What Does Furnace Efficiency Rating Mean In Plain English?

If you're researching new furnaces you've no doubt run across the acronym AFUE. I know how frustrating it is to decipher acronyms and industry jargon when all you want is a simple piece of information. So I will explain what AFUE means (just in case you're into overly technical explanations for simple concepts), and then describe a more straightforward way to think of furnace efficiency.

AFUE: Annual Fuel Efficiency Utilization

Here's the annoying technical way of describing furnace efficiency…

A 92% AFUE rating means a furnace will output 92 BTU's of heating for every 100 BTU's of natural gas input.

And here's the straightforward, non-technical way of explaining furnace efficiency…

If you have an 80% efficient furnace:

80 cents of every $1 of natural gas you put into that furnace will go to heat your home, and 20 cents of that $1 of natural gas will go out the flue pipe.

And if you have a 95% efficient furnace:

95 cents of every $1 of natural gas you put into that furnace will go to heat your home, and only 5 cents of that $1 of natural gas will go out the flue pipe.

And there you have it, the plain and simple way to think of furnace efficiency ratings - without annoying technical acronyms.