Making the Transition from CAD to BIM

Making the Transition from CAD to BIM

In today's fast-paced competitive construction market, it's no longer enough to execute a project in the real world of girders, sheet metal, pipe, and racks. These days, requests for proposals (RFPs) on most large projects now require electrical contractors to execute the project first in the virtual world using Building Information Modeling (BIM), and for good reason. Effective use of BIM can improve

In today's fast-paced competitive construction market, it's no longer enough to execute a project in the real world of girders, sheet metal, pipe, and racks. These days, requests for proposals (RFPs) on most large projects now require electrical contractors to execute the project first in the virtual world using Building Information Modeling (BIM), and for good reason. Effective use of BIM can improve design, enhance constructability, and accelerate the schedule, saving time and money for the owner as well as the project team — if only BIM software came “out of the box” designed and purposed for electrical contractors.

Yet, in the experience of EMCOR Group, Inc., headquartered in Norwalk, Conn., it's well worth the contractor's time, effort, and financial investment to make the transition. In fact, successful implementation and use of BIM requires significant investments in technology, staff, and training. With more than 200 professionals who are well versed in using BIM, EMCOR and its subsidiaries have first-hand experience with this transition.

BIM is comprised of 3D modeling concepts, information database technology, and interoperable software in a desktop computer application that architects, engineers, and contractors can use to design a facility and simulate construction. The technology enables members of the project team to create a virtual model of the structure and all of its systems in 3D and share that information with the entire project team. The drawings, specifications, and construction details are integral to the model, which encompasses building geometry, spatial relationships, geographic information, and quantity properties of building components. As a result, team members are able to identify design issues/construction conflicts and resolve them in a virtual environment well before construction begins in the real world.

Customizing BIM

The saying that necessity is the mother of invention certainly applies to BIM in the electrical contracting industry. Most of the development in BIM has focused on the purposes and needs of architectural and engineering firms. The mechanical contracting industry has the advantage of real-world models of its equipment and parts via third-party vendors. Software vendors have not built a BIM product that comes out of the box with content that completely meets the needs of electrical contractors and fabricators. As written, these programs simply reserve space for the conduit.

In 2002, the Los Angeles branch of EMCOR's Dynalectric subsidiary began evaluating what was then called “Building Systems” (now AutoCAD-MEP) for use in its business, as it saw interest grow among owners and general contractors. Since that time, the company has invested considerable resources — both dollars and hours — in systems, in-house customization, and training to boost the company's capabilities.

Over the course of six years, Dynalectric developed accurate, real-world models of more than 4,000 electrical system components by taking each piece and modeling it in 3D. A layer standard was determined and keyed (e.g., a layer for conduit, layer for hangers, etc.), and the system was configured to automatically place each type of component on the correct layer. As a result, when a BIM engineer models an electrical system on a project, it is as accurate as if it were installed on the job site (Photo 1).

Moreover, the system has been customized in-house to do everything from schedules and take-offs to automatic engineering calculations — all with the click of a mouse.

The “I” in BIM

The intelligent property database corresponds to the “I” in BIM. Intelligent property data can be extracted from the model for the purposes of engineering, take-off, and prefabrication. However, it didn't come in off-the-shelf software; Dynalectric has customized the system to enable its staff to perform these functions.

One of the main benefits of customized BIM software is being able to schedule and annotate the drawings. For example, by applying intelligent property data to conduit and parts, the staff can very quickly perform a take-off of the conduit to determine the number of linear feet or quantity of hangers. To annotate all of the conduit elevations, the system pulls live data from the actual model components in the drawing; no one has to stop and look it up.

Customization has enabled the staff to perform engineering calculations on the spot. For example, if a team member needs to calculate the load on a 10-ft section of a conduit rack, he or she clicks on it. Then, a schedule table is inserted into the drawing with the total run of 30 ft (three 4-in. EMT conduits); total load of 54.48 lb of weight per foot with copper wire and conduit; total weight of 544.8 lb; and 272.4 lb of gravity load at each anchor in each rack (click here to see Figure 1).

A set of routines was created that works inside of the intelligent property data to calculate strut loads, which recalculates automatically as the user changes the length of the object. This enables the staff to perform live engineering calculations and “what-if” scenarios very quickly and accurately.

Evolution of capabilities

An early milestone in Dynalectric's use of BIM was a $25-million project to upgrade the Hollywood Bowl in 2003. Designed by Hodgetts + Fung architects, the project included a reconception of the arch, advanced digital sound reinforcement system, and expanded stage with a halo-like acoustic canopy. Dynalectric used BIM to model 25,000 ft of conduit running through a complex “forest” of structural steel. Although the electrical BIM model was complex, it was still a rudimentary conduit model by today's standards. Yet, it was only through the use of BIM that the electrical contract could have been effectively planned and executed. Using 2D sections and elevations to try to understand the structure in the traditional method would have made it nearly impossible to effectively find a routing for all the required systems.

In 2005, Dynalectric was still the only contractor using BIM on the new Four Seasons Hotel and Spa Westlake Village, Calif., which was designed by WATG architects for owners Castle & Cook, Inc. More than 750,000 ft of conduit and support systems were routed for this six-story, 476,000-sq-ft structure, which includes 268 guest rooms, a spa, wellness center, TV studio, clinic, and conference center.

The Dynalectric team began by looking at the primary electrical service that was entering the main electrical room (Photo 2). The single line specified (20) 4-in. conduits for the two 4,000A primary feeds into the building. These raceways were routed to an already undersized and overcrowded electrical room. By modeling this area, the team was able to quickly identify the problems and clearly demonstrate the issues to the designers. For example, the staff suggested replacing more than 13 sq ft of conduit with 1.2 sq ft of busway, freeing up a large amount of space in an already congested space at no additional cost.

It is also noteworthy that more than 3,500 anchors were embedded into the structure for conduit support systems. Due to the accuracy of the model, Dynalectric was able to use 99% of these anchors.

Virtual best practices

BIM is much more than an electronic drawing tool because it allows team members full collaboration. In the best of all worlds, the general contractor (GC) is engaged in designing and implementing the BIM execution plan. This includes determining what will be modeled and at what level of detail (which varies from project to project), and facilitating mechanical, electrical, and plumbing (MEP) coordination. As every contractor knows, coordination is a give-and-take process, especially when the project is using the traditional design-bid-build delivery method, in which post-bid changes incur additional costs for the contractors.

Here's how it works in the BIM world. Each trade receives architectural and structural models from the owner. Then the trades begin routing their systems. Weekly, each trade contractor posts its systems to an FTP or other shared Web site. Typically, the GC assembles all of the models into a composite using NavisWorks Review or Manage, which enables project team members to integrate and share data and drawings from various software programs.

The composite BIM can be viewed, manipulated, and analyzed for clashes among the trades, who negotiate changes to resolve the clashes. This process continues floor by floor and quadrant by quadrant until everything finally “fits” in the virtual building.

The Miller Children's Hospital's Pediatric Pavilion at Long Beach Memorial Medical Center, completed in 2007, is a good example of this concept. It illustrates the process of a BIM-coordinated project in which the GC (Turner Construction) did an outstanding job of creating a partnered environment among project team members. As designed by the architects, the Pediatric Pavilion is a 129,000-sq-ft acute care addition with seven operating rooms, a new pediatric imaging center, 48 neonatal intensive care beds, and 24 general pediatric beds, plus a 5,500-sq-ft central plant.

At the onset of the preconstruction phase, the GC brought all of the players together to assess their capabilities, determine what would be modeled, and decide what level of detail would be produced. A CAD standard and procedures were clearly defined early on in the process, including drawing naming conventions, discipline-specific layer colors, file-sharing procedures, file origins, and model detail.

Turner Construction brought the steel subcontractor on early enough in the project so that its fabrication model was available to the coordination team. This was of critical importance to the success of the project. Normally, MEP contractors must create this from the contract structural drawings. This information is rudimentary, at best, and is only intended to convey the design intent to the fabrication contractor. By the time the fabrication contractor completes his design, many requests for information (RFIs) are processed, and the model is significantly different than what was conveyed in the original design documents. The fabrication model will contain bracing and connection plate information that is not available until their model is detailed and completed. This usually impacts MEP trades significantly at a stage in the job when it is too late to mitigate problems in a cost-effective manner.

The GC also provided accurate internal/external wall and deck models, which enabled all of the MEP detailers to work from the same data set of information, reducing interpretation errors and increasing subcontractor productivity. Thanks to realistic scheduling by the GC, the project team avoided another common mistake: under-allocation of time for preconstruction. On the Miller project, the team had approximately eight months of preconstruction prior to any deliverable milestones.

Furthermore, the GC remained engaged as an active facilitator throughout the process, handling mediation of conflict resolution, management and tracking of weekly clash detection, bringing in the design team when appropriate in order to expedite information flow, coordinating schedule management, and facilitating contractor engagement with the use of NavisWorks and interactive whiteboards in the coordination meeting room.

The project was completed using the best practices of BIM and virtual construction, resulting in an efficient and productive process and a highly successful project for all involved.

Making the transition

As noted above, successful implementation and use of BIM requires significant investments in technology, staff, and training. There is no “cookie-cutter” solution. That's why going into the process with your eyes open is essential. It is not likely that there will be software that is purposed for the electrical contractor in the very near future. Be prepared to carefully evaluate the software you are considering buying. Analyze your goals, set your priorities, and start working in that direction. At the very least, making the transition from CAD to BIM requires more powerful PC hardware and new software, along with a network, servers, and high-speed telecommunications backbone that support the process. Then, it requires a considerable investment in customizing the application software. Commitment from upper management also is a must. Without their support — both financially and ideologically — moving forward into BIM will be difficult, if not impossible.

The transition also requires a transition in terms of staffing. It takes someone with a foundation of computer skills, a willingness to learn BIM technology and the process of collaboration, and the technical and intellectual capabilities to integrate this knowledge into the electrical contracting business. To become an effective building information modeler, it is not enough to understand the software. To build a virtual electrical system, one must first have considerable experience and success building them in the real world.

That is why EMCOR selected field people who have 20-plus years of electrical installation experience and an aptitude for BIM to model these systems. The mentoring approach is the best way to train people on BIM. The basic process is to give them AutoCAD classes then one-on-one 3D training. Next, they work on projects side-by-side with experienced BIM people who transfer all of the knowledge they need to work on their own. Finally, after approximately two years, they are ready to perform BIM on their own.

Although it's a long and expensive process, the benefits of BIM are worth the investment. When BIM is effectively used, it coordinates MEP trades, expands prefabrication opportunities, eliminates rework, increases productivity, decreases labor costs, and improves the consistency of the work product. BIM is no longer the future of electrical contracting — with most owners and GCs requiring this capability, especially on large projects, the future is now.

Bratton is engineering manager, virtual design and construction, in the Los Alamitos, Calif., office of Dynalectric Los Angeles — an EMCOR Co. He can be reached at Jbra[email protected].

TAGS: content
Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.