Non-condensing furnaces are required to be 78 percent efficient, except for units designed for mobile home use. Mobile home units are required to have an AFUE of 75 percent. In June 2011, the Department of Energy (DOE) raised the efficiency requirements for many furnace styles.
The requirements were set to go into effect in May 1, 2013 and January 1, 2015. Following a January 11, 2013, court ruling, the DOE put the increase in requirements on hold pending the lawsuit's outcome.
As of May 2013, these requirements are now pending:
Non-weatherized gas furnaces must be 80 percent efficient.
Non-weatherized mobile home furnaces must be 80 percent efficient.
Non-weatherized oil furnaces must be 83 percent efficient.
All gas furnaces installed in the northern states, about 30 in total, must be 90 percent efficient.
As of January 2015, these requirements are pending:
Weatherized gas furnaces must be 81 percent efficient.
Weatherized oil furnaces must be 78 percent efficient.