High-efficiency gas furnaces have AFUE ratings of what percentage and greater?

High-efficiency gas furnaces are defined by their Annual Fuel Utilization Efficiency (AFUE) ratings, which measure the efficiency with which a furnace converts fuel into heat over the course of a year. A furnace that has an AFUE rating of 90% or greater is considered high-efficiency. This means that 90% or more of the energy in the fuel is converted into heat for the home, while only 10% or less is lost through exhaust.

Using this metric, a furnace with an AFUE rating of 90% signifies a significant advancement in technology compared to older models. Traditional furnaces often have lower AFUE ratings, typically below this threshold. Therefore, the correct understanding of high-efficiency models encompasses those with an AFUE of 90% or more, emphasizing energy conservation and cost savings on energy bills, as well as a reduced environmental impact.