If you have a furnace in your house that’s more than 15 or even 20 years old, any replacement system will have a higher energy efficiency rating. This because standard for gas furnaces have changed dramatically over two decades, and even the new mid-efficiency models have a higher standard than the mid-efficiency models at the start of the 21st century.
If you upgrade to a new furnace at the end of this year’s heating season, you can expect energy-saving performance. And if you want a major efficiency upgrade, one of the best options is a condensing furnace. These furnaces score some of the highest AFUE ratings (efficiency ratings) of any heating system on the market, with as little waste as 2%.