Willow and Hearth

95%. That’s the new minimum Annual Fuel Utilization Efficiency the U.S. Department of Energy will require of most newly manufactured residential gas furnaces, under a final rule DOE issued that raises the federal efficiency floor for the first time since 2007.

Key Points

• DOE’s rule sets a 95% AFUE minimum for new non-weatherized gas furnaces, up from the current 80% baseline.
• The agency projects the standard will save American households about $1.5 billion a year, or $24.8 billion cumulatively over 30 years.
• Manufacturers don’t have to comply until furnaces built starting in late 2028, pinned down as December 2028 by the Appliance Standards Awareness Project, a nonprofit that tracks federal efficiency rulemakings.
• The standard is codified in the Federal Register, giving it the force of law rather than a proposal.

What the Rule Actually Requires, and When

AFUE measures how much of the fuel a furnace burns actually turns into heat for the house, versus what escapes up the flue. The current federal minimum, in place since 2007, is 80% AFUE — a level DOE and the Appliance Standards Awareness Project both note nearly the entire market already exceeds. The new rule pushes that floor to 95% AFUE, a threshold that effectively requires condensing furnace technology, which wrings extra heat out of exhaust gases before venting them.

Crucially, the requirement applies to manufacturing, not to furnaces already installed or already sitting in a distributor’s warehouse. DOE’s own release frames the change as taking effect for furnaces built starting in late 2028, so nothing on showroom floors changes overnight. A furnace bought and installed today, or in 2027, is unaffected by the new floor and won’t need to be replaced early because of it.

What This Means If You’re Shopping for a Furnace Now

For homeowners whose furnace fails this winter, the practical reality is that the rule doesn’t change what’s available to buy right now. Every furnace on the market still meets only the 80% minimum, though units rated 90% AFUE and higher, including condensing models near the future 95% threshold, are already widely sold as a step-up tier.

That leaves a familiar tradeoff rather than a new one. A furnace at the current 80% minimum typically costs less upfront but wastes more fuel every month it runs. A high-efficiency condensing unit costs more to install, partly because it needs different venting, but burns less gas for the same heat output and will already comply with the standard taking hold in 2028. Since a furnace typically lasts 15 to 20 years, anyone replacing one now is effectively deciding whether to buy for today’s price or for the efficiency floor the whole market will eventually be required to meet anyway.

Context

DOE estimates the rule’s 30-year savings translate into fuel cost reductions for millions of households, alongside lower emissions from residential heating. The change follows a pattern of periodic efficiency updates to furnaces, water heaters, and other appliances that DOE revisits every several years, with the furnace floor untouched since 2007 until this rule.