You may want to look into the Scheduling/Property Data features. For individual Spaces, adding a Property Set with an automatic property for area to the Space (or Space style) and then creating a Schedule Tag to display the data would avoid having to manually type the information. For departments consisting of multiple Spaces, you may be able to use a Zone to aggregate the individual Spaces in a given department, and then use an automatic property in a Property Set to get the total area of the Zone.
David Koch
AutoCAD Architecture and Revit User
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