Optimization and control of displacement ventilation systems in buildings require accurate modeling of aeraulic and thermal phenomena involved in the establishment or the destruction of thermal stratification in the room. We carried out an analysis and developed global models on the basis of data from the Poitiers "Laboratoire d’Etudes Thermiques" experimental facility (see Figure°2). The goal is to provide tools accurate enough to describe the thermal comfort implied by such systems but of easier use than CFD codes . We propose two types of simplified models for evaluation of the temperature in the room. They are called zonal model and one-dimensional model and have been presented in a previous paper . After briefly coming back on their description we compare calculations and experimental data in terms of temperature field. We then focus on the plume representation. We also integrated the models in the CLIM2000 Building Energy Simulation Tool . This means that the elementary models can be connected to other phenomena (complex wall composition, solar input, climate scenarios, etc.) to allow a realistic representation of a room equipped with a displacement ventilation system.