Facade integrated ventilation systems have the potential to improve local air quality and occupant comfort, reduce building energy consumption and provide economic retrofit opportunities. However, existing modelling and evaluation methods are not able to sufficiently address the technology's potential capabilities. In this paper, a new model is developed specifically adapted to facade-integrated air handling units interacting with ventilated fenestration systems. The new modelling approach is based on the co-simulation of two different models through a Functional Mock-Up Unit (FMU) Interface. An airflow network model of the air handling unit is developed in Modelica and exported as an FMU based on this specification. The FMU is then simulated within an updated version of the building simulation program Fener that includes a physical model that calculates the window heat fluxes and temperatures, as well as the window gap air outlet temperature in case of ventilated facades. The different sub-models are first validated versus experimental data from a test chamber in Villafranca di Verona, Italy. Then, the full co-simulation approach is applied to a case study in which different control strategies for the fenestration system are investigated. (C) 2017 Elsevier B.V. All rights reserved.