The therm (symbol thm) is a non-SI unit of heat energy equal to 100,000 British thermal units (BTU). It is approximately the energy equivalent of burning 100 cubic feet (often referred to as 1 hcf) of natural gas. A therm factor is used by gas companies to convert the volume of gas used to its heat equivalent, and thus calculate the actual energy use. The therm factor is usually in the units therms/Ccf. It will vary with the mix of hydrocarbons in the natural gas. Natural gas with a higher than… (More on Therm)