Fenix+ 3 allows you to specify objects that should not be taken into account when modeling fire dynamics.
To do this, select the desired object on the scene and check the Ignore during fire checkbox in the object properties. As a result, the program will not transfer the selected object to the FDS file as an obstacle.
We recommend excluding only the objects that do not obstruct the spread of dangerous fire factors. For example, mesh structures that fire could still spread through.