This sort of thing will happen if you have thermostat (and humidistat) schedules that have setup/setback or internal gains with "top hat" schedules that create an abrupt changes in zone loads. setup/setback. The HVAC ideal loads system will attempt to recover from a change in loads over just thermostat in one timestep, which takes more power for a shorter timestep. Such an experiment would need to use constant thermostat schedules and gradually ramping changes in internal gains. schedules.