In this chapter, a method for energy integration of heating, cooling, and power generation and desalination systems in process industries will be studied using the Total Site integration approach. This approach can identify and measure energy production and consumption potentials of integrated process units with a holistic attitude. Integrating various units with different needs makes it possible to optimize energy generation and consumption in process industries by maximizing energy efficiency and minimizing energy consumption and related costs of the whole Total Site. This approach ensures that the Total Site system’s overall efficiency is optimal by providing a systematic method. The old methods, which were based on increasing each unit’s efficiency and cogeneration in each state, caused each unit to impact the other. As a result of this interaction, the system’s overall efficiency was reduced, or the optimal point exists only from each unit’s point of view. However, in a broader view, the systems were not optimal while working together.