by Elia Gonzalez Salas, Regional Lead for Copenhagen, Denmark and Co-Founder of Kosmos
We frequently refer to the dimensions in BIM as 2D, 3D, 4D, 5D and so on. 5D is the dimension for cost.
Since the dimensions are numbered, it suggests a sequence, where one seems to come after the other. Everybody is familiar by now with 3D and the geometrical model itself, the digital twin. However, did you know that 5D comes before 3D? Before 2D, even?
Every single construction project will define cost information before any model or sketch is produced. Because all projects will have an investment budget, this defines the scope and target the design needs to aim towards.
In business cases, we are already talking about 5D. And it is that early that we should begin defining the basis of the cost data structure.
Dimensions are therefore opposite to what the sequence suggests: parallel, and not one after the other.This is why we should imagine them not as a bar chart, where the amount of development seems to grow as the previous dimension is being defined:
But rather inverted as bars, that begin simultaneously, and will progress and develop in the timeline, all at the same time, in a parallel way:
Have you ever considered all dimensions and the information that will be produced for each of them in the ICT/BEP, before starting a new project?
Quantity Surveyors or cost specialists working and producing the fifth dimension (5D-Cost information) not only look at 3D geometries, but also 2D drawings and any other written descriptions in the project material – even when they have not yet been defined – because cost needs to cover for everything necessary for the project in the early stages. They work with all dimensions at the same time because changes in any dimension, will impact directly and indirectly the cost information. Dimensions are all interconnected and should be revised and updated every time a change occurs.
For this reason, ICT agreements and BIM Execution Plans (BEP) must include minimum requirements and conditions on how to produce the project material – not only for the final delivery, but also along the design process to facilitate the control around these specialist discipline deliveries.
In order to build good standards and grow maturity around these areas, it is necessary to involve, among others, the planners/schedulers and commercial specialists in the BIM strategy development process. Only in this way will the process take into account the output required by the disciplines not directly involved in producing design material. This is necessary in order to take full advantage of the information produced and incorporate it in the project design.
While setting up the project, it is necessary that the BIM coordinators and Quantity Surveyors meet to discuss and agree, among other things, the following:
- How many buildings will the project material be split into? Is there a need for an independent model file, and an independent specification document, for each of the buildings or will they be combined?
- Is there a schedule of areas included? What was agreed in the contract and what are the current values, split by net/gross, by building, internal and external areas, and by floors?
- Agreement regarding types of outputs (2D, 3D, etc.) for the project information: Diagrams, schedules, details, landscaping, finishes, inventory and equipment, file formats.
- Level of information for each of the design phases.
- Scheduled dates for submission after the quality assurance processes, time assigned for quantification and estimation, time remaining for quality checks and clarifications.
- How client deliverables, existing elements or objects out of project scope will be identified in the project material in order to differentiate them.
- How will change be managed, both scope change and design change?
- What design material supersedes all others? Specification, models or drawings/diagrams, so when an error is identified a decision can be taken.
- Document naming & Naming conventions.
Cost management and cost control processes will use the information above to produce:
- Pre-tender estimates
- Post-tender estimates
- Cost planning
- Risk Analysis
- Change management
- Pricing variations
- Interim valuations and payment.
Cost plans, estimates, Bill of quantities (BOQs), final accounts have historically all been managed as singular activities disconnected from previous or future phases and unrelatable between projects.
As cost specialists, we need to begin seeing our deliveries as integrated in the project, and not disjointed.
Furthermore, we should begin changing our mindset and linearity perception of projects.
We look at projects as a linear process,
- we plan them as linear
- we cost them as linear
How do we improve our budget accuracy, as well as our project control while also storing valuable commercial information along the project lifecycle?
The answer is by perceiving projects as circular. This requires standardization of our data – allowing us to close the loop on project cost circularity.
BIM is forcing integrated design (project) delivery, where the QS (Quantity Surveyor)/Cost Manager and design team design together.
We need to be aware of what collaboration means. In this regard. It will be the design itself as a direct and automated output of quantities. The quality of those quantifications will be driven by the process and having well defined requirements. Only by being involved in the decisions can good quality data output be achieved.
Automated and standardised data will uncover the potential for cost specialist to be able to:
- Analyse the data of all client projects
- Predict deviations (time, cost, risk, etc)
- Provide more accurate trends to calculate
risk and contingency more precisely - Inform data accuracy based on the quality
of data used on the algorithms, predictions, and calculations.
Ultimately, BIM implementation will allow Value Driven Cost Management since it can only be achieved as an integrated collaborative process. That is why the Digital QS needs to understand the 3D process and the tools used but does not need to be the expert. This requires regular communication in order to help each other to succeed.
It begins an integrated process. We should not wait until the design is delivered, but instead work parallel with the design to make sure the output is what is needed and expected. We should not forget that quality, as well as cost, is everyone’s responsibility.
Changes in other dimensions intrinsically affect the whole project. it is everybody’s responsibility to ensure information is aligned to minimise the impact.
