by Dr Stephen Hamil
1. Designing with objects
Following the agreement of responsibilities and deliverables in the plan of work, the team began work on the design and specification process.With respect to the design, all members of the team modelled the project in 3D. Both generic and manufacturer objects from the NBS National BIM Library were used on the project. Examples of where generic objects were used included engineering services components where the overall system was being specified by performance. For example, for the ventilation system, the overall system performance was tightly specified – but just the type of product that should serve these systems was specified. As the product selection was left to the Contractor, generic objects such as the wall-mounted axial fan were used for the ventilation system, as shown in Figure 1.1.
Where manufacturers were selected by the design team, manufacturer objects were used. Examples of this include ceilings, door sets, cubicles and floor coverings. Figure 1.2 shows an example of a manufacturer BIM object that formed part of the ceiling system in the architectural design.
Having standardised BIM objects in terms of naming convention, classification and the property sets within the objects were considered essential to the project team and the client. These rules were agreed in the BIM Execution Plan when the project team was first assembled.
2. Well-structured specifications
All of the main disciplines used NBS Create for their project specifications. Having a consistent specification structure and format across all of the disciplines created consistency for the team, and also for the Contractor who then uses these specifications.
The specifications were a mixture of performance and full specifications. For the architecture, an example of a performance specification was the cycle shelter, where the Contractor had the responsibility of submitting suitable proposals based on a durability requirement of 20 years and appropriate inclusive design considerations. An example of a full specification was the modular ceiling system, where each product specified was from a specific manufacturer’s product range. These products were added to the specification using the NBS Plus functionality where the latest manufacturer information can be inserted into the specification from the cloud.
A final method of specification used on the project is illustrated in Figure 2.1. In this example, the concrete foundation system was fully specified, but the manufacturer selection for the individual products was left to the Contractor, provided that these Figure 2.1 – A full specification for a concrete foundation system selections met the criteria specified.
3. Co-ordinating model with specification
As expected on BIM projects, the design models were coordinated at regular intervals to avoid clashes between the architecture and the engineering. In addition to this, the models and the specifications were also coordinated. Figure 3.1 shows the free NBS Plug-in being used to link the model and specification. In this example, the floor covering to the school gym is selected in the design, and the specification for this item is being viewed in the context of the model.
4. Published output
Within the BIM Level 2 process, .pdf is still the contractual output format. Each of the specifications was published to .pdf format and presented with the brand of the organisation who had responsibility for each specification.
Figure 4.1 shows the three specifications for architecture, engineering services and structural engineer in .pdf format.
5. Future developments
Going forward, it will not just be the design team that benefit from the coordination between model and specification. Emerging technologies such as the cloud and modern web browsers allow complex information to visualised without installing any software.
Within the NBS BIM Toolkit, this capability is now being tested. Within each project, users may upload their models and specifications to allow other members of the project team (such as the client, the cost consultant or the Contractor) to query and understand this information in ways not possible through traditional paper methods of working.
By utilising NBS we can have a standardised approach on our BIM projects. Objects within the model are consistently structured.
Jane Shaw, Design Manager for ISG, commented: ‘As a contractor we need consistent information from each member of the team. By utilising NBS we can have a standardised approach on our BIM projects. Objects within the model are consistently structured. The specifications from each discipline have the same structure and it is clear where design responsibility lies and where as a contractor choices and proposals are required’.
Key benefits included:
- A standardised approach to objects within the design models.
- Better coordination between the drawings generated from the models and the specification.
- A consistent set of specification documentation from each discipline for the Contractor to take advantage of.
Find out more about NBS for BIM Projects at: www.theNBS.com/bimworkflow