Building information modeling is a great step forward for the architecture, engineering and construction industry.
Michael Grose, PE
Mechanical engineer, MDP Engineering Group, Denver
As we all know, BIM models provide digital construction technology that has the “potential to reduce cost and errors, increase productivity, improve the quality of our work products, and ultimately, improve the built environment” (source: “An Introduction to Building Information Modeling (BIM),” November 2009). BIM provides a collaborative way of working using technologies that allow for more efficient methods of designing projects on any scale.
Contractors and architects have been successfully using BIM to design and construct buildings for more than two decades. Avoiding coordination conflicts during design and construction, providing comprehensive material takeoffs or presenting beautiful 3-D renderings are major benefits to early adoption. Mechanical, electrical and plumbing engineers, however, have spent most of the past decade plugging away in two dimensions. Our discipline did not demand 3-D+ modeling until quite recently, and as a result, most MEP engineers were never trained in BIM or its relevant software applications. A number of MEP consulting companies are starting to realize the opportunities that BIM creates and are now investing in their own capabilities for more efficient design.
Our firm’s first BIM project was in 2010, one year after the firm opened. In 2013, we completed our first large HVAC design for approximately 150,000 square feet using Revit MEP software. In 2014, our company designed 450,000 sf using Revit, but still just HVAC systems. In 2015 and the first half of 2016, the total scope of our BIM projects skyrocketed to over 1 million sf of full HVAC, electrical and plumbing design. Under increasing demand from developers, architects and even governments, similar changes are occurring within MEP design firms across the country and worldwide. For example, in England, government programs were implemented to promote BIM adoption in the construction industry, including phased implementation and mandatory adoption by central government departments.
My colleagues and I have learned a lot about designing MEP systems as part of the intelligent building information model. We cut our teeth using Revit MEP and, along the way, we have discovered a few recurring issues. More importantly, we have identified some real-world workarounds to address these issues, and ultimately help improve MEP 3-D design in the construction industry.
Staff. The largest obstacle for MEP design firms attempting to convert to BIM from 2-D programs, such as AutoCAD, is staffing. The older generation of engineers have been using 2-D software for 20 years or more and have been understandably resistant to learning new programs. The younger generation of MEP engineers are surprisingly not yet learning to use BIM software in school. The few students who do learn BIM software are generally in architectural programs or enrolled at technical or community colleges. These students typically have little knowledge of MEP systems and require extensive on-the-job training. I was lucky to be exposed to HVAC design during my undergraduate studies, but I have interviewed or met very few engineers with the same experience.
Despite these staffing challenges, we are striving to use BIM software for all large construction projects. Therefore, we’ve had to develop a strong in-house BIM program. An important first step was hiring a full-time BIM manager. With his guidance, we are actively developing implementation plans, adopting company standards for 3-D modeling and generating standard content for BIM modeling.
Staff education will be the next big hurdle. Companywide educational seminars are held on a regular basis, but only so much can be learned about a complex software program while sitting at a conference-room table. To address this, we make it our mission to support each other and sit down one-on-one with engineers and designers new to Revit modeling. We also encourage our employees to self-educate using company-provided tutorials, or subscribing to related online forums or YouTube channels. An alternative to in-house training is to send employees offsite to multiday training sessions. However, as a company, we have prioritized training our engineers in-house while using our company standards. Because of this in-house training effort, and a few strategic recent hires, we now have a core of professionals familiar with the use of Revit software.
Schedules. One of the biggest benefits of Revit is the automatic scheduling of modeled equipment and elements. On the other hand, this is also one of the main challenges facing MEP engineers due to the lack of global standards for shared parameters. The official Revit style guide acknowledges the need for standards and attempts to direct users on proper naming and use. But, so far, there is no agreed upon convention.
Our workaround for this issue is to develop a custom file for shared parameters that will be synchronized with equipment schedules. Due to the way parameters are identified in the BIM database, we have to load our custom parameters into each new family we receive from a manufacturer. This process is time consuming, but it allows for a consistent appearance and format of schedules.
Equipment. A common issue we run into during design is the lack of manufacturer-generated BIM models available for download. Generic models work fine for equipment such as air diffusers and valves, because they only vary slightly between manufacturers. But larger equipment, such as a rooftop unit or generator, has unique properties that vary from manufacturer to manufacturer. Using generic models for this type of equipment means that we lose the detailing or operational parameters that reflect the actual equipment being scheduled. This defeats the main purpose of BIM, which is to create an accurate representation of the systems being designed in order to promote coordination among the trades. Unfortunately there is no convenient workaround to this issue. The availability of equipment models is increasing over time as manufacturers begin to respond to the demand for BIM/Revit models of their equipment. But, in the meantime, we continue to use a generic model as a placeholder for large equipment.
@ Hosting. On multiple occasions we have observed equipment modeled on the fourth floor end up on the 10th floor of an architect’s model. How did this happen? When an architect moves a hosting element like a ceiling or wall, MEP elements can unintentionally be moved, orphaned or deleted. As a workaround, we host ceiling mounted elements, like diffusers and lights, to reference planes that we create in the MEP model. This method of hosting allows architects to move ceilings or walls without having to worry about accidentally moving the MEP systems. However, a downside of this method is that the reference plane elevations we create in our MEP model may not match identically with the architect’s ceiling elevations. Misaligned elevations can cause issues with the proper visibility of elements such as ducts, diffusers and lights in the ceiling plan.
Shortcuts sometimes used by architects lead to inconveniences in the MEP model. We have worked on projects with typical hotel rooms or apartment units that were modeled in a 2-D format and then copied throughout the building. When an MEP engineer creates a 3-D model, the existence and placement of walls is important for hosting lights, receptacles, grilles and many other pieces of equipment. As a workaround, we have created placeholder walls so that we can then provide a 3-D model; however, these placeholders can create discrepancies between disciplines. Properly modeled hosting elements will lead to fewer inconsistencies and coordination errors.
Conclusion. Things are changing quickly in the AEC industry. The bright future that BIM promises has yet to be fully realized, but each year we’re moving closer to it. There certainly will be additional challenges for the MEP Revit user, but our design approach acknowledges that despite these short-term challenges, the long-term goal of fully adopted BIM modeling will improve the quality of our work and the industry’s work as a whole.
