In the quest for smoother digital data sharing and exchange between various architecture, engineering and construction software platforms, most stakeholders are eyeing the same target: interoperability. The ability to transfer design information seamlessly throughout a building project promises to save all parties involved–from owners to contractors–time and money, sources agree.

While the general destination might be clear, the road to interoperability in the construction industry is anything but a straightaway. Leaders of the six-year-old International Alliance for Interoperability, Oakton, Va., which has led the charge and established software standards, acknowledge that opinions vary on how to move interoperability from research into practice. Still, most are optimistic that payback is in sight.

"This is no longer just a concept," says Richard Geissler, IAI North America executive director. "We have major companies implementing [our standards] in products. We couldn't say that a year ago. But are we as far along as we should be? No."

Geissler cites a lack of funding and ever-changing technology, including file formats, as factors complicating the pursuit of interoperability.

Bob Webb, treasurer of IAI NA and executive vice president of construction manager Bovis Lend Lease in Charlotte, N.C., agrees that implementation has been elusive. "It's proven much harder than we thought," he says. "But it's critical to the long-term health of our industry, so we're pushing for it."

Webb says owners need to see more of a financial incentive to embrace interoperability on a wide scale. One fledgling nonprofit research group aiming to demonstrate that construction automation, including interoperability, can save owners money is FIATECH.

Development of interoperability standards has proven a complex task. To enable more data sharing, IAI developed specifications, called industry foundation classes (IFCs), that define buildings based on objects such as walls, doors and windows. Using a common object-based model instead of a drawing-based model geared around generic entities such as lines and arcs, software products can more readily share the same data for tasks as diverse as design, analysis, quantity estimation and code checking.

IAI published its first IFCs as Release 1.5 in 1998, followed by R2.0 in 1999. A handful of software vendors developed prototypes for both versions. A more development-friendly or "extensible" version, R2x, was released last year with "a more stable platform," says Geissler.

SMART FILES Shared Data Files Contain information for all parties involved in a building project.

In 1999, a group of software vendors seeking to "jump-start" implementation formed Building Lifecycle Interoperable Software (BLIS). Using IFC R2.0 but working independently of IAI, the BLIS group focused on just a portion of the IFC model and developed a demonstration of interoperable software among IFC-compliant vendors. "We saw [IFCs] as a huge model that would take years to implement, so we targeted some particular end-user cases," says Richard See, BLIS director and program manager for advanced product development at Microsoft Corp., Redmond, Wash.

Microsoft has incorporated R2.0 into its Visio diagramming tool, and is one of 50 organizations–most of which are also IAI members–participating in BLIS. Others include Graphisoft, Budapest; Timberline Software Corp., Beaverton, Ore.; the U.S. Dept. of Energy's Pacific Northwest National Laboratory in Richland, Wash.; and Lawrence Berkeley National Laboratory in Berkeley, Calif. The demonstration–presented at the A/E/C Systems computer show in Chicago in June–showed how project data could be shared between various software products during design, energy analysis, quantity takeoff and code checking.

Timberline, a developer of estimating and accounting software, is combining its BLIS involvement with development of a new product called CAD Integrator, says Chris Bernhardt, product manager for Timberline. The product builds a database of object information from a design file and automates quantity takeoff, accomplishing in five minutes what used to take several hours or even days, claims Bernhardt.

Graphisoft found the BLIS project a natural fit because the company's ArchiCAD program was developed around an object-based model, says Chris Barren, Graphisoft vice president of architecture. "Object-based design enables interaction between building elements," he says, citing examples of moving a column and relying on the software to move the associated beams accordingly.

While not formally sanctioning BLIS, Geissler says IAI is "delighted" that BLIS is implementing IFCs. He cautions that most "BLIS" products are still at a demonstration level, however. According to See, eight products are now shipping with IFC compatibility and another six are slated to ship by year-end.

CAD vendors Autodesk Inc., San Rafael, Calif.; Bentley Systems Inc., Exton, Pa.; and Nemetschek AG, Munich, did not participate in the BLIS project, largely because it is geared around R2.0 and the companies favored a jump from 1.5 to 2x. Andrew Stein, Autodesk's director of strategy and business development, says, "...2x is the most current format."

Autodesk implemented R1.5.1 in its Architectural Desktop product and is implementing R2x in its next release.

Bentley "felt IFC 2.0 had some deficiencies," says Brad Workman, a Bentley vice president for engineering information creation. Bentley's Microstation V8, due to come out this fall, also incorporates R2x. Nemetschek "is supporting IAI and not any other side streams," says Rasso Steinmann, a Nemetschek senior consultant.

HOW IT WORKS The IFC model is geared largely around the Standard for the Exchange of Product Model Data (STEP), a specification developed by the International Organization for Standardization. STEP, which is in turn built around a language called EXPRESS, is designed to cover a project's cradle-to-grave lifecycle, including information on geometry, component attributes and relationships between components.

IFC-compatible software typically incorporates third-party tools that output platform-specific data in a universally understood EXPRESS-based format. A CAD file, normally saved in a native drawing format such as DWG or DGN, would also be output in an IFC format. An estimating or analysis program could then open the IFC file, recognize standard objects such as walls, windows and doors, and perform its own tasks on the same pool of information.

The IFC data model is intended to cover virtually every aspect of a building. This may prove impossible. "If you try to solve a real problem, you have to extend the model," says John Kunz, a senior research engineer at Stanford University's Center for Integrated Facility Engineering, in Stanford, Calif. "The process for extension isn't really worked out yet."

Kunz and graduate students have employed R2.0 to develop software that automates cost estimation and simulates handicap accessibility. R2x, and a future release, R3x, may provide the extension capabilities that CIFE and others are seeking, says Geissler.

IAI and other groups are also developing standards for outputting information in extensible Markup Language (XML), a variation of the Hypertext Markup Language (HTML) used to publish Web documents. The BLIS group included both IFC and XML output options in its demonstration products.

The construction industry has developed several variations of XML-based solutions. Bentley helped develop aecXML, a building-based schema, now overseen by IAI, geared for e-commerce and e-procurement. Autodesk recently introduced DesignXML, a means for transferring selected portions of a design without exporting the entire drawing.

Autodesk and Intergraph also co-developed LandXML, an XML schema tailored for land development. It is one of the few schemas for a nonbuilding application. Most interoperability efforts focus on buildings. However, the concepts could be applied to other engineered structures, say sources.

FRAGMENTATION While Geissler insists multiple interoperability tracks are not fragmenting the overall mission, others disagree. Godfried Augenbroe, associate professor of Architecture at Georgia Tech, sees IFC and XML-based solutions as separate endeavors that lack a common vision. "The IFC effort and the aecXML initiative...can only deliver 'part' solutions, unless they expand their original scope and start overlapping," he says.

Augenbroe adds that IFC-based solutions appear to be gaining more international acceptance, while XML solutions are more "American-flavored." IAI, with nine chapters representing 24 countries, is maintaining a global approach, though funding varies widely among different nations. Finland has invested $35 million. The North American IAI chapter, with 120 members, is funded largely by dues, which range from $1,000 to $10,000 per organization.

The U.K. chapter has 70 corporate members that contribute about $150,000 annually, along with $100,000 from the government's Building Research Establishment, says Beryl Garcka, u.k. IAI's technical coordinator. She feels more government funding is sorely needed. "We have some of the best technical expertise, but we don't get the government backing," she says.

Fragmentation and limited funding might be preventing participation. London-based Arup, one of the largest multidisciplinary engineering firms, sees no reason to subscribe to IAI, says David Brown, general manager of the firm's in-house computer software division. "There are a lot of standards," he says.

Reluctance of design professionals to share information is also a barrier. Mervyn Richards, interoperability specialist with international construction and real estate group Laing Ltd., London, says designers would rather distribute drawings than real data to avoid litigation. "People are hiding behind their professional indemnity," he says.

Norbert Young, chairman of the IAI NA and president of the McGraw-Hill Construction Information Group, New York City, the parent company of ENR, agrees: "We're battling more cultural issues than technical ones."