BIM Tools and
Parametric Modeling
The significant distinction between
Building Information Model (BIM) software and Computer Aid Drafting (CAD) tools
are the ability to input parameters determined by the user. These
parameters allow one to attribute unique identity among objects within a
family, while also commanding constraints. Constraints can relate to
relationships with other objects, geometry, dimensions, etc. Unique identities
for specific elements can also be attributed such as: airflow, velocity,
lumens, etc. The hierarchy of these objects and elements are referred to as
families, which share specific common attributes.
A
critical benefit of parametric-modeling is its ability to increase
productivity, mainly for construction documentation value. Traditional drafting
software requires manual edits that often result in human error. However, BIM
software allows global changes to take place automatically. This dramatically
reduces the effort in making small changes that may occur during the design
process. For instance, when the change in a duct size changes on one sheet view
(for purposes of construction documentation) it will also change in all sheets
related to that change. This is especially notable because time can be expended
on design rather than drafting.
From
a contractually point of view BIM software such as Revit can also help to
reduce patent and latent ambiguities in these drawings that serve as contract
documents. In “Successful Contract Administration For Constructors and Design
Professionals” by Charles W. Cook, BIM is referenced as a tool that in its
development can help with coordination. As building become more complicated and
new types of systems such as: security, telecommunications, etc. are involved
coordination becomes crucial. Various designers can work within the same model
and coordinate the way in which systems interact to prevent “crashes”. Warnings
are displayed in parameters do not meet buildable conditions. This is because Revit
allows for a 3-dimensional explicit representation of the building, whereas 2D
traditional CAD software can only provide an implicit model. Another advantage
of Revit is the intelligence to formulate quick schedules for contractors to
process cost estimations.
Expanding beyond Revit,
software that allows for quick input an generation for energy and design
analysis is called Trane TRACE 700. It enables users to input information on a
building and create a baseline model to be compared with various other types of
mechanical system. This allows designers to make important decisions and know
the implications of various systems for an optimal design.
Some shortcomings of BIM software
today are a result of its ability to model a large amount of details. With so
many systems modeled in one central model, the capabilities of such software
have surpassed the available memory and processing power of contemporary
computers. However, it is believed that these issues with naturally decreases
as computers get faster. Additionally, the complexity of the software results
in a bigger learning curve, which take a longer time to gain proficiency.
Sources:
[1] Eastman, Charles M. BIM
Handbook: A Guide to Building Infromation Modeling for Owner, Managers,
Designers, Engineers, and Contractors. Hoboken, N.J: Wiley, 2008.
Web.
[2] Cook, Charles W. Successful Contract Administration: For
Constructors and Design Professionals. New York: Routledge, 2014.
Print.
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