Case study: Lab project uses both VDC, BIM
This project takes a very different approach to the inclusion of a model as part of the deliverable. The project has not yet been bid, thus the client is confidential.
In July 2017 CannonDesign contracted with a laboratory client to perform the design of a comprehensive equipment installation within an existing building shell space. The project scope includes the installation of client proprietary equipment and documentation of the distribution and interconnection of this equipment using both derived and client specific requirements for that distribution. The project scope of work requires both the development of stand-alone two-dimensional drawings and specifications for procurement and installation, as well as a building information modeling in Autodesk Revit.
The purpose of the model was clearly defined to “identify/reduce/eliminate conflicts and interferences prior to the start of installation and provide coordination of the space and ensure accessibility for operations and maintenance.” A further request was that the model be developed to a level that allows for the early installation of hanger supports and planning of equipment move-in/out as well as ongoing maintenance. The client was very specific about level of development for elements to be installed and provided Table 2 defining that LOD and desired outcome.
Using this table as a starting point, CannonDesign developed a BIM execution plan that identified how the project model would be developed through the various stages of preliminary submittal. The BIM execution plan was very specific in defining how the model was to be coordinated; given the level of detail desired for the client proprietary equipment, it was understood that the model would become quite large and cumbersome almost immediately. Separate Revit design models were planned for the existing architectural, structural and mechanical, electrical and plumbing content to maintain manageable model size.
The client provided a point cloud scan of the existing shell space and AutoCAD drawings of the original shell space design, which were used by CannonDesign to create the building model, the first major task of the project. Three-dimensional PTC Creo models of the proprietary equipment and proposed layout were also provided by the client. The creation of the Revit content illustrating the client proprietary elements and required clearances and the location of those elements within the building model was the second and a time-consuming task of the project.
Models of the various proprietary equipment components were transformed to Revit content using Autodesk Inventor as an intermediate step as illustrated in Figure 2. Even with the Revit design model separation noted above, the Revit elements representing client proprietary equipment and incorporating working clearances were so large that they needed to be reduced to a more simplistic form in the working model, as otherwise in full definition the model took more than an hour to regenerate.
The next task of the project was to develop the distribution between equipment using the client specified components and parameters. This was no small feat, as the client required that the model be developed to the point of showing final equipment connections, instrumentation and hangers. Beyond the ability to fully coordinate various elements in the model to the point of defining final equipment connections and fittings, the task of being able to create representative two-dimensional drawings that illustrate that coordination was a crucial part of the project development.
To facilitate two-dimensional illustration of the modeled information, key areas were defined as subzones at large scale for coordination; once the model had been coordinated in these various areas, multiple section cuts and isometric drawings of the elements were created to illustrate that coordination in two-dimensions. In addition to the sections and isometrics, various detailed views have been generated and the model has been used to generate bills of materials for the various components that will be incorporated into the procurement package. Cost estimates also used the model to estimate down to the individual fitting level.
The model created for this project is not currently planned to be released to contractors in support of the procurement of the work. The owner has indicated a reluctance to limiting the contractor pool to those that can successfully use the model and has insisted that all the information needed for bidding the work be available through two–dimensional drawings. Capturing the highly developed model in two–dimensional drawing form has precipitated the creation of an extraordinary number of drawings, on the order of 400 overall for a space smaller than 5,000 square feet.
Once the project has been bid and awarded, the model will be used to support the virtual design and construction of the work. The selected contractor will be allowed to use the model to the best of its ability for further coordination and to plan sequencing of the work once it is on board. That sequencing and coordination, including the allowance for construction and installation clearances, currently is being reviewed as part of the design effort using the model. The coordinated model is being manipulated using worksets to illustrate sequence of work and verify access for phased installation of elements once earlier phases have been completed. That illustration has driven revisions to the proposed sequence of installation, such that the design team and owner can be confident that the work can be performed in the manner desired.