Keep a GFA-by-usage schedule right on the sheet next to the drawings that explain it, instead of a separate report readers have to cross-reference.
Add an area schedule
Click Area schedule in the Insert bar to add a table summarizing area by usage, built from the model, GFA, GBA, and NSA per usage.
Select the table to open its controls:
Hide lines: remove the table's grid lines.
Counts: add No. and Units columns.
↻: recompute the table from the latest model. An area schedule doesn't update on its own, so refresh it after a model change.