While negotiations continue on proposed revisions to federal minimum efficiency standards for residential non-weatherized gas furnaces, the increase that was decided in the 2007 rulemaking – which includes increasing minimum efficiency from 78% AFUE to 80% AFUE – took effect Nov. 19.
AFUE stands for annual fuel utilization efficiency, and is a measure for furnaces roughly comparable to the SEER rating for air conditioning units.
However, increases above that level have been under consideration since a more stringent federal rule was introduced in 2011, which was successfully challenged in court by the American Public Gas Association. The Department of Energy’s current proposal for non-weatherized gas furnaces is 92% AFUE, requiring condensing combustion.
Negotiations for modification of this proposed minimum are still underway, but so far have not led to a replacement or supplemental change to the official federal notice of proposed rulemaking.
The 78% AFUE furnaces that have already been produced can be sold, but they can no longer be manufactured. For the time being, 80% AFUE is the least-efficient furnace that can be manufactured.
NAHB will continue to update members if and when the Department of Energy settles the challenge and makes a ruling. For further information contact Don Surrena at 800-368-5242 x8574.