7/7/2016: Update: In fact the files are not actually taking up real space; it just appears to take up hard drive space.
I’ve set an entire folder inside my OneDrive to “available online only” ….. and all of the files have uploaded…. however the files still appear to be taking up local hard drive space. I use an app to visualize the biggest files and folders on my machine…. it is called WinDirStat and is available for free to use and download. WinDirStat is clearly showing that the folder and files are still using space on my local hard drive. I’ve check my onedrive status and it reports “Files are up to date.” I’ll report back if I find a solution.