13. Glossary


Abbreviations for Architect/Engineer, Architect/Engineer/Contractor. Architect/Engineer/Contractor/Facility Manager
Building Information
Building Information Model—Product
An object-based digital representation of the physical and functional characteristics of a facility. The Building Information Model serves as a shared knowledge resource for information about a facility, forming a reliable basis for decisions during its lifecycle from inception onward.-1-
Building Information Modeling—Process
A collection of defined model uses, workflows, and modeling methods used to achieve specific, repeatable, and reliable information results from the model. Modeling methods affect the quality of the information generated from the model. When and why a model is used and shared impacts the effective and efficient use of BIM for desired project outcomes and decision support.
Building Information Management—Data Definition
Building Information Management supports the data standards and data requirements for BIM use. Data continuity allows for the reliable exchange of information in a context where both sender and receiver understand the information.-2-
Computer Aided Design. A geometric/symbol based computer drawing system that replicated hand drawing techniques.
The model and facility data for the commission, operations, and maintenance of the project shall satisfy the Construction Operations Building Information Exchange (COBIE) requirements, and be submitted in compliance with the commissioning requirements. The data expected from BIM for facility handover shall conform to the following standards: VA-SEPS, Uniformat, OmniClass, Geospatial, NBIMS, COBIE, NCS, and IFC standards for building information. COBIE data in the form of the COBIE Excel Spreadsheet and related commissioning information shall be delivered electronically in formats suitable for integration into current and future CAFM systems.
General Services Administration Guidelines
Guidelines used by the General Services Administration: GSA Building Information Modeling Guide Series: 02 – GSA BIM Guide for Spatial Program Validation, v 0.96, (April 2007) are some of the first developed for use in Federal buildings and can offer valuable insight into Building Information Modeling. They can be found on the GSA's web site.
The Institute of Electrical and Electronics Engineers defines interoperability-3- as "the ability of two or more systems or components to exchange information and to use the information that has been exchanged." James A. O'Brien and George M. Marakas, authors of Management Information Systems, further define interoperability as "being able to accomplish end-user applications using different types of computer systems, operating systems, and application software, interconnected by different types of local and wide area networks." Semantic interoperability refers to the ability to interpret the information exchanged automatically to produce results that are deemed useful by the end users of both systems.
Industry Foundation Class
Industry Foundation Class (IFC) is a system of defining and representing standard architectural and construction-related graphic and non-graphic data as 3D virtual objects-4- to allow data exchange among BIM tools, cost estimation systems, and other construction-related applications in a way that preserves ability to perform analysis on those objects as they move from one BIM system to another.
VA accepts the latest IFC format. For VA projects, a design professional either saves or exports an IFC file from the BIM-authoring software of their choice for the following tasks:-5-
  • Coordination of BIM models and related design disciplines.
  • Clash detection
  • Rules-based checking
  • Building Code compliance
  • Sharing models between different BIM-authoring softwares
  • COBIE data derived from BIM models
  • Energy testing data derived from BIM models
  • Systems simulation
The OmniClass Construction Classification System is a classification system for the construction industry, developed by the Construction Standards Institute (CSI) and is used as a classification structure for electronic databases. As the basis of its tables, OmniClass incorporates other existing systems currently in use, including MasterFormat™ for work results, UniFormat for elements, and EPIC (Electronic Product Information Cooperation) for structuring products.
The Space and Equipment Planning System (VA-SEPS) is a database shared by the Army, Navy, Air Force, and VA as a tool, based on medical need, to determine the space and medical equipment necessary to support the requirements for space.
Space Calculations
VA-SEPS calculates net square feet (NSF) for a department's constituent spaces. Then VA-SEPS aggregates these areas to Departmental Net Square Feet.-6- The VA-SEPS user may modify the net square feet for a functional space as professional judgment requires. Based on space type,-7- rules apply a Departmental Net to Departmental Gross (DNTDG) factor to yield a Departmental Gross Square Foot (DGSF) area.-8-
That DGSF area is then multiplied by a "building conversion factor," yielding a Building Gross Square Foot (BGSF) figure for that department. The BGSF figure represents how much of the gross building area is contributed by the particular department. The standard baseline Building Net-to-Gross factor used by VA-SEPS and VA is 1.35.
This is known as the "two-step method," and is the one currently in use for VA VA-SEPS. The two-step method allows varying the building conversion factor to suit a department's distinctive net-to-gross factor, while the Building Net-to-Gross Ratios (shown below) take into account the distinctive net-to-gross factors resulting from facility type.
The sum of all the BGSF areas for the various departments constituting the proposed design will sum to the gross area of the building.
  • Net square feet (NSF) is the floor area between the walls of a room or defined space.
  • Department Net Square Feet (DNSF) is the sum of the net square feet of all of the individual rooms and spaces within a department.
  • Building Net Square Feet (BNSF) is the sum of all of the Department Net Square Feet within a building/facility.
  • Department Gross Square Feet (DGSF) is the floor area within the boundaries of a functional department as defined by a space planning criteria chapter, including floor area occupied by rooms/spaces, walls defining the spaces, and circulation corridors connecting the different rooms of the department.
  • Building Gross Square Feet (BGSF) is the floor area of the entire building or project, which includes floor area occupied by rooms/spaces, walls, corridors, conveyances, mechanical/utility rooms, and shafts."
Accordingly,-9- "users adjust this factor [1.35] so as not to exceed the following Building Net-to-Gross Ratios:"
Figure 3 - Building Net-to-Gross Ratio Limits
VA Outpatient Clinic / Outpatient Clinic Additions 90% (1.90 x NSF)
VA Medical Center 100% (2.0 x NSF)
VA Clinical / Clinical Support Addition (Any chapter not indicated below) 90% (1.90 x NSF)
VA Community Living Center (Nursing Home) 70% (1.70 x NSF)
VA Mental Health Residential Rehabilitation Treatment Program (Domiciliary) 60% (1.60 x NSF)
VA Mental Health Hospital 85% (1.85 x NSF)
The project is constrained by the Net-to-Gross Ratios for the design's total building gross area. The building Net-to-Gross Ratios are downward constraints on VA-SEPS' bottom-up progressive aggregation.
The PFD resulting from VA-SEPS may thus be a list of named spaces, each with a NSF figure, an intermediate department-by-department DGSF area, a BGSF area, and a budgetary cost.
All required functional areas and associated support spaces shall fit within this resulting space, determining and specifying their adjacencies and construction costs. Some adjacency descriptions may occur in comments and notes belonging to equipment and/or to certain functional areas and may be provided as part of the VA-SEPS export.
Net square feet (NSF) as defined above, shall be the defining kernel of space-counting procedures for the VA and must be adapted for use in BIM modeling that is based directly on the PFD coming out of VA-SEPS.-10-
Space Measurement
VA adopts a fundamental method of measuring area that synchronizes in a practical way with major BIM authoring tools. TIP: When representing double wall in the BIM, build the wall components or layers into a single wall object. This allows for quantity take off by material, or by system, and simplifies the overall building of the model.
Area: The area bounded by the inside faces of surrounding walls, minus the area bounded by the outside faces of contained full height columns will be the net area of a space.-11-
BIM authoring tools allow areas to be automatically delineated based on the footprint of surrounding walls which create a polygon, or based on a manually drawn polygon. The areas of contained columns can be automatically subtracted in a flexible, size-dependent way, to yield a net area meeting the VA's definition.
Manual methods for delineating areas are required to allow centerlines of adjacent spaces to be used while allowing the corridor face to bound the space on the corridor side.
Volume: Space volume is determined manually and geometrically by specifying an area footprint and assigning a height to it. Volume calculations in BIM do not change any existing volume guidelines found in VA documentation.-12-
Volumetric calculations may require some adjustments in how the BIM is constructed and how space is delineated, in particular with regard to multistory spaces, and cavity walls. As with BIM tools that create and place building elements, BIM "space objects" must be used in the way prescribed by the BIM authoring software if volumes are to be correct, if equipment location reports are to be correct, and if the exported IFC model for analysis is to yield correct results. For example, the count of occupied space volume under sloped building elements is typically adjusted to accommodate concepts of usable space. On the other hand, equipment can occupy the space otherwise not counted as usable. The Design Team may find that for correct reporting purposes, different categories of space enclosing nearly the same volumes will have to be defined in the BIM and reported out judiciously.-13-

-1- National BIM Standards BIM product definition.

-2- Semantic Interoperability.

-3- Institute of Electrical and Electronics Engineers. IEEE Standard Computer Dictionary: A Compilation of IEEE Standard Computer Glossaries. New York, NY: 1990.

-4- IFC also sometimes refers to its non-proprietary file extension, "IFC."

-5- As of May 2009, IFC2x4 has its feature set frozen and is concluding the beta-1 test phase.

-6- See also for use of the term "Programmed Departmental Net Square Feet."

-7- …also designated as "DNTG" in various places. See also for the chapters in design guides describing departments and associated DNTDG factors. There are about 60 functional space types using 12 different factors.


-9- See These are really gross-to-net ratios, since the ratio values are greater than or equal to 1. See also

-10- The VA definition of Net square feet (NSF) appears to be the same as GSA BIM Area.

-11- GSA calls this "GSA BIM Area" which was formerly called "GSA Net Area." (GSA BIM Guide Series 02, v 0.96 (May 2006).

-12-For example, see Appendix 1-A, VA Hospital Building System, HVAC Design Manual for New Hospitals, Replacement Hospitals, …, (February 2008), for the description of Hospital Building System modules and the designations which BIMs must carry if VAHBS is used.

-13- For informational purposes only, A/Es new to BIM may find "Section 04," subsections 4.1.1ff in GSA BIM Guide Series 02, v 0.96 (May 2006) to provide a helpful discussion of what the basic space modeling issues may be, and some insight regarding the various BIM-authoring tools and how they might handle the situations described. Readers are advised that some BIM software may have changed in ways which render the publication somewhat dated.

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