Information systems play an important role in today's advanced information society. The concentration and performance of the information processing devices that make up these systems are increasingly rapidly, and this has led to an increase in the heat concentration of Data Centers as well. For this reason, air conditioning systems for Data Centers must offer a high level of reliability to constantly maintain appropriate room temperatures. In this paper, we will use the previously proposed calculation method to conduct the following studies, targeting cases in which the systems have actually been implemented. 1) Simulation to grasp the reliability characteristic in the system. 2) The factor given to the reliability of an air-conditioning system is grasped using the Taguchi method.