The gas and oil equipment efficiencies that are calculated represent the percentage of the fuel's energy that is delivered to the dwelling as useful heat. The Gas Appliances Manufacturers Association presented information on AFUE ranges for oil and gas furnaces shipped each year which have been used in the past to estimate an average AFUE value for new oil and gas equipment. After 1991, average efficiencies could not be estimated using GAMA data. These published data based on US Department of Energy efficiency tests and calculations indicate that residential oil heating equipment has historically operated at higher efficiency than gas fired equipment. Equipment efficiency directly impacts fuel use, heating costs, and air pollution emissions.
Higher efficiency reduces fuel costs and emissions.
While the difference in the average efficiency between new oil and gas heaters has narrowed in recent years, oil continues as one of the most efficient home heating sources. In fact, oil burner particulate emissions have decreased by a factor of 20 over the past three decades and are now approaching near-zero levels. See figure three, below. These minimal soot emission rates by modern home oil burners are much lower than emissions from most other combustion equipment, as shown in figure four, below. Clearly, properly adjusted home oil burners are now one of the cleanest combustion sources with smoke and soot emission rates that are comparable to natural gas burners.