 should not be compared directly as if they are the same rating scale.
- SEER2 is only one factor to consider when choosing an HVAC system.
- Proper system sizing and installation are essential for efficiency and comfort.
Understanding these numbers makes it much easier to compare air conditioners and heat pumps and make an informed decision for your home.
Need Help Choosing an Energy-Efficient HVAC System?
At VMP HOME, we help homeowners find heating and cooling solutions that fit their home, comfort needs and budget.
As a Lennox Premier Dealer, our team can help you compare air conditioners and heat pumps, understand SEER2 and other efficiency ratings, and choose a properly sized system for your home.
Whether you are replacing an older air conditioner, considering a new heat pump or simply trying to understand your options, our team is here to help.
Contact VMP HOME
VMP HOME Inc.
📍 785 Westney Rd S #28, Ajax, ON L1S 7G1
📞 +1 (416) 551-2008
✉️ [email protected]
🌐 www.vmphome.com
Contact VMP HOME today to request a free estimate and learn more about energy efficient air conditioners and heat pumps for your home.