Commercial Warm Air Furnaces


Commercial warm air furnaces (CWAFs) are defined as units with capacities of at least 225,000 Btu/hr (British Thermal Units per hour). They are designed to supply heated air through a duct system. In practice, commercial furnaces are gas or propane heating sections of packaged roof-top units (RTUs) used for small- to mid-sized commercial buildings. RTUs are essentially air conditioners that may also contain a heating section.


The current standards for CWAFs took effect in 2023 and specify minimum thermal efficiency levels of 81% for gas-fired equipment and 82% for oil-fired equipment. The standards were based on a consensus agreement between manufacturers and efficiency advocates.

In 2023, DOE finalized a determination not to amend the standards for CWAFs. 


Much greater energy savings from commercial warm air furnaces are possible using condensing technology. Condensing furnaces extract additional heat by condensing the water vapor in the flue gases and reach efficiency levels of 90% or higher.

In 2023, DOE amended the test procedure for CWAFs to establish a new metric, Thermal Efficiency Two (TE2), that accounts for jacket losses and part-load operation in addition to capturing flue losses. However, the current standards are based on the older metric.

Savings through what year?: 2053
Energy saved (quads): 0.23
CO2 savings (million metric tons): 12
Net present value savings ($billion) 3% discount rate: $1.0
Net present value savings ($billion) 7% discount rate: $0.3


Federal Date States
Potential Effective Date of Updated Standard 2029
Updated DOE Standard Due 2024
3rd Federal Standard Effective 2023
Potential Effective Date of Updated Standard 2019
3rd Federal Standard Adopted (DOE) 2016
Updated DOE Standard Due 2016
2nd Federal Standard Effective 2003
2nd Federal Standard Adopted (DOE) 2001
1st Federal Standard Effective 1994
EPACT Initial Federal Legislation Enacted 1992
1st Federal Standard Adopted (Congress) 1992

Timeline reflects state standards from 2001 to present; federal standards from inception to present.