"During bright, sunny days in the winter, ventilation may be needed to keep temperatures at an acceptable level for good plant growth. The fan and tube system introduced several years ago has become popular throughout the industry for this purpose. It mixes the cold outside air with the warm greenhouse air before it reaches plant level."1
I toyed with the idea of leaving it up in hopes that it would run again, but with the damage already inflicted on the greenhouse, we are not holding any heat. Once the roof blew off last Spring, there was just no sense in holding out for returning this greenhouse to a former state: we're exposed directly to the outside through 20-25% of the roof, gaps where the "walls" are pulling off the supports, and entire windows and louvers missing. We also have no heat source; if a boiler still exists, it would be in the Fire & Iron building and all pipes between boiler ad buildings have been severed or corroded.
So with this old tube laying sloppily over pipes and supports, it trapped water, had some bad biofilms/bacteria growing, and often fell making it difficult to move or work.
I decided there was nothing to lose in pulling this nasty thing down. Worse case scenario we have to purchase a new tube one day (assuming the louvers and fans are all replaced and run again, and the walls and roof should somehow be made useful).
1https://ag.umass.edu/greenhouse-floriculture/fact-sheets/ventilation-for-greenhouses