AFUE Ratings Guide

If you’re considering an upgrade to your furnace, one of the first steps is to determine an efficiency rating. That first choice will have an effect on your up-front costs and what you pay for home heating down the road. With this handy guide, you’ll understand more about AFUE ratings and how they affect you.

What Is an AFUE Rating?

AFUE stands for Annual Fuel Utilization Efficiency. It is a standard for measuring how efficiently a furnace or boiler switches fuel into heat for your home within a 12-month period. 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 the output of heat from the furnace or boiler to the fuel it consumes in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other factors that diminish efficiency. The result is displayed as a percentage, representing the share of fuel converted into heat.

Calculating a furnace’s AFUE rating involves conducting a standard test cycle to assess the heat output and fuel consumption. This test cycle is structured to simulate normal heating conditions throughout the year, including both on and off periods. The heating system is then run at peak capacity for an extended 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 past few decades with hopes to encourage energy efficiency and reduce greenhouse gas emissions. In 2023, the minimum rating for new gas furnaces was recalculated to be 81 AFUE. From 2015 to 2022, the South and Southwest regions had a minimum rating of 80 AFUE, and the North required furnaces to be rated 90 AFUE or better. Better AFUE ratings cut down energy consumption, lowers power bills and curbs the environmental consequence of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When researching for new furnaces, you may find many models around 80 and 90 AFUE, but not much in between. This is mainly because the technology necessary to exceed 80 AFUE causes a substantial leap in performance.

The 80 AFUE threshold has been the minimum requirement for gas furnaces in the U.S. since the 1990s. At this level, furnaces transform 80% of the fuel they consume into heat, with the remaining 20% forfeited to the atmosphere through the flue.

Gas furnaces must integrate more advanced technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These technologies help the furnace grab heat from the fuel source more effectively, boosting efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at approximately 98.5 AFUE.

How Do AFUE Ratings Determine Furnace Prices?

The total price of a furnace with a higher AFUE rating is typically more than that of a lower AFUE-rated furnace. After all, more sophisticated technologies come with a higher price tag. The exact cost difference is based on the furnace manufacturer, size and efficiency rating.

When considering the purchase price of a more efficient furnace, remember the ongoing energy savings that awaits you. The potential to save money on fuel bills for the next 10 years or longer will definitely allow you to recoup the extra up-front investment.

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

Although a higher AFUE rating results in more efficient home heating and lower energy bills, we are not recommending that everyone should buy a 95 AFUE furnace. Below are a few factors to think about when comparing costs and efficiency ratings:

  • Seasonal weather conditions: The colder the weather, the more your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. Because of this, higher AFUE ratings are most suitable in cold climates that demand more heating than cooling to sustain a pleasant indoor temperature.
  • How long you’ll live in this home: If you imagine living in your home for a long time, purchasing 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’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace would not be recommended.
  • The cost of fuel: The impact of an efficient furnace is more noticeable when the price of fuel is higher. 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

If you’re looking for the ideal furnace system for your needs and budget, turn to Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the initial costs and long-term benefits of different AFUE ratings to guide 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 no-cost furnace installation estimate, please contact a Service Experts office near you.