f BIM is virtual construction then BIM objects are virtual products and virtual building materials you bring to the construction site. You cannot build anything without materials and products. In this article we will describe what BIM objects are and why they are critical for lifecycle BIM.
We will look at some common usage scenarios and workflows for BIM objects and focus on their role in handover from construction to operations.
Then we will introduce some common BIM object repositories. We will look at the content, structure and functionality of these repositories and see how far along they have come. We look at what formats are supported and how properties and documentation are mapped to common exchange formats in the industry.
Most of the manufacturer specific BIM object libraries are free for the consumer (designer, contractor and owner) the same way that product catalogues and brochures are free to the public. We will briefly see who are building object libraries and how the business models of providing free repositories are.
As expected, we will see that this is an immature industry. Both the use of BIM objects and the BIM libraries themselves have shortcomings. We point out some of the limitations, and mention ways we hope the industry will evolve.
What are BIM objects?
BIM objects are digital equivalents of products or materials. If you come from a CAD world you could say that the BIM objects are the BIM version of CAD symbols/ blocks but with much more data and intelligence involved.
The BIM object usually have 3d geometry that describe their physical appearance. In addition the BIM object have metadata that describes it. That metadata could be what kind of object is it (e.g. a door), how is it classified (e.g. according to omniclass), what is its performance (e.g. acoustic values), what material is it (e.g. wooden frame), what are its expected lifetime (e.g. 10 years) etc etc.
The easiest way to experience BIM objects is taking the IKEA kitchen planner for a spin. The planner have all the items in the IKEA kitchen catalogue as intelligent objects in an online register. Consumers can drag and drop these objects into a virtual environment representing their kitchen. They can switch between 2D floorplan and 3d modelview during the design process, whatever suits their needs. When placing objects they will snap into place or give you warning if some constraints are violated. You can then modify the details of each component to suit your needs and wants (Front finishes, handles, drawers etc). You can also add other components like lighting, furniture etc to get a total view/ model of your kitchen project. During the design process you always have a list of items (bill of materials) with the cost and availability of each line item. If the cost is too high or you want to try out different alternatives you can make edits and compare different alternatives.
When you are done and you order you get a set of work drawings, a list of components and links to assembly instructions. You can save your kitchen model for future modifications.
Before we get further in the discussions - we know that there are different definitions as to what BIM objects are. We know we sometime use the term to describe the object template (the item in the catalogue, the Revit family, the ArchiCAD GDL object) and sometime the component instance (the specific BIM element representing a specific thing “to be” or thing “as is”. Dependent of what discipline you represent and what tools you are using you may not agree on our use of the term BIM object in the article below. Feel free to join add comments below and help us clear things up.
Types of BIM objects
When thinking about BIM objects it is important to understand the difference between “generic” and “specific” objects. Generic objects, or library objects, are used during the initial design and represents the need for some material or equipment with some function and/or certain performance characteristics. You know you need a door to connect the spaces and you specify fire rating, security characteristics, acoustic values etc. However the exact door or supplier have not been selected yet so there are lots of properties that is not defined yet.
Specific objects or manufacturer objects are virtual representations of the door to be installed/ has been installed. This means that the geometry and characteristics of the door can be more specific.
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