The Seasonal Energy Efficiency Ratio

The seasonal energy efficiency ratio, or SEER, allows individuals to determine their HVAC system’s energy-efficient. The higher the final number is, the more efficient the system is. It is determined by dividing the average cooling output of a system by the average energy expended during that time. The average production is measured in British Thermal Units or BTUs, and the average energy expended is measured in watts. The result will be a number from 6 to 23. The most popular systems boast a SEER of 20 or higher. A system with a SEER of 20 would use 1/20th of energy as one with a SEER of 10, even though they may have the same output.

What Is the Seasonal Energy Efficiency Ratio?

SEER, or seasonal energy efficiency ratio

The seasonal energy efficiency ratio, or SEER, allows individuals to determine how energy-efficient their HVAC system is. The higher the final number is, the more efficient the system is. It is determined by dividing the average cooling output of a system by the average energy expended during that time.

The SEER is best understood as a maximum efficiency rating for when the entire HVAC system is functioning correctly. It is similar to the average miles per gallon (mpg) a vehicle possesses. Just as you cannot continue to drive your car at top speeds forever without eventually stopping for fuel. HVAC systems will also eventually lose efficiency if they run hour after hour. However, the SEER rating represents the most efficient that your HVAC system can be while running.

The SEER is strongly related to the theories of thermodynamics. Thermodynamics is one of the most significant branches of physical science. It has to do with the study of heat and its relationship to other forms of energy. Heat itself is understood as a form of energy. Therefore, making a functioning HVAC system and air conditioner is necessary. The SEER measures the heat pump’s efficiency in converting electricity into cooling energy. The higher the SEER rating, the greater the efficiency with which the heat pump can operate.

When calculating the SEER, an individual is responsible for understanding how energy is used over a period of time to generate cooled air. Some of the most common units to see are British thermal units (BTUs) and watts. A British thermal unit is the energy required to heat a single pound of water by 1 degree Fahrenheit. The actual amount is 1,055 joules, which would be the equivalent of 252 calories of energy for a living organism.
A watt, meanwhile, is a unit of power utilized by the International System of Units. It is essential for understanding the basics of thermodynamics and often electrical energy in general. It is the equivalent of 1 joule per second.

A joule is one of the smallest units of energy, which is why it is often used to calculate much larger units. It is best understood as the amount of energy transferred to an object when a single force of 1 newton acts on an object over 1 meter. When calculating the SEER, it is impractical to use joules because higher energy levels are required to quantify the output of a basic air conditioning unit. Therefore, the British thermal unit (BTU) is sometimes used instead.


How to Calculate Your SEER

One of the most critical steps to utilizing and understanding SEER is being able to calculate the ratio. SEER is measured in BTUs. An individual needs to know the BTUs per hour and watts per hour of their air conditioner to perform the calculation. Next, they need to calculate the average use of the air conditioner over the summer in both units. The simplest way to do so is to multiply both units by 1,000 hours, the average time an air conditioner spends in operation during late spring and summer. This will give the total BTUs and wattage used during the season.

The equation will be BTUs x 1000 and watts x 1000.

Once both of these numbers have been calculated, the SEER can be determined through the following equation: (BTUs x 1000)/(watts x 1000) = SEER.

BTUs = 7,500

Watts = 3,500

(7,500 x 1,000) = 7,500,000

(3,500 x 1,000) = 3,500,000

7,500,000/3,500,000 = SEER Rating 2.14


SEER’s Relation to EER and COP

It is common to hear similar acronyms such as EER and COP when discussing SEER. Any cooling device’s energy efficiency ratio (EER) is received by calculating the ratio of output cooling energy to input electrical energy. The ratio is determined at any operating point. Therefore, it is a necessary term that allows individuals to see just how energy-efficient their HVAC system is.

It is common to assume an outside temperature of 95 degrees Fahrenheit and a return air (or interior) temperature of 80 degrees Fahrenheit when calculating the ratio. The relative humidity is also averaged to 50%, even in notably wet and dry climates.

Like the SEER, the EER has its basis in thermodynamics. It is related to the COP, or the coefficient of performance. The main difference between the EER and COP is that the calculated COP of any cooling device is designed to be without units. This is because the assigned numerator and denominator are expressed using the same units, avoiding the mixed units utilized by the SEER and EER.

The downside to using mixed units for the SEER and EER is that there is no immediate physical sense to either number. While the ratios produced are beneficial for determining overall machine energy efficiency, it cannot be quantified as they lack a central unit of measurement. For this reason, obtaining a physical example of the EER is done by multiplying the COP or EER by the conversion factor from BTU/h to watts. This conversion factor is expressed as EER = 3.41214 x COP.

The SEER is another form of the COP (or EER) expressed in units but is not a single operating condition. Instead, it is an expected overall performance or average performance of an air conditioning unit in a specific region. Because the SEER is designed to be an average, it is calculated with the same interior temperature of 80 degrees Fahrenheit.

However, it has a range of exterior temperatures. One downside to using the SEER rather than the EER is the lack of allowance for different climates. This means the EER can be used to show how energy efficiency is affected by a variety of exterior temperatures as any given season cools.

The relationship between the SEER and EER is linear, so a 3 SEER unit would be expected to have an EER of 9. This means that the higher the SEER, the more efficient the air conditioner. The current minimum SEER for newly manufactured central air conditioners is 13, so any unit with a higher SEER will be more efficient. However, the price difference between different units with the same SEER can be staggering. So it is essential to consider the overall cost of installing and operating the air conditioner when deciding on a purchase.

One way to increase efficiency without sacrificing comfort level is through smart technology that allows for optimal programming of an air conditioner. This can help minimize energy use while still maintaining a comfortable indoor environment. When calculating the efficiency of an air conditioning unit, it is essential to consider how much cooling and heating you need. And your budget to make the most energy-efficient choice possible.

So, this means the SEER is the COP or EER expressed in BTU/hr/W, but it has been slightly adjusted to compensate for a range of weather conditions. The EER, meanwhile, will only be for a single stagnant state, and the COP is the physical manifestation of the ratios once assigned actual units and a method of measurement. In other words, the SEER shows how efficient an air conditioner would be throughout a season. At the same time, the EER is for specific weather conditions.

If someone knows the SEER of their unit, they can calculate the EER. For most central residential cooling units, the EER will be equal to 0.875 x SEER. The SEER will almost always be a higher value than the EER for the same piece of equipment. So, an individual trying to measure the energy efficiency of their air conditioner should almost always be able to generate a SEER that is proportionally larger than the EER.

Individuals interested in converting SEER to EER can use the following formula:

EER = -0.02 × SEER² + 1.12 × SEER

Unfortunately, the formula does not work for all climates, particularly those that are extremely hot or cold.


US SEER Standards

The United States government became invested in the energy efficiency of residential and commercial HVAC systems beginning in 1987. Before that period, companies could manufacture their range of products depending on industry technology. In 1987, legislation was passed, and it went into effect in 1992. The legislation set energy efficiency standards for residential and commercial heating, ventilation, and air conditioning systems.

The new standards required manufacturers to meet a minimum level of efficiency for their products when compared to other similar models on the market. This meant that more efficient HVAC systems could be more expensive than older versions of the same product. The legislation also made it possible for the federal government to assist companies with new research and development of more efficient technologies.

This first piece of legislation determined that all air conditioners needed to meet a minimum SEER rating of 10. In addition, residents were not responsible for immediately replacing their aging units but did need to buy more energy-efficient models once the original air conditioner broke. The legislation also recommended that homeowners replace older equipment before putting their houses on the market.

As technology continued to advance, the United States government chose to revise the standards placed on new HVAC equipment once again. In 2006, the required SEER rating became 13. Concessions were made to accommodate units designed to be more affordable for the average homeowner, as not all demographics would be able to purchase high-quality equipment that met the federal standards. A new number was created for air conditioners to be considered Energy Star rated.

Those units needed to have a SEER of 14.5. The required rating for furnaces was also increased. The new minimum AFUE became 80%. These additions to the legislation helped ensure that homeowners were using more energy-efficient products in their homes, but there were still some drawbacks. For example, many units that met the new standards could not be used in specific areas because they did not have the proper certifications. This meant that homeowners in those areas would not be able to take advantage of the new, more efficient units. The other issue was that the cost of these new units was still relatively high, which made them inaccessible to many people.

In 2011, the US Department of Energy (DOE) decided to revise energy conservation rules to accommodate better the wildly varying climates in different parts of the United States. As a result, beginning January 1, 2015, new split-system air conditioners were introduced for southern and western states. The requirements for these units are 14 SEER and 12.2 EER. In addition, any split-system air conditioner installed outside of the southern and western United States needs to meet a minimum of 13 SEER.

While geographic differences in climate largely drove the DOE’s change in policy, it also reflects the fact that advances in technology have made it possible to produce more energy-efficient air conditioners. In particular, the use of inverter-driven compressors has made it possible to create air conditioners with much higher SEER ratings. In addition, inverter-driven compressors can vary their speed, which means they can run more slowly when cooling demands are low and more quickly when cooling needs are high. This results in much greater energy efficiency than fixed-speed compressors, which run at a constant speed regardless of conditions.

It should be noted that the US SEER standards are designed to be manageable. The majority of HVAC manufacturers in the American market can produce more efficient models with higher SEER and EER because of continuing technological development in the field.


Current Maximum SEER Ratings

As of 2020, the highest attainable SEER rating is 42. Unfortunately, these air conditioners tend to be mini and ductless and, therefore, not practical for most residential homes. The highest numbers attained by a central ducted system are almost always 10-20% lower than the SEER of a ductless model. This is to accommodate for energy that is lost through the transmission of air via pathways. Nevertheless, there are plenty of high-efficiency air conditioners on the market with a SEER rating in the 20s.

When it comes to ground-source AC units, some models can reach a total SEER rating of 75. In these systems, the entire HVAC system is based on the temperature of the ground or water source on which the HVAC is reliant. So, energy efficiency can vary wildly depending on temperature fluctuations, especially in a region with a varying climate.

At the same time, the SEER ratings do not accommodate the energy required to operate the pumps associated with ground-source air conditioners, meaning energy is used but not incorporated into calculations. This can create misinformation and misleading numbers, even if the intent is still good. to operate the pumps associated with ground-source air conditioners, meaning energy is used but not incorporated into calculations. This can create misinformation and misleading numbers, even if the intent is still good.


Why SEER Matters

SEER is significant when determining whether or not a residential property is energy-efficient. When an air conditioning unit is operating with any rating under 13, it is considered inefficient. It does not meet the baseline for equipment in the United States. This means energy is being wasted, and the homeowner could pay for extraneous energy use. A SEER rating of 13 and above is the standard for energy efficiency. The higher the rating, the more efficient your unit will probably be. For those interested in investing in an appliance that could save them money on their utility bills over time, it’s worth looking into units with a SEER rating of 16 or 17.

The benefits of having a higher SEER rating are not only limited to saving money on your utility bills. More efficient units tend to have fewer repair issues and last longer than their less efficient counterparts. In other words, you may spend less on maintenance and repairs over the unit’s lifetime if you choose one with a higher SEER rating.

Before purchasing any form of air conditioner, it is vital to ensure that it meets basic energy standards. Individuals interested in spending less money over an extended period should search for a unit that has a higher SEER ranking.

It can be challenging to determine the ranking of an air conditioner when someone has not seen it in use, which is why most manufacturers are required to list either the SEER or the EER of the product on the appliance itself. It can often be discovered on a large black and yellow sticker placed on the side of the device. If only one ratio is present, then the calculations shown in this article make it possible to determine the opposite ratio with little effort.



Knowing the seasonal energy efficiency ratio of any air conditioner is essential for making informed decisions about HVAC systems. In addition, as sources of energy like coal and petroleum decline, it has become more critical for the average individual to focus on making conscious, energy-efficient choices for their own home.

There are numerous equations available to simplify calculations, including the following:

(BTUs x 1000)/(Watts x 1000) = SEER

EER = -0.02 × SEER² + 1.12 × SEER

Meanwhile, the COP is best understood as a stagnant number that does not require calculation.

The ongoing demand for more renewable energy sources may help reduce the SEER requirements of air conditioners, but it is unlikely. At the moment, the government of the United States remains focused on trying to ensure less energy is wasted during the production of cooled air. This costs less for the consumer and puts a minor strain on potentially struggling urban infrastructure.

The ongoing interest in lower consumption and more natural resources has many people concerned about the future of air conditioning systems. At this time, it seems unlikely that any significant changes will occur within the next few years. However, as time goes on and technology becomes more advanced, we may see significant advancements in this field that could reduce energy use and increase building efficiency.

Translate »
Refer a Friend