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Homes here in Milford, MA, depend heavily upon air conditioning in the summer. According to the Energy Information Administration, it makes up about 19% of your home’s energy use. The cost associated with that energy and the strain AC use puts on the energy grid are both high. That’s why the US government mandates minimum efficiency standards for all air conditioning systems. To help you judge the relative efficiency of ACs, every unit has something called a SEER rating. Here is everything you need to know about SEER ratings and how to use them to make smart AC purchases.
What Is a SEER Rating?
SEER stands for seasonal energy efficiency ratio. It’s a numerical efficiency rating given to air conditioning systems sold in North America. The number results from a formula that simulates how much energy an AC would use during an average summer. The idea behind the SEER system is to allow a simple way for you to compare AC efficiency at a glance. At a basic level, the SEER rating system is simple to use. In short, the higher an AC’s SEER rating, the more efficient it is. Right now, the least efficient AC you can buy here in Milford has a SEER rating of 14.
Who Invented SEER Ratings?
SEER ratings are an invention of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). They were introduced in 1975 to support the goals outlined in the Energy Policy and Conservation Act of 1975 (EPCA). That law included suggested efficiency targets for a variety of home appliances, including air conditioners. Those voluntary targets didn’t become mandatory until 1987, however. At that time, the new minimum efficiency for air conditioners nationwide was a SEER rating of 10.
The SEER Rating Formula
To calculate a SEER rating for a given AC, manufacturers begin with a much simpler efficiency measure called EER. That stands for energy efficiency ratio. It’s the result you get when you divide an AC’s hourly cooling output in BTUs by its wattage. This lets you know how much energy the air conditioner would use in an hour while at maximum power.
However, most homeowners don’t run their AC at maximum power at all times. So, the SEER rating attempts to simulate real-world usage using a formula. The formula assumes that your AC will run with an average outdoor temperature between 82- and 83-degrees Fahrenheit. Then, it applies an AC’s EER to the following usage assumptions:
- Running at 100% capacity for 1% of the time
- Running at 75% capacity for 42% of the time
- Running at 50% capacity for 45% of the time
- Running at 25% capacity for 12% of the time
In that way, the SEER model reflects how much energy an AC might use under real-world usage conditions. Unfortunately, it isn’t perfect. One reason is that the testing used to arrive at a SEER rating happens in a laboratory setting. As a result, it doesn’t accurately account for things like the static pressure in the average home’s ductwork. While that may sound inconsequential, it results in AC systems performing less efficiently in real homes. It is precisely that kind of shortcoming that led to the creation of a successor to SEER called SEER2.
The Difference Between SEER and SEER2
To the end user, there’s little difference between the SEER and SEER2 standards. It involves a change to the testing procedures used to calculate AC efficiency. Specifically, it includes a modified blower testing procedure that increases static pressure by a factor of 5. That refers to the resistance an AC blower motor faces when trying to push air through a home’s ductwork.
Right now, AC manufacturers are still navigating the transition to SEER2, so not every unit may have the new rating. So, you must be mindful of this when shopping for a new AC. Look carefully at the specifications of any unit you’re considering to see if it has a SEER or SEER2 rating. If necessary, you can roughly convert between the two ratings to allow for fair comparisons. To do it, divide a SEER rating by 1.05. This will give you an approximate equivalent SEER2 value.
Comparing AC Efficiency Using SEER
Unfortunately, the SEER rating system only partially succeeds in its goal of helping consumers gauge relative AC efficiency. This is because SEER ratings don’t reflect linear efficiency gains. The higher the SEER ratings go, the less efficiency you gain from each step up. Take, for example, the difference between a 15 SEER AC and a 16 SEER AC. In that case, you’d get a 6.67% efficiency gain by choosing the latter. However, the difference in efficiency between a 22 SEER AC and a 23 SEER AC is only 4.54%. That complicates things when you try to figure out if a more efficient and expensive AC is worth its price.
Fortunately, it isn’t hard to calculate the efficiency difference between two SEER ratings. To do it, you begin by dividing the higher SEER by the lower SEER. Then, subtract one from the resulting number. Then, to convert your result into a usable percentage, multiply your answer by 100%.
You can also use an AC SEER rating to estimate how much a given system may cost you to operate. To do that, just divide the BTU output of the AC you’re considering by its SEER. That will let you know approximately how many watts, on average, the AC uses each hour. You can divide that number by 1,000 to convert your answer to kWh. Your power bill will tell you how much you pay for electricity by the kWh. Using all of that information, you will know exactly how much an AC will cost you to operate per hour.
You may be shocked to find out how little a more efficient AC will save you on electricity. That’s especially true when you compare those savings to the price premiums commanded by high-SEER ACs. Generally speaking, if you can’t recoup the price premium of an AC within 15 years, you never will.
Your Trusted AC Efficiency Experts
Since 2003, Tingley Home Services has been a leader in efficient AC solutions for homes in Milford. We offer complete HVAC services, including installation, repair, and maintenance. Our HVAC experts can help you choose a new AC that meets your efficiency goals and budget. We also sell and install heat pumps and work with the Mass Save program. We can help you navigate that program to help you qualify for big rebates on new heat pump systems. Plus, we also offer residential electrical services, should you need those too. We’re also Better Business Bureau accredited with an A+ rating and maintain high customer ratings on Angi. We also have a long list of glowing reviews from our many satisfied customers. So, if you need an efficient AC solution for your Milford home, call Tingley Home Services today!
