Thread:ChishioKunrin/@comment-26900371-20181125052849/@comment-4010415-20181125065139

True, though my high school had a rather small greenhouse for one of its classes near the agriculture building, so I think they come in varying sizes. It's just that my first impression was just rows and rows of greenhouses.

Also, upon looking again, the first concept art at the end of episode 5 shows the structures and depicts the walls as being clear windows, lending more to the possibility of them being greenhouses with frosted-over windows.