An open source Modelica package for a specific type of Phase Change Material (PCM) ventilation unit is developed. The model is built as a part of the Termonet library of components from Modelica Standard Library (MSL) and International Building Performance Simulation Association (IBPSA) library aiming at open source models for households and utility companies to help to integrate sustainable technologies into district energy networks. The PCM heat exchanger model instantiating IBPSA library fluid components is compared to the MSL PCM implementation with no fluid components and Matlab-inspired textual Modelica model. MSL-based and textual models are shown to produce identical results, whereas an account of fluid properties leads only to a slight deviation. This can motivate the use of the MSL and IBPSA-based models as control and emulator models in model predictive control applications. Essential fluid models from IBPSA library can be compiled and simulated using OpenModelica with minimal tuning, which shows the potential of the IBPSA library as a fully open source building performance simulation tool.