Integrated Energy Efficiency Ratio (IEER) measures the cooling efficiency of air conditioners and heat pumps under variable load conditions throughout a season. Unlike steady-state ratings, IEER accounts for part-load performance at 100%, 75%, 50%, and 25% capacity levels, weighted to reflect real-world usage patterns. This metric provides a more accurate representation of seasonal efficiency than single-point ratings.
Technical Specifications
IEER is expressed in BTU/watt-hour and calculated using four weighted operating points based on the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 340/360. Higher IEER values indicate better efficiency. Commercial rooftop units and split systems typically achieve IEER ratings between 16 and 22, depending on size and technology level. The rating assumes outdoor temperatures of 95°F and specific indoor conditions.
Practical Applications
IEER is primarily used for commercial cooling equipment above 65,000 BTU/hr capacity. This rating helps facility managers and engineers compare equipment efficiency more accurately than EER alone, leading to better lifecycle cost analysis and energy savings estimates. Building codes and energy standards increasingly require IEER documentation for equipment selection and commissioning purposes.