It doesn't seem that long ago that computer-aided design was the new catchphrase—a magic bullet that transformed design from untold hours of manual drafting to drawings that morph with the click of a mouse. Now “BIM” has become the new buzzword. Building Information Modeling is an evolving concept, but the National Institute of Building Sciences (NIBS) describes it as a digital representation of both the physical and functional characteristics of a building. Although the technology has been around for a while in one form or another, BIM is hitting the mainstream as its capabilities—along with its ease of manipulation—improve.
Never before has a piece of software allowed architects to design and document a project with a single application, building electronically before they build physically. The simultaneous generation of a 3-D model from plans and elevations enables architects to instantly study their schemes from all angles, thus identifying problems early on and solving them before they become expensive change orders down the road. They can check for mechanical clashes (say, ductwork that conflicts with a structural beam), generate construction schedules, and attach Web-based manufacturer data (such as framing parameters or fire rating) for a wall—either downloaded directly or through embedded links. Accuracy, speed, and economy are improved, since changes to one type of drawing automatically update the others, reducing the chance for errors and waste.
Part of BIM's sudden appeal, too, is driven by the industrywide call to sharply reduce the carbon footprint of buildings, which are responsible for almost half of greenhouse gas emissions annually. Many architects are taking up the 2030 Challenge, a global effort to hit targets set for reducing fossil fuel consumption in new buildings (learn more about this in our next issue). What has many people excited is BIM's potential for uploading early versions of models to energy consultants, who can extrapolate the building envelope's R- and U-values and estimate what the utility bills might be. As architects tweak a building's specs, massing, or orientation, they can quickly get a detailed analysis of how those changes affect energy performance.
Thus far, BIM's market penetration has been fairly small. But some experts believe that's about to change. “This year we're turning the corner, in terms of percentages of people moving from kicking the tires to starting to use it,” says Dana K. “Deke” Smith, FAIA, executive director of the buildingSMART alliance at NIBS in Washington, D.C. “We went through multiple areas of the industry, looking at how many designers, contractors, owners, and operators are using BIM, and came to the conclusion that 2008 is when the big difference is going to start to appear. You can't go anywhere now and not get some introduction to BIM.”exploring the possibilities
In its most sophisticated scheme, BIM is not only a design and delivery tool, but one that's meant to be used by a building's various stakeholders throughout its life cycle—what's known as interoperability. A recent PowerPoint presentation by Smith included complex diagrams illustrating the mind-boggling array of data that theoretically can be attached to a single project's building information model, from geospatial and environmental statistics to legal documents, operational and maintenance issues, and data for use in the building's eventual renovation, recycling, and disposal. As such, the payoffs are potentially huge for large institutional and public facilities. But Smith says BIM isn't just for big, complicated buildings like Frank Gehry, FAIA's Walt Disney Concert Hall. “The key is that you can go through and test a building, evaluating alternative energy uses and materials,” he explains. “You're able to predict what it will cost the owner to operate the house.” Over time, “as we do more analysis and estimating, we can continually improve the products, so the reliability and quality of the numbers continues to get better.”
What's more, BIM packages and preserves information for posterity. When it comes time to remodel, often plans don't exist for a house; they have to be redrawn before design and approval can commence. “It costs money every time to go through those steps. It's accepted as the way we do business and those costs are embedded, so people don't really see that it's a waste, but it's non-value-added effort,” Smith says.
KieranTimberlake Associates' Loblolly House on Maryland's Chesapeake Bay called attention to the fact that BIM could be used for houses. Designed in 2005, it was the firm's first foray into building information modeling and went on to win a 2007 AIA BIM Award. It also happens to be the weekend residence of partner Stephen Kieran, FAIA, so it provided a flexible schedule and the freedom to push the learning curve on design, fabrication, and procurement. Project architect Marilia Rodrigues and another KieranTimberlake (KTA) colleague enrolled in a class on how to use Autodesk's Revit, adding skills as the project progressed. What they were really testing was how BIM could be used to speedily and accurately deliver an innovative assembly system. Given the sensitive ecosystem and shortage of local labor, the architects created the entire house out of custom-prefabricated components, some of which incorporated preinstalled mechanical and electrical systems. These intricate factory-made boxes were then delivered to the site and connected to each other and an aluminum scaffolding framework with a wrench.
Rodrigues says the computer modeling allowed them to not only understand precisely how the parts would be fabricated but also how they would fit together on site. “Ninety-five percent of the job went together exactly as we pictured it,” she says. “When there was a problem, it was usually because we hadn't taken the time to model it. On the aluminum frame, for example, which we spent a lot of time modeling to make sure the connections would go together perfectly, assembly was smooth.”
Since then, KTA has used BIM to design more conventional buildings—including two large dormitories and two dining halls for Cornell University—though not to its full potential. “At Cornell, they want our CAD drawings, not our Revit drawings,” Rodrigues says. “It's a slow-moving movement. We use BIM internally for design and construction documents, but we're not handing them off to a contractor yet. Our hope,” she adds, “is that things are moving that way, but there are contractual barriers—who owns the model, who owns the problems and errors within it? That was the beauty of Loblolly. We were able to take a lot of risks and test the possibilities. Our conclusion was that there are a lot of possibilities.”
One possibility BIM offers is the chance to improve design by exchanging modeling files quickly and efficiently with experts anywhere in the world. This idea was tested last January in an event called BIMStorm LAX, a 24-hour virtual charrette in which building industry professionals designed some 30 Los Angeles city blocks without leaving their own offices. By uploading 3-D models generated from his ArchiCAD Graphisoft program to a central BIMStorm server, participant Michael Scarmack, AIA, of Lancaster, Ohio, got instant feedback on his multifamily housing scheme from a green roof expert in Boston, a structural engineer in Hawaii, and cost estimators at Pennsylvania State University. “It was exciting to be able to incorporate disciplines I never considered using, like a real estate appraiser and GIS mapping,” Scarmack says. “My first phone call on a project is always to the zoning office, and there were links and uploaded maps available. Imagine a world where we have instant access to that information. A practice like mine may not need all those features—maybe only ones that ensure I get a LEED-certified building, if that's the goal.”