In addition to geometry, a BIM object also contains a variety of relevant non-graphical data such as material strength, insulation value, finish, surface reflectivity, light transmission or fire rating. They can also carry links to other associated documentation such as technical data, warranty and maintenance information.

BIM-compliant data is also being made available for a variety of materials, finishes and coatings (glass, paint, etc). Although these don't have the same 3D graphical importance as the other categories, their non-graphical data is increasingly critical to successful use in BIM.

Because both the graphical and non-graphical attributes are stored in a normalized database format inside the objects, they are machine-readable, meaning they can be electronically extracted and used by software programs. There is a rapidly expanding array of model-based programs that leverage these attributes to perform valuable processes, such as:

• Accurately visualizing appearance from a variety of perspectives and environmental conditions
• Conducting analysis or simulation processes such as lighting design or building performance
• Extracting quantity information for budgeting and cost estimating
• Developing specifications
• Evaluating alternatives and substitutions
• Planning tactical project execution

This article will focus on BIM objects of building products and manufactured materials which come to a job site ready to install (as opposed to raw materials that are used at a construction site such as concrete or lengths of conduit). Because they represent a large percentage of the objects in a building that is created in BIM, and they contain both graphical and non-graphical data, the intelligent objects of building products and materials play a critical role in the successful use of BIM from design, through construction and into facility management. Industry consultant and former Construction Specifications Institute (CSI) executive Roger Grant sums it up simply with his perspective that "the building information model is just a big product model."

Types of Building Product Content for BIM

There are different types of BIM content, related to the characteristics and installed use of the products and materials they represent.

Parametric Objects

Many products are commercially available from building product manufacturers (BPMs) in a wide variety of configurations. For example, doors are available in an almost limitless number of combinations of heights, widths, thicknesses, materials, panels, lites, finishes, hardware options, frame types, fire ratings, sound transmission coefficients, blast resistance, etc. The same goes for windows, which also involve a vast selection of glass types and thermal properties. While it is possible to develop an individual BIM object for each possible iteration of available features for any product like this, it is not a practical approach.

A parametric BIM model can contain data to generate multiple instances of a product, based on user needs for a particular project. Image courtesy of CDV Systems