Generally, resource leveling does not affect costs, because its aim is to have zero over-allocation of resources on the project. So, if a resource is over-allocated for a certain period, it distributes the over-allocation of the resource over a longer period which will lengthen the schedule but does not affect the project cost because the number of working hours does not change.
Note that in some cases, the resource leveling does affect costs, here's how:
- If the resources are paid over-time (the over-time will no longer be paid when the resource are leveled). This means that the costs will be reduced in this case.
- If the project incurs a penalty if it's finished late. In this case, the costs will increase.