Glossary · Heating, cooling & ventilation
EER / EER2
Also called: energy efficiency ratio
Cooling efficiency measured at one hot test condition rather than averaged over a season; useful for judging performance on the hottest days.
What it means
Unlike SEER, which averages over a season, EER measures steady-state efficiency at a single hot outdoor condition, so it's a better guide to electricity use on peak days. EER2 is the version used since 2023. For ground-source heat pumps, EER is the standard cooling rating.
Why it matters in an audit
A high EER keeps electricity use down on the hottest days, so it matters most where summers are hot and when a heat pump does the cooling.
Typical numbers
Reference values with their sources. Your energy advisor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| ENERGY STAR heat pumps (spec 6.2) | Split EER2 ≥ 11.0; single-package ≥ 10.0 | energystar.gov ↗ |
| Ground-source heat pumps, NRCan minimum | 16.2 open loop; 13.4 closed loop | natural-resources.canada.ca ↗ |