Friday, 10 August 2018

Creating BIM Objects to International Standards

This blog post includes a few extracts from my BiLT NA presentation at St Louis, USA. Rather than a printed 'hand-out' this is a brief summary with hyperlinks to useful links and some of the video sequences from the live examples...

1. The need for standardization
Standardization allows for efficiencies and reduced risk. The illustration below shows a number of examples of where geometry has been standardized (bricks, blocks, opening sizes or ceiling tiles, air conditioning units, lighting) and where technology has been standardized (HTML, CSS, Scripting in websites. The earliest examples of standardization are believed to be from the Indus Valley civilization when weights were used for trading.
Improve efficiencies and lower risks through standardization
The history of NBS has been around standardization, more specifically around standardization of specification structures in the UK. NBS was formed in 1973 around an industry need for this and has played a leading role in the Uniclass initiative over the decades.

When the UK Government BIM mandate was announced, process, information exchange and classification was standardized for BIM projects. However, at NBS we believed that there was a gap in the market with respect to standardizing BIM objects. We had been part of the team developing the BS 8541 series, but believed that the industry needed more.

2. Common areas of frustrations
Following a number of customer focus group sessions and practice visits we discovered that there were a number of frustrations around the quality of BIM objects being distributed and used in the industry. An illustration of three of these frustrations are highlighted in the examples below..

Example problem 1 - Badly built objects
Modelling tools such as ArchiCAD and Revit had allowed functionality to be linked to parameters. But many objects broke when these parameters were modified. In the example below, when the generic tank object is modified, the geometry completely breaks.

Example problem 2 - Objects with inconsistent information
BIM is about information in addition to the geometry. However, if care is not spent keeping the information consistent, then it cannot really be utilised for scheduling, material take off, analysis etc... In the example below, two doorsets are shown from the same content source. Immediately inconsistencies are apparent.

Example problem 3 - Objects that are 'over-modelled'
Modelling tools allow the object author to model as much geometry as they wish. Equally, many tools allow for fabrication models to be imported into workflows designed for architecture. The result is objects that have a file size that is far bigger than needed for the purpose. In the example below, every screw-thread and bolt is modelled on an air conditioning system.

3. NBS BIM Object Standard
In order to support the industry, at NBS we developed an easy-to-understand BIM Object Standard. This can be accessed for free at:

This standard was developed in consultation with industry, working with experts in the UK, Australia and Canada. The standard pulls in the best practice from sources such as IFC, COBie, international classification systems and the BS-8541 series. Although the examples provided in this blog post are illustrated using Revit, the standard has been written to be platform independent.

This standard is split into five main sections and examples are provided below from each of these sections:

NBS BIM Object Standard - 1. General requirements
This section covers the use of language, generic or manufacturer identification and IFC class type.

NBS BIM Object Standard - 2. Infomation requirements
This section covers the type/instance properties, naming, IFC and COBie property sets, standard properties and properties to cover certification and environmental credentials.

NBS BIM Object Standard - 3. Geometry requirements
This section looks at the Goldilocks principle of 'just right' - not too much geometry, but enough geometry that it is fit for purpose. An example of too much geometry would be the nuts and bolts on the air conditioning unit. An example of not enough geometry would be wanting to show doors and windows at a particular scale and not showing the correct visuals per the international standard.

NBS BIM Object Standard - 4. Functional requirements
Considerations such as what surface an object should be hosted to, indication of operation and maintenace zones and functionality that doesn't break the object. The example below shows a generic MEP object that assists an engineer when designing around spatial constraints.

NBS BIM Object Standard - 5. Metadata requirements
Considerations around file naming and abbreviations. The example below shows that objects can easily be located when displayed in a list if they are named consistently.

4. Useful resources
This is the object standard that all NBS National BIM Library objects are authored to. This now represents objects from over 300 leading manufacturers and it is increasingly becoming the content creation guide used by practices around the world.

In addition the standard itself, the following links are useful for anyone creating objects.
  1. buildingSMART
    IFC 2x3 and 2x4 schemas are particularly useful for the class types and standardising key performance properties.
  2. BIMForum LOD
    Illustrative examples, mainly around geometry, for typical elements found in the built environment.
  3. BIM Toolkit
    Thousands of LOD and LOI definitions mapped to Uniclass 2015.
    Classifications for use when working to North America standards and practice.
    Classifications for use when working to UK BIM Level 2.
  6. National BIM Library
    Shared parameter files, Revit templates and plug-ins for Revit and ArchiCAD.
  7. National BIM
    1000s of generic and manufacturer objects that may be downloaded for either immediate use on a project, or for a basis of customisation to create an object for a particular purpose.

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