AFUE Ratings Guide

If you’re considering an upgrade to your furnace, one of the first steps is to decide on an efficiency rating. That first choice will impact your up-front costs and what you pay for home heating as time goes on. 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 an industry-standard measurement for 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 estimated by calculating the ratio of the heat coming from your furnace to the fuel it utilizes in the process. This calculation factors in the energy lost through exhaust gases, radiation and other factors that diminish efficiency. The result is expressed as a percentage, representing the share of fuel converted into heat. 

Calculating a furnace’s AFUE rating involves conducting a common test cycle to quantify the heat output and fuel consumption. This test cycle is intended to simulate ordinary heating conditions over the year, including both in-season and out-of-season periods. The heating system is then run at peak capacity for an extensive period to establish 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 in an effort to increase 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 called for furnaces to be rated 90 AFUE or higher. Better AFUE ratings lessen energy consumption, lowers utility bills and decreases the environmental impact of heating your home. 

Why Do Gas Furnaces Jump from 80 to 90 AFUE? 

When browsing around for new furnaces, you may discover many models around 80 and 90 AFUE, but not much in between. This is due to the technology needed to exceed 80 AFUE forces a considerable leap in performance. 

The 80 AFUE threshold has been the minimum expectation 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 secure higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These features help the furnace pull heat from the fuel source more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at approximately 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Costs? 

The price of a furnace with a higher AFUE rating is normally more than that of a lower AFUE-rated furnace. Not surprisingly, more sophisticated technologies come at a cost. The exact cost difference will depend on the furnace make, size and efficiency rating. 

When thinking about the up-front cost of a more efficient furnace, remember the ongoing energy savings that awaits you. The ability to save money on utility bills for the next ten years or longer will allow you to recoup the higher up-front investment. 

Should You Buy a Furnace with the Highest AFUE Rating Possible? 

Although a higher AFUE rating translates into better home heating and lower energy bills, we are not recommending that every homeowner should purchase a 95 AFUE furnace. Listed below are some factors to consider when evaluating costs and efficiency ratings:  

  • Local weather: The colder the temperatures, the more your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. For that reason, higher AFUE ratings are most suitable in cold climates that take more heating than cooling to sustain a comfortable indoor temperature. 
  • How long will you live there?: If you envision living in your home for quite a while, buying a high-efficiency furnace could be a good investment because it will pay for itself over the next few years in energy savings. On the other hand, 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 benefit of an efficient furnace is more pronounced if your energy costs are high. You’ll see the savings in your bottom line once your furnace converts a higher percentage of fuel into usable heat for your home. 

Consider a New Furnace Today 

For help determining the best heating system for your needs and budget, select 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! To find out more or to schedule a free furnace installation estimate, please call a Service Experts office near you