The file ocupant_contam.ctm uses a single CO2 contaminate and
and occupant source type which is referenced by all the internal
flow nodes.

The file occupant_contam_manual.ctm is an alternative regime
which was edited by a user to exclude certain zones like
corridors and the air handling boxes from the assessment.

Most occupied spaces will have the same predictions but 
those minor zones tend to be lower as air is only passing
through.
