What Is the SEER Index Rating and How Is It Calculated?

Michael Tobias
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    -The Seasonal Energy Efficiency Ratio or SEER is an efficiency metric for unitary air conditioners (and air-source heat pumps in cooling mode).

    -The Air-Conditioning, Heating and Refrigeration Institute (AHRI) developed the SEER to describe cooling performance under a wide range of typical weather conditions.

    -The SEER can be compared with the MPG value of a car. Just like a car with a higher MPG consumes less fuel, a cooling system with a higher SEER consumes less electricity.

    -The SEER is a ratio of cooling output (in BTU) and electricity input (in watt-hours), considering the entire cooling season.

    -Unlike other energy efficiency metrics, which are calculated for a single operation condition, the SEER considers a range of outdoor temperatures from 65°F to 104°F.

    -In the US, the minimum acceptable SEER is 13 in northern states and 14 in southern states as of 2022. The requirement increases to 14 and 15 in 2023.

    Having a numerical indicator of energy efficiency is useful when purchasing any piece of equipment. For example, we look at the gas mileage value when comparing vehicles, since a higher MPG results in fuel savings. The SEER or Seasonal Energy Efficiency Ratio is the metric used to describe unitary air conditioners, as well as air-source heat pumps operating in cooling mode.

    The SEER is very useful when comparing cooling equipment, since it provides a clear indication of the efficiency you can expect. In this article, we will provide an overview of how the SEER value is determined and how it translates into electricity consumption. For a given cooling load in BTU/hour or tons of refrigeration, the air conditioner or heat pump with the highest SEER will have the lowest electricity consumption.

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    Space cooling equipment with a higher SEER not only reduces your electricity bills. You can also qualify for incentives such as the new energy efficiency tax credits and rebates, introduced by the Inflation Reduction Act in August 2022.

    How Do HVAC Manufacturers Calculate the SEER Value?

    air conditioners

    Traditionally, the performance of heating and cooling equipment has been described with the Coefficient of Performance (COP) or the Energy Efficiency Ratio (EER). Both metrics describe energy efficiency, but using different units.

    The COP is the ratio of cooling output and electric power input, when both values are measured in the same unit (typically watts or kilowatts). For example, an air conditioning system that delivers 3,200 W of cooling for every 1,000 W of electric power has a COP of 3.2.

    The EER is also a ratio of cooling output and electric power input, but the output is measured in BTU/hour and the input is measured in watts. For example, an air conditioner that delivers 12,000 BTU/hour when consuming 1,000 W has an EER of 12. You can convert a COP value into an EER value if you multiply the COP by 3.412.

    Although the COP and EER are useful, they have a major limitation: they don’t describe the efficiency of cooling equipment under the wide range of temperatures you can expect during summer. For this reason, the Air Conditioning, Heating and Refrigeration Institute (AHRI) developed the Seasonal Energy Efficiency Ratio (SEER), which describes average performance during the cooling season.

    The EER is calculated for a single operating condition - an indoor temperature of 80°F and an outdoor temperature of 95°F, at 50% relative humidity. On the other hand, the SEER calculation considers a range of outdoor temperatures from 65°F to 104°F. 

    What Is the Minimum SEER for Air Conditioners in the US?

    As of 2022, the minimum SEER value accepted by the US Department of Energy is 13 in northern states and 14 in southern states. In 2023, the minimum requirement will be increased to SEER 14 in northern states and SEER 15 in southern states. However, you can currently find air conditioning units with SEER ratings as high as 25-30 in the US market.

    The requirements for air conditioners and heat pumps with the ENERGY STAR label are more stringent. The US EPA requires a SEER of at least 15 for air conditioners and heat pumps with a capacity below 65,000 BTU/hour. This requirement applies for both split-type units and packaged units.

    Typical Savings When Upgrading to Higher SEER Air Conditioners

    air conditioning savings

    A professional energy modeling service is recommended if you want an accurate calculation of heating and cooling costs in your building. However, you can estimate the savings of an air conditioning upgrade based on the SEER rating of your current units and the upgrades being considered.

    An air conditioner with a cooling output of 24,000 BTU/h and the minimum SEER 13 rating can be expected to consume around 1,846 watts (24,000 divided by 13).

    • Assuming this unit operates for 250 hours in a month, the consumption is 461.5 kWh.
    • At an electricity price of 20 cents/kWh, this air conditioner adds $92.30 to your bill.
    • In a multifamily building with 30 of these air conditioners, the electricity cost is $2,769.

    If these air conditioners are replaced with SEER 25 units, the average power consumption of each unit decreases to only 960 watts. The energy consumption per unit drops to 240 kWh, equivalent to $48. In total, all 30 units would be consuming around 7,200 kWh at a cost of $1,440 per month.

    In this simplified example, the upgrade from SEER 13 to SEER 25 air conditioners saves over 6,600 kWh per month, equivalent to more than $1,300 in monthly bills (assuming 30 AC units).

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    Tags : air conditioner upgrade efficient air conditioning Seasonal Energy Efficiency Ratio Energy Efficiency Ratio SEER

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