Multizone Energy Simulations (MES) tools are available to simulate coupled heat and mass transfers in complex buildings. These tools are suitable for the design of HVAC systems and the seasonal or annual assessment of building energy consumptions or building ventilation efficiency. However, they usually assume that the air in each building zone is perfectly and instantaneously well mixed. This assumption can be unsatisfactory for large spaces, for weak airflows, and for zones with strong constraints (e.g., zones having localized heat or pollutant sources). To overcome this problem, we use a Computational Fluid Dynamics (CFD) method as well as the Zonal method to estimate airflows and temperature profiles in one or a few rooms where details are required. Then these detailed models are coupled with the MES model to predict coupled heat and mass transfers within the whole building. We developed an MES program by means of a model library we have implemented in the object-oriented simulation environment, SPARK. With this program, we are able to predict radiative, convective and conductive heat transfers in presence of moisture or pollutant species in complex buildings including their basic HVAC components. In this seminar, we first describe the MES program and how it is constructed using SPARK as well as the zonal method. Then, we describe how the detailed models are coupled with the MES program within SimSPARK. Finally, we demonstrate how the coupled MES/detailed-model program is used to determine heat and mass transfers in a 4-zone heated and ventilated building consisting of 3 offices connected to an atrium.