AFUE Ratings Guide

If you’re thinking about upgrading your furnace, an important first step is to determine an efficiency rating. This will impact your up-front costs and what you pay for home heating in the coming years. This guide is intended to inform you 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 changes 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 estimated by calculating the ratio of the heat coming from your furnace to the amount of gas or diesel it consumes in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other variables that diminish efficiency. The result is displayed as a percentage, representing the amount of fuel converted into heat.

Determining a furnace or boiler’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 operates at maximum capacity for a prolonged period to determine 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 in an attempt to promote 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 required furnaces to be rated 90 AFUE or higher. Better AFUE ratings cut down energy consumption, lowers power bills and curbs the environmental impact of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When researching for new furnaces, you may notice many models around 80 and 90 AFUE, but not much in between. This is due to the technology required to exceed 80 AFUE causes a significant leap 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 turn 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue.

Gas furnaces must incorporate more innovative technology to achieve higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and supplementary heat exchangers. These technologies help the furnace pull heat from the fuel source more effectively, raising efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at about 98.5 AFUE.

How Do AFUE Ratings Impact Furnace Prices?

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

When considering the purchase price of a more efficient furnace, don’t forget 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 additional 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 reduced energy bills, we are not recommending that all homeowners should choose a 95 AFUE furnace. Listed below are some factors to take into account when comparing costs and efficiency ratings:

  • Climate: The colder the weather, the more your high-efficiency furnace operates, and the faster you will realize an overall savings from your investment. Therefore, higher AFUE ratings are most beneficial in cold climates that need more heating than cooling to maintain a comfortable indoor temperature.
  • How long will you live there?: If you envision living in your home for a long time, purchasing a high-efficiency furnace might be a good investment because it will pay for itself over time in energy savings. On the other hand, if you plan to move in the near future, the extra cost of a higher AFUE-rated furnace may not be worth it.
  • Energy prices: The benefit of an efficient furnace is more noticeable if your energy costs are high. You’ll experience noticeable savings once your furnace converts a higher percentage of fuel into usable heat for your home.

Install a New Furnace Today

For help determining the ideal furnace 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 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 no-cost furnace installation estimate, please get in touch with a Service Experts office near you.