Fascinating what Google Scholar searches can find sometimes. Did a search for “indoor microbiology” and this came up Investigations of fungal diversity in wooden structures and soils at historic sites on the Antarctic Peninsula by Brett Arenz and Robert Blanchette. In the paper the authors discuss culture based studies of fungi isolated from various buildings in Antarctica and discuss the implications regarding historical presentation and microbial diversity. So if you think you can’t do any interesting field work if you work on the “built environment” you would be wrong.