Current home heating systems work better and at higher energy efficiency than ones from 20, 30, even 10 years ago. We can chalk this up to an investment in research to improve the products, as well as the nebulous idea of “progress.” But there are specifics behind why heaters waste less energy today than the models of the not-too-distant past.
For example, look at the natural gas furnace. Gas furnaces once had AFUE ratings between 56% and 70%. That means that even at the most efficient level, a furnace was converting only 70% of its natural gas into heating power and letting 30% go to waste.
Fast-forward to today. The best furnaces available for homes have AFUE ratings of 98.5%, which means only 1.5% of the natural gas goes to waste. Lower-end furnaces can have AFUE ratings between 85% and 90%. The standard for a furnace to earn the ENERGY STAR label from the Department of Energy is 90% AFUE.
