The "I" In BIM: Which Information Should Be In Your BIM Model?
BIM is all about sharing and managing information – and there’s heaps of data that can be used to enrich your models.
Just think of all the information that can be used to describe just one object in a system: dimensions, price, material type, brand, and several other types of data. But since you want to maintain a high design speed, plus a model that’s light and easy to work with, how do you decide which information should actually be in it?
As BIM is about collaborating with other parties, it depends first and foremost on what information is required by construction partners during the different project phases. For one party, an Excel sheet with a list of components may suffice, but a BIM coordinator might need the 3D models in IFC format. This means that setting and managing expectations is of paramount importance.
The BIM Execution Plan
A starting point for managing expectations is the BIM Execution plan. This plan lays out the different roles and responsibilities within the BIM process and defines the key deliverables. Having a plan like this in place encourages early collaboration and communication between parties and will make expectations clear.
One thing that most likely will be discussed in the BIM Execution Plan is the desired Level of Development, level of information, or level of detail. These are concepts that can be quite useful when making agreements and setting expectations. However, it is important to know the difference between the three terms to avoid confusion and make sure you are not making your models unnecessarily heavy.
So what information is needed in your project depends on the requirements and expectations that are set by your construction partners. These requirements will also depend on the type of project:
Example - An electrical system in BIM
When designing an electrical installation in BIM, electrical engineers must take into account inspection, maintenance, and expansion possibilities, for which parties need the right documentation later in the construction process. For residential buildings, a simple circuit explanation in the form of a list or a table is generally sufficient. But for non-residential construction projects, the complexity may require a more detailed overview. Local standards may prescribe that for larger electrical installations not only floor plan drawings must be present, but also schematics representing the structure and layout of the installation. A block schedule or installation diagram may be required:
1. The block schedule gives an overview of the complete circuit and distribution system and clarifies how the panels are related. It also shows the total connected power and the phase distribution.
2. The installation diagram gives an overview per distribution panel, which contains all information about the structure and the layout of the installation, such as the connected power per circuit and power type, expected consumption based on simultaneity, protection, cable data, phase distribution, type of connection point such as lighting, and distinguishes between lighting- and power circuits and earthing devices.
By knowing which information is required for your project, you know what data should be in your model. In case of an electrical system, the Building Information Model makes it easy to generate the block schedule or installation diagram from the model. From the BIM model, you can extract data from the floor plan and enrich the schedule with additional information. This way, the electrical engineer can always provide their partners with the actual data they need – and ensure it’s always up to date with the model.
Setting your model up for success
After determining the required information, the design process can start. However, not all information may be known from the beginning of the project. This information may become clear as the BIM process progresses. An MEP engineer, for example, usually starts with creating a generic design, which he or she continues to refine and enrich with more specific information. By working this way, the duplication of work is avoided and the engineer is off to a strong start:
Example - A ventilation system in BIM
1. Based on a structural model, the MEP modeler quickly creates space definitions in his own model. These space definitions are filled with the parameters that are required to design the installations. In the case of a ventilation system, the desired flow rate will be linked to the space definition.
2. An advantage of BIM is that if the structural design is adjusted, the space definition will change along with the installation model. After all, the space definition is linked to the boundaries of the architectural model. An additional advantage is that the desired flow rate will be automatically adjusted to the modified dimensions of the space definition.
3. Based on the desired flow rate, the ventilation system can be set up generically. By placing flow arrows in rooms, the entire requirements of a building section can be quickly set up. Because the required flow rate is known, it is possible to design directly with the right duct dimensions. The advantage of this is that it immediately becomes clear which and how much space the ventilation system requires.
4. This space requirement can then be used at an early design stage to work more efficiently with, for example, a manufacturer. After all, the aim of BIM is to share knowledge and to promote cooperation between parties across the entire construction team.
Add extra information to your model
Depending on the purpose of your model, there’s a lot more additional information that can be added to make other steps in the building process more efficient. Think, for example, of manufacturer specific content, which is useful for:
Creating BOM (Bill of Material) lists
Creating prefab sets
Making reliable calculations for MEP systems
You can also think of 4D, 5D or 6D BIM applications. For 4D BIM, the building plan is visualized; 5D-BIM adds cost and materials to the model, so it’s possible to estimate the effect of a decision on the cost of a design at an early stage; whereas 6D-BIM includes maintenance data which is useful for lifecycle management.
Whether you need to deliver extensive BIM models or a simple drawing, by determining early on in the process which information is needed, all parties benefit from the information in the model. This ensures a smooth workflow – from design to maintenance.
How do you decide which information is in your model? Let us know in the comment section below!