Not sure if anyone does this differently, but if you build all your rooms and add calc points to them, you can double wall the whole project without having to place calc points again.
1. Click Create a room and click the "Specify Calculation Points For Room box." in the pop-up.
2. Build room and place calc points on desired plane. click OK
3. Check top left of the rooms and objects tab for Surface edit drop down
4. Click window (rooms only)
5. Make window over entire project.
6. Click "Tag all Surfaces" tab at the top
7. Click drop down for Single wall and change to double wall. Click OK
After this is done, your POV will reset and all your rooms will be double walled but all your calculation points will still be present. this is especially useful for big jobs with a lot of rooms like schools and hospitals. Hope this helps!
Title should say Bulk Double Wall. and it wont let me edit, oh well