Proton Exchange Membrane Fuel Cells (PEMFCs) are widely applied in electricity generation and electric vehicles. However, they face limitations in their further applications due to high energy consumption of the cold-start process. Therefore, the investigation of energy consumption and energy management is critical for PEMFCs. This work presents a numerical model for energy consumption considering the phase change of coolant for PEMFCs during the cold -start process by circulation of coolant as heat source. The heating power, pump load, as well as the total power consumption are analyzed. Finally, the optimum working condition of the cold-start process is studied.