A Guide to Efficiency Ratings for HVAC Units

When you’re shopping for a new HVAC unit, cost is always a concern. That being said, you can’t ignore the other set of numbers! Understanding efficiency ratings is just as important as comparing price tags.

In this Discount HVAC Buying Guide, we’ll break down how HVAC efficiency ratings work in simple terms so you’ll have the knowledge to choose the best equipment. You’ll be able to determine which ones give you the right type of performance with meaningful energy savings. That balance is how you can make your upfront investment really count!

What Are HVAC Efficiency Ratings and Why Do They Matter?

HVAC efficiency ratings measure how effectively a system works in any given property. More specifically, it’s about how the equipment converts fuel or electricity into heating and cooling. The most common ratings for HVAC units are their SEER rating, AFUE rating, HSPF rating, and EER rating. These numbers relate to a system’s overall energy performance, along with its cooling capacity and heating efficiency. It’s all managed under standardized testing that’s set by the Department of Energy.

By following this Discount HVAC Buying Guide, you’ll be in a better position to understand each type of rating. From there, you can move forward with confidence knowing that your new system will meet your efficiency requirements and provide you with the long-term cost savings you’re after.

How Do Efficiency Ratings Affect Your Energy Bills?

A higher efficiency rating typically means lower energy consumption. That naturally leads to lower monthly energy usage, which should  result in lower bills. Over time, upgrading to a more efficient HVAC system can mean you’ll end up seeing significant yearly savings. It’s all about weighing the pros and cons for the big picture long-term. Higher-efficiency systems usually come with a higher initial cost, but since that equipment often saves you money, paying a little more upfront to see a meaningful reduction in your ongoing operating expenses might be worth it.

What Does SEER Mean for Air Conditioners and Heat Pumps?

The SEER rating stands for Seasonal Energy Efficiency Ratio. This measures a system’s air conditioner cooling efficiency over a typical cooling season. Put simply, the higher the SEER number, the greater the energy efficiency. This applies to both air conditioners and heat pumps running in the cooling mode.

What Is a Good Efficiency Rating for an AC Unit?

Today’s modern efficiency standards require most new central AC units to meet a minimum SEER rating of 14–15, but this depends on the region. From that threshold, a good efficiency rating for most homes will then fall between 16 and 18 SEER. 

How Much More Efficient Is a 20 SEER vs. an 18 SEER?

A higher SEER number gives you better performance. But looking at the hard numbers, a 20 SEER system is roughly 10–12% more efficient than an 18 SEER unit. The improvement in energy savings from 18 to 20 is real, but the price difference may not always justify the upgrade. If your region of the country does not have long, hot summers, then it may be a better financial decision to go with a lower SEER since the energy savings won’t offset the increase in price. Be sure to think about your usage!

What Is AFUE and How Does It Apply to Furnaces?

The AFUE rating stands for Annual Fuel Utilization Efficiency. This is how the efficiency of heating systems converting fuel into heat is measured. For example, a furnace with a 90% annual fuel utilization efficiency works to turn 90% of fuel into usable heat. 

What’s the Difference Between 80% AFUE and 95% AFUE?

An 80% AFUE furnace loses 20% of its fuel energy through exhaust. On the other hand, a 95% AFUE unit will only waste 5%. That 15% difference means you’ll see significantly better heating efficiency, especially in colder climates where furnaces are running more frequently. Thinking about where you live is part of making a wise decision.

What Does HSPF Tell You About Heat Pump Efficiency?

The HSPF rating, or Heating Seasonal Performance Factor, measures heat pump performance in your system’s heating mode. Specifically, it calculates the total amount of heat the system delivers over an entire heating season (measured in BTUs) divided by the total electricity it consumes during that same period (measured in watt-hours). Testing is performed under controlled conditions that simulate a range of outdoor temperatures, so the rating reflects seasonal performance rather than a single point in time.

Put simply: Higher HSPF ratings are proven to connect to better winter efficiency. Current federal standards typically require HSPF ratings of at least 8.2. From there, high-efficiency models will exceed 9 or 10. So do you need less or more?

For example, if you live in a colder climate where your heat pump handles most of your home’s heating, then a 9 or 10 HSPF rating could make a noticeable difference in your energy savings during the winter months. Higher ratings are especially beneficial for homeowners who plan to stay in their home long term because they’ll be able to enjoy lower monthly utility bills. It’s also a smart call when you’re replacing an older, lower-efficiency system and looking to maximize overall performance and comfort. In mild climates, though, you could probably stick with the lower HSPF ratings and still make out just fine for your bottom line.

What Is EER and When Does It Matter?

The EER rating, or Energy Efficiency Ratio, measures performance at peak outdoor temperatures. Unlike SEER, which gives you a number that averages seasonal performance, EER evaluates efficiency under steady, high-heat conditions. This means that in hot climates where cooling units operate continuously, going with a strong energy efficiency ratio will usually be the right call. It means you’ll be getting better overall system performance, along with improved reliability.

What SEER Rating Qualifies for a 2025 Tax Credit?

To qualify for federal incentives in the 2025 tax year, systems will typically need to meet specific Energy Star certification levels. Most tax credits are going to require split-system air conditioners that reach at least 16 SEER2 (the updated testing standard). You can confirm eligibility with your local HVAC expert. Or, if you’re looking ahead to the 2026 tax year, you might want to review the current Department of Energy guidelines before making your purchase.

What Is the $5000 Rule for HVAC?

The "$5000 rule" is a simple formula for property owners to use when deciding whether to make a repair or upgrade their HVAC equipment altogether. You just multiply the age of your current system by the repair cost. If that total exceeds $5,000, then it’s generally safe to say that replacement will be the smarter choice.

If you’re looking at a typical Discount HVAC Buying Guide, looking at this rule along with the other suggestions can help you determine the best course of action with your budget. In the end, it might be worth investing in a new system that comes with an improved HVAC efficiency rating instead of repairing older HVAC equipment that’s already on its way out.

How Much Money Can Higher Efficiency Ratings Actually Save You?

Looking at efficiency has a very practical purpose. It’s about protecting your budget! For example, upgrading from a 14 SEER to an 18 SEER system can reduce your cooling energy consumption by 20–30%. That means lower monthly bills. The same goes for switching from 80% to 95% AFUE. This can lower your heating fuel usage by 15% or more.

Of course, the actual cost savings depend on your local climate and system usage, along with local utility rates. But what’s even more important is whether the equipment is installed correctly by a qualified HVAC expert. Make sure you’re going with a trusted professional to get the best efficiency rating possible every day.

 

Should You Always Buy the Highest Efficiency Rating Available?

Everyone has their own situation, so it’s not necessarily a hard and fast rule to always go with the highest efficiency rating possible. While yes, a higher efficiency rating will reduce your long-term energy costs, it’s worth noting that the highest-tier models often come with some higher upfront pricing. 

In moderate climates, going with mid-range energy-efficient HVAC systems may offer the best balance. You’ll get the benefits of both initial cost savings and long-term performance. If you don’t need a high-powered system to get you through dramatic weather, why not make the call to save a little more on the equipment itself?

When you look at the facts in this Discount HVAC Buying Guide, you’ll hopefully see that HVAC efficiency ratings are designed to help you choose the right heating and cooling solution. There’s no one-size-fits-all solution. You have to find the system that fits your home, budget, and comfort goals—and that’s always going to be unique! Surplus City Liquidators offers a variety of quality HVAC units, and we’re happy to answer any questions you may have.