Do you mean timestep or run period? These are both tunable. The main timestep is set by the Timestep object (and there are some other timesteps in other objects too). The run period is set by the SimulationControl and RunPeriod objects. There is extensive, searchable, navigable documentation for all EnergyPlus inputs and options here: http://bigladdersoftware.com/epx/docs...

The basic simulation timestep in EnergyPlus is user-defined, with allowable values ranging between 1 minute and 60 minutes. For more details on this simulation parameter, see the documentation of Timestep. Click here for more details on the Time Marching Solution.