The Many Dimensions of BIM


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Building Information Modelling, or BIM, seeks to break down the silos between all the participants engaged in the design and build of a building, by providing an integrated, virtual model of the structure in 3D. One of the main challenges in erecting a large commercial building is that there are so many players and different companies involved. The software they use differs from company to company; the architects could be using Autodesk’s AutoCAD, while the structural engineers use Bentley Microstation. With the thousands of engineering software products out there, it is to be expected that this will occur, and it adds time and risk to any project. Any approach that promotes a common view of the structure for everyone working on it is to be welcomed.

3D BIM modelling is used, not only by the architects and structural engineers, but also by the MEP (mechanical, electrical and plumbing) engineers. Traditionally, MEP design is only incorporated into a building once the architectural and structural model is in place. Conduits for cabling and wiring and ventilation shafts are included in the architectural drawings, but whether they are adequate or suitable for the MEP engineering is often only found out once construction is underway. If there are problems, the participants have to go back to the drawing boards (literally) to accommodate any MEP design such as the HVAC system. Using a BIM model enables the MEP engineers to sort out any problems before the first foundation is poured or the first brick is laid.

While this approach is a great improvement on traditional CAD design, and provides a common virtual platform for collaboration (the CDE or Common Data Environment), more was needed and extra dimensions were added to the model, resulting in 4D, 5D, 6D and even 7D, with each dimension enriching the model and enabling better delivery within time and budget. Although 4D and 5D BIM are clearly defined, there are different schools of thought as to what constitutes 6D and 7D, and we have taken the approach that 6D is about “greening” the building, its sustainability and energy efficiency, while 7D focuses on lifecycle management.

3D BIM – Design for All

3D BIM is the anchor and the focus for everyone who has a role in taking the building from concept to completion. Once the building is completed, the BIM takes over the maintenance and lifecycle management responsibility. The model is constantly updated and refreshed to ensure that maintenance is proactive rather than reactive. The power of having a 3D model of the building  at concept stage is in the opportunity it offers to everyone to check and test that their contribution to the project is integrated and does not clash or collide with other parts of the design. If there is a conflict, this can be resolved before construction and not in mid-stream.

4D BIM – Rethinking the Schedule

If there is a requirement that must be changed due to one or more conflicts as mentioned above, it may impact the project schedule. An unexpected delay because of some relatively minor structural problem can have a domino effect, affecting the start date for the various MEP companies, drywall contractors and shopfitters. To integrate the project schedule within the BIM added another dimension, 4D. The transparency that 4D adds to the model enables participants firstly to be aware of how they are impacted and secondly to be able to suggest mitigations and alternatives that will prevent the project falling behind.

5D BIM – What are the Costs?

Changes to the schedule imply that there will be additional costs. It makes sense to integrate both the estimated and actual costs as well as the history of all changes applied to both the estimates and actuals. This has given rise to 5D BIM. It is also useful for assessing different scenarios, for instance if there was a delay in the project which has resulted in the original lighting contractor being fully committed to another project, determining alternative contractors and comparing proposals/quotations.

One might argue that 4D and 5D BIM are catered for by project management, however, with large projects it can happen that certain activities or scope changes are overlooked, which should not happen when they are integrated into the building model. Any engineer who has worked on a very large project will empathise with this; a typical example was where a dam was being built and there were three project teams monitoring the project on Primavera, Microsoft Project and Excel. Depending on which plan you consulted, the project was running at a $5 million loss, breaking even or making a $7 million profit, and each team was adamant that they were using the same data.

6D BIM – Going Lean and Green

We are all aware of the pressures we are exerting on our planet’s limited resources, and the focus in this century is on long-term sustainability over short-term gain. Old buildings need to be retrofitted to minimize energy consumption and collect waste heat; Europe has many of these projects running under the aegis of the European Commission. New buildings need to be designed and built to be as energy-efficient as possible. The goal is to obtain LEED (Leadership in Energy and Environmental Design) certification, or at least build in conformance with LEED requirements.6D BIM is both about the original design and about maintenance going forward, which introduces the final (up to now) dimension of 7D BIM.

7D BIM – Building Life Cycle management

Traditionally, once a building was completed, it was handed over to the owners together with copious electronic and paper files covering all the aspects needed for facilities management. With 7D BIM, an elegant and integrated model of everything that needs to be known about operating the building is presented in the Common Data Environment.  Everything from contact details to user manuals and guarantees is accessible in one place. Any subsequent changes to the building are recorded in the model. For instance, for the lighting of an auditorium:-

  • the original lighting design using Relux could be included, as well as the design company’s details
  • the details of each lighting product used
  • the suppliers from where it was sourced
  • the company that did the the installation
  • the expected life of the product
  • and any warranties.

Armed with similar information for every aspect of the built environment, the facilities manager can manage the building efficiently, scheduling required service visits, keeping a watchful eye on products that are reaching the end of their useful life and attending to the day-to-day issues that ensure he is never idle.

Can one Justify Adopting BIM?

As can be inferred from the many dimensions of BIM, there is a path to BIM maturity, and it is a long journey. 3D BIM is achievable; it may require purchasing or upgrading to another product in your current vendor’s portfolio, for instance, moving from Bentley Microstation to AECOsim Building designer, or from AutoCAD to Revit. This change brings a learning curve and resistance to change, but the benefits outweigh the disruption and costs. Moving up the curve to 4D and 5D BIM can then be contemplated once 3D BIM is in place.

It is not an easy path for any company to successfully adopt and use 5D BIM, and some of the prerequisites are integrating the different technologies and software, acquiring and learning how to use some of the BIM software and, most difficult of all, accepting the change in approach. There are substantial costs to be incurred and plenty of teething problems, but once mastered, overruns, rework and other problems that plague the AEC industries, and the risks they bring, are considerably reduced, if not completely eliminated.

McKinsey cites 5D BIM as one of the 5 biggest disruptors of the construction industry, along with the Internet of Things and predictive analytics. They pointed out in a 2016 article that large construction projects typically are up to 80% over budget and take 20% longer to complete than original estimates.

Source: McKinsey and Co –

They also note that productivity in the AEC sector has been declining rather than improving. Working collaboratively will reduce both risk and uncertainty for architects, engineers and those commissioning the buildings.

There is no doubt that BIM is the way to go, all it takes is convincing the executive to take the risk and provide for the additional costs to be incurred. It is important to recognise that this is a change in thinking, not a software buying spree – there is no single vendor that has all the answers for all the dimensions of BIM.

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