Building Information Modeling

Nassau’s new airport, consisting of almost 60,000 square meters of mostly new construction with some renovation, presented a building challenge about as complex as they come.

To tackle that complexity, project leaders brought all disciplines together into the design process much earlier than many of them had ever worked before. “When I say ‘all disciplines,’” says Stanis Smith, “I mean ‘all disciplines’ – architectural, structural, mechanical, electrical, baggage system, fire suppression, interior design, the whole works.”

Smith, senior vice president for Stantec, the prime consultant providing full architectural, engineering and specialist design services on the project, credits building information modeling, or BIM, for enabling this collaboration.

Model of Nassau Airport

Model of Nassau Airport

To explain BIM, Smith paints a 2D design workflow caricature. “The architect dreams up a concept and throws it over the wall to the structural engineer,” Smith says, “who figures out the structure, then throws it over the wall to the mechanical engineer who figures out the mechanical systems, then throws it over the wall to the electrical engineer…”

In BIM, project participants from different disciplines enter all their parameters into a shared model up front, not sequentially. “BIM software enables complete coordination,” says Bruce McCallum, Senior Application Specialist for Autodraft Inc. “We don’t rely on human input to coordinate drawings, but rather a database that knows where each view is.”

“BIM forces engineering disciplines to be part of the design process much earlier than they used to be,” Smith adds.

Among other benefits, BIM backers laud an improved ability to try different design scenarios. “You can establish variables between components, and when you change a variable, other things will react according to rules you establish,” says Dave Stevens, AEC Sales Manager for Autodesk Canada. “You can understand the effects of given changes while they’re on the drawing board.”

Finding errors on the drawing board should also mean improved final designs. Sasha Nikodijevic offers the example of a chemistry lab: “Before it was constructed, it was all flat CAD files,” says the national business manager, Autodesk, for Global CADD Systems. “Project leaders were concerned, so they modeled the project using BIM. In three weeks of BIM work, they found three different areas within the lab that would have caused a projected $300,000 worth of cost overruns.”

“The reduction of RFIs is huge to the owners and the architects,” says McCallum. “This frees up both cash and resources during the construction phase. It lets architects work on other jobs once the building permit is issued.”

Information drawn from BIM systems also bring suppliers into the act. “We’re seeing 3D designs being taken directly into fabrication,” says Smith. “Fabricators bypass traditional 2D drawings.”

The same logic applies to construction. “One municipality created a 3D model using BIM,” says Nikodijevic. “They feed that data to GPS-equipped machine-controlled grading equipment that automatically controls the height of the blade to cut at the right level.”

Using the database, architects can render plans, elevations and other technical elements to help non-technical people understand projects.

This facilitates cost decisions as well. “Rather than just seeing the underlying number, we can analyze decisions while looking at the entire space and make better decisions about what can be removed to meet constrained budgets,” says Sherry Whetten, director of technology for aba architects, pc.

Owners also draw information from BIM. Nikodijevic points to the oil and gas industry, which already models plants in 3D. “They can produce training videos showing things like shutoff valves before the facility is even built,” he says.

Complete sets of building parameters make LEED certification easier to attain. “Part of the LEED process is calculating material quantities and deciding where those materials are in the building,” McCallum says. “In BIM, material takeoffs are available immediately.”

Workers on the job site are getting into the act as well. “We’re starting to see handheld units that store CAD drawings,” says Nikodijevic. “You can walk around a building and locate where things are supposed to go.”

Beau Turner claims that many contractors already perform their own versions of BIM on large projects to perform collision detection. By “large,” Turner offers a current project value of five million dollars.

“A couple years ago, that number was higher,” says the director of business development for Autodesk integrator Avatech Solutions. “It’s becoming more cost-effective.”

Certain builders export building parameters into Green Building Extensible Markup Language, or GBXML. “It allows further building performance analysis in outside applications in ways that haven’t been done before,” McCallum says.

The insights that flow from both BIM and outside applications can help design teams analyze “non-physical” yet equally important dimensions. For instance, time, the commonly accepted fourth dimension, helps project teams sequence construction phases.

“We can identify the move-in date from information plugged into the model,” Whetten says, speaking of a recent aba project. “It wasn’t the answer the client was looking for, but being able to set a realistic move-in date up front was quite beneficial.”

Cost, the fifth dimension, enables teams to foresee cash flows over the life of a project.

Builders are also starting to use dimensions from manufacturing and supply chain scenarios, such as the procurement process and operational lifecycle. “These are just starting to get noticed,” Turner says.

These BIM-fuelled advantages are strengthening trends like integrated project delivery (IPD). “You pull together at the earliest stages all project stakeholders: the architects, the contractors, the engineers, the owners,” Stevens says. “Contractually, you establish relationships in terms of shared outcomes, risks and gains.”

“This harnesses the talents and insights of all project participants early in the process. It focuses everybody on optimal results and the maximum value for the owner.”

McCallum’s take is more amusing: “In really rough terms, the owner puts a bag of money on the table and says: “This is how much I’m willing to spend to build this building. Whatever’s left over at the end is yours.’”

Tighter coordination might change more than the projects affected. “The whole traditional design-bid-build process may, over time, be supplanted by other types of building processes and relationships,” Stevens says.

Theoretically, BIM helps all stakeholders deliver better buildings and earn project bonuses. In practice, Whetten has seen BIM play another role: as a tool for assigning blame.

“In one situation,” she explains, “it became a more hostile environment simply because there was more information.” Whetten chalks this up to individual personalities on the project team, but adds: “With BIM, you don’t stop to think that with more information, there’s more to fight about.”

On balance, Whetten’s BIM outlook is still positive. “If you have that contract structured before you start, you avoid the finger-pointing,” she says. “If you point the finger at somebody else, you cheat the whole team out of their reward.”

BIM may also help foster working relationships with other disciplines. For instance, Nikodijevic believes civil engineers may join in the design process. “Even though BIM refers to buildings,” he admits, “there are pipes underneath, there’s the site the building sits on.”

Visions of enhanced collaboration depend in part on the availability of BIM tools for all disciplines, but not all required tools exist yet.

“The architectural and structural packages are well-developed,” says Mikko Leppänen, an architect with Stantec Architecture. “The MEP package lags behind the other two.”

“Our baggage system designer had to build all the components of the baggage system,” Smith adds. “Many of the modules we needed for this project we had to build from scratch.”

For such modules to add value, the industry must develop an independent, vendor-neutral file format, and industry foundation classes: “a generic way to exchange information so that it’s not held in check by any one vendor,” Turner explains.

Smith has identified what he wants in BIM-ready professionals: collaborators who visualize, think and work in 3D. “That’s a pretty unusual skill set, and our industry hasn’t yet evolved to the point where those people are readily available,” he says.

The promise of BIM lures many in AEC to this still-fresh design approach. Proponents are also bullish about the learning curve since, according to McCallum: “The tools are called ‘wall, door, window,’ for example, whereas a traditional line-based CAD system would use “line, arc, circle,” and we would use those lines and arcs to represent walls, doors and windows.”

“These models are not just lines on paper that look like walls, doors and windows. These are incredibly complex detailed buildings that go right down to light switches and allow the design process to be documented in ways that we never could have before.”

Huge amounts of detail in the model can prove costly and overburden the model, so Leppänen urges designers to tailor the level of detail in their models to fulfill the purpose of those models – construction, costing, rendering, sustainable design – and no more.

Getting that level right demands effort and discussion among the entire group of project stakeholders. On a current project at Edmonton Airport, Stantec’s client requested a BIM deliverable.

“Now we’re trying to wrap our heads around what exactly that BIM deliverable is,” Leppänen says. “What level of model information do we include in there? On a project that size, you don’t model every door handle.”

Helping people understand BIM, while not as big a job as it used to be, can still prove difficult. “People tend to think of BIM as AutoCAD and a ‘sketchup’ all in one,” says Whetten. “That doesn’t begin to cover the information attached to it.”

“BIM is a workflow,” she adds, “not software.”

“The front end of the design process is very heavy now because of what the software allows. It demands that you redefine how you practice architecture.”

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