What percentage is the threshold for high-efficiency gas furnaces in terms of AFUE?

High-efficiency gas furnaces are defined by their Annual Fuel Utilization Efficiency (AFUE) rating, which measures the efficiency of a furnace in converting fuel to heat over the course of a year. The threshold for a furnace to be classified as high-efficiency is set at 90% AFUE or higher. This means that at least 90% of the energy in the gas is converted into usable heat for the home, while 10% is lost through various inefficiencies, such as exhaust.

This classification is important because higher efficiency translates into lower energy bills and reduced greenhouse gas emissions, contributing to a more sustainable energy usage approach. Furnaces operating below this threshold are considered mid-efficiency or standard efficiency, which typically ranges from 80% to 89% AFUE. Understanding these classifications helps consumers make informed choices about their heating systems and encourages the adoption of more efficient technologies.