Thursday 25 April 2013

BIM, specifications and IFC

When we set out to update our NBS plug-in for Revit we were looking at some big functionality improvements. (1) Drag and drop of BIM objects from the National BIM Library, (2) Synchronised NBS design guidance with the model and (3) Automatic creation of a specification from the model.

However, quite often it’s the little “experimental” items of work that are strangely the most exciting. Our Software Development team have been working closely with Professor Steve Lockley from BIM Academy who has been doing some amazing work writing a set of components that read and write to/from IFC. The results have been so good that we’re going to release them as “beta functionality” in the toolbar.
The big IFC button
Consider the walkthrough below…

Within a design there will be different types of objects. Figure 1 below is a screenshot of a simple plan showing two types of door – a small internal door (D10 and D11) and a larger external door (D13). The door types have been associated with the NBS Create specification and these associations are indicated in the tagging.
Figure 1 - Instances of types of doors
Jumping across to NBS Create now, the specifier is selecting to specify the door in terms of its overall system performance. Figure 2 shows that clauses covering fire, acoustic and security performance are being added to the job.
Figure 2 - Specifying by system performance in NBS Create
The specifier can then start to complete the specification. However, the tricky part here is knowing what to specify in the specification model and what information to add to the geometric BIM (see previous post following LRUG discussions). Dimensions should be in the geometric model. Workmanship and information on accuracy, samples, tolerances etc… should be in the specification model. But what about key performance information?

Figure 3 shows that the specifier has chosen to complete this in the specification. The advantages of this are that the technical guidance, links to standards and regulations, practice guidance and suggested values are all at hand here.
Figure 3 - The process of specification
So how does our IFC export help here?

We have a little configuration file that allows the user to link the key property sets together between the geometric model (in this case Revit) and the specification model (NBS Create). So not only are the databases connected, not only are the type objects connected… but now the key performance properties are also connected. Figure 4 below shows the structure of this configuration file. Maybe in the future we’ll write a nice little user interface into this. But as far as XML files go – it’s pretty straight forward.
Figure 4 - The configuration file
So the user can now generate an IFC file that contains information from both the geometric and specification model. Figure 5 below shows that in an IFC viewing tool (and many free tools are available), the key performance properties of the door can be easily viewed within the IFC Pset_DoorCommon property set.
Figure 5 - Viewing the combined information set in an IFC Viewer
Where the IFC viewing software has information take off capabilities – then scheduling information is easy. Figure 6 below shows the information from all of the doors in the design In Solibri Model Checker v8.
Figure 6 - A rich, integrated door schedule - done
So, exciting stuff.

All of this hopefully demonstrates the power of well-structured objects, clever software and trusted, quality technical guidance. This is the journey we are on with NBS National BIM Library and NBS Create – we hope you like the direction we are going…

…and one final big shout out to Professor Steve Lockley, Research Director at BIM Academy – great behind the scenes IFC work has made our software developers lives easier.
Prof BIM - Still never beaten me at golf :)


  1. a quick search from today shows 24 revit references, 8 autodesk ones, none of any other bim tool. as an open bim fan i must quit...

  2. does this new plugin have any interoperabiltiy with NBS Building or is it just with NBS Create?

    We currently use a pre-generated NBS Building specification exported to a database and keynotes assigned to objects in the model. By the looks of this new one its geared towards Create only???