Level 2 BIM: What do we want from models?
The production of building information models (BIM) is a fundamental part of a Level 2 BIM project. But are we being specific enough when we ask project teams to provide us with ‘models’ – do they really know what is expected of them and what the models are going to be used for?
This is important if we are going to tie the delivery of Level 2 BIM together using the CIC BIM Protocol (this contractually captures Level 2 BIM requirements).
The protocol refers to different types of ‘models’ (models, specified models, federated models and project team models). Regardless of the model type it is clear that:
- The BIM protocol is reliant upon the existence of a model production and delivery table - this should be appended to the BIM Protocol
- The model production and delivery table should identify models which are termed as ‘specified models’
- If a model is not detailed in the model production and delivery table then there is no obligation to provide the model
In drafting the model production and delivery table, there should be no ambiguity about the client’s minimum requirements for specific models, so thought needs to be given to:
- How the ‘specified models’ are referenced in the model production delivery table (architectural model, structural model, substructures model, federated x, y, z model)
- How the minimum content of the models is defined (possibly thinking about elements, sub-elements, systems, component/products)
- How accurate the geometry of model objects should be at each information exchange (level of detail)
- How accurate model object specification data should be at each information exchange (level of information)
- Required model uses (visual uses such as understanding elevations and spatial relationships and data uses, such as cost and programme modelling/management activities)
If there is direct appointment of design team members by the client, then the model production and delivery table should also identify parties responsible for developing the specified models, so it is clear who is doing what and when. If all designers are appointed by the contractor, then as far as the client is concerned, all models are generated by the contractor.
So, whether you are a client, a designer, a contractor or a designing sub-contractor, it is essential that the model production and delivery table is comprehensive and you understand it. If it is – Level 2 BIM here we come! If it isn’t, then it’s back to the drawing board…quite literally.
Associate Professor, University of Nottingham