Energy Efficiency Ratio Calculator
Calculate the Energy Efficiency Ratio (EER) for cooling systems, appliances, and HVAC equipment
EER Rating
Efficiency Grade
Equivalent COP
Efficiency Rating
Calculation Breakdown
| Parameter | Value |
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Understanding Energy Efficiency Ratios
Energy efficiency ratings measure how effectively a cooling or heating system converts electrical energy into useful thermal energy. Higher ratings mean lower energy consumption and operating costs for the same amount of cooling or heating. These metrics are essential for comparing HVAC equipment and making informed purchasing decisions.
Key Efficiency Metrics
- EER (Energy Efficiency Ratio): Cooling capacity in BTU/h divided by power input in Watts, measured at a single outdoor temperature (95°F / 35°C). Higher is better.
- SEER (Seasonal Energy Efficiency Ratio): Total cooling output over an entire season divided by total electrical energy input. Accounts for varying temperatures across a typical cooling season.
- COP (Coefficient of Performance): Ratio of useful heating or cooling provided to the work (energy) required. A COP of 3.0 means 3 units of thermal energy per 1 unit of electrical energy.
- HSPF (Heating Seasonal Performance Factor): Similar to SEER but for heating mode of heat pumps, measured in BTU/Wh over a heating season.
Efficiency Rating Comparison
EER Ratings
- • Poor: Below 8.0
- • Average: 8.0 - 9.9
- • Good: 10.0 - 11.9
- • Excellent: 12.0 - 13.9
- • Superior: 14.0+
SEER Ratings
- • Minimum (US): 14 (since 2023)
- • Average: 14 - 16
- • Good: 16 - 18
- • High Efficiency: 18 - 22
- • Ultra Efficient: 22+
COP Ratings
- • Electric heater: 1.0
- • Old heat pump: 2.0 - 2.5
- • Standard heat pump: 2.5 - 3.5
- • High-efficiency: 3.5 - 5.0
- • Ground-source: 4.0 - 6.0
Conversion Between Metrics
The different efficiency metrics are mathematically related and can be converted between each other:
- EER = COP × 3.412 (since 1 W = 3.412 BTU/h)
- COP = EER / 3.412
- SEER ≈ EER × 1.12 (approximate seasonal adjustment)
- EER ≈ SEER / 1.12
US Federal Minimum Efficiency Standards
The US Department of Energy (DOE) updated residential central air conditioner and heat pump minimum standards effective January 1, 2023, under the Energy Policy and Conservation Act:
- Split-system AC (South): SEER2 14.3 / EER2 11.7
- Split-system AC (North): SEER2 13.4 / EER2 n/a
- Split-system heat pump: SEER2 14.3 / HSPF2 7.5
- Packaged AC (South): SEER2 13.4 / EER2 10.6
- Packaged heat pump: SEER2 13.4 / HSPF2 6.7
Note: SEER2 and EER2 use updated M1 testing procedures with higher external static pressure, resulting in slightly lower numbers than legacy SEER/EER for the same equipment.
References
The formulas and efficiency standards used in this calculator are based on authoritative industry and government sources:
- U.S. Department of Energy - Central Air Conditioning
- ENERGY STAR - Central Air Conditioners and Heat Pumps
- ASHRAE - Standards and Guidelines for HVAC Systems
- U.S. Energy Information Administration - Energy Use in Homes
- ACCA (Air Conditioning Contractors of America) - Industry Standards
- International Energy Agency (IEA) - The Future of Cooling
Note: This calculator provides estimates based on standard formulas and industry definitions. Actual equipment performance varies with installation quality, ductwork, refrigerant charge, ambient conditions, and maintenance. SEER ratings assume a typical cooling season across a range of outdoor temperatures (67°F to 102°F). Always consult manufacturer specifications and a qualified HVAC professional for precise system sizing and selection.
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