A hydrocarbon-producing facility includes a first energy subsystem to receive input energy from an energy source and byproduct energy generated by a second energy subsystem connected to the first energy subsystem, the first energy subsystem to perform work using the input energy and the byproduct energy. A method of analyzing energy performance in the hydrocarbon-producing facility includes identifying the byproduct energy received by the first energy subsystem from the second energy subsystem over a duration, determining energy intensity indices at corresponding time instants during the duration for the first energy subsystem, each energy intensity index based on the input energy, the byproduct energy, and output parameters of the work performed using the input energy and the byproduct energy, comparing the energy intensity indices to each other, and determining an efficiency of the first energy subsystem in response to comparing the energy intensity indices to each other.