A computer program product including computer usable program code embodied on a computer usable medium, the computer program product comprising: computer usable program code for identifying job performance data for a plurality of representative jobs; computer usable program code for running a simulation of backfill-based job scheduling of the plurality of jobs at various combinations of a run-time over-estimation value and a processor adjustment value, wherein the simulation generates data including energy consumption and job delay; computer usable program code for identifying one of the combinations of a run-time over-estimation value and a processor adjustment value that optimize the mathematical product of an energy consumption parameter and a job delay parameter using the simulation generated data for the plurality of jobs; and computer usable program code for scheduling jobs submitted to a processor using the identified combination of a run-time over-estimation value and a processor adjustment value.