It "can" be done, but is not very elegant.
You will need to duplicate something in order to make a phased project, so make a choice: layers, files (as noted before) or elements.
For layers and files, solutions have been posted.
If you want to have everything in the same model, it can be done by duplicating elements and using the "show on current renovation filter/show on all relevant filter" option. Set your renovation filters (phases in your case) and then set the status for each element.
Existing elements to remain might use "show in all relevant filters".
Existing elements to be demolished in other phases, demolition objects in different phases, and new elements might need to be duplicated per phase and tagged with "show in current renovation filter" option.
It will be more complex if you want to show, for example, phase1 with only exist+demolish and then phase1 with exist+new, as those would need to be two different renovation filters and thus you would need to duplicate elements "to be shown in a single filter" to be able to show them in both...
like I said... it "can" be done.
What would you like to duplicate
