Assume you have defined the flow rates for showers, which are only used for intervals of 15 minutes. However in simulation results you may find that these showers never seem to have produced any flows and energy consumption.
As I have observed, the reason can be that the number of simulation time steps is too low. However, If you use a weather file where the number of intervals per hour is not 1 (one), but e.g. 2 (timestep=30 minutes), EnergyPlus does not allow to increase the simulation time step number, which in this case paradoxically has to be 2 also. If you increase the number of simulation time steps, EP will respond with the error message:
Number of intervals per hour on Weather file does not match specified number of Time Steps Per Hour
and the simulation will fail.
To me this seems as a logical inconsistency in EnergyPlus, in my view it would be plausible to set the time step numbers to multiples of the number of intervals/hour in the weather file.
Why does EnergyPlus not allow this and can this be rectified in future releases ?