Normally, potential saving calculation is the most saving that customer can realize when implementing the project. By the way, when we have to guarantee the saving, we have to include uncontrollable parameter, safety factor, operation condition and production condition in the calculation. All of those parameters may be different case by case depend on the solutions proposed. Therefore, guarantee saving is usually lower than potential saving but the payback period of the project should not be over than customer criteria (3 years in this report).