SEER Energy Savings Calculator

How Does the Calculator Work?

So, you want to know more about the SEER calculator? Here’s a basic explanation of how it works. The calculator’s primary purpose is to help you compare the cooling costs of two air conditioners with different SEER ratings, and to estimate your savings over a one year, five year, ten year and fifteen year time period. 

The calculator determines how much you are spending on cooling your home per year based on four factors:

• the SEER rating of your current air conditioner (learn how to find your AC’s SEER rating)
• Your air conditioner’s size (in tons)
• the cost of electricity per kilowatt-hour (Kwh) in your state and
• the annual cooling hours for your location (estimated by the EPA in 2002).

It then compares this data with that of a higher efficiency air conditioner to determine how much an AC with that SEER rating could save you annually in cooling costs. The air conditioner energy calculator also displays your projected cumulative savings over a five year, ten year and a 15 year period. In most cases, the potential savings are pretty amazing!

What is SEER?

SEER is the rating system representing the energy efficiency of air conditioners and heat pumps. It stands for Seasonal Energy Efficiency Ratio. The higher the number, the less electricity the air conditioner or heat pump consumes.

SEER is officially defined in the AHRI (Air Conditioning, Heat and Refrigeration Institute) Standard 210/240, “2008 Standard for Performance Rating of Unitary Air-Conditioning & Air-Source Heat Pump Equipment”.

How is SEER Rating Calculated?

According to the AHRI standard, SEER is calculated by first determining the total amount of heat removed from a home during a typical year’s cooling season. This number is expressed in Btu’s (British thermal units¹). The Btu’s are then divided by the total electrical energy the air conditioner or heat pump uses during that same cooling season. This is expressed in watt-hours (Wh). So, SEER = Btu / Wh.

SEER is also calculated based on indoor and outdoor temperature. Naturally, the outdoor temperature during a typical cooling season is not constant. It varies based on weather and climate. The SEER equation makes an effort to account for this by mimicking a typical cooling season, using a range of possible outdoor temperatures, 65°F to 104°F to be exact. These temperatures are divided into 8 sets or “bins” of 5° increments. Each bin’s average temperature is assigned a fraction of the total annual cooling hours.  The indoor temperature, on the other hand, is based on a set 80° with a 50% relative humidity. (This applies to the temperature of the return air, not the supply air.)

If this explanation isn’t in-depth enough for you, feel free to hunker down for some further reading in the AHRI standards document.

It should be noted that this is the way we calculate SEER in the USA. The Europeans have their own rating system, called ESEER (European Seasonal Energy Efficiency Ratio, to state the obvious).

¹A British thermal unit (Btu) is essentially a unit of heat. 1 Btu is equivalent to the amount of heat it takes to raise the temperature of one pound of water by one degree Fahrenheit.

A Note About HSPF and EER

We should also note two other HVAC energy efficiency acronyms you might come across – namely, HSPF and EER. While these are not addressed on our AC energy savings calculator, it’s important to know what they mean. 

In addition to a SEER rating, heat pumps also carry an HSPF rating, related to the efficiency of its heating capabilities. (In case you don’t know, the only difference between a heat pump and an air conditioner is that a heat pump is able to run in both directions. It simple terms, it can either cool your home by transferring warm air from the inside of your home to the outside, or it can heat your home by transferring warm air from the outside, inside.) Thus, HSPF stands for Heating Seasonal Performance Factor.

Similar to SEER, HSPF is calculated by dividing the total Btu’s¹ of required to heat your home during a typical season by the total watt-hours of electricity the heat pump consumes during that same season.

EER, standing for Energy Efficiency Ratio, is also similar to SEER and is calculated in a nearly identical manner (Btu/Wh). The main difference is that EER doesn’t take into account fluctuations in the average outdoor temperature during the cooling season. Instead, its basis is a constant outdoor temperature of 95° F. On the other hand, SEER calculations, as discussed above, are made based on outdoor temperatures ranging from 65°F to 104°F. Both SEER and EER equations use the same set indoor return air temperature.

What are the Current Air Conditioner Efficiency Standards?

Ever wondered why you can’t find an air conditioner with a lower than 13 or 14 SEER rating anymore? That’s because there are national energy efficiency standards that enforce a minimum SEER rating on all air conditioners and heat pumps sold and installed. The latest update to these standards went into effect on January 1, 2015. This map shows the current minimum SEER, HSPF and EER ratings by region:

Air conditioning efficiency standards in the USA are set to undergo more changes in the coming years. On May 26, 2017, the Department of Energy (DOE) published a notice confirming an effective date of January 1, 2023 for the next set of energy conservation standards.

All this being said, it is still possible to own an air conditioner with less than the minimum SEER rating. In fact, if your air conditioner dates from before the first efficiency standards went into effect in the 1990’s, it may carry as low as a 6 SEER rating. (If this describes your AC, then you probably already noticed that the “current air conditioner” slider on our energy savings calculator doesn’t go below 9 SEER. Hint, hint.)

How Do I Find My Air Conditioner’s SEER Rating?

If you’re unsure of your air conditioner’s efficiency rating, here are a couple ways you can easily find it:

• First, go outside and look at your condenser unit. Many newer air conditioners have a large, yellow sticker on the side that clearly states the SEER rating along with some other specs.
• If your unit doesn’t have a yellow sticker, or if the sticker is too weather-beaten to be legible, trying looking at your air handler. The air handler is probably somewhere inside your home, in the attic, or in your garage. There might be a sticker on it with some information about your unit, including the SEER rating.
• If these two options fail, you can try locating your air conditioner’s manufacturer, model number and the serial number. This information should be written somewhere on the condenser or the air handler. You can then go online and look up the manufacturer’s website. Once you’re on their website, you have two options. You can either:
  • call the manufacturer’s customer service hotline, give them your model and serial number, and ask them for your unit’s SEER rating; or,
  • locate a local, certified dealer of that manufacturer’s products (most manufacturer websites have a dealer locator) and call them. Many companies will be happy to help you in your quest.

If none of these options worked for you, this article has more tips on how you might be able to find your AC’s SEER rating. Best of luck!

Mismatched Systems

It must be noted that your air conditioner’s condenser and air handler must match in order for the unit to perform at its top potential efficiency. 

What do we mean by “match”? Most manufacturers make their air handlers compatible only with certain condensers for optimal performance. HVAC contractors are generally required to install air conditioners in these matched sets, but this unfortunately does not always happen.  If your unit is mismatched, it’s unlikely that it will achieve the SEER efficiency promised on its label. Rats!

What is AC Tonnage?

We know what you might be thinking – and no, tonnage does not refer to the physical weight of your air conditioner. Although tonnage is often referred to as the AC’s “size”, this really means its cooling capacity. More specifically, it tells how much heat the unit is able to remove from your house in one hour. For instance, a one ton air conditioner can remove 12,000 Btu’s of heat from your house in one hour’s time. A two ton air conditioner can remove 24,000 Btu’s, and so on.

So, what size of air conditioner do you need to effectively cool your home? That depends on various factors such as your home’s square footage, the number of occupants and the number of windows. Here’s a chart containing some of the typical AC sizes by square footage. If your home is larger than these examples, you may need multiple air conditioners working simultaneously. Anything over a 5-ton air conditioner is considered a commercial size and is not available for residential use.