What’s a Good AC Efficiency Rating? SEER2, EER2 & AFUE Explained

If you’ve ever compared different Residential AC Systems, you’ve probably noticed those efficiency labels, SEER2, EER2, and AFUE. They might look like technical jargon, but they actually determine how much you’ll spend on energy bills and how well your system performs in extreme weather.

A higher AC efficiency rating means your unit can cool your home using less electricity. It also means lower utility bills, longer system lifespan, and fewer carbon emissions. The good news? Understanding these ratings isn’t as complicated as it seems. Once you grasp the basics, you can confidently choose the right system for your home or business, one that fits your comfort needs and saves money over time.

We help customers find the right HVAC equipment and replacement parts that meet today’s energy standards. Let’s break down what each rating means and how to know if your system is performing efficiently.

Why Efficiency Ratings Matter More Than Ever

HVAC systems account for almost half of a home’s total energy use. That’s why the U.S. Department of Energy (DOE) updated its testing standards in 2023, replacing SEER, EER, and HSPF with new SEER2, EER2, and HSPF2 metrics. These changes reflect real-world conditions, like duct pressure and variable outdoor temperatures, making today’s ratings more accurate than ever.

If you’re buying a new system, comparing AC unit efficiency ratings helps you:

• Lower your monthly utility costs.

• Qualify for rebates or tax credits.

• Maintain consistent indoor comfort across seasons.

• Reduce your environmental footprint.

The higher the rating, the more energy your system saves, and the faster it pays for itself.

SEER2: Seasonal Efficiency That Reflects Real Conditions

The SEER2 rating, or Seasonal Energy Efficiency Ratio 2, measures how efficiently your AC or heat pump cools your home over an entire season. It’s similar to miles per gallon for your car: the higher the SEER2, the less energy your system uses to produce the same amount of cooling.

Federal law now requires new systems to meet the following minimum SEER2 ratings:

• 13.4 SEER2 or higher in northern states.

• 14.3 SEER2 or higher in southern and southwestern regions.

However, if you want optimal comfort and long-term value, look for systems rated 16 SEER2 or above. These units often feature variable-speed compressors and smart thermostatic controls, which allow your system to run longer at lower power, maintaining a steady temperature and improving humidity control.

To give you a sense of range, a basic 13.4 SEER2 model is sufficient for mild climates or small homes, while high-end 18–20 SEER2 units deliver outstanding comfort and up to 30% lower cooling costs in warm, humid areas.

EER2 vs SEER2: Comparing Peak and Seasonal Efficiency

Both EER2 and SEER2 measure how well an air conditioner uses electricity, but they do it differently.

• SEER2 measures efficiency over time, including cooler and hotter days throughout the season.

• EER2 measures efficiency at peak performance, specifically, when it’s 95°F outside, 80°F indoors, and humidity is 50%.

If you live in a consistently hot region like Arizona, Nevada, or Florida, EER2 is just as important as SEER2. It tells you how your system will perform during the hottest days when your cooling demand is highest.

For instance, two units could both have a SEER2 rating of 16, but if one has an EER2 of 12.5 and the other 11, the higher-rated unit will stay efficient during extreme heat, potentially saving you hundreds of dollars over the lifespan of the system.

Ideally, look for systems with at least EER2 11.5 and SEER2 15 or higher to balance cost, performance, and long-term savings.

AFUE vs SEER: Understanding Heating vs Cooling Efficiency

When it comes to heating systems like furnaces and boilers, you’ll see another key metric, AFUE, or Annual Fuel Utilization Efficiency. While SEER2 and EER2 apply to cooling, AFUE measures how efficiently your furnace converts fuel (natural gas, propane, or oil) into heat.

A furnace with a 90% AFUE rating converts 90% of the fuel into usable heat, wasting only 10% through exhaust. Older furnaces, especially those installed before 2000, often operate at 70% AFUE or less, meaning nearly a third of your energy is wasted.

High-efficiency models today reach 95–98% AFUE, which translates into significant fuel savings over time. So, when comparing AFUE vs SEER, remember:

• AFUE = heating efficiency for fuel-based systems.

• SEER2 = cooling efficiency for electric systems.

If your home uses both, a balanced setup, a high-AFUE furnace and a high-SEER2 AC, will deliver maximum comfort and energy savings throughout the year.

What’s a “Good” HVAC Efficiency Rating?

So, what numbers should you aim for when evaluating your HVAC efficiency rating? Generally, anything above these thresholds is considered efficient by today’s standards:

• SEER2: 15–17 (very good), 18+ (excellent).

• EER2: 11–12 (solid), 12.5+ (exceptional).

• AFUE: 90–94% (good), 95–98% (top-tier).

Your ideal rating depends on your climate and budget. A homeowner in a cold northern state benefits more from a high-AFUE furnace, while someone in Texas or California will see greater savings from a high-SEER2 AC.

Keep in mind that systems with higher ratings often cost more upfront, but they save enough on utilities over time to offset that difference, especially when you factor in rebates or seasonal promotions.

How to Choose the Right System for Your Home

When shopping for a new HVAC setup, it’s easy to get lost in the details. But focusing on the right metrics and installation quality will help you make a decision that lasts for decades.

Start with your home’s needs and climate. If you live in a region with long, hot summers, choose a high-SEER2, high-EER2 system with strong dehumidification features. If winters are your main concern, prioritize a high-AFUE furnace or a hybrid system with both heating and cooling efficiency.

Other important factors include:

1. Proper sizing: An oversized unit short-cycles and wastes energy, while an undersized one struggles to keep up. Always request a professional load calculation before purchasing.

2. Installation quality: Even the most efficient system can lose 20–30% of its performance due to poor installation.

3. Duct condition: Leaky ducts reduce efficiency and unevenly distribute air. Inspect and seal them before replacing your system.

4. Smart controls: A programmable or Wi-Fi thermostat fine-tunes temperature control and reduces energy waste.

How to Improve Efficiency Beyond the Ratings

Even the best-rated system can underperform without proper maintenance. To keep your AC unit efficiency ratingconsistent over time, remember these fundamentals:

• Schedule seasonal maintenance to clean coils, change filters, and inspect refrigerant levels.

• Check your home’s insulation, poor insulation can undo much of your efficiency gains.

• Keep vents and returns unobstructed for better airflow.

• Use ceiling fans to circulate air and reduce load on your AC or furnace.

Consistent upkeep not only protects your investment but also helps your system maintain its rated performance throughout its lifespan.

Turning Ratings Into Real Savings

Efficiency ratings like SEER2, EER2, and AFUE may sound technical, but they’re really about one thing: helping you get the most out of every dollar you spend on energy.

Remember that SEER2 measures how efficiently your system cools over the entire season, EER2 measures how it performs during peak heat, and AFUE applies to heating systems and tells you how well your furnace converts fuel to warmth.

At Voomi Supply, we make it simple to find HVAC systems that meet modern efficiency standards. Our curated selection of Residential AC Systems is backed by expertise, fast shipping, and proven quality.

Understanding your efficiency ratings is the first step, choosing a system that performs to those standards is where the real value begins.