EER2

Definition

EER2 stands for Energy Efficiency Ratio 2. It measures a heat pump's cooling efficiency at a single, demanding outdoor temperature of 95°F. Unlike SEER2, which averages performance across a range of temperatures, EER2 focuses on peak-day performance. This rating is particularly relevant for understanding how well a system will cool your home during the hottest parts of the year when the unit is working hardest. It's a stricter test than its predecessor, EER, reflecting more realistic operating conditions.

Why it matters

EER2 is crucial for homeowners in hot climates or those concerned about cooling performance during extreme heatwaves. A higher EER2 means your heat pump will use less electricity to cool your home when outdoor temperatures are at their highest, directly impacting your utility bills during peak summer months. For instance, a system with an EER2 of 12.0 will be noticeably more efficient on a 95°F day than one with an EER2 of 9.0, leading to lower operating costs and potentially better comfort. In regions where air conditioning is heavily used, a higher EER2 can translate into significant long-term savings. It also helps ensure your system is appropriately sized and won't struggle to maintain indoor comfort when demand is highest.

Where you'll see it

You will typically find the EER2 rating listed on a heat pump's specification sheet, an AHRI (Air-Conditioning, Heating, and Refrigeration Institute) certificate, or sometimes on a contractor's quote. It's usually presented as a single number, like 'EER2 11.5' or 'EER2 13.0'. For heat pumps, a typical EER2 range might be from 9.0 to 12.0. A premium, high-efficiency system might boast an EER2 of 12.5 or higher. An EER2 below 9.0 could indicate a less efficient unit or one primarily designed for heating-dominant climates. Always compare EER2 ratings when evaluating systems for hot climates; a higher number is always better. Look for this alongside SEER2 and HSPF2 ratings.

Common mistake

A common mistake is to solely focus on SEER2 and overlook EER2, especially in hot climates. While SEER2 provides an average seasonal efficiency, it can mask a system's poor performance on the hottest days. A system with a high SEER2 might still have a relatively low EER2, meaning it performs well on average but struggles and consumes a lot of power during peak heat. Homeowners might then experience higher-than-expected electricity bills or inadequate cooling when they need it most. Always consider both ratings; if you live in an area with frequent temperatures above 90°F, a strong EER2 (e.g., 11.0 or higher) is just as important as a high SEER2.

See also

• SEER2
• HSPF2
• BTU/hr
• Compressor