ArcelorMittal is a world leading steel and mining company where the final chemical, mechanical and thermal treatments of steel coils typically occur in the cold rolling mill hall (10.000 m²). In this area a high temperature heat network is present to ensure a minimum air temperature of 15 °C and 60 % maximum relative humidity to prevent rust formation on the stored steel coils. In previous year a numerical thermal model has been made in Python of the heat network in order to calculate the heat transferred from the different components present in the heat network to the hall. This model was a first step to optimize the energy use of the heat network. So far little is known about how the air temperature and humidity are affected by the transferred heat. By using computational fluid dynamics (CFD) the air flows in the hall could be modelled and in an ideal case this information could be linked with the information of the available thermal model.