EER (Energy Efficiency Ratio)
The Energy Efficiency Ratio (EER) measures how efficiently an air conditioner converts electricity into cooling. It is calculated by dividing cooling output (BTU per hour) by power input (watts) at a steady test condition, typically 95°F outdoor temperature. A higher EER means more cooling for each watt of electricity, making it useful for comparing units under consistent conditions.
💡 Key Takeaways
- ✓The Energy Efficiency Ratio (EER) measures how efficiently an air conditioner converts electricity into cooling. It is calculated by dividing cooling output (BTU per hour) by power input (watts) at a steady test condition, typically 95°F outdoor temperature. A higher EER means more cooling for each watt of electricity, making it useful for comparing units under consistent conditions.
- ✓EER is a point-in-time efficiency metric, while SEER measures seasonal efficiency.
- ✓Higher EER units usually cost more upfront but can lower operating costs.
- ✓Proper installation and maintenance are essential to achieve rated efficiency.
EER (Energy Efficiency Ratio)
/iː iː ˈræʃiəʊ/
Definition
The Energy Efficiency Ratio (EER) measures how efficiently an air conditioner converts electricity into cooling. It is calculated by dividing cooling output (BTU per hour) by power input (watts) at a steady test condition, typically 95°F outdoor temperature. A higher EER means more cooling for each watt of electricity, making it useful for comparing units under consistent conditions.
What does EER mean for an air conditioner?
EER is the cooling output divided by watts used at a fixed test condition, showing how efficiently the unit cools.
Source: The Cooling Company
Quick Facts
How EER (Energy Efficiency Ratio) Works

EER compares steady-state cooling efficiency.
Real-World Application
When choosing a new AC, comparing EER ratings helps homeowners pick a model that cools efficiently and can reduce long-term energy costs, especially in hot climates with heavy cooling use.
Pro Tip
EER is a great benchmark, but size, insulation, and climate matter too. An HVAC pro can help match the right unit to your home for real-world efficiency.
“EER is a great benchmark, but size, insulation, and climate matter too. An HVAC pro can help match the right unit to your home for real-world efficiency.”
Important Things to Keep in Mind
- EER is a point-in-time efficiency metric, while SEER measures seasonal efficiency.
- Higher EER units usually cost more upfront but can lower operating costs.
- Proper installation and maintenance are essential to achieve rated efficiency.
Did You Know?
EER was created as a standardized benchmark so consumers could compare cooling efficiency across models.
FAQ
Is a higher EER always better?
Generally yes for efficiency, but overall comfort and cost depend on sizing, ductwork, and installation quality.
How is EER different from SEER?
EER is measured at a single outdoor temperature, while SEER averages efficiency over a cooling season.
Do all air conditioners have an EER rating?
Most do, especially room and central AC units, but labels may emphasize SEER2 for seasonal efficiency.
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