I have worked in building maintenance and repair. One thing that is extremely hazardous to a concrete building is too much water. I have seen many concrete planters that crack and result in water leaks for lower levels. Standing water in concrete structures is a huge no no. I do not have a lot of experience in engineering on this matter, but whenever I see a solar punk sky scraper with vegetation on its exterior, I think “cool, but maintenance and inspection must be horrible! Repairs must cost a fortune when those roots and moisture degree the concrete.”
What engineering controls does one need to create a durable structure while exposed to constant moisture needed for vegetation, and the vegetation itself? I know there are green sky scrapers with gardens all over. What is the maintenance of those structures? Do they hold up\last as long as bare concrete structures?
We discussed it a bit recently here https://slrpnk.net/post/1783839
I think many of the projects we see actually done (and which inspire artworks) are vanity projects that are not very practical or cost effective (like full grown trees on roof-tops).
But there are many ways to green roof-spaces that do not require standing water or all that much maintenance.