Glossary · Heating, cooling & ventilation
SEER / SEER2
Also called: seasonal energy efficiency ratio · SEER rating
An air conditioner's or heat pump's cooling efficiency averaged over a whole cooling season; higher is better.
What it means
SEER2 replaced SEER in 2023 when the test procedure changed to better reflect real installations, and the numbers aren't directly comparable. It's a seasonal average, while EER or EER2 shows efficiency at a single hot condition. In heating-dominated climates, SEER matters less than heating ratings such as HSPF2 and COP.
Why it matters in an audit
Minimum SEER2 is set by regulation and ENERGY STAR and rebate levels sit above it, so it's a quick check on how efficient a quoted system is at cooling.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| US federal minimum, split air conditioners (2023) | North 13.4; Southeast and Southwest 14.3 below 45,000 BTU/h, 13.8 at 45,000 BTU/h and above | www1.eere.energy.gov ↗ |
| US federal minimum, heat pumps and packaged units (2023) | Split heat pumps 14.3 nationwide; single-package air conditioners and heat pumps 13.4 | www1.eere.energy.gov ↗ |
| US regions | North = states with 5,000+ heating degree days; Southwest = AZ, CA, NV, NM; Southeast = AL, AR, DE, FL, GA, HI, KY, LA, MD, MS, NC, OK, SC, TN, TX, VA, DC, PR and territories | www1.eere.energy.gov ↗ |
| ENERGY STAR heat pumps (spec 6.2) | SEER2 ≥ 15.2 | energystar.gov ↗ |
In the United States
In the Southeast and Southwest the regional minimum applies by installation date, so contractors can't install a non-compliant split air conditioner there after January 1, 2023.