Organize Drawing by Area

My projects have multiple area's under the same contract. For example Building 1 , Building 2, Civil, & City improvements. Right now there is no way to create a sub folder under drawings (at least that I can see). So when I open my drawings all these are together in the same list. To organize it, I have to rename each page by area ( B1, B2, Civil,...). This just alphabetizes the sheets but takes forever. This is still way too confusing for the field guys. They need to be able to open the drawings, select which area they need to see, then only see those drawings. It will prevent a lot of confusion and potentially a big mistake. This could also be helpful with revisions. If a new drawing set is released, you can have a folder by revision to see what changed.