AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, an early choice in the process is to decide on an efficiency rating. That first choice will have an effect on your up-front costs and what you pay for home heating in the future. With this handy guide, you’ll understand more about AFUE ratings and how they affect you.

What Is an AFUE Rating?

AFUE is short for Annual Fuel Utilization Efficiency. It is an industry-standard measurement for how efficiently a furnace or boiler switches fuel into heat for your home over the course of a year. The higher the AFUE rating (on a scale of 0% to 100%), the more efficient the system is at converting fuel into usable heat.

How Is AFUE Measured?

AFUE ratings are determined by calculating the ratio of a furnace’s heat output to the amount of gas or diesel it utilizes in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other elements that diminish efficiency. The result is expressed as a percentage, representing the share of fuel converted into heat.

Determining a furnace or boiler’s AFUE rating involves conducting a conventional test cycle to assess the heat output and fuel consumption. This test cycle is structured to simulate typical heating conditions in the course of the year, including both in-season and out-of-season periods. The heating system then functions at peak capacity for an extensive period to define its peak performance.

What Is the Minimum AFUE Rating in 2023?

The U.S. Department of Energy (DOE) has slowly increased HVAC efficiency ratings over the last few decades with hopes to increase energy efficiency and reduce emissions that harm the ozone/atmosphere. In 2023, the minimum rating for new gas furnaces was set to 81 AFUE. From 2015 to 2022, the South and Southwest regions had a minimum rating of 80 AFUE, and the North mandated furnaces to be rated 90 AFUE or higher. Better AFUE ratings cut down energy consumption, lowers power bills and reduces the environmental impact of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When searching for new furnaces, you may notice many models around 80 and 90 AFUE, with little in between. This is because the technology necessary to exceed 80 AFUE forces a substantial rise in performance.

The 80 AFUE threshold has been the minimum expectation for gas furnaces in the United States since the 1990s. At this level, furnaces convert 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue.

Gas furnaces must integrate more sophisticated technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These technologies help the furnace extract heat from the fuel source more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s best furnaces cap out at about 98.5 AFUE.

How Do AFUE Ratings Affect Furnace Prices?

The cost of a furnace with a higher AFUE rating is usually more than that of a lower AFUE-rated furnace. Basically, more advanced technologies come at a cost. The exact cost difference depends on the furnace manufacturer, size and efficiency rating.

When thinking about the purchase price of a more efficient furnace, don’t forget the future energy savings that awaits you. The real chance to save money on energy bills for the next 10 years or longer will allow you to recoup the additional up-front investment.

Does It Make Sense to Buy a Furnace with the Highest AFUE Rating Possible?

While a higher AFUE rating translates into better home heating and reduced energy bills, we are not recommending that every homeowner should purchase a 95 AFUE furnace. Here are the factors to consider when reviewing costs and efficiency ratings:

• Local weather: The colder the climate, the longer your high-efficiency furnace operates, and thus, provides an earlier ROI. Because of this, higher AFUE ratings are most beneficial in cold climates that need more heating than cooling to keep a comfy indoor temperature.
• How long you’ll live in this home: If you picture living in your home for many years, choosing a high-efficiency furnace could be a smart investment given that it will pay for itself over the coming years in energy savings. But, if you plan to move in the near future, the extra cost of a higher AFUE-rated furnace probably does not make sense.
• Energy prices: The impact of an efficient furnace is more pronounced if your energy costs are high. You’ll experience noticeable savings as your furnace converts a higher percentage of fuel into usable heat for your home.

Get a New Furnace Today

For help determining the best heating system for your needs and budget, choose Service Experts Heating, Air Conditioning & Plumbing. We can help you figure out the up-front costs and long-term benefits of different AFUE ratings to steer your decision. We are so certain that you’ll love working with Service Experts that we offer a 100% satisfaction guarantee! For more information or to schedule a complimentary furnace installation estimate, please get in touch with a Service Experts office near you.