SEER vs. SEER2 — What’s the Difference?

What SEER Actually Measures

SEER stands for Seasonal Energy Efficiency Ratio. It measures how much cooling a system produces (in BTUs) relative to the electricity it consumes (in watt-hours) over a cooling season. A higher number means the system uses less electricity to deliver the same cooling output.

A 16 SEER system is meaningfully more efficient than a 14 SEER system. A 20 SEER system is substantially more efficient than either. In the Dallas climate — where your AC runs from late May through September — the efficiency difference shows up clearly on your utility bill.

The U.S. government sets minimum efficiency standards. Before 2023, the minimum in the South (including Texas) was 14 SEER. As of January 2023, the minimum is 15 SEER2 for residential systems under 45,000 BTU/hr.

What Changed with SEER2

The core change is the test conditions. Under the original SEER standard, systems were tested at very low static pressure (0.1 in. wc.) — conditions that didn’t accurately reflect what systems actually experience when pushing air through a real home’s ductwork.

SEER2 raised that test pressure to 0.5 in. wc., making the test conditions more representative of actual installed performance. The result: SEER2 ratings run lower than SEER ratings for the same physical equipment. A system that earned a 17 SEER rating will typically earn about 16.3 SEER2 under the new standard.

This doesn’t mean systems got less efficient in 2023. It means the ratings now more accurately reflect what you’ll experience in your home.

How to Compare Old and New Ratings

If you’re comparing a quote for a new SEER2-rated system against an older SEER-rated system you remember, use this rough conversion: divide the old SEER rating by 1.04 to get the approximate SEER2 equivalent.

| Old SEER | Approximate SEER2 |

|—|—|

| 14 | ~13.4 |

| 15 | ~14.4 |

| 16 | ~15.4 |

| 17 | ~16.3 |

| 18 | ~17.3 |

| 20 | ~19.2 |

The key rule: compare SEER2 to SEER2 when evaluating new equipment quotes. Comparing a SEER2 number directly to an old SEER number will make the new system look less efficient than it actually is.

What This Means When Buying a New System in Dallas

If you’re replacing an older system in Dallas, the efficiency jump is often significant regardless of SEER2 ratings. A 14 SEER system from 2010 being replaced with a 16 SEER2 system today represents a real improvement in both efficiency and technology — variable-speed components, better humidity control, quieter operation.

For most Dallas homeowners, systems in the 16–18 SEER2 range deliver the best balance of upfront cost and long-term energy savings. Ultra-high-efficiency systems (20+ SEER2) have longer payback periods but offer noticeably better comfort — particularly humidity management — through variable-speed compressor technology.