Non-assignable categories are included to complete the list of space use categories, including custodial/building service, restrooms, circulation, and mechanical. When the total area of the assignable space use categories is added to the total area of the non-assignable space use categories, they provide the net usable area of a building:
Net Usable Area = Assignable Area + Non-assignable Area
It is recommended that institutions include these areas in their space inventories for the several important purposes outlined earlier in section 4.1, under Space Use Category Structure. Definitions of the three categories of non-assignable space are provided in chapter 3. As with all other space use classifications, institutions also may wish to track non-assignable areas with special physical characteristics, functions, or equipment (e.g., elevators for freight, passengers, and dumb waiters; public rest rooms for female, male, or unisex use, as well as handicapped accessibility, etc.) through the development and application of additional subcategory codes.
Physical assets (e.g., site improvements, major site utility distribution, etc.) that do not fall within the limits of a building are considered infrastructure. Suggested categories for infrastructure assets are provided in chapter 6 and appendix D.