AFUE Ratings Guide

If you’re thinking about upgrading your furnace, an important first step is to decide on an efficiency rating. This will influence your up-front costs and what you pay for home heating down the road. Use this guide to learn 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 changes 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 a furnace’s heat output to the fuel it requires in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other factors that decrease efficiency. The result is stated as a percentage, representing the amount of fuel converted into heat. 

Calculating a furnace’s AFUE rating includes conducting a common test cycle to measure the heat output and fuel consumption. This test cycle is designed to simulate normal heating conditions over the year, including both hot and cold periods. The heating system is then run at full capacity for a prolonged period to establish its peak performance. 

What Is the Minimum AFUE Rating in 2023? 

The U.S. Department of Energy (DOE) has steadily increased HVAC efficiency ratings over the past several decades in order to encourage energy efficiency and reduce greenhouse gas emissions. 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 greater. Better AFUE ratings lessen energy consumption, lowers energy bills and curbs the environmental consequence of heating your home. 

Why Do Gas Furnaces Jump from 80 to 90 AFUE? 

When shopping for new furnaces, you may notice many models around 80 and 90 AFUE, with little in between. This is mainly because the technology needed to exceed 80 AFUE creates a considerable jump 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 use more sophisticated technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and supplementary heat exchangers. These technologies help the furnace grab heat from the fuel supply more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s most popular furnaces cap out at about 98.5 AFUE. 

How Do AFUE Ratings Affect Furnace Prices? 

The price of a furnace with a higher AFUE rating is normally more than that of a lower AFUE-rated furnace. In the end, more sophisticated technologies come at a cost. The exact cost difference will depend on the furnace manufacturer, size and efficiency rating. 

When evaluating the initial cost of a more efficient furnace, keep in mind the future energy savings that awaits you. The ability to save money on fuel bills for the next ten years or longer will allow you to recoup the higher up-front investment. 

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

While a higher AFUE rating results in more efficient home heating and lower energy bills, this doesn’t necessarily mean every homeowner should purchase a 95 AFUE furnace. Listed below are some factors to consider when reviewing costs and efficiency ratings:  

• Climate: The colder the weather, the more frequently your high-efficiency furnace operates, and the sooner it will provide a return on investment. Therefore, higher AFUE ratings are most appropriate in cold climates that need more heating than cooling to keep a comfortable indoor temperature. 

• How long will you live there?: If you picture living in your home for many years, buying a high-efficiency furnace could be a good investment since it will pay for itself over the next few years in energy savings. However, if relocating is in your plans within the next couple of years, the extra cost of a higher AFUE-rated furnace would not be recommended. 

• Fuel costs: The affect of an efficient furnace is more evident when the price of fuel is higher. You’ll realize the savings each month once 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, turn to Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the up-front 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.