The following nonassignable categories are included to complete the list of space use categories. When the total area of the assignable space use categories is added to the total area of the nonassignable space use categories, they provide the net usable area of a building as per the formula in section 3.1, Overview of Building Measurement Terms.
Net Usable Area = Assignable Area + Nonassignable 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 nonassignable space are provided in chapter 3. As with all other space use classifications, institutions also may wish to track nonassignable 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.
Definition: The sum of all areas on all floors of a building not available for assignment to an occupant or for specific use, but necessary for the general operation of a building.
Description: Included should be space subdivisions of the three nonassignable space use categories-building service, circulation, and mechanical-that are used to support the building's general operation.
Limitations: Deductions should not be made for necessary building columns and projections. These small areas are excluded as the represent an insignificant percentage of the total area of an average-sized space. Capturing their area would be unduly burdensome relative to the very small contribution they would make toward precision. Areas defined as assignable should not be included.
Nonassignable spaces required for physical access to floors or subdivisions of space within the building, whether directly bounded by partitions or not. Included are: fire towers, elevator lobbies, tunnels, bridges, stairways, and receiving areas such as loading docks.
Nonassignable spaces used to support a building’s cleaning and public hygiene functions such as janitor's closets, small custodial spaces, maintenance material storage areas, trash rooms for non-hazardous waste and public restrooms.
Nonassignable spaces of a building designed to house mechanical equipment and utility services, and shaft areas. This includes central utility plants, boiler rooms, mechanical and electrical equipment rooms, fuel rooms, meter and telecommunication closets.
The remaining area within the gross square footage of a building is structural or “construction” area, which cannot be occupied or put to use. (See section 3.2, Definitions of Building Areas.) Institutions may wish to include this area using the ZZZ code to have a complete inventory for all the building areas that add to the Gross Area total for a floor and for a building.
Definition: The sum of all areas on all floors of a building that cannot be occupied or put to use because of structural building features. This area is the algebraic difference between Gross Area and Net Usable Area. Examples of building features normally classified as structural areas include exterior walls, fire walls, permanent partitions, unusable areas in attics or basements, or comparable portions of a building with ceiling height restrictions, as well as unexcavated basement areas
Limitations: This area is not measurable but can be calculated by the formula:
Structural Area = Gross Area - Net Usable Area