Energy Efficiency Ratio

Updated on March 26, 2024
Article byWallstreetmojo Team
Edited byWallstreetmojo Team
Reviewed byDheeraj Vaidya, CFA, FRM

Energy Efficiency Ratio (EER) Definition

The Energy Efficiency Ratio (EER) is a ratio calculation used to measure the energy efficiency rating of various cooling systems. Its primary purpose is to compare different appliances’ operational efficiency and energy costs, aiding consumers in making informed purchasing decisions.

Energy Efficiency Ratio (EER)

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The primary application of the energy efficiency ratio calculator is evident in heating, ventilation, and air conditioning (HVAC) systems. This metric proves valuable for consumers when selecting appliances, allowing them to understand the energy cost relative to efficiency. Additionally, it assists in determining the operational lifespan of the appliance.

Key Takeaways

  • The energy efficiency ratio is a crucial formula for calculating the efficiency of an appliance over the cost consumed. In short, it considers the capacity and power utilized to operate a system.
  • It can occur in multiple appliances. However, a majority of them include HVAC. For instance, air conditioners, refrigerators, computer miners, heaters, and similar others.
  • The formula for EER calculation includes a ratio of total heat or cooling capacity produced divided by the power consumed.

Energy Efficiency Ratio Explained

The energy efficiency ratio refers to the calculation used to compare the efficiency and energy cost of different electrical appliances, especially those providing cooling or heating effects upon installation, such as air conditioners, heaters, and refrigerators. Consumers can use this ratio to identify the best appliance within a suitable budget. A higher air conditioner energy efficiency ratio is generally favorable, with many producers recommending an EER of 12 as ideal for such items.

The ideal temperature for energy efficiency ratio calculations may vary in different regions. Various factors influence the energy efficiency ratio, including the current environment, climate, appliance size, and associated features. Higher temperatures generally result in a higher EER, while colder regions may demand a lower ratio.

The appliance’s size and multiple components’ presence can also impact the energy efficiency ratio. Larger appliances might have higher ratios, but smaller ones with efficient thermostats can achieve a competitive combined energy efficiency ratio. Producers often incorporate energy-saving components to reduce carbon footprints and overall costs, providing consumers with options to spend less while acquiring the best appliances.

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The formula for determining the energy efficiency ratio is as follows:

EER=Output Cooling Energy in BTU/ Input electrical energy in Wh


EER=Total cooling or heating capacity/Total electrical power consumed

In this formula, the total capacity represents the appliance’s ability to provide a cooling or heating effect, measured in British Thermal Units (BTUs). Similarly, total energy is the power consumed by a particular appliance, measured in Watts.


Let us look at some hypothetical and real-world examples of energy efficiency ratios to understand the concept better:

Example #1

Suppose Alfred and Kenny want to buy a new refrigerator and air conditioner for their renovated house. However, they were pretty confused with the variety of models in the market. Therefore, they decided to use the EER formula to make the decision. From the variety, Alfred and Kenny landed on two models. Following are the details of the appliances:

(Cooling capacity and Energy consumed)Air conditionerRefrigerator
Model #112,000 BTU per hour and 900 Watts11,000 BTU per hour and 900 Watts
Model #27000 BTU per hour and 800 Watts12,000 BTU per hour and  950 Watts

Air conditioner (Model #1 and #2)

EER = 12000 / 900                   EER = 7000/ 800

       = 13.3                               = 8.75

Refrigerator (Model #1 and #2)

EER = 11,000 / 900                      EER = 12,000 / 950

       =  12.2                                      = 12.6

From the above calculation, the energy efficiency ratios of different models are visible. As a result, Alfred decided to go with Model #1 for the air conditioner and Model #2 for the refrigerator.

Example #2

According to recent crypto updates as of October 2023, Bitmain, the miner supplier, has unveiled its latest Bitcoin miner, the “Antminer T21.” This miner boasts a computing power of 190 terahashes per second (TH/s) and an energy efficiency metric of 19 joules per terahash.

Notably, energy efficiency is a crucial factor in cryptocurrency mining hardware, representing the power consumption per unit of computing power. In this case, the Antminer T21 demonstrates an efficiency of 19 joules per terahash, indicating a competitive energy-efficient design.

In addition to its computing prowess, the Antminer T21 is equipped to maintain a temperature of 45 degrees Celsius during operation. This feature is essential for optimal performance and longevity of the mining hardware.

Prospective customers eagerly await the release of the Antminer T21, which is expected to reach them by January 2024. The availability of this advanced miner introduces new possibilities for cryptocurrency miners seeking enhanced performance and energy efficiency.

Energy Efficiency Ratio vs Seasonal Energy Efficiency Ratio

Although EER and SEER aim to calculate energy efficiency, their environment differs. So, let us look at their differences:

Key PointsEnergy Efficiency RatioSeasonal Energy Efficiency Ratio
MeaningIt refers to the ratio used to measure the efficiency of the appliance to the capacity providedSEER is a formula used to calculate the average cooling capacity of the appliance during a cooling season like winters
PurposeIt focuses on calculating the energy efficiency of a cooling appliance like ACs in the winter season.It focuses on calculating the energy efficiency of a cooling appliance like ACs in the winter season
EnvironmentEER reflects the system’s efficiency at peak hoursSEER is more biased over comparing the system’s efficiency during seasonal climate

Frequently Asked Questions (FAQs)

1. What is the importance of the Energy Efficiency Ratio (EER)?

The EER is vital as it quantifies the efficiency of heating, ventilation, and air conditioning (HVAC) systems. It represents the ratio of cooling output to energy input, helping consumers and businesses make informed decisions about energy-efficient appliances. A higher EER signifies lower energy consumption, reduced electricity bills and environmental impact.

2. What are the Energy Efficiency Ratio (EER) benefits?

The primary benefits of a high EER include cost savings on energy bills and a reduced environmental footprint. Appliances with higher EER values operate more efficiently, reducing electricity consumption. This saves consumers money and contributes to sustainability efforts by decreasing overall energy demand and greenhouse gas emissions.

3. What are the Energy Efficiency Ratio’s (EER) limitations?

Despite its advantages, EER has limitations. It doesn’t consider external factors like climate variations, potentially providing an incomplete picture of real-world efficiency. Additionally, EER may not capture the full range of features affecting a system’s performance, leading to discrepancies between theoretical and actual energy savings. As a static metric, it might not accurately reflect a system’s efficiency under diverse operating conditions.

This article has been a guide to Energy Efficiency Ratio (EER) & its definition. We explain its formula, examples & comparison with seasonal energy efficiency ratio. You may also find some useful articles here –

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