Damian, I have actually also seen some pictures of someone that grew orchids on a swamp cooler. It was done for the very reason you are doing it, to grow cool growing orchids.
I didn't realize you were in AU. A little Northern Hemisphere bigotry I guess. Sorry.
You may have come across an English translation I attempted for the instructions on how to build this thing. Looks like the original instructions are now gone. I won;t post a link to it since I don;t have permission to post it but I am still trying to get in touch with the author. There is a fellow Patrick Blanc who inspired this construction who does it on a grand scale.
Living Walls | EcoGeek | Green, Building, Some, System, Wall