Objects and naming conventions
Rather than permitting object naming to follow the typical conventions of the particular design practice responsible, or even to follow the standard families systems in design packages such as Autodesk® Revit® software products, it is important to agree at project inception how model objects will be named to allow them to be used most effectively by the whole design team. For the quantity surveyor this is particularly important as one of their key roles is in the collation and sorting of the data to form meaningful cost plans.
From the quantity surveyor’s perspective, agreeing to incorporate NRM descriptors into the BIM object parametrics at the BIM execution plan stage allows successive developments in the model to align cost comparisons through the cost plan stages as well as to benchmark costs across projects against data held in house.
It has been noted that individual clients often require cost outputs to be presented in accordance with their own modelling preferences; object naming conventions should be agreed and adopted from the outset to enable this to happen.
Once implemented successfully the process of extracting useable quantities is greatly simplified and cost models can be almost entirely automated. The quantity surveyor’s value can then be maximised in interrogating the efficiency of the design with reference to the client’s requirements.
Team/data exchange formats
The different members of the design team may use different BIM authoring tools. Secondary tools may also be used for other purposes such as clash detection, data validation and 4D sequencing/programming (which can be used to review phasing – but this may be dependent on procurement route and contractor involvement). These should all be defined in the BIM Execution Plan (BEP).
The exchange formats need to be agreed between the parties and the QS/cost manager (as a recipient of data) needs to state what formats and versions they require (such as IFC, DWF, DWFx, DWG, PDF).
There are various BIM measurement software products available. The QS/cost manager needs to determine the tools and exchange formats that suit their particular service delivery and software platform, as well as consider any capability issues. Different software platforms will have different implications for the QS/cost manager.
IFC is an industry-wide open and neutral data exchange format that will interact with the majority of measurement software. However, a check with the design consultant’s software provider is recommended, to understand how the measurement software tool will process the building elements and objects, as this may compromise the integrity of the electronic data being exchanged.
It is important that early liaison with the design team is undertaken and it is often beneficial to test exchange workflows early in the design process.
(Note that design information may be presented in viewing software products, which do not support measurement.)