The air interchange performance between the modules is an important factor in the atmosphere revitalization system of International Space Station (ISS) to maintain a habitable environment for the crew during on-orbit activities. A SINDA/FLUINT model of the integrated ISS air quality control system was constructed in support of pre and in-flight predictions of cabin air temperature and humidity, and CO2 partial pressure. This model calculates masses and partial pressure for the major gas constituents, such as O2, N2, CO2, and H2O. This model also simulates the effect of crew activities and their location in the station. The elements are linked together in terms of air interchange in the models via Inter-module ventilation (IMV). The air in each volume is assumed to be perfectly mixed. Latent loads and IMV air are assumed to be immediately and uniformly distributed throughout the cabin air volume of each element. This paper presents a description of the model and analysis generated using this model.