What is Energy Efficiency Ratio (EER)?

Feeling that heat seeping through, even when your AC is on full blast? Or perhaps you’re ogling those energy bills, hoping there’s a cheat code to whittle ‘em down? You’re not alone. But if there’s one neighborhood trend that lets you keep your cool without spending a bundle, it’s knowing a few key numbers. And the largest one you are looking at? Energy Efficiency Ratio, or EER.

So what is Energy Efficiency Ratio? No need for the fluff, let’s just get right down to it.

What is EER (Energy Efficiency Ratio) and Why It’s Your Hiding-in-Plain-Sight HVAC Powerhouse

Well, let’s get down to brass tacks. Energy Efficiency Ratio (EER) is essentially your cooling system’s report card. It’s an essential metric that lets you compare how effectively your air conditioner or heat pump can turn electricity into something that feels like cooling. Think of it as a ratio: for every bit of electrical juice you give it, how much cool air does the air conditioner spit out? That’s your EER. The more that number grows, the better your unit is doing at its job. That’s doing more with less, and let’s be real, that’s aggressively flaunting saving money AND the planet.

That ratio juxtaposes the cooling power of your system (expressed in British Thermal Units, or those BTUs of cooling power per hour) with the total electrical input it sucks down (in watts). Simple, right? Hold that thought! There’s a new shortening in town that you should know about: EER2.

EER2: Updated Efficiency Rating – Your New Standard

If you’ve been around long enough, you may be familiar with EER, but if you’re shopping for a new cooling system today, you’re probably seeing “EER2.” What’s the deal? EER2 is an extended and beefed-up version of EER. This new code actually took effect on all cooling equipment installed on or after Jan. 1, 2023.

Why the change? So, it’s that the old way of doing the EER test was nice, but the new way EER2 test is much better. It accounts for higher external static pressures, meaning you get a more realistic interpretation of how a unit will function in your real home. Because of these more strenuous test conditions, do not be surprised if the EER2 values are slightly less than older EER numbers for similar models. The unit didn’t get worse, the test got smarter.

The EER2 ratings that aren’t just pulled out of a hat. They’re calculated under some narrow, real-world-like conditions: an outside temperature of 95°, indoor temperature of 80 and humidity level of 50 percent. This configuration is meant to simulate those peak cooling times when your AC has to kick in.

Crack the Code: The EER and EER2 Formulations

So, enough talk, let’s get deep without getting too bogged down. In fact, the formula to be used for determining EER (fort EER2, too, because the formula is the same, only the test conditions differ) is very simple:

EER is a ratio of cooling capacity (in British thermal units [BTUs] per hour) to power (in watts).

Let’s work through a few simple examples to make it extra super clear:

Scenario 1: Picture an air conditioning unit that can produce 24,000 BTUs of cooling in an hour and chews up 2,000 watts of electricity.

EER = 24,000 BTU/hr / 2000 wattsc= 12parms a 2.7pFODINAT 24072200300 or) =Example 3: Determine the specific power (P/W) per unit volume of ice produced [5].

EER = 12

That is, for every watt of electrical power it consumes, that particular unit will deliver 12 BTUs of cooling. Not bad for investing some energy!

Scenario 2: You have another AC. This one provides 12,000 BTUs of cooling and uses 1,200 watts.

EER= 12,000 / 1,200 = 10.

EER = 10

See? You’re looking to jockey higher numbers here in any case. It’s how your unit ranked on the efficiency log.

EER/EER2 is Your Home’s Best Friend… here’s why; The advantages

So why care about EER and EER2 after you’ve taken a little pop quiz on them? The latter number is ours, and all the other ones are yours, tied straight to your wallet, your comfort, your planet. Opting for a system with a high EER2 is not just a smart choice — it’s a power play.

The reason understanding these ratings is your home’s best friend:

• Big Savings through Lower Energy Bills: This is the huge one, isn’t it? The higher the EER2, the leaner, meaner, cooling machine you’ve got. It consumes far less electricity to deliver to you the same excellent cooling output. What does that mean for you? Lower utility bills and more money to keep in your bank account. Just think what you could do with all that extra dough every months. That’s a serious win.
• Less Environmental Impact: And speaking of your money, a high EER2 unit is also a victory for Mother Earth. If your system consumes less of it, that diminishes the overall demand for fossil fuels that power the grid. Less demand means less greenhouse gas emissions, and that, my buddy, is how you shrink one’s carbon footprint. It’s about being responsible, stress-free.
• Enhanced Cooling and Comfort: Not only will you save money, but you will also get to enjoy life. A unit with a high EER is a heat-removal champion in your home. That directly translates into cooler, more consistent cooling performance and more comfort, especially when those outside temperatures are trying to melt your face off. And no more hot spots, no more indoor sweat. Just plain, simple comfort.

Said another way, a high EER2 system is not a purchase obliviated; it’s an investment in comfort, an investment in savings, and an investment in a healthier planet.

EER2 vs. SEER2: The Efficiency Metric Tag Team

Okay, so now you’re getting clever with EER2. But then you may encounter another acronym: SEER2. What’s the distinction, and do you need to know about both? Absolutely. Think of EER2 and SEER2 as two key players in the efficiency game who, when broken down separately, perform different tasks.

EER2 (Energy Efficiency Ratio 2): This is like the previous version, but it does the same test except this time at a single, peak cooling temperature – namely 95°F outdoor. It would be like calculating your car’s fuel consumption when you’re flooring it on a motorway. It’s a snapshot, a single piece of data, about how your unit reacts under pressure.”

SEER2 (Seasonal Energy Efficiency Rating 2): This number gives us an expanded look. SEER2 tracks the efficiency of your air conditioner over a full cooling season. It accounts for a mix of outdoor temperatures, from a comfortable 65°F all the way to a blistering 104°F. So, if EER2 is your car’s highway cruise driving performance, SEER2 is its combined fuel economy over a year of all sorts of driving. It’s an average of cooling effectiveness across diverse temperatures.

Why do both matter? The picture that SEER2 takes of your air conditioner is a good one, but EER2 is important as well, especially if you live in areas of the country with high levels of sustained heat and humidity, such as in the South. Why? Because if 95°F (or even hotter!) is a regular summer day where you live, you may know from experience: Drips and dribbles don’t really cut it., how efficiently your unit is able to operate at that peak temperature becomes all the more important.

Here’s the rub — a unit can have a SUPER high SEER2, which indicates that it is SUPER efficient under mild conditions. But if its EER2 is lousy, the same unit may get fussy and develop a thirst for power when it’s truly hot outside. For 80% of the summer, you could be comfortable with them, but that 20% of really hot weather could completely dismantle your budget and your comfort. Knowing both ratings can help you choose a unit that performs when you need it most.

Fair Game: Regional Codes and ENERGY STAR® Mandates

It’s not simply a matter of choosing a good number — there are actual rules in place. The minimum efficiency standards for air conditioners in the United States are defined by the Department of Energy (DOE), but regional requirements varies according to SEER rating. That is to say, minimum in the North might be different from the Southwest or Southeast.

Here is a simpler breakdown of how some regional standards shake out for cooling systems, given the parameters in the DOE’s guidelines:

The 11.7 EER2 applies to products with a certified SEER2 less than 15.2. The 9.8 EER2 applies to products with a certified SEER2 greater than or equal to 15.2. *The 11.2 EER2 applies to products with a certified SEER2 less than 15.2. The 9.8 EER2 applies to products with a certified SEER2 greater than or equal to 15.2.

Then on top of these energy regional standards, there is the ENERGY STAR® designation. This is the ultimate in energy conservation. If a unit wears that signature blue tag, you can be certain that it has had to adhere to some seriously stringent standards issued by the U.S. Environmental Protection Agency.

In order for that ENERGY STAR® emblem to grace an HVAC product, it has to meet certain minimums for EER2, SEER2, and in the case of heat pumps, even HSPF2 (Heating Seasonal Performance Factor2). And if you want to get fancy, for split systems, the outdoor unit-which notoriously makes more noise than the indoor unit-must be matched to compatible indoor coils. A team on a quest for maximum productivity.

For instance, to be ENERGY STAR® certified you’ll need:

• Central Air Conditioners (CAC) Split systems must have a minimum ≥15.2 SEER2 / ≥12.0 EER2.
• Minimum ≥7.8 HSPF2 / ≥15.2 SEER2 / ≥11 EER2 for Heat Pump (HP) split systems.

These specifications ensure that when you buy a new unit, you are purchasing a product that will actually be efficient.

Increase Your EER: What Counts & How To Increase

So you have a system, or you’re considering a new one. There’s no indication on how to make sure it’s always operating at peak efficiency, meaning an equivalent EER (or EER2)? It’s not just about the digits on the box. There are a few factors that contribute to how much energy your HVAC is truly using. Knowing them could be your secret weapon to slashing those energy bills.

Factors Influencing the Performance of EER/EER2 or EER3:

1. Size and Capacity of Equipment: This is a huge one. It’s a little like buying clothes — if it’s so large, it’s sloppy; if it’s too small, it’s uncomfortable. Same for your HVAC. An undersize system is going to fight and fight and fight to cool your space, continuously running and never really getting it cool because it’s a relatively small unit relative to the amount of cooling you want — and it’s wasting energy. An oversized system? It will cool your room too quickly and short-cycle (blast on and off repeatedly) without removing moisture adequately, causing potential inefficiency and that clammy feeling. Size matters when it comes to efficient energy use.
2. Insulation and Sealing: Your HVAC system is struggling to keep your home comfortable. But if that conditioned air is escaping through cracks, gaps and poorly insulated walls, it is akin to filling a leaky bucket. Good insulation and a tight seal (which brings us back to windows, doors, ductwork) are nonnegotiable. They retain the cool air and keep the hot air outside, reducing the burden on your HVAC.
3. Maintenance / Tune-Up / Regular Service: This is more than a way of keeping your unit from breaking down; this is a way of keeping your unit lean and mean. Clogged air filters limit airflow, causing your system to work harder. The inability for blocked coils to exchange heat properly is murder on your EER. Worn-out components? They’re just energy sinks. Regular maintenance and quick repairs are very much necessary in order to keep the energy efficiency of your system.

Tips YOU CAN ACTUALLY USE To Make Your System More Efficient (And Your EER Better! ):

Are you ready to help energy work harder for you? Below are a few of the more straightforward (but effective) ways you can help make your system more efficient in use:

• Upgrade to a More Efficient Unit: If your system is outdated, you may need to change it out. Newer models, especially ENERGY STAR® certified models, have much higher EERs which results in direct savings and pay-off. It’s a good investment that yields dividends.
• Make Sure it’s Installed and Sized Correctly: This is a biggie. And don’t have just anyone set up your system. Rely on an experienced HVAC contractor to help match your unit to your home’s particular requirements and ensure a quality installation.
• Clean or Replace Air Filters Regularly: This one is such an easy win. A dirty filter restricts airflow across the air handler, causing your system to unnecessarily work harder. Put it on your schedule, make a reminder, get it done.
• Don’t Forget to Lock It Up: It may not be apparent, but the obvious considerations often get overlooked first. Stop letting that precious cool air out, if you run an AC.
• Employ Ceiling Fans: They are more than decorative. Wind-chill effect Ceiling fans cool you off by making you feel cooler rather than actually lowering the temperature of the room. That means your a.c. doesn’t have to work as hard, saving energy and giving it a little rest.
• Raise Those Thermostats When You’re Not Home: No need to keep an empty house cool. And when you’re out of the house, nudge the thermostat up a couple of degrees. It will save energy, and your system won’t have to work so hard to catch up when you return. Smart thermostats like these make it a no-brainer.
• Seal Air Leaks in Your Home: Look for leaks around windows, doors, electrical outlets, and ductwork. Fill them in using caulk or weatherstripping. It’s like repairing holes in that leaky bucket we just talked about.
• Make Sure the Unit is Level: When it comes to outdoor units, in particular, a unit installed level means efficient draining and operation.
• Keep Heat-Producing Appliances Away from the Thermostat: Lamps, TV and, yes, direct sun exposure, can trick your thermostat into thinking your house is warmer than it is, which may cause your AC to work harder than it needs to and waste energy.
• Fan Speed: In most cases medium or hign fan speed. But on the very dewy days, low fan can actually increase dehumidification and comfort. It’s a nice little trick for those sticky days.
• Employ Interior Fans With Window Air Conditioners: With window air conditioners, you can use a small interior fan to spread the cool air more completely and reduce your overall power usage (and, perhaps, both help and give your air conditioner a warming break).

With these consider in place and these tips applied, you’re not just reading about EER, you’re living it.

Picking Your Champion: Choosing the Right System Based on EER2

All right, you’ve got knowledge in your corner. So now that you’ve learned all this EER2 wisdom, how do you actually use it to choose the optimum cooling system for your house? “Not all points are created equal,” Ms. Goodspeed said It’s not just about racking up the highest number; it’s about what makes sense for your own unique circumstances.” Consider it recruiting your dream team; after all, you could use the comfort and savings.

And here is what to keep in mind when you’re in the market for a new system:

• Climate Matters: If you reside in an extremely hot and dry climate, the high EER2 rating will not be a luxury but a necessity. And remember, EER2 measures efficiency when it is at peak super-hot temperatures. So if your summers are relentless, this metric is your co-pilot to top form.
• Energy Savings vs. Cost: The classic tug-of-war. Units with higher EER2 ratings are generally more energy-efficient, and that translates into chunks hacked off your monthly cooling bills. The flip side? They may cost more in the first place. But here’s the rub: in many cases, the learning’s long-term savings dwarf the upfront cost, meaning a higher EER2 unit is a much wiser financial bet over the life of the system. It is an investment, not an expense.
• Size and Cooling Needs: We’ve been hammering this home, but it’s just that crucial. Even if you land a unit with a phenomenal EER2 rating, if it isn’t sized correctly for your home, you’re leaving money and comfort on the table. An undersized unit will never be able to keep up, and an oversized unit will short-cycle and cause humidity problems and waste energy. That it better get right, because all those fancy numbers are meaningless and worth squat.
• Hire the Pros: Most people are not going to want to take that on themselves. The surest way to be an informed consumer make working with an experienced HVAC consultant your first step to make an informed decision. Whether you select a Trane Comfort Specialist™, a Carrier® or a Lennox dealer, these pros can size your AC so that you can stay comfortable while maintaining an energy-efficient footprint. They’re the gatekeepers to your optimal comfort and efficiency.

Selecting a system is a major decision, and with EER2 working for you and an expert to guide you, you’re on the road to success.

Beyond EER: Other Terms Used to Measure Energy Efficiency

EER is a star, but it’s also part of a larger galaxy of terms for efficiency. Being familiar with a few more can help give you an even more complete picture of how energy works in your home and beyond.

• Coefficient of Performance (COP): COP is EER’s European brother, in particular for heat pumps or air conditioners. Whereas EER is based on BTUs/hr per watt, COP is generally a simple ratio of output (heat or cooling) to input (electricity) provided in equivalent units. Fun fact: a COP of 1.0 is approximately the same as an EER of 3.4. So when you see COP, you can think of similar efficiency metrics, but with different units, if that makes sense.
• Heating Seasonal Performance Factor (HSPF/HSPF2): Where EER and SEER focus on cooling, HSPF (and its successor, HSPF2) is all heat, which is good for heat pumps. It indicates a heat pump’s overall energy efficiency over an entire heating season. Louisiana and California The Higher The HSPF2 = the more efficiently the unit delivers heat to your home.
• Energy Efficiency (General Definition): At its widest, energy efficiency—referring to the term’s use in engineering and science—describes a goal of minimizing the amount of ‘wasted’ energy. It’s a measure of how efficiently something uses energy, specifically, the ratio of the useful output of a process to the energy input into that process. Think about boiling water: the “useful output” is the hot water, and the “energy input” is the electricity or gas you’ve put in. The criteria are output over input cost and the future should be about the same for all. “The idea to use optimisation as an approach applies to everything from the performance of a house to industrial manufacturing, where we can compute with thermodynamic, thermo-physical, thermo-economic, and economic criterions,” explains Favrat.
• Energy Payback Period: This one is playing the long game. For something like an energy storage system (batteries, for example, for solar panels), the energy payback returns the total life-cycle electricity produced by that system to all the energy it took to build, install, maintain and finally decommission it. It’s a question of how quickly the system must “pay back” the energy invested in its construction.

It is also important to mention that the term EER is not only limited to HVAC systems. For instance, it crops up in cutting-edge computing, like deep learning platforms, where the unit can be TFLOPS (teraflops, a measure of computing power) per watt, which tells you how much computing power you get for every watt that’s being sucked up. This is to show how important energy efficiency is becoming for all industries – not only to be able to cool your home.

Summary: Being wise with your EER (energy efficiency ratio)

Knowing what is the Energy Efficiency Ratio (EER) — and its newer, more accurate cousin EER2 — is a game changer when it comes to keeping your home comfortable and your energy bills manageable. It’s your hand at the wheel when you’re surfing the realm of air conditioners and heat pumps, too — steering you toward units that are seriously powerful and fabulously efficient.

And when you potential purchase a high EER2 unit, you’re not just getting comfort, you’re investing in long-term savings and a smaller carbon footprint, during the hottest parts of the day. Just keep in mind it is the EER2 so it’s going to be a peak performance while still important, especially if you live in a hotter climate.

Don’t go it alone. As always, your best move is to call your favorite HVAC pro. They can walk you through choosing and correctly sizing a system that will best suit the unique needs of your home, making sure you’re fully enjoying the value of your purchase.

With that said, now you should be empowered to make wise decisions that will keep you cool and comfortable for years and years, and make the most of your Energy Efficiency Ratio.

EER Frequently Asked Questions

What is a good EER2 value?

The good value for EER2 really depends on which kind of split system we are looking at and its capacity. Higher is usually better on the rating scale for energy efficiency. As a reference, many EERs for utility rebates on heat pumps begin at EER2 11.7 or a little bit higher and for air conditioners, 12 and higher. For ENERGY STAR® certification, Central Air Conditioners (CAC) split systems must meet a minimum of ≥12.0 EER2.

How does EER compare with EER2?

Both EER and EER2 indicate energy efficiency, however; EER2 is an energy efficiency ratio developed at a later date. EER2 utilizes a more recent/accurate test procedure that will account for higher external static pressure which can yield higher actual system SEER. Due to these more severe test requirements, type EER2 values generally tend to be slightly lower fraditional type EERs of equivalent equipment. EER2 was adopted for all cooling equipment installed on or after January 1, 2023.

Question About the differences between EER2 and SEER2.

Both EER2 and SEER2 calculate energy efficiency, but they do so at different times and under different circumstances. The EER2 rating is a certain efficiency chart at peak (95°F outdoor) temperatures. Think of it as a picture of performance, cut in the harsh midsummer sunshine. SEER2 (Seasonal Energy Efficiency Rating 2) The efficiency ratings are based on the systems performance over an entire cooling season. Efficiency is established based on a 65°F indoor temperature and a 95°F outdoor temperature. efficiency specifications are based on a 107°F outdoor temperature and a 80°F indoor temperature. Both are important, but EER2 specifically addresses performance in extreme heat.

Why it matters more in hot climates EER2?

Note: EER2 is particularly important in hot climates like the Southern U.S., because it gauges how efficient units operate at 95°F. If you live in an area where temperatures are around or over that in summer, your EER2 rating indicates how your cooling system will stand up to and function in sweltering, high-demand conditions. A unit can have a high SEER2 but a low EER2, suggesting it is efficient in moderate conditions but might have hard time when it gets really, really hot.

How do I make my current AC EER (/ energy efficiency) better?

Even if you don’t, you can still greatly improve the efficiency of your system:

• Keep air filters clean or replace them frequently to maintain good airflow.
• Close doors and windows during AC use.
• Having the ceiling fans on to help circulate air can also help make you feel cooler.
• Turn up the thermostat when you’re not at home.
• Weatherstrip any spaces in your home’s insulation, windows or doors.
• Make sure your outdoor unit is level so water removal is easy.
• Don’t put appliances that give off heat near your thermostat.
• Consider having regulary maintenance by an professional HVAC technician yearly.