AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, one of the first steps is to determine an efficiency rating. That first choice will influence 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 a standard for measuring how efficiently a furnace or boiler converts 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 heat coming from your furnace to the amount of fuel it requires 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 proportion of fuel converted into heat.

Calculating a furnace or boiler’s AFUE rating entails conducting a standard test cycle to assess the heat output and fuel consumption. This test cycle is intended to simulate typical heating conditions throughout the year, including both in-season and out-of-season periods. The heating system then functions 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 past few decades in an attempt 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 higher. Better AFUE ratings reduce energy consumption, lowers utility 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 required to exceed 80 AFUE creates a substantial rise in performance.

The 80 AFUE threshold has been the minimum criteria for gas furnaces in the USA 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 integrate more sophisticated technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These techniques help the furnace pull 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 Influence Furnace Costs?

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

When considering the initial cost of a more efficient furnace, keep in mind the long-term energy savings that awaits you. The potential to save money on utility 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 results in more efficient home heating and reduced energy bills, we are not saying every homeowner should choose a 95 AFUE furnace. Listed below are some factors to consider when comparing costs and efficiency ratings:

  • Seasonal weather conditions: The colder the temperatures, the longer your high-efficiency furnace operates, and thus, provides an earlier ROI. For that reason, higher AFUE ratings are most appropriate in cold climates that take more heating than cooling to maintain a pleasant indoor temperature.
  • How long will you live there?: If you imagine living in your home for some time, buying a high-efficiency furnace may be a wise investment given that it will pay for itself over time 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 probably does not make sense.
  • Energy prices: The affect of an efficient furnace is more noticeable when energy costs are higher. You’ll experience noticeable savings when 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 best furnace system for your needs and budget, select Service Experts Heating, Air Conditioning & Plumbing. We can help you sort out the initial costs and long-term benefits of different AFUE ratings to steer your decision. We’re so confident you’ll be satisfied with our services that we offer a 100% satisfaction guarantee! To find out more or to schedule a complimentary furnace installation estimate, please get in touch with a Service Experts office near you.