As of 2015, natural gas is cheaper than heating oil, which leads to lower operating costs. The volatility of the oil market and projected stability of the natural gas market makes gas the most popular fuel for new furnaces.
Natural gas furnaces are slightly more efficient at extracting heat from fuel, although the difference can be slight in newer models. Natural gas releases less carbon monoxide, making it a better option for those concerned about the environment. However, the benefits of natural gas wane in areas where gas lines are not provided. Oil is generally easier to store than natural gas bottles, and the price advantage shrinks when using bottled fuel.