All posts by Jay Merlan

BIM Levels: As explained by The NBS

BIM Levels is a new concept to most of the building industry. Not to be confused with Level of Design (LOD), BIM levels are compliance standards in which projects may (or may not) adhere to. Below is an excellent write-up by The NBS of The UK describing what to expect from each BIM Level.

The NBS considers Level 3 BIM as “the holy grail” of building information modeling, however I believe there will be conflicts between disciplines if all trades have direct access to a single model. In a perfect world it would be amazing to have the ability to collaborate in real-time on a single model, but I believe there needs to be some sort of approval process of proposed changes between trades. I don’t see this being possible on the Revit platform in its current state, so let’s just hope that AutoDesk develops a solution for this BIM Level. I believe that Autodesk’s BIM 360 Glue is an attempt at this level of collaboration, although it is in its infancy stages.

BIM Levels Explained
The concept of ‘BIM levels’ (and ‘BIM level 2 compliance’) has become the ‘accepted’ definition of what criteria are required to be deemed BIM-compliant, by seeing the adoption process as the next steps in a journey that has taken the industry from the drawing board to the computer and, ultimately, into the digital age.

The government has recognised that the process of moving the construction industry to ‘full’ collaborative working will be progressive, with distinct and recognisable milestones being defined within that process, in the form of ‘levels’. These have been defined within a range from 0 to 3, and, whilst there is some debate about the exact meaning of each level, the broad concept is as follows:

Level 0 BIM

In its simplest form, level 0 effectively means no collaboration. 2D CAD drafting only is utilised, mainly for Production Information (RIBA Plan of Work 2013 stage 4). Output and distribution is via paper or electronic prints, or a mixture of both. The majority of the industry is already well ahead of this now (source: NBS National BIM Report 2014).

Level 1 BIM

This typically comprises a mixture of 3D CAD for concept work, and 2D for drafting of statutory approval documentation and Production Information. CAD standards are managed to BS 1192:2007, and electronic sharing of data is carried out from a common data environment (CDE), often managed by the contractor. This is the level at which many organisations are currently operating, although there is no collaboration between different disciplines – each publishes and maintains its own data.

Level 2 BIM

This is distinguished by collaborative working – all parties use their own 3D CAD models, but not necessarily working on a single, shared model. The collaboration comes in the form of how the information is exchanged between different parties – and is the crucial aspect of this level. Design information is shared through a common file format, which enables any organisation to be able to combine that data with their own in order to make a federated BIM model, and to carry out interrogative checks on it. Hence any CAD software that each party used must be capable of exporting to one of the common file formats such as IFC (Industry Foundation Class) or COBie (Construction Operations Building Information Exchange). This is the method of working that has been set as a minimum target by the UK government for all work on public-sector work, by 2016.

Level 3 BIM

Currently seen as the holy grail, this represents full collaboration between all disciplines by means of using a single, shared project model which is held in a centralized repository. All parties can access and modify that same model, and the benefit is that it removes the final layer of risk for conflicting information. This is known as ‘Open BIM’, and the UK government’s target date for public-sector working is 2019? Current nervousness in the industry around issues such as copyright and liability are intended to be resolved – the former by means of robust appointment documents and software originator/read/write permissions, and the latter by shared-risk procurement routes such as partnering. The CIC BIM Protocol makes provision for these.


Dynamo Workflow: Change your sheet parameters with one click.


If you’ve submitted drawings using Revit sheets in the past, you’ve undoubtedly run into the issue where some of your “Checked by” and “Designed by” parameters say “Author”. As far as I know, there is no easy way to change them all globally from within Revit.

I’ve created a simply Dynamo Workflow that will change all of these sheet parameters in a batch. This is a great Workflow for beginners because it is so simple and easy to follow and dissect.

In the future, I will further breakdown the workflow to help beginners understand exactly what Dynamo is doing when this Workflow is run. (116 downloads)

Worksets used to control visiblity and graphics are a big no-no.

Can we, as a community, agree that using worksets to control visibility of elements is a horrible idea? There have been a number of models in my recent years where elements’ visibility are controlled based on the workset they are modeled on.

Yes, it is easier to turn off multiple worksets based on your personal preference, but on a 500,000 square foot project with over 30 MEP engineers, designers, and BIM Specialists working simultaneously on it, you are asking for trouble.

Unfortunately, there have been more than a few models that I’ve seen set up this way and I will chalk it up to lack of experience. Below are a few reasons you should not use worksets to control visibility. Please take this advice into consideration before you set up your first Revit MEP model.

  • HUMAN ERROR: You are risking someone putting something on the wrong workset and it showing up on a view that you did not intend it to.
  • INABILITY TO USE WORKSHARING PROPERLY: Worksets were designed to help users share a model by checking entire worksets out. If elements’ V/G settings are controlled with worksets, you lose the ability to check worksets in and out using a workflow that makes sense.
  • THERE ARE NO LAYERS IN REVIT: If your views’ V/G settings are reliant on worksets, then it appears that you have successfully created AutoCAD-style layers in Revit. This is not a good thing! Layers have always been a struggle and do not contain intelligence in the true BIM fashion.
  • YOU ARE USING A SINGLE PARAMETER: Visibility and Graphics should be controlled using filters so that you will have the ability to utilize the infinite number of parameters to turn things on or off, change colors, customize line weights, and more.

Revit has extremely powerful visibility and graphics control right out of the box, without having to create any extra steps other than the initial setup of your templates. Revit was designed to control elements by categories, filters, and phases (more on each of these topics later).

While it is somewhat easy to assign a workset with each element in your model you are trusting that all of your users will put elements on the proper workset. Think about it this way, how often have you seen AutoCAD objects drawn on the wrong layer?