To see room volumes on the Properties palette, in tags, and in room schedules, enable volume computations. 
Note: Volume computations may affect Revit performance. You can turn on volume computation to prepare and print schedules or other views that report volumes. Then turn off the feature. 
- Click Architecture tab
Room & Area panel drop-down
 (Area and Volume Computations).  
- On the Computations tab of the Area and Volume Computations dialog, under Volume Computations, select (to enable) or clear (to disable) Areas and Volumes. 
 
- Click OK.