How SEER2 15+ energy efficient air conditioners handle heat and humidity.

Energy efficient air conditioners that tackle our region’s tough conditions.

Replacing or upgrading your AC with a SEER2 15+ energy efficient air conditioner may not be as exciting as a cool summer road trip to an icy northern lake, but if you’re tired of sweltering inside your own home, it could be a close second. 

Whether your family has lived in the Tennessee Valley for generations or you’re experiencing your first summer in our beautiful seven-state region, you know — or you’ll soon discover — that heat and humidity are the area’s dynamic discomfort duo. They’re tough on you, and they put the hurt on your home’s AC unit. 

Fortunately, modern air conditioning technology helps maintain comfortable indoor humidity levels and consistent indoor comfort during peak heat season. Understanding what SEER2 means and why a SEER2 15+ system can help you save money on energy costs year after year is what this article is all about.

You can read from start to finish or click on a link below to jump to sections that you’re most interested in.

What does SEER2 mean and why does it matter for your home?

SEER2 vs. SEER: what changed and why it matters.

What’s a good SEER rating?

Why high humidity makes your home feel hotter.

How heat and humidity impact your AC system.

What’s a variable-speed compressor, and how are they different from single-stage compressors?

Is it time to upgrade or replace my air conditioner?

What does SEER2 mean, and why does it matter for your home?

What is SEER2? Glad you asked! We’ve already written about the top 4 benefits of higher SEER2 ratings, but read on for a more detailed explanation.

SEER2 stands for Seasonal Energy Efficiency Ratio 2. Think of it as the miles-per-gallon rating for your air conditioner (or heat pump): The higher the number, the more you save on energy. 

The new SEER2 rating went into effect a couple of years ago, but lots of homeowners are just now learning about the new ratings. In fact, you may continue to notice products marked with both a SEER and SEER2 ratings while manufacturers adopt the new standards. 

So what does SEER2 do, exactly? It measures your system’s total cooling output over a season divided by the total energy it uses to get there. A higher SEER2 rating means your system works smarter, not just harder — and that translates directly into lower cooling costs for your household.

Curious about how SEER2 is calculated? We asked our experts, and you can find the answer in our SEER2 FAQs.

SEER2 vs. SEER: What changed and why it matters.

The original SEER system has been in use since 1992 and measures efficiency under controlled, laboratory-style conditions. SEER2 uses a more realistic testing method that accounts for real-world factors such as ductwork resistance, filters, registers and variable outdoor conditions that actually affect how your system performs day-to-day.

Because the SEER2 testing conditions are more realistic, SEER2 numbers are typically lower than the old SEER numbers for the same equipment. 

It’s worth pointing out that SEER2 ratings are generally 4%-5% lower than equivalent SEER ratings for the same equipment. This doesn’t mean the equipment is less efficient! What it really means is that the testing is more realistic (HVACtoolkit.org).

What’s a good SEER2 rating for energy efficient air conditioners?

Taking our region’s heat and humidity demand into consideration, the Department of Energy recommends a minimum of 13.4 SEER2 for new packaged air conditioners (ICCsafe.org). However, selecting a unit with a higher rating means even greater savings. 

A 20 SEER2 system is approximately 54% more efficient than a 13 SEER2 system. For a typical 3-ton system in the Southeast running 2,000 hours annually at $0.15/kWh, upgrading from 13 SEER2 to 20 SEER2 could yield 10-year savings of nearly $3,000 (HVACtoolkit.org).

Why high humidity makes your home feel hotter.

Before we get into how your AC system handles all of this, it helps to understand what’s actually happening inside your home when humidity is high. You know, during May, June, July, August, September and bits of October. 

It’s the humidity, not the heat! Really. Your body cools itself through perspiration and the evaporation of that perspiration. However, when the air is already saturated, evaporation slows, and your body can’t cool itself as effectively as it can when humidity levels are low. That’s why a 90° F day with 85% humidity feels much “hotter” than a 98° F day with drier air. But we’re not advocating for moving to Arizona, we’re looking at new air conditioners! 

Comfortable indoor humidity levels generally fall between 30% and 50%. For those of you with stringed, fretted instruments, humidity closer to 50% is ideal. When your home’s humidity creeps above that range, everything feels sticky and heavy — even if your thermostat is telling you something else. 

You may find yourself grumping, “Why does my house feel humid with the AC on?” The answer could be that your system is short-cycling — something that happens as units age or if your system isn’t properly sized to your home. When a system turns off before it’s done its dehumidifying job, then your home will feel sticky no matter what the thermostat tells you. 

Your discomfort might also be rooted in poor airflow or running a system that isn’t designed to handle our region’s intensely hot and humid summers.

If you’re not sure what the culprit is, look for a trusted contractor who can help you get to the root of your discomfort and make recommendations tailored to your home and your comfort needs. You can search our Quality Contractor Network for free. 

How heat and humidity impact your AC system.

If heat and humidity are the dynamic discomfort duo, then your air conditioner is the supercooling wonder of the HVAC world: It lowers the temperature in your home and removes moisture from the air.

When an AC system runs, warm air passes over the cold evaporator coil. That coil does double duty by lowering the air temperature and causing water vapor to condense from the air. Basically, it works the same way a cold glass of lemonade “sweats” on a humid afternoon, cooling the air around it. 

That collected moisture drains away, leaving your home with drier, cooler air.

Unlike with burgers and boxes of chocolate, bigger isn’t always better when it comes to your AC. If your system is too large for your home, it cools the air quickly but shuts off before it’s had time to pull adequate moisture out. This is when your thermostat tells you one thing, but your body is telling you an entirely different story.

Uneven cooling — hot or cold spots from room to room, or one floor that’s never quite right — is another common sign that your system is working inefficiently or isn’t well-matched to your home.

Reliable cooling in extreme heat means your system should be able to run long enough to manage both temperature and humidity — not just race to hit a number on the thermostat and shut off.

What’s a variable-speed compressor, and how are they different from single-stage compressors?

A single-stage compressor is a lot like a new puppy: It’s either running full blast or it’s off. A variable-speed compressor is more like a well-trained, middle-aged retriever: It speeds up or slows down to match your needs. 

In terms of your air conditioner, a variable-speed compressor cruises at low speed during moderate days, sipping power. When the heat and humidity hit hard, it ramps smoothly. This modulation cuts wasteful on/off cycling, reduces electrical stress at startup and holds steadier indoor temperatures. The result is higher SEER2 efficiency, fewer temperature swings, less wear on parts and lower cooling costs over time.

Although some 15 SEER2 air conditioners use variable-speed compressors, most of them do not. However, most 17 SEER2+ systems incorporate variable-speed compressors and advanced, energy efficient condenser technology.

Is it time to upgrade to an energy efficient air conditioner?

According to the Department of Energy, replacing a 10-year-old unit with a newer, more efficient model can save you up to 20% on cooling costs. When you combine that with a rebate from TVA EnergyRight and your local power company, the savings are even greater!

With proper care (check out this blog for more information on tune-ups: “8 reasons why seasonal residential HVAC maintenance is a good idea”), most HVAC systems can last between 15 and 20 years. Unfortunately, however, efficiency and efficacy drop significantly well before a system reaches the end of its life. A 10- or 12-year-old system may still be running, but it’s likely working harder and costing you more than a modern replacement would.

As you make a decision about whether or not it’s time to replace your air conditioner, consider your answers to these questions:

• Is your home consistently uncomfortable, even when the AC is running?
• Do you notice hot or cold spots in your house?
• Does your AC keep every room comfortable?
• Has your energy bill crept upward over the past few summers without a clear explanation?
• Is your system more than 10 years old?
• Are repairs becoming more frequent or more expensive?

If you answered yes to several of these, it may be time to schedule a Home Energy Evaluation or have a TVA-vetted contractor from the Quality Contractor Network evaluate your current system and discuss your options.

Rebates are available on energy efficient central air conditioning systems. 

If you’re ready to upgrade, TVA EnergyRight and your local power company are ready to help make it more affordable. We’re offering a $400 rebate on 17 SEER2 or higher systems and $250 on 15-16.99 SEER2 units.

Our rebates are available on systems installed by a member of the Quality Contractor Network. They’ll even submit the paperwork for you!