Electrical Engineering in BIM Software
Most building information modeling (BIM) software is considered terrible for electrical engineers. The software is typically created first for architects and focuses on 3D modeling design. Once the architects are happy, then some attention is given to the needs of structural and mechanical engineers, whose work has enough mass in it to have an impact in 3D. Electrical engineering, in the end, gets virtually ignored because it is considered too tiny to see. Most BIM software is written thinking, “If you can’t model it in 3D, does it even matter?” but for electrical engineers, it does.
What Electrical Engineers Need from BIM
Very little of the work of an electrical engineer depends on the 3D model. Instead, the electrical model and corresponding calculations are the main concerns. For example, in a 3D model, switchgear is represented by a large box. An electrical engineer is concerned about the configuration of all the electrical components inside it, like the bus, disconnects, breakers, and fuses. For BIM to be truly useful for an electrical engineer, it needs to understand all those internal components and not just the physical dimensions of the enclosure.
A Scorecard for Electrical Engineers
Below are a series of ten questions that are used to evaluate BIM software for electrical engineering. It is not necessary to install the software to score it like this since the answers are all an easy “yes” or “no” based on the BIM software marketing materials. If the score is high enough, it can then move on to a more thorough installation and evaluation.
1. Does engineering exist?
This first question is the most basic; check to see if the BIM software acknowledges the existence of anyone other than architects. There needs to be an explicit mention of engineering. If “AEC” appears, it receives credit for half a point since engineering is part of the acronym, although if that is the only mention of engineering, it can be safely ignored.
2. Does MEP exist?
The word “engineering” covers multiple disciplines. Often when digging into a BIM program, it is discovered that engineering refers to structural engineering. The software needs to specifically call out MEP.
3. Does electrical engineering exist?
Once there’s mention of MEP, it is important to look specifically for electrical engineering. The three letters of MEP are very different. The software should talk about each of them separately from each other.
4. Can you insert electrical devices?
This question is the minimum baseline for having BIM software that is usable for electrical engineers. It needs the capability to insert electrical devices on a floor plan to create construction documents. At this level of the scorecard, the software has the potential to replace AutoCAD in the electrical workflow. It is at least something to consider using. Anything below this level can be immediately rejected.
5. Can you create a panel schedule?
At this level, the usefulness of the BIM tool becomes clearer, since creating a panel schedule implies several important features for electrical design. Specifically, the need for load and voltage on devices, the ability to connect those devices to a panel, and finally link together multiple panels. If it can do all that, the tool is moving beyond what AutoCAD does and is beginning to use BIM in a way that is helpful for an electrical engineer.
6 and 7. Can you perform a voltage drop calculation? Can you do panel load calculations?
The next step after creating a panel schedule is using that information to calculate voltage drop and calculate the feeder and service load on a panel. The model built in question five can be used for the features. Does the software move beyond the basic electrical model and use it for something interesting? Score the software at “6” if it has one of these features or at “7” if it has both. There is some variability in BIM software regarding which of these two are included.
8. Can you do a fault current calculation?
Many BIM software products include voltage drop calculations but completely ignore fault current calculations for short circuit analysis. The underlying model needed for the two calculations is incredibly similar. Most of the work is determining the wire sizes and lengths. If there is sufficient information for voltage drop, there’s only a little more information needed for fault calculations, mostly related to motors.
It is interesting to note that very few BIM software programs can perform fault current calculations. With a little more development effort, much BIM software could move from a score of “7” to “8”.
9. Can you do a single-line diagram?
Single-line diagrams are where the 3D roots of BIM start to show. BIM has difficulty grasping the idea of modeling devices on a diagram without knowing their location in physical space. As a result, single-line diagrams are often forgotten and left to be drafted manually and separate from the rest of the model.
The single-line diagram is the core of the electrical model for electrical engineers. The first step of electrical design is usually building the single-line diagram, and this happens long before there is a 3D model to work in. BIM software built with electrical engineers in mind acknowledges this reality; create the single-line diagram first, and once there is a floor plan from the architect, then it is possible to start locating panels and transformers.
10. Can you do multi-family dwelling load calculations?
This last question is not as precise as the others. What is needed here is to look to see how deep the electrical calculations go. Multi-family dwelling calculations are an example of what is needed, even if the design is not specifically residential. If the BIM software includes this calculation, that indicates it is also going to include many other in-depth calculations. If it doesn’t include a multi-family dwelling but has other electrical design features like arc-flash, selective coordination, or motor circuit sizing based on MCA and MOCP, it can be scored as a “10”.
Evaluating BIM Software for Electrical Engineering
Using this set of questions on the Electrical BIM Scorecard, it’s possible to quickly evaluate BIM software for use by an electrical engineer. A minimum score of “4” is needed to even consider it, and most BIM software is going to score a “6” or “7”. Anything with a score of “8” or higher is located at the current frontier of BIM software for electrical engineers.
See the full Electrical Building Design Show video on this topic, below.
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