Model Buildings

A BIM model includes every detail a design team conceives. It might show a proposed structure’s square footage, footprint size, superstructure, exterior treatment, ductwork, plumbing, electrical systems, heating and cooling systems—the more information, the better the model.

Designers can then virtually walk through the conceptual building. As they make changes, they can see the effect these changes will have on everything from a building’s energy efficiency to its traffic flow. They can then use that knowledge to create and test a building that most nearly matches the owner’s requirements—all without moving a single shovelful of dirt.

BIM offers the construction industry a variety of benefits: improved design visualization, automated changes, better troubleshooting, more efficient and greener structures, less waste, more accurate cost estimates, better site preparation, and closer collaboration. Because it allows designers to solve problems before construction begins, it saves time and money for the owner—and typically everyone else involved.

Visualization and Clash Detection

Construction designers say they prize BIM’s ability to let them visualize a project in ways that would be much more difficult using a two-dimensional drawing. “By doing it in a model, we can see a different view,” Jensen says.

Jensen also values BIM’s ability to automatically make the changes necessitated by design adjustments. If he changes the air flow to a particular room, for instance, the software “updates my duct sizing and variable air volume box, all the way back to the fan. The automation is great,” he says.

As the software makes automated upstream design changes, it adjusts the materials list accordingly. “If I change the air flow, the model number and size of that box will automatically change on the equipment schedule,” Jensen says. BIM software also tracks the way a change will affect the building’s construction schedule.

BIM’s visualization help is particularly useful when it catches conflicts between design elements. “We don’t want to have to back up from the design process as it moves forward,” notes Dick Bates, director of virtual building at Minneapolis-based Ryan Companies U.S., Inc. “We don’t want to end up with a mechanical room that’s not large enough to fit the equipment that needs to go in it, or an interstitial space that doesn’t have enough room above the ceilings.”

A problematic space typically results in a change order, and extra time and money spent on a correction. With BIM, by contrast, designers catch the problem before it ever reaches the physical world. “It’s much easier to move electrons that it is to move concrete,” Jordani notes.