Modeling Green

Structural steel, HVAC, plumbing and some electrical contractors on the project are using model data to automate their fabrication process. “By prefabricating systems or sections of systems offsite, you have less cutting and work in the field, which by default is less productive,” Barrett says.

Image courtesy of Turner Construction

3-D rendering of the façade for the 14-story, 188,000-sq.-ft. Columbia Science building. Modeling information facilitated the prefabrication of the some of the curtainwall elements for the $230 million structure.

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Hatfield says he is starting to see the façade industry using BIM to prefabricate curtain walls and metal panels. “If we create the BIM model with enoughsophistication, fabricators can access and use the data,” he adds. “For sophisticated facades, data may need to be extracted and imported into a façade modeling package and then delivered to the manufacturers.”

“Major MEP subcontractors working with Turner are reporting 15 to 30% less materials waste when Turner implements our Virtual Trade Coordination process on a project,” Barrett says. “We are trained to track the waste we create and what we do with that waste. With BIM you fundamentally avoid creating it in the first place. Given those benefits I would make the proposition that a BIM job is a green job.”

Future Developments Barrett sees a tremendous opportunity in using BIM/VDC tools to retrofit existing buildings. Mayor Michael Bloomberg’s PLANYC 2030 estimates that 85% of the buildings that will exist in 2030 are already built. “If you are going to have a dramatic impact on reducing the carbon footprint by 30% in 2030 [as advocated in mayor’s plan], you have to look at existing buildings,” Barrett adds.

BIM in conjunction with analysis software can create “what-if” scenarios to compare baseline operating cost of an existing building with the operating costs after retrofitting the building with new windows, additional insulation or upgraded equipment and systems, Barrett says. Combining modeling information with cost of the equipment and construction will produce life-cycle studies and payback analyses of various options, he adds.

Another opportunity lies in integrating BIM with facility management systems to help clients manage their buildings. “Since BIM is a database-centric tool, it can talk to other databases,” Barrett says. “That is exactly what we are looking at right now. How do we use the database and the great information in the database for other purposes, such as talking to facility management systems?”

Major BIM vendors are working on interoperability standards and are acquiring analysis software with an eye toward developing integrated suites of services. But even within its own suites of products, vendors face interoperability challenges, Genlser’s Sanders says.

Skidmore, Owings & Merrill’s Seletsky says a transfer protocol is needed that allows two-way communications between BIM and the analysis tool. “I can do an analysis of my Revit [BIM] model using Ecotect [energy analysis tool], but what I can’t do is shoot the information back in the other direction,” he adds. “I can’t apply certain constraints in Ecotect and see what the resulting geometry or BIM model is going to be.”

Beyond interoperability, firms are developing guidance to help teams make smart sustainable design decisions using BIM. “People tend to over model or over analyze things too early, when it is not informing the design process,” Sanders says. “It all gets back to how you marry a process to the new technology and tools.”