Finally, the time periods with regard to first group 101 are determined. If there would have been no other groups/schedules to take into account, lights 44 to 47 would have been allocated time periods 121 to 124 of
The group order in which time periods are determined for the groups may depend, for example, on when the group was formed. For example, if a new group is formed, a schedule may be determined for the new group while taking into account the schedules for the existing groups. Alternatively, a new schedule may be determined for all groups, including the new group. In this case, the group order may be arbitrary, for example. Alternatively, an optimization algorithm may be used to determine which of the different group orders produces the most energy efficient schedule, for example.