You need a new air conditioner. Perhaps the central AC doesn’t satisfy your needs, or maybe you just created a new addition in your home. The bottom line is that you need a moderate air conditioner to fill the gap.

So, you’ve been doing research, online and offline, and one thing has caught your attention – SEER ratings. All the experts you speak to say you should highly prioritize SEER ratings when selecting an air conditioner.

“No problem,” you say. “I’ll do it.”

The problem is – your favorite HVAC store only has 14 SEER and 18 SEER air conditioners! So now you’re even more confused, wondering which one would make the best choice.

Read on to determine why the SEER rating is a critical consideration when shopping for or assessing air conditioners. We also discuss how to choose between a 14 SEER and 18 SEER air conditioner.

## What is SEER Rating?

The SEER rating is a measure of an air conditioner’s energy level of energy efficiency. It gives you the answer to “how efficient is the AC?”

Energy efficiency is an important factor in air conditioning because keeping your home cool in the summer (and warm in winter) can be very expensive.

Most homeowners and renters pay hundreds of dollars in heating and cooling costs annually. Some even end up paying a few thousand. Indeed, studies show that heating and air conditioning account for over 50% of energy costs in the average American home.

An energy-efficient air conditioner is purposely designed to minimize energy consumption. As a result, the AC keeps the home cool and comfortable without drawing too much electric power.

The Department of Energy adopted the SEER rating and several other ratings to help homeowners determine energy efficiency for different ACs. The SEER value also helps shoppers compare different air conditioners to make the best choice based on their needs.

## How Efficient is 14 SEER vs. 18 SEER?

First off, both 14 SEER and 18 SEER are excellent efficiency ratings. According to the Department of Energy, any SEER rating above 13 is good.

However, perhaps you’ve already found out that the higher the SEER rating, the more efficient the air conditioner. It means that the 18 SEER air conditioner is more efficient than the 14 SEER model. Indeed, air conditioners sated 16 SEER or higher are considered highly efficient.

Anyway, how efficient is a 14 SEER AC vs. an 18 SEER AC? Is the difference significant enough to sway purchase decisions, or would the extra investment negate any long-term benefits? Let’s find out.

**How to Calculate AC Energy Consumption **

The best place to start is to understand how to calculate the SEER value. This will help us determine how much electricity an air conditioner draws at 14 SEER vs. 18 SEER.

The easiest way to calculate the SEER value is to divide the total cooling output of the air conditioner by the total energy/electricity input over the same period. Since it’s a “seasonal” value, we need to find the totals for an entire cooling season.

According to the DoE, the average cooling season lasts 125 days per year. The DoE also assumes that the average family runs the air conditioner for eight hours/day. Thus, the cooling season (in hours) is equivalent to 125 days x 8 hours/day = 1,000 hours per year.

Thus, SEER = AC BTU/hour rating x 1,000 days divide by AC kWh rating x 1,000 days. So, it comes down to BTU rating/AC kWh rating.

Thus, to determine how much power an air conditioner consumes per hour, we can divide the BTU rating by the SEER rating. For instance, a 30,000 BTU air conditioner rated 20 SEER consumes 30,000/20 = 1,500 watts per hour = 1.5kw/hour.

**How Efficient is a 14 SEER AC?**

Now that we know how to determine energy consumption rates, it’s easy to calculate how much electric power a 14 SEER AC draws per hour or even per day or year.

Assuming that you’re shopping for a 30,000 BTU air conditioner, perhaps for the living room, a 14 SEER air conditioner would draw 30,000/14 = 2,142.86 watts per hour. This is equivalent to 2.14 kilowatts per hour.

A quick extrapolation shows that the AC would draw about 17,142.86 watts, equivalent to 17.14 kilowatts per day. Over a heating season, the figure is 2,142.86 kilowatts.

We can go one step ahead and calculate the cost of running the 14 SEER air conditioner per day and over a cooling season. Using the current electricity prices in the US, i.e., 13.76 cents/kWh or $0.1376/kWh;

- The cost to run a 30,000 BTU, 14 SEER AC in a day = $0.1376 x 17.14 = $2.36
- The cost to run a 30,000 BTU, 14 SEER AC in a year = $0.1376 x 2,142.86 = $294.81

**How Efficient is an 18 SEER AC?**

We can follow the same process to determine the energy efficiency of a 30,000 BTU air conditioner rated 18,000 SEER. Again, we begin by dividing the BTU rating of the air conditioner by the unit’s SEER rating to determine the hourly energy consumption then extrapolate to determine daily and yearly electricity consumption.

So, in a day, a 30,000 BTU AC consumes 30,000/18 = 1,666.67 watts. This is equivalent to 1.67 kilowatts per hour.

Extrapolating for an entire day, i.e., eight hours, we get 1,666.67 x 8 = 13,333.33 watts, which equals 13.33 kilowatts. Over the entire year, the figure comes to 13,333.33 x 125 = 1,666,666.67 watts = 1,666,67 kilowatts.

We can also calculate the cost of running the AC per hour, day, and over a year. In a day, it costs $0.1376/kWh x 1.67 kilowatt hours = $0.2298. Thus,

- The cost to run the AC per day = $0.2298/hour x 8 hours = $1.8383
- The cost to run the AC per season = $1.8383/day x 125 days = $229.792

**What’s the Difference?**

Since you’re trying to choose between a 14 SEER and 18 SEER AC, it’s only sensible to determine the difference between the two to see if it’s big enough to sway your decision. And, indeed, it is.

Per day, you spend $2.36 – $1.84 = $0.52 more when running a 14 SEER air conditioner. Therefore, over the entire cooling season, or a year if you like, you spend about $65 more to run the 14 SEER air conditioner!

Maybe you also want to know how much more you’d spend or save over the life of the appliance, considering that an air conditioner is a significant investment for most families. The average lifespan of an air conditioner is 12 to 16 years, with 14 considered the middle point.

Thus, you’d spend $910 more on cooling costs over the life of the appliance if you go for the 14 SEER model. Or, you could save $910 by choosing the 18 SEER unit over the 14 SEER option.

## What’s Your Choice?

Of course, energy efficiency is just one in a long list of factors you should consider when shopping for an air conditioner. Other key factors include size, durability, the size of your home, and the home’s insulation value. Even your geographical location matters a lot.

However, you can see that picking the wrong SEER rating or ignoring SEER values altogether can be a big mistake. Fortunately, you can now make the right decision.