Integration: BIM design

An analysis from the United States, by Ed Paul from Arup, explores from an interesting point of view the limitations and needs of the integration process between different disciplines, with special focus on MEP/FP related BIM models.

‘Building information modeling (BIM) is used frequently when working across multiple disciplines. Is it possible for BIM to be done correctly for mechanical, electrical, plumbing, and fire protection (MEP/FP) design? Numerous factors come into play when integrating BIM into the MEP/FP engineering and design process. It is up to the design team to take the best from each variation of modeling and apply the appropriate elements to create a successful process.

Expectations are never the same on any engineering project. Everyone has various ideas of how BIM will be incorporated, and quite a few of them are unrealistic. The MEP/FP engineering team needs to set appropriate expectations with the architect and owner at the onset of the project. Before defining these expectations, we need to understand why divergent expectations exist.

When we say or hear BIM, it is often interpreted to mean 3-D modeling using Autodesk Revit. While other platforms are available, most architects use Revit, which sets the expectation that MEP/FP models will also use Revit. The main concern is related to the detail and accuracy that an architect or owner might expect because he or she doesn't completely understand the MEP/FP software or process. Architectural models are detailed and dimensioned to a high level of accuracy, and it is expected that MEP/FP models will match that accuracy, an attitude also shared by the client/owner. This sets the precedence in architectural and structural models, which are required to provide dimensional control for the contractor as an element of design. MEP/FP design work rarely, if ever, has the same level of detailing. However, as MEP modeling software became mature enough to be used on major projects, expectations were already set for similarly detailed MEP/FP models.

Contractors have also become accustomed to using architectural/structural models directly to create their 3-D coordination models; increasingly, they expect the MEP/FP models to have the same detail and accuracy. For example, a general contractor was completely surprised by my "negative" response when he asked about modeling all the conduit runs in the electrical model. MEP/FP design models are created primarily to show design intent. While support modeling and constructability are secondary drivers, they are still important, as the subcontractors make a substantial investment in the trade coordination exercises and rely on that information from the design models.

Keeping this in mind, the MEP/FP models should focus on overall dimensional accuracy of equipment, ducts, pipes, and other items that will require coordination with other disciplines. This virtual coordination for physical location must satisfy everyone's needs, including those of the facility engineers who will eventually maintain the equipment and facility. These expectations should be clarified in meetings with the various teams when collaborating to create a joint BIM execution plan (JBEP).

Collaboration to create the JBEP is another key factor for a successful project. Quite often the request for proposal (RFP) for a potential project is accompanied by the client's BIM requirements. The JBEP is simply a response to the requirements, defining the plan and processes that will be used throughout the length of the project to meet the goals. If the RFP or the client does not have any BIM requirements, it is still in the best interest of the project team to create a JBEP so that all members understand what is created and delivered to each other-and finally to the client at turnover. Without an agreed-upon JBEP, teams often move forward with their own definition of BIM goals, which results in misaligned expectations, at times allowing the architect and/or contractor to continually ask the MEP/FP engineers and designers for small changes in the model's detail or accuracy that may add up to a significant amount of work beyond the contractual scope.

When creating the JBEP the MEP/FP team needs to pay special attention to topics like roles and responsibilities, BIM uses, model organization/setup, models exchange, level of development (LOD), modeling matrix, software used, and data export. Quite often Construction-Operations Building Information Exchange (COBie) is required as a data deliverable, though it is not always clear how it will be used by the owner. While all the elements of the JBEP are important, the topics noted above are the core working parts of a well-defined BIM execution plan. Once these topics are defined in the plan, effort must be maintained to stay within the bounds of the JBEP.’