AGC’s Winter 2011 BIMForum, Part 2

Last month, AECbytes published the first of a two-part series that provided an overview of the AGC (Associated General Contractors of America) BIMForum organization and captured the highlights of its recent event, which was held on February 10 and 11 in San Diego, California. The event was focused on the theme “BIM and Building Enclosures,” which stemmed from the recognition that the building envelope is one of the most litigious and expensive aspects of building construction. Part 1 covered the presentations from construction firms such as DPR, Mortensen, and BNBuilders, as well as from the design firm, SMMA, and the construction management firm, Dimeo Construction, on how they were using BIM more effectively to meet the challenges of designing and constructing complex building envelopes. We also learned in more depth about the risk management challenges of building enclosures from the law firm, Faegre & Benson. As part of the “rapid-fire” presentations from technology vendors, Tekla demonstrated a brand new application for model-based collaboration called Tekla BIMsight, while Beck Technologies showed recent innovations to its DProfiler application including construction sequencing and a new Revit plug-in that allows DProfiler models to be opened in Revit and used for further design development.

In this follow-up article, we will look at the remaining presentations from AEC project teams that I was able to attend at the BIMForum event, as well as more rapid-fire presentations from vendors including Scenario VPD and EaglePoint. I will also present my overall impressions of the event and how it compares with other technology-focused conferences in the AEC industry.

Using BIM to Design and Construct Building Envelopes

A presentation by Trent Nichols of JE Dunn Construction focused on the case study of one of its recent design-build projects—an eight story Patient Care Tower commissioned by the University of Missouri Health Systems. HOK was the architect for the project and worked in collaboration with JE Dunn. Construction began in 2010 and the building is expected to be completed in early 2013. What makes this project unique is its modular skin system, which involves constructing the steel frame offset, shipping and erecting it on site, and subsequently mounting prefabricated curtain wall panels on it (see Figure 1). The use of BIM technology was critical for this project, as the unique construction of the prefabricated wall panels required two levels of analysis—a system level analysis, which was used to verify the layout of the entire skin system, as well as a component level analysis, which was used to verify that the connections of the modular panels would perform as desired. JE Dunn received the design model from HOK, which it then reviewed against the composite construction model that it put together from the individual models created by each of the subcontractors. These models were posted on an FTP site and used as the basis for design review meetings to make the necessary adjustments to the design—it was critical to do this early on since the panels were prefabricated offsite and any errors would result in waste and delays. The use of BIM allowed the construction team to analyze the components of the structure at a very high level of detail. All of these were created as custom components in the BIM model and did not come in “off the shelf” BIM libraries.

In another presentation focused on a specific project, David Graue of HNTB Architecture and Sean Zook of PCL Construction Services described the BIM methods and techniques used to design, estimate, and coordinate the exterior envelope for San Diego Airport’s Terminal 2 expansion project, which is currently under construction. The expansion will add 470,000 square-foot, three stories, and 10 new gates to the terminal building, providing expanded dining and shopping options as well as terminal, roadway, parking and airfield improvements (see Figure 2). This is a design-build project, with HNTB as the architect and a joint venture of Turner, PCL Construction Services, and Flatiron responsible for the construction. All of these firms, especially HNTB and Turner, are well known for their BIM implementation, so BIM was naturally deployed for this project, and that too from start to finish. (See this article published in the San Diego Business Journal about the BIM implementation on the San Diego Airport project, written for a general business audience.) The modeling process started with documenting the existing building that the expansion had to connect smoothly with. Although this was a large project involving many firms, the project team still worked on a central model, with 10 to 15 people in the model at any one time. Revit was the BIM platform that was used, and its model linking capabilities were used to link about 15 different disciplinary models together into the master model. The project team used several strategies to cope with some of the challenges of modeling large projects in Revit, such as scheduling a different time for each team member to save to the central model to avoid conflicts and shorten save time, keeping the model as clean as possible and avoiding too much complexity, and always keeping the warnings level in Revit down to 20 or 30 (these can easily number into the 100s if the modeling is sloppy). In addition, Riverbed’s WAN technology was used to accelerate model sharing. Autodesk Design Review was the main application used for design coordination.

With regard to the building envelope in particular, it was complex, comprising of several different systems such as curtain walls and trusses applied to inclined and curved forms. While modeling it, HNTB took constructability into account as well, adding information to it that could be used for estimating, pre-construction planning, and construction analysis, a process that was described in more detail by PCL. Because the project was so large and challenging, PCL found it helpful to use Excel to create a matrix showing all the different parts of the model, including details and snapshots, so that it was more organized and easier to understand. Care was taken to set the model to the appropriate level of detail before sending it to a specific recipient. Color coding was added to the model to highlight different element groups or specific design and construction issues. For bidding, copies of the model were provided to the exterior envelope contractors, allowing them to leverage the work done on the model and develop their own designs more accurately (see Figure 3). The design and construction team attributes a lot of the success in the BIM implementation of this project to its owner, the San Diego Airport Authority, which was very progressive, saw the value of BIM, and strongly supported it use on the project.

We had a brief presentation on the use of laser scanning for building envelopes from Ken Smerz of Precision 3D Scanning, which provides services for scanning and processing point cloud data as well as related consulting and training services across the US. While the use of laser scanning for capturing as-built conditions for renovation and retrofit projects in the AEC industry is well known, we are increasingly seeing laser scanning being used for new construction projects as well, as demonstrated by DPR in its BIMForum presentation (covered in Part 1). Laser scanning can be used to check the construction status and exact dimensions of what has already been built and compare it with the design intent to detect any errors as well as ensure that subsequent elements will fit correctly, or otherwise make the necessary adjustments to them. As building projects grow in size and complexity, accuracy gets more important since even small dimensional errors can get magnified and cause problems in fitting elements together. This is especially critical for prefabricated elements such as wall or roof panels which are designed for precise fits and have very small margins of error. A good example of how laser scanning was used to address this challenge was in the City Center project in Las Vegas, where over 6200 roof panels fit right the first time thanks to a laser scan taken of the curved roof frame. As shown in Figure 4, the point cloud of the frame was processed into a 3D wireframe model, which was then used as the basis of the 3D model of the entire structure to ensure a correct fit of the individual panels. Thus, laser scanning can be used to maintain accuracy throughout the construction of a project, and both the hardware and the software involved are becoming increasingly cheaper and easier to use. However, we still don’t have any automated ways of converting point clouds to 3D models, let along BIM models—it is all currently done through manual processing. This remains a huge hurdle in the more widespread adoption of laser scanning technology, but hopefully, some solutions to this problem will emerge soon.

Using BIM for Performance Analysis for Building Envelopes

In addition to highlighting the use of BIM for design coordination and construction, a couple of the BIMForum presentations also illustrated how BIM could be used to assess the performance of building envelope systems. Andreas Phelps of Simpson Gumpertz & Heger, who has worked extensively on the design, construction, and investigation of building envelope failures, focused on performance-based information modeling and the benefits that can be achieved by integrating different performance-based analysis applications. In contrast to the popular notion of using a 3D building model for whole building analysis—of the kind promoted by leading energy analysis tools such as IES and Ecotect—the presentation advocated the use of many smaller and more detailed performance-based tools for analyzing several different aspects of a building such as glazing, wall construction, curtain wall systems, and so on, and evaluating their thermal, structural, moisture, fire-retardation, and other properties that would be relevant to their performance. Examples include WUFI, an application for calculating the coupled heat and moisture transfer in building components, and ABACUS, a finite element analysis application that can be used for structural and fire analysis. Most of these applications are still based on 2D input about the elements or systems being analyzed as they used very complex calculations—the use of 3D would make the calculations even more complex and time-consuming.

With the growing move to BIM, the challenge is to integrate the results of these intensive partial analyses of elements and systems into the whole building design and analysis. While Phelps’ presentation did not describe how this could best be done, it did serve to highlight the importance of multiple detailed analyses to fine-tune a design. One example that was presented was the new Baha'i temple planned near Santiago in Chile. Designed by Canadian architect Siamak Hariri, the structure has a complex shape with nine exterior “wings” that torque upwards, overlapping at the apex to create a dome (see Figure 5). A detailed structural analysis of the structure looked at over 300 nodes and tested the individual panels making up the wings, based on which the panel shape was changed from being rectilinear to triangular. The materials that will be used for the structure, including cast glass and alabaster, were tested for strength, moisture, and transparency, using digital tools as well as physical mock-ups. Thus, the use of performance analysis tools, while critical, cannot fully replace the need for physical mock-ups, which was also borne in the presentation by Rick Khan of Mortenson Construction that was described in Part 1.

We then had a presentation that was specifically focused on the acoustical analysis of buildings, which is something that we don’t typically hear a lot about when building analysis is discussed. It was presented by Craig Janssen and Andrew Mitchell of Acoustic Dimensions, an acoustics and performance technology consulting firm. When it comes to buildings, there are three main noise controlling aspects to consider: preventing external noise from coming into the building; preventing noise from inside the building traveling out; and preventing noise from within a space being transmitted to adjacent horizontal or vertical spaces. Within a building, noise travels to other spaces directly through walls and slabs as well as through joints; these can be addressed with specific strategies such as adding insulation or acoustical foam in cavities, and sealing joints with metal, wood, or acoustical caulk. While the firm is often called in to resolve sound problems in retrofits, it also occasionally consults on new projects as well. An example is the new SaRang Community Church being built in southern Seoul in Korea, where Acoustic Dimensions worked as a consultant to determine ways to keep the sanctuary and chapel spaces in the building quiet and undisturbed from the traffic noise of the densely populated urban site (see Figure 6).

The firm worked with Beck Group, which is providing the architectural design services for the project, and used its Revit design model for detailed acoustical analysis, based on which it developed several sound isolation strategies including special wall and ceiling panels, and additional curtain walls. It has developed a plug-in tool for Revit MEP called AIM (Acoustic Information Model) Workbench that calculates the noise level in each space throughout a project, using detailed information about building elements and MEP systems from the model as well as other relevant data such as project location and occupancy (see Figure 7).  Needless to say, good results need accurate building data and a high level of detail. Typically, acoustical analysis is done too late, if at all, and the presentation pointed to the need to have some macro decision making tools for acoustics in addition to the detailed level analysis enabled by plug-ins such as AIM. These macro level tools could be developed similar to “apps” for smartphones and other mobile devices, allowing easy access to information such as acoustic properties of materials, noise level of a site based on its location, and the subsequent calculation of noise transmission through a building based on its location and envelope materials.

Additional Perspectives on BIM and the Building Envelope

The San Diego BIMForum also included some additional presentations on how BIM can be used to address the building envelope challenge. Stephen Hagan of the GSA highlighted the importance of building envelopes with statistics showing that airtight and well-construction envelopes can save 40% of the building’s energy consumption, which is even more critical taking into account that buildings account for 38% of the total energy use of all sectors. Also, uncontrolled rainwater penetration and condensation are two of the most common threats to the structural integrity and performance of the building envelope, accounting for up to 80% of all construction-related claims in the US. Several research and industry efforts are underway to address the envelope challenges, including NIBS Building Enclosure Councils, laboratory efforts in the Department of Energy, ASHRAE and ASTM standards developments, the USGBC LEED standard, as well as specific envelope commissioning requirements. The GSA is now mandating that an air/moisture barrier be used in all new construction and should also be employed wherever possible during remediation of existing exterior envelopes.

Another government perspective came from Roger Grant of NIBS, who provided an overview of the different NIBS councils and projects working in the area of BIM and envelope design, as well as summarized the attributes for assessing a building envelope’s performance from several different points of view: architectural, structural, mechanical, fenestration, and owner/operation. He also described the OPR (Owner’s Project Requirements) tool, a web-based planning tool developed by NIBS that can be used to establish requirements for critical parameters and performance objectives for a design, and subsequently analyze multiple design alternatives and assess their respective costs and performance tradeoffs.

We also heard from Steve Jones of McGraw Hill who talked about the importance of bringing BPMs (building product manufacturers) in the BIM process and the work that McGraw-Hill has done to facilitate this. It already has close to 5,000 BPM customers and is engaging them in BIM through a two-part BIM Content program in its Sweets catalog. The first part is providing access to manufacturer-specific BIM product models through Sweets—currently over 80 BPMs are participating in this initiative. The second part of the McGraw-Hill initiative is a workflow application that builds BIM content on-the-fly based on specific project needs and inserts it in the model. Four BPMs have already completed these applications for their products; they include DuPont, Firestone, Georgia Pacific, and Assa Abloy. The applications are currently available as plug-ins to Revit, with a plan to expand to other BIM formats in the future. The plug-in applications can be used to replace generic element information and rough geometry in the model with manufacturer-specific, highly detailed elements that meet specified performance criteria (see Figure 8). The plug-in automatically extracts the building geometry and other relevant information from the model. Additional attributes and requirements can be added later while using the application to search for specific elements and systems to replace the generic ones in the model. The applications also include links to analysis engines such as EnergyPlus, allowing, for example, the moisture and energy analysis of a selected wall assembly to be simulated to review its performance.

Technology Updates from Scenario and Eagle Point

In addition to Tekla and Beck Technologies, the BIMForum event featured rapid-fire presentations from two other technology vendors, Scenario VPD and Eagle Point. Of these, the Scenario VPD solution was completely new to me. Scenario was actually started in 1995, but worked initially in the turnkey construction and fabrication industry. Here it experienced firsthand the value of digital modeling as an effective vehicle for articulating design intent and precise rendition of detail, which led it to develop a Virtual Project Delivery (VPD) technology that spans a project's life-cycle and incorporates all members of the building team. It developed this in partnership with the KHS&S Group, a large international design-assist specialty building company, which acquired Scenario in 2008. The mission of Scenario VPD is to make “BIM plus the building data work in real-time.” To this end, it has just released its Communication, Collaboration and Control (C3) software system for the AEC industry which allows building design and construction team members 24-7 access to live integrated project data. It utilizes a web-based central server where all project and BIM data is stored and aggregated in one place within a common real-time platform. Building team members access data using a pull-down menu that automatically integrates with leading AEC applications including Revit, Navisworks, and AutoCAD. The system includes additional capabilities such as live project tracking, revision control, information routing, and review of BIM and project documents. Team members can perform real-time BIM and trade coordination, including live clash management, whether they are working at the same location or are geographically dispersed. They can also work offline and upload changes when reconnecting to the Web.

We also heard from Eagle Point, which showed how its Pinnacle Series can improve a firm’s ability to implement BIM technologies and processes with a set of tools and techniques that can be used to define, publish, and monitor its everyday workflow processes. It is comprised of three applications, Process Mapper, Task Navigator, and Workflow Monitor. The Process Mapper application defines project and operational processes in a graphical environment, showing their dependencies and including detailed instructions and ties to technology tools (see Figure 9). The Task Navigator provides users with on-screen instructions and shortcuts needed to complete their tasks, and can integrate links to design and modeling applications like Revit, Navisworks, AutoCAD Architecture, and AutoCAD, as well as email and other office applications. The Workflow Monitor can be used to monitor how well a process is working by analyzing the tasks that people have completed to see where the process could be improved, or if coaching is needed to improve work efficiency. Overall, the Pinnacle Series can be used by AEC firms to standardize their workflow processes firm-wide, capture their “best practices” and ensure their execution, get people up to speed fast from any experience level, and help enforce consistency of information. The ability to electronically diagram workflow processes and communicating them to everyone can greatly enhance productivity.

Overall Impressions

I found the BIMForum event an interesting change from other AEC technology conferences that I regularly attend, which include vendor-specific events such as Autodesk University and Bentley’s Be Inspired as well as more general events such as the AIA TAP (Technology in Architectural Practice) conferences. It was very interesting to learn more about BIM from the construction perspective, which is often missing from the more architect-centric AIA TAP events. At the same time, the BIMForum also featured several architects and engineers, both among the presenters as well as the audience, helping to provide a more balanced view of BIM thinking and implementation across the entire AEC industry. It is, to some extent, filling in the gap left by the AIA TAP event, which seems to be losing some momentum—the 2010 TAP conference was held as a one-day event with the option to attend virtually, which several attendees, including myself, availed of.

Conference attendance in general has, of course, declined because of the economy, but you would not think this from the BIMForum event, which at over 300, was very well attended. This number was also significantly higher than the attendance at the last BIMForum event, which is remarkable given that the event is held three times a year. It is obvious that the event is gaining in popularity and is filling a need that AEC professionals have for attending an in-person, vendor-neutral event focused on BIM and other advanced technologies, where they can learn about what other firms are doing, get concise vendor updates on their product enhancements, and network with like-minded professionals from other firms who share the same interests and belief in the importance of technology. The broadening of the BIMForum’s focus beyond construction to also include design has made it relevant to all AEC professionals. It is especially a useful forum for architects and engineers to become more familiar with the progress that contractors are making with advanced technologies such as BIM and their current thinking on it.

In terms of the actual content that was presented, not all of it was focused on showing “mind-blowing” work by contractors using BIM, so those expecting to see highly advanced use of technology may have been somewhat disappointed. (For example, see reader comments on the AECbytes blog posted in response to the publication of Part 1.) However, since the BIMForum event happens thrice a year, its objective is not to highlight the most cutting-edge work being done in construction using BIM, but instead to focus on a specific theme, such as the use of BIM for the “building enclosure” which was the theme of this particular event.

The next BIMForum will be held in Chicago on June 9-10 and is planned on the theme of “Where Does Design End and Construction Begun?”

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at lachmi@aecbytes.com.

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