Fenix+ 3 application allows you to to specify objects (for example, roofs, walls, stairs, doors, floors, landings) that must be ignored when simulating fire dynamics. It is recommended to ignore only those objects that are not obstacles to the spread of dangerous fire factors (DFF), for example, cell structures. For this, select the desired object on the scene and in the properties of this object, check the box for the Ignore in case of fire parameter.
As a result, the application does not transfer the selected object to the FDS file as an obstacle.