In December 2023 the U.S. Department of Energy finalized a new efficiency standard for residential furnaces: every new non-weatherized gas furnace must reach at least 95% AFUE. The rule applies to units manufactured on or after December 18, 2028, and it raises a minimum that had sat at 80% AFUE since 2007. Gas-industry groups challenged it in court and lost, so it is settled law — DOE projects it will save consumers about $24.8 billion in energy bills over 30 years.
Because 95% AFUE can only be hit by a condensing furnace, the practical effect is to end the standard 80% non-condensing furnace for new manufacture. This matters to anyone replacing a furnace today. Buy a 95%+ condensing unit now and you are simply ahead of the rule — you get the lower bills immediately and never face the transition. The one thing to plan for is venting: moving from an 80% to a 95% furnace means new PVC venting and a condensate drain, which a good contractor will price into the job up front.
Two cautions keep this honest. The rule governs new equipment, not your existing furnace — an 80% AFUE furnace already in your home is legal to keep, run, and repair, and there is no requirement to rip out a working unit. And the standard is not a reason to be rushed into a replacement before yours has actually failed; it is a reason, when you do replace, to skip the bottom-tier 80% unit and choose the efficiency level the country is moving to anyway.