EER2 (Energy Efficiency Ratio 2) is the updated 2023 standard for measuring the cooling efficiency of an air conditioner at a specific outdoor temperature of 95°F. Unlike the older EER rating, EER2 accounts for higher "Static Pressure," providing a more realistic calculation of how the unit will perform once installed in your home. A higher EER2 rating, found on our Sierra Smart models, means the unit produces more cooling per watt of electricity used during peak heat. While SEER2 measures seasonal averages, EER2 tells you how well your unit will handle the hottest "Triple-Digit" days of the year. This is a crucial metric for customers in the South or Southwest where peak demand performance is a priority. We clearly list the EER2 for all our Wall Mount R454B units to help you compare real-world operating costs. Choosing a high EER2 system can qualify you for localized energy rebates and significant long-term savings. It is a key part of our commitment to being an "Efficiency Pioneer" in the industry.