SEER2 Explained

SEER2 is the current U.S. seasonal cooling-efficiency rating for residential central air conditioners and heat pumps.

It represents the total cooling delivered over the defined cooling season divided by the total electrical energy consumed during that seasonal test.

ENERGY STAR expresses SEER2 in Btu per watt-hour.

Source: ENERGY STAR Heat Pump Criteria

What Does SEER2 Stand For?

SEER2 stands for Seasonal Energy Efficiency Ratio 2.

It replaced the older SEER rating nomenclature for equipment tested under DOE's newer Appendix M1 procedure beginning with the 2023 efficiency-standard transition.

DOE notes that SEER2 and HSPF2 are the updated rating values under the newer test method.

Source: DOE/FEMP Residential Air-Source Heat Pumps

Is SEER2 the Same as SEER?

No.

They describe the same broad concept - seasonal cooling efficiency - but they are determined under different test procedures.

Do not apply a simplistic universal conversion factor to every piece of equipment.

When shopping in 2026, compare current equipment using SEER2.

What Is a Good SEER2 Rating?

For current ENERGY STAR residential split-system heat pumps, the minimum qualifying SEER2 is 15.2.

ENERGY STAR also requires at least:

• 11.0 EER2
• 7.8 HSPF2

for a standard split-system heat pump.

Source: ENERGY STAR Heat Pump Criteria

Premium systems can exceed 20 SEER2.

That does not automatically make them the best financial purchase.

Does Higher SEER2 Mean Lower Electric Bills?

For the same cooling load and properly functioning systems, higher seasonal cooling efficiency should reduce cooling electricity use.

But annual bill savings depend on:

• climate
• cooling load
• thermostat settings
• electricity rate
• duct losses
• installation quality
• system sizing
• humidity-control strategy
• actual part-load operation

A homeowner in Phoenix may value a SEER2 upgrade very differently from a homeowner in a cool northern climate.

SEER2 vs. EER2

SEER2 is seasonal.

EER2 measures cooling output relative to electric input at a defined operating condition.

That makes EER2 useful as a point-condition metric rather than an entire-season rating.

Standard ENERGY STAR split heat pumps require EER2 of at least 11.0 alongside the SEER2 requirement.

Does SEER2 Measure Heating Efficiency?

No.

Use HSPF2 for seasonal heating efficiency.

Use COP when you need heating efficiency at a specific operating condition such as 5°F.

HSPF2 explained

Is 20 SEER2 Worth It?

Maybe.

Calculate the incremental energy savings against the incremental installed price.

For example, compare:

• actual cooling load
• annual cooling hours
• electricity rate
• installed-price difference
• ownership period

Do not pay $5,000 extra because 20 sounds more efficient than 16.

Price the energy difference.

Does Variable Speed Increase SEER2?

Variable-speed inverter systems often achieve high seasonal ratings because they can operate efficiently at part load rather than cycling at one fixed capacity.

But variable speed is not valuable only for the efficiency number.

It can also affect:

• comfort
• humidity control
• sound
• cycling
• capacity range

Should You Buy the Highest SEER2 Available?

Not automatically.

Prioritize:

1. correct sizing
2. installation quality
3. climate fit
4. heating performance if relevant
5. local service
6. net installed cost
7. then incremental efficiency

A correctly installed 16 SEER2 heat pump can be a better asset than an oversized 22 SEER2 system.

Compare Heat Pump Efficiency and Installed Cost

Ask contractors to quote the exact matched-system SEER2, not only the outdoor-unit marketing number.