One of the problem in chilled water pumping system is the degradation of performance of the control valve system that makes the energy consumption is less efficient. Thermomechanical method is proposed in this research to control the VSD of the pump to increase the energy efficiency of the pump. This method needs physical input references from the piping system using sensor that installed and connected to the main controller using wireless sensor network with Zigbee communication. This method was tested in the arduino prototype simulation. First simulation is simulated the less performance condition of the control valve and the result of the coefficient of performance (COP) is 1.07 with efficiency margin is 16.4%. Second simulation is simulated the good performance condition and the result of the COP is 1.67 with efficiency margin is 37.2%. From those result can be concluded that thermomechanical method can increase the energy efficiency if the control valve system is in the good performance condition. If the control valve system is less performance, this method can't give the energy efficiency as good as if the control valve at the good performance condition. Nevertheless, this method can increase the efficiency margin at the less performance condition of control valve.