Boilers are used for heating residential and commercial spaces via hot water or, less commonly, steam. Residential boiler efficiency is rated in AFUE (Annual Fuel Utilization Efficiency). The higher the AFUE, the more efficient the boiler.  Commercial boilers, used in commercial buildings and multi-family residential, are rated according to their thermal efficiency.

Research, policies, and programs related to residential and commercial boiler efficiency can be found in the links below and to the right. For specific efficiency tips and guidance on residential boilers, click here.