Big BIM Little BIM – an MEP Force Highlight


September 19, 2019 | All

The combination of the construction labor shortage and more demanding schedules and budgets for building projects is creating an opportunity – a need actually – for mechanical, electrical and plumbing trades to fill the role of helping determine constructability of buildings and develop constructible models. This was the overarching message of the MEP Force 2019 keynote address by Josh Bone and Jonathan Marsh, of Caisson.

Both construction technologists conceded that won’t happen overnight. There are still (pardon the expression) building blocks required to get ready for the next step. Employees in the MEP trades need to develop the skills to understand the model – the virtual plan of how the building will be built – and what’s involved in the planning stages of design. If they’re going to sit at the table during early planning, they need to understand the model environment.

Historically, that hasn’t been done, and the workflows have resulted in myriad projects going over budget and beyond schedule, so often, in fact, that it’s a running joke in the construction industry. But the cost to the construction industry is no joke. Mechanical and electrical contractors have approximately 50% of the entire building and half of the risk that it will be their part of the project that causes overruns. So why shouldn’t they be involved at the beginning? Bone and Marsh stressed that, if brought in early in the process, the trades can bring value to the building that no one else can offer. They can “sharpen” the building and make it efficient.

One of the challenges of construction projects is developing a unique BIM process that makes sense for the workflows involved. Bone explained that the BIM process being recommended to building owners today is spelled out in The National BIM Guide for Owners (NBGO),, developed by the National Institute of Building Sciences to provide building and facility owners with a consistent reference for including BIM in contractual documents with their building project team. The process, Design-Bid-Build, results in BIG BIM.

image 18

Marsh pointed out that BIG BIM is not a great process for the trades. You get the model, and it puts the design of all the mechanical systems at the END. This is the point where the facilities manager might tell you that all your valves are at the wrong place, requiring you to draw it a second time. It’s also the point where the chosen equipment may require another design iteration. The trades assume most of the risk in a process like this. This cycle in effect “pitches it over the wall” from one guy to the next guy to the next, and it most likely requires a redesign at each step. “It’s a dangerous circle,” Marsh cautioned. All of those redesigns could be avoided if the maintenance team would be involved in the planning process.

Using the NGBO, yes, a standard set of BIM documents can be developed during the design and construction of the facility, as well as for maintenance and operations of the facility upon handoff. BUT, as Bone pointed out, “Owners don’t know how to build mechanical systems. They know the level that mechanical systems need to perform at (which is engineering), but they don’t know how to build them.” And that’s the bottom line of why trades need to be part of the design process.

Bone explained that the BIG BIM process isn’t about making the building efficient and making money yet, so BIG BIM on every job is unrealistic. Buildings need to be designed that are already optimized. Properly executed, there’s not a “lifecycle” of BIM; “everyone needs to be in there at once.” If they are, instead of having separate BIG BIM and little BIM, the end result is a collaborative model that eliminates a lot of problems that won’t show up until just about the end of construction (where about one-quarter of the scope resides). Bone’s message to owners: “You need to get a collaborative team working on your building, not one person followed by another person followed by the next person.”

image 17

Bone explained, “Little BIM happened because contractors wanted to make money, and this was the most efficient and profitable way to fabricate. Mechanical rooms were modeled because they were high dollar value areas. Then the process moved to the rest of the building.” Marsh added, a common sentiment was, “I can’t believe you planners made these decisions without us.”

BIM can diagnose and mitigate the risk on the job, in effect serving as a “risk” insurance policy. How much do we need to coordinate? What can be fabricated offsite? What can be done from a 4D and 5D standpoint?

image 16

Bone, who speaks to owners during many of his presentations around the country, said they need to be educated that BIM isn’t always about return on investment. A conversation with an owner might explain how information silos will be leveled and teams will come together. Delivery can be described based on what brings the most value to all the players on the project. “The BIM process brings teams together,” he said.

MEP Force 2020 registration is now live. If you would like to reserve your spot at next year’s event at a reduced rate, visit the registration page today. Take advantage of the opportunity to interact with others in the trades, discover the latest innovations, and learn how to prosper your business in the rapidly changing MEP industry.