This article contains definitions of various terminology used in reference to building area. See the Space Inventory Handbook page for related articles. See the SIMS User Guide for instructional SIMS articles.
This article includes:
Summary
Gross Square Feet (GSF): Area within the exterior building facade.
Net Square Feet (Net): Interior area that can be occupied and accessible by foot. Calculated wall face to wall face, which includes assignable and non-assignable square feet. Excludes structural area.
Structure: Comprised of exterior walls, interior walls, utility chases, and other structural elements. Areas do not contain room numbers.
Assignable Square Feet (ASF): Interior areas available for assignment, excludes non-assignable and structural areas.
Non-Assignable Area (NSF): Common areas associated with the operation of a building, consisting of custodial, mechanical, public restrooms, and circulation spaces (hallways, stairs, and elevators).
Cleanable Square Feet (CSF): Gross square feet, excluding mechanical, structural and custodial areas. Mechanical: Comprised of mechanical rooms, IT/Data closets, electrical closets, etc.
Detailed Definitions
Gross Area
- Definition: The sum of all areas on all floors of a building included within the outside faces of its exterior walls. This includes floor penetration areas, however insignificant, for circulation and shaft areas that connect one floor to another.
- Basis for Measurement: Gross Area is computed by physically measuring or scaling measurements from the outside faces of exterior walls, disregarding cornices, pilasters, buttresses, etc., which extend beyond the wall faces. Exclude areas having less than a three-feet of clear ceiling height.
Measured in terms of gross square feet (GSF):
Gross Area = Net Area + Structural Area.
- Description: In addition to all the internal floored spaces obviously covered above, Gross Area should include the following: excavated basement areas; mezzanines, penthouses, attics; garages, enclosed porches, and corridors, provided they are within the outside face lines of the building, to the extent of the roof drip line. The footprints of stairway, elevator shafts and ducts (examples of building infrastructure) are to be counted as gross area on each floor through which they pass.
- Limitations: Exclude open areas such as parking lots, playing fields, courts, and light wells, or portions of upper floors eliminated by rooms or lobbies that rise above single-floor ceiling height.
- Exception: Include top, unroofed floor of parking structures where parking is available.
Net Area
- Definition: The sum of all areas on all floors of a building either assigned to, or available for assignment to, an occupant or specific use, or necessary for the general operation of a building.
- Basis for Measurement: Net Area is computed by summing the Assignable Area and the Non-assignable Area.
Measured in terms of net square feet (NSF):
Net Area = Assignable Area + Non-assignable Area.
- Description: Included should be space subdivisions of the nine primary space room type categories.
- Limitations: Deductions should not be made for necessary building columns and projections. Areas defined as structural should not be included.
Assignable Area
- Definition: The sum of all areas on all floors of a building assigned to, or available for assignment to, an occupant or specific use.
- Basis for Measurement: Assignable Area is computed by physically measuring or scaling measurements from the inside finishes that form the boundaries of the designated areas. Exclude areas having less than a three-feet of clear ceiling height.
Measured in terms of assignable square feet (ASF)
Assignable Area = Sum of the nine primary room type Categories, excluding 0x - Building Services. - Description: Included should be space subdivisions of the 8 primary room type categories, excluding 0x - Building Services (Classrooms; Laboratories; Laboratory Services; Library, Museum & Study; Offices; General Use; General Service; Medical/Clinical; and Residential) that are used to accomplish the institution’s mission.
- Limitations: Deductions should not be made for necessary building columns and projections. Areas defined as Non-assignable, Building Circulation, and Structural should not be included.
Non-Assignable Area
- Definition: The sum of all areas on all floors of a building not available for Assignment to an occupant or specific use, but necessary for the general operation of a building.
- Basis for Measurement: Non-Assignable Area is computed by physically measuring or scaling measurements from the inside finishes of surfaces that form the boundaries of the designated areas. Excludes areas having less than three-feet of clear ceiling height.
Measured in terms of non-assignable area
Non-Assignable Area = Sum of the space defined using the 0x - Building Services room type category. - Description: Included should be space subdivisions of the non-assignable room use category (Building Services) that is used to support the building’s general operation.
- Limitations: Deductions should not be made for necessary building columns and projections. Area defined, as Assignable, Building Circulation, and Structural should not be included.
Building Circulation Area
- Definition: That portion of the Gross Area, whether or not enclosed by partitions, which is required for physical access to some subdivision of space.
- Basis for Measurement: Building Circulation is computed by physical measuring or scaling measurements from the inside finishes of surfaces that form the boundaries of the designated areas. Or, when such spaces are not enclosed by walls or partitions, measurements should be taken from imaginary lines which conform as nearly as possible to the established circulation pattern of the building. Excludes areas having less than three-feet of clear ceiling height.
Measured in terms of area:
Building Circulation = Sum of the building 0A-Circulation root type category. - Description: Building Circulation should include, but not be limited to: Corridors (access, public, service, also “phantom”: for large unpartitioned areas); elevator shafts; escalators; fire towers or stairs; stairs and stair halls; loading platforms (except when required for operational reasons and, thus, includable in Assignable Area); lobbies (elevator, entrance, public; also, public vestibules); tunnels and bridges (not mechanical)
- Limitations: When assuming corridor areas, only horizontal spaces required for general access should be included, not aisles which are normally used only for circulation within suites of rooms, auditoria, or other working areas, which may have room numbers associated with them. Deductions should not be made for columns and projections necessary to the building.
Structural Area
- 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.
- Basis for Measurement: Precise computation by direct measurement is not possible under these definitions. It is determined by calculating the measured Gross Area less the measured Net Area and the measured Building Circulation Area.
Measured in terms of structural area:
Structural Area = Gross Area – Net Area – Building Circulation.
- Description: Examples of building features normally classified as structural Areas include exterior walls, firewalls, permanent partitions, unusable areas in attics or basements, or comparable portions of a building with ceiling height restrictions, as well as unexcavated basement areas.