What is the Goal?

BIM has several benefits, but each project will need to define what the underlying goal is for using BIM. Is the primary purpose to ease and visualize the design process or drawing creation? Is its purpose to use it to perform quantity take-offs? Is the purpose for fabrication? Will it be used for analysis? Is it to be used as a maintenance database? What if the project or task only involves a feasibility study?

Let’s start off with an example building design project. A Certificate of Practice holder (Holder) and engineering consultants will be designing a building for a traditional Design-Bid-Build contract. The client has no requirements for BIM, and no contractor is involved at this stage. One of the consultants would like to use BIM to improve coordination and collaboration, and to reduce design and construction risks. Although this desire comes from one consultant, to really achieve coordination and collaboration it’s important that the design consultants collectively agree to participate in BIM. Why? Because BIM practiced only by one or two consultants is of little value towards collaboration and coordination of the entire project. If, for example, the mechanical engineer isn’t aware of BIM’s purpose on the project, and simply models representative ducts, without true sizing, then any coordination with the ceiling or MEP systems to the interstitial space wouldn’t be accurate or reliable.

Similarly, if the purpose and use of BIM veers off its initial goal (design and collaboration), the benefits can be limited, or extra investment needed. If the contractor obtains a copy of the BIM used in the above example with the goal of using it to plan their concrete pours and sequence of cladding work, they may find it difficult to do so because the concrete hasn’t been modelled in separate pieces that relate to the contractor’s pour schedule, and cladding components in BIM won’t have been grouped according to the different phases of work. While it’s not impossible for the contractor to edit the BIM to suit their needs, everyone must realise the client and design team need to understand and agree on what BIM will be used for, and then work towards that common goal.

Creation of a BIM Execution Plan

Before you get started, create a BIM Execution Plan. This execution plan is a detailed playbook for how everyone engages with BIM. It establishes what the BIM is used for, and what the required outputs are. It also outlines practical items such as which version of which software to use, and exchange or hosting methods, so all consultants are collaborating on an up-to-date BIM – essentially how a team will deliver the BIM project. Even if the project only involves the client and Holder, a BIM Execution Plan is needed; since it dictates how a project is delivered, and helps define expectations.

Consider the following topics in this plan:

• Purpose of BIM: Clearly identify the main purpose or goal of BIM. Why are you using it? What is the design team’s endgame for BIM? What does the contract require relating to BIM? Without this clearly defined, there is no shared understanding of what the limitations of the BIM will be and what it was developed for. For example, a Holder may be relying on the structural engineer to develop a detailed BIM for coordination, however the structural engineer may believe this is only for conceptual and rendering purposes, and may not model in sufficient detail or accurately enough, making coordination extremely difficult.
  
  
• BIM specific deliverables: Identify what the expected or required end-products are. Do the client or the contractor require a copy of the BIM file? Are other database outputs required? Like a 2D process, all expectations and requirements should be identified to avoid scrambling at the last minute to produce required documents.
  
  
• Lifespan of the BIM: Identify what the BIM lifespan will be. Some projects or scopes may be limited, and therefore the BIM may only be used for feasibility studies, or the initial preliminary design phase. Does the client require a “Record BIM”? Do they require the contractor to have a copy of the BIM? Understanding what phases the BIM will be used for is important. For example, if the project team decides to use BIM only for the design phase they’ll structure how and what they populate the BIM with for this purpose, and their fees would reflect that level of effort as well. If the client later expects the BIM to be used during construction, the project team will not have adequately priced for this on-going BIM support. Similarly, if the contractor is hoping to use the BIM for pricing and fabrication, it may not align with how the project team has organized the BIM and modelled the components.
  
  
• Level of Development (LOD): LOD specifications provide a vocabulary on how developed a BIM will be. For example, its categories (100, 200, 300, 350, 400, and 500) clarify what level of modelling detail is needed - from conceptual to generic to specific. The LOD category alerts the consultants to the level of accuracy needed, what types of elements should be represented in the model, and helps clarify for end-users of the BIM, what the model has been developed for. For example, if an LOD 200 is used (which includes only approximate geometry, size, and location), all project members know and understand in how much detail they are required to model and reflect elements in the BIM environment. Those developing the model then know they can represent an exterior wall simply, potentially as a single form, rather than having to model all the studs, sheathing, insulation, and cladding.
  
  
• Participating BIM Consultants: Identify all consultants who will be using BIM.
  Software/Platform, Version. Identify the software used and the version. Consider the interoperability of files between versions and platforms, and any extra steps needed to exchange cross-platform files. Software aligned under a single platform may simplify interoperability, and provide a more seamless work arrangement between consultants. Consider if the client has a specific format requirement. Like 2D delivery, knowing what software each consultant is using, how to exchange files among different software packages and versions is important to smooth delivery. By discussing and deciding up front in the BIM Execution Plan, consultants can plan accordingly, or agree to use a single platform or version to simplify the file exchange process.
  
  
• Collaborating/Hosting Platform: Identify how the various consultants’ BIM files will be made available for other parties to reference in their BIM. This could be through hosting on a collaborative platform (which enables to the files to be live referenced, therefore receiving updates as changes occur), or by frequent file exchanges. If live referencing is not possible, a frequent exchange schedule should be enforced so the consultants are not developing their BIM based on old information.
  
  
• QA/QC BIM Plan: Methods of spot-checking quality and progress of the project should be outlined. This may include interactive reviews, scheduled clash-detection reviews, and other error-checking tasks. The frequency and method of BIM quality reviews and clash detection program usage should also be outlined. For example, consultants of a project team may each develop their models, but if no one is actively looking and coordinating the interdisciplinary BIM, everyone is just designing in isolation.
  
  
• BIM or CAD Standards: Similar to 2D, if there are specific standards to follow they should be outlined here.
  These are just a few pertinent points that should be discussed and agreed on prior to starting any work. Having a BIM execution plan is vital to aligning all teams across the consultants to work towards a consistent goal. While BIM can be extremely beneficial, BIM is not a panacea, and will not correct poor delivery. It’s also important that fees are appropriate for the level of effort and expected output. By establishing a BIM Execution Plan, fees can be planned and allocated according to the parameters of the Execution Plan.

BIM: Project Delivery Timing

With BIM, the focus is on designing and developing the project in the BIM environment, with less emphasis on the 2D drawing creation; at least not typically in the initial preliminary design phases. In such early phases it may be more important to develop a conceptual model to test the design, allocate the spaces, and convey the general intent. Equipment placeholders may be used at this stage with the clear understanding that sizing confirmation is to follow. It may also simplify the process to perform milestone reviews in the BIM environment during preliminary phases, rather than output early to 2D drawings. This type of arrangement needs to reflect the project and client requirements, since some clients require 2D drawings at all stages, regardless of BIM usage.

Much of the planning behind drawing production follows the important steps you’d normally use for traditional 2D delivery – planning your drawing through a cartoon set, and complying with client requirements for CAD standards or drawing standards. One major difference between 2D CAD and BIM is that BIM requires an earlier decision-making process. Since BIM gives you a more detailed and integrated representation, and is built in a data-rich environment, it prompts for design decisions to be made earlier in the life of the project.

Applying the mindset of 2D CAD delivery to BIM delivery is likely the biggest mistake one can make, because it fails to recognize that BIM requires a change in the design process, not just a change in software. BIM requires a paradigm shift.

Caveats of BIM

BIM is not a panacea. There are common BIM misconceptions. Be aware of the following:

• BIM is not just software - BIM is not just about knowing how to use the software. There are many other aspects behind BIM that require more knowledge about the BIM process, and about both design and construction. Learning BIM software is a feat, and is needed, but that is not entirely what BIM is about.
  Designing in BIM requires more design and construction knowledge. In the past with traditional 2D drawing delivery, separate individuals or teams would work on plans, elevations, sections, wall sections, and details. Those new to the industry would gain experience on the simpler plans, on schedules, and eventually gain enough experience to graduate through the series of drawings to ultimately work on details. This is because details require more technical knowledge about how the different components connect, how they are installed and the sequence of construction on site. With BIM, the organization and allocation of work packages may be different. For large, complex buildings, teams may be organized to handle different components of the design - one team may oversee the exterior cladding, the other may oversee all interiors. What’s important is those who are modelling should understand details - where items are placed, and why, or how their placement impacts the other components.
  
  
• BIM means an earlier detailed design process. In the past, some consultants simplified their work using single line diagrams to represent their systems, whether it was beams or ducts. They would outline the placement of the single lines, and then simply write in the size of the beam, the size of the duct, or indicate all the door sizes only in a schedule. This would sometimes be finalized well past the 90% complete stage. But with BIM, because accuracy is needed to gain many of the benefits of BIM, sizing decisions need to be made earlier, and the actual sizes used to build the model. This puts pressure on the designers to advance their work, perform calculations, and make decisions earlier in the design phase.
  
  
• Garbage In, Garbage Out (no matter how good the visualizations look). BIM's ability to accurately visualize the design can mislead the viewer as to how accurate the representation is. In BIM it’s important to remember garbage in equals garbage out. Faking sizes, configurations, or the relationship of one element to another effectively makes the model useless for any collaboration which depends on accuracy or spatial relationships. Therefore, it is very important that even though BIM makes things appear real, inaccurate modelling can’t be tolerated.
  
  
• Everything is Not Automated - With enhanced automation and streamlined processes it’s easy to assume BIM is a miracle pill. The reality is that thought and consideration are still needed. For example, clash detection - which highlights elements which interfere with one another - is a common tool in BIM programs – It is often used to detect issues such as a pipe through a column or door. Additional scripts or modelling can be added to detect other interferences such as encroachments into egress routes. Someone still needs to evaluate if the modelling or the placement of elements makes sense or if there is a better way to do things? Is there a better layout in which a simple relocation of a door placement results in a better or more useful space?
  
  
• Without a BIM Execution Plan, You can Easily Fall off the BIM Path. BIM doesn't magically happen without good planning. It is not just started by playing around with software, expecting it to result in a highly collaborative, detailed, and integrated model, at least not without a lot of extra effort, and a steep learning curve. Without a BIM Execution Plan it is very easy for teams to lose sight of the goal, and in difficult times some may even want to abandon the BIM in favour of the greater comfort of a tried and true 2D delivery method.

Summary

BIM is an incredibly powerful tool with associated processes that can aid our design and delivery methods. It is also a complex process which shouldn’t be misconstrued. Trying to grasp the constantly developing technology behind BIM software can be daunting, but don’t be scared. Arm yourself with knowledge, and plan your path forward.