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BUILDING INFORMATION MODELLING
in later in the process. Now,” he says,
“when a project starts, everybody who is
going to be involved gets together in a
room and talks about coordination, who
is going to be responsible for what, and
when the model should be ready to be
delivered to an MEP engineer.” Burke
notes that BIM causes more communication
than previously possible “because we
have this model with which to share the
information in a much more dynamic,
graphic and accurate way.”
That information is the real power
of BIM. “I always say that the ‘i’ in BIM
should be capitalized,” emphasises Burke,
“because that is the most important part
of the process. As an engineer draws a
structural component, the information
about that component is embedded in
the object, including engineering properties
— the type of steel used, the weight of
that steel and its dimensional properties.”
INFORMATION EXCHANGE
That all of this information can be so
easily shared is part of what makes BIM
so important to the industry. “If an
MEP engineer changes the size of an
air-handling unit — which changes its
electrical properties — that information
is automatically updated on the electrical
engineer’s drawing so that he knows that
the circuit might [need changing]. Once
that change is made,” he explains, “the
architect also sees that perhaps there
is more room in the space because the
air-handling unit is now smaller, so it’s
the information sharing that is the key
to BIM.”
The other advantage to BIM is that
it allows for the virtual testing of what
Prowse calls the “what-if scenarios.” “Let’s
say that you have a huge piece of equipment
that has to come into a building
throughout a construction cycle,” he
explains. “When you know the exact
physical requirements to get it through,
you can hold off on putting this wall
in, or on putting that piece of concrete
there until that other task is done. All of
a sudden, maybe you don’t need to bring
in that crane and your costing can be
controlled, your scheduling can be better
planned — any time that you’re not taking
steps backwards, you’re realizing savings.”
One of the greatest advantages of
BIM is in the area of design for LEED
credits. “Previously,” notes Burke, “energy
testing and analysis couldn’t be done
until the building was built. Now, the
HVAC engineer can take the Revit model
from the architect and do his heat and
energy load calculations on it to find out
how much energy he is going to need to
heat and cool the building. He can even
make suggestions to the architect — ‘If
you just rotate the building on the site
by 15 degrees, we can save $5,000 a
year in heating or cooling costs, or if we
change the roof to this or the orientation
of something,’ so BIM really is a huge
advantage there.”
This wholesale change in the process
has also modified contractual arrangements.
“The AIA [American Institute of
Architects] here in the States,” says Burke,
“has written whole new contracts for BIM
because clarity is essential around issues
like who owns the model, and who is
Builders' Digest Quarter 3 2010 | 31