AFUE Ratings Guide

If you’re considering an upgrade to your furnace, an important first step is to decide on an efficiency rating. That rating selection 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 an acronym for Annual Fuel Utilization Efficiency. It is a measure of 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 output of heat from the furnace or boiler to the fuel it utilizes in the process. This calculation factors in the energy lost through exhaust gases, radiation and other elements that reduce efficiency. The result is displayed as a percentage, representing the proportion of fuel converted into heat.

Calculating a furnace’s AFUE rating involves conducting a standard test cycle to quantify the heat output and fuel consumption. This test cycle is designed to simulate typical heating conditions in the course of the year, including both in-season and out-of-season periods. The heating system is then run at peak capacity for a prolonged 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 improve energy efficiency and reduce emissions that harm the ozone/atmosphere. In 2023, the minimum rating for new gas furnaces changed 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 better. Better AFUE ratings reduce 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 shopping for new furnaces, you may find many models around 80 and 90 AFUE, but not much in between. This is as a result of the technology required to exceed 80 AFUE triggers a significant jump in performance.

The 80 AFUE threshold has been the minimum criteria 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% sacrificed to the atmosphere through the flue.

Gas furnaces must incorporate more innovative technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These techniques help the furnace pull heat from the fuel supply more effectively, increasing efficiency from 80 to 90 AFUE or higher. Today’s most popular furnaces cap out at about 98.5 AFUE.

How Do AFUE Ratings Impact Furnace Costs?

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

When evaluating the purchase price of a more efficient furnace, don’t forget the future energy savings that awaits you. The ability to save money on fuel bills for the next ten years or longer will permit you to recoup the higher up-front investment.

Is It Smart to Buy a Furnace with the Highest AFUE Rating Possible?

While a higher AFUE rating translates into more efficient home heating and reduced energy bills, this doesn’t necessarily mean every homeowner should buy a 95 AFUE furnace. Here are the factors to think about when reviewing costs and efficiency ratings:

  • Local weather: The colder the climate, the more frequently your high-efficiency furnace operates, and thus, provides an earlier ROI. Therefore, higher AFUE ratings are most suitable in cold climates that require more heating than cooling to sustain a pleasant indoor temperature.
  • How long will you live there?: If you picture living in your home for some time, buying a high-efficiency furnace could be a smart investment since it will pay for itself over time in energy savings. But, if relocating is in your plans within the next couple of years, 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 when the price of fuel is higher. You’ll see the savings in your bottom line as your furnace converts a higher percentage of fuel into usable heat for your home.

Consider a New Furnace Today

When trying to find the ideal furnace system for your needs and budget, rely on Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the up-front costs and long-term benefits of different AFUE ratings to inform your decision. We know you’ll love working with Service Experts so much so that we offer a 100% satisfaction guarantee! To learn more or to schedule a free furnace installation estimate, please call a Service Experts office near you.