SEER to EER Conversion Calculator
Convert SEER (Seasonal Energy Efficiency Ratio) to EER (Energy Efficiency Ratio) using the industry-standard formula developed by Carrier and widely adopted by AHRI (Air-Conditioning, Heating, and Refrigeration Institute).
Formulas
Step 1 — EER at Standard Condition (95°F outdoor):
EER = −0.02 × SEER² + 1.12 × SEER
This quadratic relationship was derived empirically by Carrier and is the industry-standard conversion adopted by AHRI (Air-Conditioning, Heating, and Refrigeration Institute) in Standard 210/240. It accounts for the fact that SEER is a seasonal average measured across a range of temperatures (65°F–104°F), while EER is a single-point rating at 95°F outdoor / 80°F dry-bulb / 67°F wet-bulb indoor.
Step 2 — Temperature Adjustment (optional, non-95°F designs):
EER_adjusted = EER − 0.07 × (T_outdoor − 95)
A linear correction factor of 0.07 BTU/Wh per °F deviation from 95°F, sourced from DOE/ORNL research and used in ACCA Manual J residential load calculations.
Step 3 — COP (Coefficient of Performance):
COP = EER ÷ 3.412
Conversion factor: 1 watt = 3.412 BTU/hour (exact thermodynamic constant).
Assumptions & References
- SEER (Seasonal Energy Efficiency Ratio) is measured per AHRI Standard 210/240 across a cooling season temperature distribution weighted toward a 65°F–104°F outdoor range.
- EER (Energy Efficiency Ratio) is a single-point measurement at exactly 95°F outdoor dry-bulb, 80°F indoor dry-bulb, 67°F indoor wet-bulb per ARI Standard 210/240.
- The quadratic formula EER = −0.02·SEER² + 1.12·SEER is valid for SEER values between 8 and 30; accuracy degrades slightly above SEER 30 for inverter-driven variable-speed systems.
- For variable-speed (inverter) systems, SEER2 (post-2023 DOE standard) uses a slightly different test protocol; this calculator uses the legacy SEER/EER relationship.
- Minimum federal SEER standards (DOE 10 CFR Part 430): 14 SEER for split systems in the South/Southwest US; 13 SEER in the North (as of 2015 standards; 2023 standards introduced SEER2).
- ENERGY STAR qualification requires ≥ 15 SEER (split systems) or ≥ 12 EER (room ACs) as of 2023.
- References: AHRI Standard 210/240-2023; Carrier Engineering Reference Handbook; DOE/ORNL Report ORNL/TM-2004/144; ACCA Manual J 8th Edition.