What is an AFUE rating?

What does an AFUE rating mean for a furnace?

Simply put, the AFUE rating is a measure of your furnace’s efficiency. In practical terms, efficiency is measured by comparing the money you spend on fuel costs vs. the amount of heat you get from that fuel.

Example: 95% AFUE rating
For every $1 you spend on energy fuel costs (i.e. natural gas), 95 cents is turned into heat for your home. Pretty simple!

AFUE stands for Annual Fuel Utilization Efficiency. Canada’s Energy Efficiency Regulations require a minimum AFUE of 90% and some furnaces may be as high as 98%. The rating provides a quick, at-a-glance metric for comparing the efficiencies of different makes and models of furnaces.

Which furnaces have the best AFUE rating?

Take a look at our comparison to get familiar with the main types of furnaces.


ENERGY STAR is a designation given to the most energy-efficient furnaces with an AFUE rating of 95% or higher. The program is regulated by Natural Resources Canada. Only furnaces with exceptional energy efficiency can earn a ENERGY STAR label. You can get more information on the ENERGY STAR program here.

What is EnerGuide?

Also regulated and administered by Natural Resources Canada, the EnerGuide label compares the energy efficiency of a single furnace to other similar furnaces. You can get more information about EnerGuide here.

When purchasing a new gas furnace, understanding the AFUE rating is a great place to start. It’s the single-most important measure for high efficiency, which saves you money over the long term and contributes to a cleaner environment.