What SEER2 Means

SEER2 stands for Seasonal Energy Efficiency Ratio 2. It measures how efficiently a central air conditioner or heat pump cools your home over an entire cooling season. A higher SEER2 number means the system uses less electricity to produce the same amount of cooling.

The formula: SEER2 = total cooling output (BTUs) ÷ total electrical energy input (watt-hours) over a typical cooling season.

A 20 SEER2 system produces the same cooling as a 13 SEER2 system while using about 35% less electricity. Over a Chicago summer, that difference shows up on your ComEd bill every month.

SEER vs. SEER2 — What Changed

The DOE updated its testing methodology effective January 1, 2023. The new standard (SEER2) uses a higher external static pressure in testing — meaning the equipment is tested under conditions that more closely reflect real-world duct systems. As a result, SEER2 ratings are typically about 5% lower than the equivalent SEER rating for the same equipment.

A system rated 16 SEER under the old standard is roughly equivalent to 15.2 SEER2 under the new standard. The equipment didn't get less efficient — the test got more realistic.

All new residential AC equipment sold after January 1, 2023 is rated in SEER2. If you see a SEER rating on older equipment, you can multiply by approximately 0.95 to get the rough SEER2 equivalent.

Minimum SEER2 Requirements for Chicago

Chicago is in the North region under DOE climate zone definitions. The minimum SEER2 for new split-system central air conditioners in the North region is 13.4 SEER2 as of January 1, 2023.

This is the floor — the least efficient new equipment you can legally install. Most homeowners benefit from going higher, but how much higher depends on your situation.

How to Choose the Right SEER2 Level

13.4–14.3 SEER2 (Basic): Code-minimum efficiency. Best for homeowners on a tight budget, rental properties, or homes where the AC runs infrequently. Lower upfront cost, higher operating cost.

15–16 SEER2 (Better): The sweet spot for most Chicago homeowners. Meaningful efficiency improvement over minimum equipment, reasonable payback period, and widely available across all major brands. This is the most popular tier D's Air installs.

17–19 SEER2 (Best): High-efficiency single-stage or two-stage equipment. Good choice for homes that run the AC heavily from June through September, or homeowners planning to stay in the home for 10+ years.

20+ SEER2 (Elite): Variable-capacity inverter systems. The most efficient option available. Best for homeowners who prioritize comfort and efficiency above all else, or who have high cooling loads. Higher upfront cost, lowest operating cost, and the most consistent comfort.

Payback Period: Does Higher SEER2 Pay Off?

The payback period depends on how much you run your AC, your local electricity rate, and the price difference between efficiency tiers. In Chicago, where summers are hot and humid but the cooling season is shorter than in the South, the payback math is less favorable than in Phoenix or Houston.

A rough rule of thumb: upgrading from 13.4 SEER2 to 16 SEER2 saves roughly $80 to $150 per year on a typical Chicago home. The price premium for the higher-efficiency unit is usually $400 to $800. That's a 3–8 year payback — reasonable if you plan to stay in the home.

Upgrading from 16 SEER2 to 20 SEER2 saves another $60 to $100 per year, but the premium is larger. Variable-capacity systems also provide better humidity control and more consistent temperatures, which many homeowners value beyond the energy savings alone.

EER2 — The Other Rating

EER2 (Energy Efficiency Ratio 2) measures efficiency at a single operating condition — typically a 95°F outdoor temperature. While SEER2 reflects seasonal average performance, EER2 reflects peak-day performance. A high EER2 means the system handles the hottest days efficiently.

EER2 matters most for Chicago homeowners who experience heat waves where temperatures stay above 90°F for multiple days. A system with a strong EER2 rating will maintain comfort and efficiency even on the worst days of the summer.

SEER2 and Tax Credits

The Inflation Reduction Act (IRA) provides a federal tax credit of up to $600 for qualifying central air conditioners. To qualify, the system must meet or exceed the Consortium for Energy Efficiency (CEE) Tier 2 efficiency threshold — currently 16 SEER2 / 12 EER2 for split systems in the North region.

Ask D's Air about current qualifying models and how to claim the credit when you file your taxes. Credits are non-refundable and subject to annual limits — consult a tax professional for your specific situation.

The Bottom Line

For most Chicago homeowners replacing an aging system, 15–16 SEER2 is the right target — meaningful efficiency improvement, reasonable cost, and solid payback. If comfort is the priority and budget allows, a 19–20 SEER2 variable-capacity system delivers the best overall experience. D's Air will help you run the numbers during your free in-home estimate. Call (773) 940-0965.