Ill be, I have a radio tower site set up similar to that, except flex goes in
the side of the building where a small window used to be. The flex had
completely shreded (took about 12 years though). They did not want
metal duct, so I had to put new flex up with aluminized exterior.
I seen the same deal with a residential unit. Someone put a self contained trailer unit on a house via flex ran through a basement window. At least the put a damper to shut of any air flowing outside in the winter. We removed the unit and put in a split system