SEER2 is the new cooling efficiency rating for air conditioning equipment that took effect January 1, 2023. It replaces the SEER rating.
It is a test procedure update designed to better reflect installed field conditions for air conditioners and heat pumps. The testing is more strict, so the results are more accurate.
The result of SEER2 testing will be lower efficiency ratings than for the previous SEER testing.
Seasonal Energy Efficiency Ratio and SEER2 rating applies to AC units, heat pumps, packaged systems and evaporator coils.
What Does SEER2 Mean?
The acronym stands for Seasonal Energy Efficiency Ratio version 2.
The SEER2 rating addresses how well the equipment uses the electricity to produce cooling of the air.
Higher is Better: A higher SEER rating means that the equipment is more efficient than units with a lower rating.
Did you know? The new DOE minimum efficiency rating system was developed by the US Department of Energy in 2016. But the HVAC industry successfully fought its implementation for several years finally agreeing in 2019 to a start date of January 1, 2023.
What is the Difference Between SEER and SEER2?
The difference is in how strict the testing requirements are.
HVAC technicians use an external pressure testing method to calculate efficiency. The test uses a method called “inches of water in column,” written as “in. WC”. It measures how much the external pressure forces the water in the column to rise.
New: The SEER2 testing uses .5 in. WC external pressure (.5 inches rise in the water column).
Old: The SEER testing used just .1 in. WC external pressure.
As a result, the new SEER2 rating tests using an external pressure that is five times higher than the old method. This is considered a far more accurate means of measuring the efficiency of cooling equipment.
The calculation is the same as it was for SEER, but because the test conditions have changed and become more stringent, results are lower.
What is The Difference Between SEER and SEER2 Calculations?
The difference is about 8.5% in efficiency ratings. Taking air conditioners from several popular brands as an example, here is a SEER vs SEER ratings chart for 7 models.
| SEER Rating | SEER2 Rating |
| 28 SEER | 25.8 to 26.7 SEER2 |
| 22 SEER | 20.2 to 21.1 SEER2 |
| 21 SEER | 19.2 to 20.0 SEER2 |
| 19 SEER | 17.5 to 18.1 SEER2 |
| 17 SEER | 15.6 to 16.2 SEER2 |
| 16 SEER | 14.7 to 15.3 SEER2 |
| 15 SEER | 13.8 to 14.3 SEER2 |
Technically, the difference is close to 4.5% in controlled testing. However, since equipment varies slightly, the overall differences can range as high as 7%.
How is SEER2 Calculated?
It is calculated by the air conditioning output of the unit divided by the total amount of electric energy used during that period.
Specifically SEER2 efficiency is the ratio of BTUs, or British Thermal Units, of heat removed from the spaced compared to the amount of energy used specified in watt-hours required to achieve the cooling.
Each piece of equipment is measured for efficiency while operating at 25%, 50%, 75% and 100% capacity. But cooling systems don’t run at these outputs equally. The figures used for how much each unit runs at each level are:
- 25% capacity 12% of total use
- 50% capacity 45% of total use
- 75% capacity 42% of total use
- 100% capacity 1% of total use
That adds up to 100% of total use, and when the capacities and run times are averaged, the weighted average used for SEER2 calculations is 58%.
The purpose of testing at various output capacities is to simulate how much the unit runs and how hard it works during various times during the entire cooling season. This allows for standardized testing of each piece of equipment.
SEER2 Regional Differences
Along with the change in testing method, the US Department of Energy has implemented new minimum efficiency compliance levels for all cooling equipment. These are sometimes called DOE 2023 rules.
Are SEER2 rules the same for everyone?
No. They are regional. Since climate affects how much an air conditioner is used, the rules are more stringent in the warm and humid South than in the cooler North.
Here are the two regions of the country. The South can be divided into Southeast and Southwest for heating requirements, but the cooling regulations are the same.
North – Highlighted in Blue
All HVAC systems installed in the North Region comply with SEER2 if they meet these efficiency levels:
| SEER2 (New) | SEER (Old) | |
| Central AC & Packaged AC | 13.4 SEER2 | 14.0 SEER |
| Central Heat Pump | 14.3 SEER2 | 15.0 SEER |
For the South Region – everywhere not highlighted above in bright blue as the North Region, the requirements are:
| SEER2 (New) | SEER (Old) | |
| Central AC | 14.3 SEER2 | 15.0 SEER |
| Central Heat Pump | 14.3 SEER2 | 15.0 SEER |
| Packaged AC | 13.4 SEER2 | 14.0 SEER |
Manufacture vs Installation Date Requirements
The HVAC equipment industry has generally used Manufactured Dates for air SEER rating compliance for air conditioners and heat pumps rather than Installed Dates.
In other words, if the national or efficiency ratings were increased, any equipment that did not meet the new standards could be installed as long as it was manufactured before the new ratings took effect. There is a change in the South.
In the South Region, a system Manufactured prior to 2023 that does not meet the new SEER2 standards cannot be installed.
In the North Region, this rule is not in effect. The inventory of equipment produced prior to 2023 that does not meet the new standards can still be installed.
SEER2 Efficiency for Energy Star
Because of the new ratings, the 2023 Energy Star SEER2 criteria has naturally changed too. The efficiency level necessary to become Energy Star rated for split system central air conditioners and for heat pumps is equal or greater than 15.2 SEER2.
Has the Energy Star SEER / SEER2 minimum efficiency level changed over the years?
Yes, quite a lot. Since 1992, in 21 years, it has risen from 10 SEER to 13.4 or 14.3 SEER2 depending on the region. That represents a 34% to 43% increase.
What Does SEER2 Mean for You?
In the South Region of the US, it will mean that the least efficient AC of any kind central AC, heat pump, mini split, packaged unit, etc., will be of a higher efficiency than last year.
A higher price will likely also result, since price is based in part on that rating.
In the North Region, you might have to buy a more efficient unit too, at least when the current inventory of units manufactured before 2023 is gone.
The advantage of air conditioning that is more efficient is energy savings and lower energy costs.
