Understanding AFUE: How It Impacts Your Furnace Efficiency

When it comes to keeping your home warm and comfortable during the cold winter months, your furnace plays a crucial role. But have you ever wondered how efficiently it is operating? One of the key metrics to assess furnace efficiency is the Annual Fuel Utilization Efficiency (AFUE) rating. In this blog post, we will delve into the world of furnaces and AFUE to help you understand how they relate and why it's essential to consider AFUE when selecting or maintaining your system.

What is AFUE?

AFUE stands for Annual Fuel Utilization Efficiency, and it's a rating system used to measure the efficiency of a furnace or boiler. Essentially, AFUE represents the percentage of fuel that is converted into usable heat. The higher the AFUE rating, the more efficient the furnace is at converting fuel into heat for your home. For example, if a furnace has an AFUE rating of 90%, it means that 90% of the fuel it consumes is converted into heat, while the remaining 10% is lost as waste.

Why is AFUE Important?

Understanding the AFUE of your furnace is crucial for several reasons:

Cost Savings:

Furnaces with higher AFUE ratings are more energy-efficient, which means they can heat your home while consuming less fuel. This results in lower energy bills and long-term cost savings.

Environmental Impact:

High AFUE furnaces produce fewer greenhouse gas emissions, making them more environmentally friendly. By choosing a furnace with a high AFUE, you reduce your carbon footprint.

Home Comfort:

An efficient furnace not only saves you money but also ensures your home remains warm and cozy throughout the winter. You won't have to constantly adjust the thermostat to maintain a comfortable temperature.

Resale Value:

A high-efficiency furnace with a good AFUE rating can add value to your home and make it more attractive to potential buyers.

How to Calculate AFUE

To determine the AFUE of your furnace, you can use the following formula:

AFUE = (Useful Energy Output) / (Total Energy Input)

Useful Energy Output refers to the heat produced by the furnace and distributed throughout your home, while Total Energy Input accounts for the total amount of energy or fuel consumed by the furnace. Be sure to check the manufacturer's documentation for accurate information on your systems AFUE rating.

Choosing a Furnace with a High AFUE

When purchasing a new furnace, it's essential to consider the AFUE rating. Energy-efficient furnaces may have higher upfront costs, but they provide long-term benefits in terms of savings and environmental impact. Look for furnaces with AFUE ratings of 90% or higher for the best efficiency.

Regular Maintenance

Maintaining your system is also key to maintaining its efficiency. Regular inspections, cleaning, and tune-ups can help ensure that your furnace operates at its highest efficiency levels. This means you get the most out of your investment and enjoy a warm and comfortable home.


Understanding AFUE and its relationship with your furnace's efficiency is essential for homeowners looking to save on energy costs, reduce their environmental impact, and maintain a comfortable home. A high AFUE rating not only benefits your pocket but also contributes to a greener and more sustainable future. So, the next time you're in the market for a new furnace or need to evaluate your current one, consider AFUE as a critical factor in your decision-making process.

Here at Kennon Heating & Air Conditioning we want you to enjoy your home to the fullest. That starts with making sure that the air in your home is clean and at the perfect temperature for you. If we can help in any way, please contact us via email or phone (678) 251-9776. Stay cool, stay cozy.