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| The U.S. Information
Foundation of BIM |
BIM is what we all expected computer-aided design (CAD) to be,
but now we know it requires information standards to be productive.
Fortunately, we now have both information standards and software
companies that support and empower them.
Today, after much education on the part of the
AIA, the International
Alliance for Interoperability (IAI), the National Institute of Building Sciences
(NIBS), industry consultants, and technology companies, we have
a term coined by Jerry Laiserin, that we all can use for this
process: BIM, or Building Information Modeling.
What Is a BIM
Process?
First, it's significantly more than
transferring electronic versions of paper documents. It's more than
pretty 3D renderings with construction documents as a separate
function. It's about information use, reuse, and exchange, of which
electronic documents are just a single component.
When integrated 3D-2D model-based technology is
linked with information, design firms have a faster,
higher-quality, richer design process. Risk is reduced, design
intent is maintained, quality control is streamlined, communication
is clearer, and higher analytic tools are more accessible.
Lower-level tasks such as drafting, view
coordination, document generation, and schedule creation are
automated. Drawings that represent different views of the same
building object are automatically updated when modified.
We finally can harness the power of computers in
a real value-added design process that doesn't just mimic
drafting.
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| Different standards, but
they don't compete. |
Benefits and Returns of
the BIM Process
With all the
benefits of a BIM process, why are some firms hesitant to change
from electronic drafting to a model-based process? It may be the
software they use. Certainly the software a firm uses defines and
shapes its process options. Other firms may have a painful
recollection of transitioning from paper to CAD without information
standards and support from the CAD companies.
Fortunately, we aren't condemned to repeat
that history. Some software companies have already been
incorporating accepted graphic and information standards into their
software.
The U.S. Coast Guard (USCG), now a part of the
U.S. Department of Homeland
Security, was one of the first organizations to move to U.S.
National CAD Standard (NCS)/IAI-compliant software. The USCG's
model-based standard is Graphisoft's ArchiCAD. Through the work
with NIBS, the NCS, IAI, and the USCG, Graphisoft shows us the
blend of these standards and the productivity gains when
information standards are supported in BIM software.
NIBS supports U.S. standards. NIBS is the
overarching organization supporting NCS and the IAI in the United
States. It supports the construction industry committees defining
the construction process. These committees then work with IAI and
NCS technical groups that create the standards. Committees meet
regularly on different aspects of construction data.
 The
NCS defines standards for many aspects of electronic
building-design data, including:
The National CAD Standard. The NCS
is a product from the cooperation of the AIA, CSI, and NIBS. The
NCS represents a consensus among architects, engineers, and experts
from the construction industry about how to classify building
design data and streamline communication among owners and design
and construction project teams based on paper-centric information
delivery. After several years of informal teaming with technology
companies, NCS has developed a more formal program for technology
companies. For more information, see the Web site at www.nationalcadstandard.org.
 The IAI IFCs
(Industry Foundation Classes)
More than 10 years
ago, after BIM processes were already in use, IAI groups began
creating model-based standards to avoid repeating our 2D CAD
history. The knowledge in the IAI is the defined information and
workflow valuable to any firm.
The intention of the IAI is to specify how "things" that could
occur in a constructed facility (including real things such as
doors, walls, and fans as well as abstract concepts such as space,
organization, information exchange, and process) should be
represented electronically. These specifications represent a data
structure supporting an electronic project model useful in sharing
data across applications. The 2D graphics represented by the NCS is
a subset of this model information.
Each specification is called a "class." The word "class" describes
a range of things with common characteristics. For instance, every
door has the characteristics of opening to allow entry to a space;
every window has the characteristic of transparency so that it can
be seen through."Door" and "window" are names of classes.
The classes defined by the IAI are termed Industry Foundation
Classes (IFCs) for the following reasons:
- IFCs are defined by the AEC/FM
industry.
- They provide a foundation for the shared
project model
- They specify classes of things in an
agreed-upon manner that enables the development of a common
language for construction.
 The IAI
IFC is the only construction information standard recognized by the
International Standards Organization (ISO). For several years,
Graphisoft has played a leadership role, working with NIBS and NCS
committees, to blend the power of ArchiCAD's parametric objects
with the model-based open standards of IAI IFCs.
How Do These
Standards Fit Together in Software That Benefits the
Designers?
Some people believe that a BIM process
represents more work, with the benefit going to the client and not
to the architect. If the architect is using electronic drafting
tools instead of an integrated parametric object-based system, then
this may be the case. But firms that use intelligent tools will see
the payback in their design process through improved productivity,
reduction of error, and faster production through automation. The
example below explains the use of NCS, IAI IFCs, and
intelligent objects in production.
1) We'll start with a
client needing a room and establishing some general requirements.
In 2D electronic drafting with NCS, we would show a floor plan,
walls as polylines on a CAD Layer, a door symbol, a room stamp, and
notations. When it is time to place our drawings on paper for
plotting, we would use the NCS to organize the construction sets.
Other information would be handled separately and not integrated
into our CAD file.
2) With IAI IFC-compliant
software, the model can support not only NCS standards but also
integrated data that support design decisions. We can start with an
IFC-SPACE that not only carries a plan view but also carries its
geometric size, square footage, and volume. We can create and do
reports on stacking diagrams and the like.
3) As the design
progresses, we can use an IFC-WALL for quantity take-offs, thermal
or energy calculations, and other analysis. This is the same wall
used in our construction document views and our rendering. Even at
this level, we can more fully determine whether our design meets
our client's needs.
4) Product objects such as an IFC-DOOR or WINDOW
allow a higher refinement to our design. Calculations and costing,
which used to happen only after construction sets were more
complete, can be done in the first days of a project.
5)
Walls or objects can automate the creation of
details, schedules, and levels of structure and provide
product-specific installation needs. 4D construction scheduling can
be tied to objects for construction sequencing.
6) Our design complete, the model information,
including traditional CAD views and product data, is ready to
automatically populate IAI IFC-compliant facility management
software. Clients that manage buildings want these models, and
architects have a value-added product once the design is
complete.
7)
The benefits of object intelligence enhance
NCS in other ways. What were simple graphic elements have been
given intelligence to help automate the task they
represent.
 8) This Drawing Title is now an intelligent object
that automatically shows the scale of the drawing it supports. If
the scale of the drawing changes, so does the indicator on the
graphic. This type of automation greatly reduces construction
document errors and coordination.
BIM Isn't BIM without the NCS and
IAI IFCs
In integrated model-based
software, the NCS and IAI IFC represent the graphic and model
foundation for BIM to work as a design process. BIM without these
standards is proprietary and ultimately not interoperable.
The BIM process is both vision and reality for many organizations
and firms. In 2002, .dwg was taken out of the NCS, and the USCG
modified its software to support NCS/IAI-compliant software. Its
model-based software became Graphisoft's ArchiCAD.
"ArchiCAD is thus far the only CAD product to incorporate support
for both the NCS and the IAI IFC in the same program," Jerry
Laiserin stated in the April 2002 issue of Architectural
Record.
More software companies should explore how to
make their software support these standards. If they want to
provide maximum productivity and align with design's changing
business models, they will make the evolving IAI and NCS standards
part of their core systems.
Dianne Davis is president of AEC
Infosystems and Object Model Leader for the U.S. Coast Guard
Regional Strategic Plan. She is a founding member of ShiP. In
addition, Davis has participated for several years on both NCS and
IAI committees and cochairs the Futures and Trends Committee at
NIBS. Her clients include: U.S. Coast Guard, U.S. Army Corps of
Engineers, the National CAD-GIS Technology Center, National Park
Service, Army Research Lab, NIST, and many private-sector firms.
Davis can be reached by e-mail at d.davis@aecinfosystems.com.
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