Executive guide to BIM: part 1

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What is Building Information Modelling and is it relevant to me? This is a question asked by many in today’s construction sector. This two-part guide will attempt to answer the questions that may arise relating to a BIM adoption strategy.

BIM is an acronym that is much used and very much misunderstood. It is not a new term — it was first coined in the 1970s — nor does any one party own it, commercially or collectively. This partly explains one of the problems with it: Because no organisation can claim ownership or oversight, clear definitions and standards have been slow to emerge and confusion has spread. This situation has been exacerbated by some parties inappropriately or tenuously jumping on the Building Information Modelling (BIM) bandwagon in an attempt to leapfrog the competition or re-launch existing products and / or services.

For many, the move to BIM can be more cultural than it is technological and the impact can be far reaching in terms of upheaval as well as reward. It is important to grasp the principles and methodologies of BIM, as well as the implications on the team workflow, but also to seize the opportunity to work more closely with other stakeholders in improved collaboration and co-ordination, often referred to as supply chain collaboration.

BIM is not a topic exclusive to architects, engineers and constructors and in the wider construction sector BIM is no less relevant, even if it is arguably misdiagnosed as more of a sideline issue.

If you are a manufacturer or supplier of products to the building industry then the use of BIM may range from creating a suitable library of virtual elements to match your products, to altering your manufacturing workflow to accommodate BIM data received electronically.

BIM libraries can be made available to designers who are specifying components, and hence act as a great new sales opportunity, but which BIM software or format do you opt for?

If you are a client, contractor, topographical surveyor, quantity surveyor or facility manager then BIM may have a part to play, but your interaction with it may be varied. For many it may be simply a case of ‘wait and see’.


The nature of the underlying database means that, once created, if an object is subsequently updated or changed, these changes reflect in all relevant 2D and 3D views simultaneously, and any annotation is also updated, thereby maintaining the co-ordination of the model as well as all views of the model.

If you only take one statement from this guide, let it be that the most important part of BIM is the ‘I’ in the middle.

Information is king. In the BIM methodology, data is collated, modelled, manipulated and managed, but always with an understanding of the object to which the data relates.

Isn’t this just CAD with bells on?

When drawing boards were (largely) replaced by monitors plus a succession of tablets, keyboards, mice and other input devices, developers of CAD software focused on mirroring the techniques and processes of the drawing office, whilst removing some of the repetition and making the job easier and faster along the way.

The adoption of BIM with all of the associated upheaval has been equated to this switch to CAD, but the consequences for the drawing office can be considerably more far-reaching. Technically, of course BIM is CAD in that CAD is Computer Aided Design, but pushing semantics aside, the industry has come to draw a distinction between the two, with the involvement of the computer being a foregone conclusion.

BIM cheat sheet

BIM is an acronym for Building Information Modelling. This might be stating the obvious but it is worth clarifying because some argue that BIM can refer to Building Information Management, and messaging from software firms can vary. Both interpretations are correct. But sometimes the word ‘modelling’ causes BIM to be wrongly pigeon-holed as ‘fancy 3D graphics’, especially when those writing about BIM tend to use fancy 3D graphics.

So what does it mean?

BIM can be summarised as a methodology which is fundamentally concerned with the collation and management of information relating to a construction project, manipulated through a 3D awareness of inter-relationships between objects and their associated data.

Follow that?

This means that a virtual building model is developed and information is collated from manufacturers or through the decision-making process of design. This model is analysed, tweaked, tested and revised, before a full-scale replica is built on site. It is built twice — once in the virtual world and again in the real world. Drawings are no longer a prerequisite deliverable from a BIM workflow, but when required they, along with schedules and other deliverables are simply interrogations of this pool of graphical and non-graphical information.

What’s the deal with data?

One big difference surrounds text on a drawing; instead of information being entered using a text tool which is akin to sticking a post-it note onto a sketch, data is added as a property of the relevant elements which are placed within the model. Generic tags are then used to extract and report the captured information and annotate the drawing. If a change is made to the information, that change is reflected in all views and reports which reference those elements, even if that data is stored externally and associated through a unique ID which relates it back to the modelled element.

So what technology do I need for BIM?

BIM is a methodology, not a software tool; no one application can deliver the whole BIM picture, nor should it. Technically, BIM methodology could be applied using a pencil and a spreadsheet application, and it could equally apply to road, rail and infrastructure. Other terms can be used to describe the same process for different related sectors, such as Graphical Information Systems (GIS) in mapping and larger-scale project management; Facility Information Management (FIM) for electronic O&M manuals.

OK that sounds reasonable

To keep things simple, we are talking about BIM for building projects; it should be rich in non-graphical information; and built with reference to a 3D Model.

It is not simply a case of applying traditional techniques to a new technology, but the adoption of new methodologies and business practices that denote BIM. Aspects of BIM will replace the drawing production side of CAD as it will similarly replicate some of the actions traditionally performed by spreadsheets and databases for quantitative analysis and component specification.

It is a common misconception that buying a piece of software is the answer to adopting a new business / design strategy. Also affected will be the team structure, job titles and project management; communication with suppliers and contractors; client deliverables; collaboration with other project stakeholders; fee structures and contract form; legal liabilities; insured risk and mitigation; and the benefits and rewards can be equally comprehensive, but only if the adoption of the process and workflow is managed well.

Buying the wrong software or pouring money into inappropriate training can result in an expensive and painful exercise.

How and where do I buy BIM?

Does Revit equal BIM and BIM equal Revit? Several misconceptions need to be explained, including the idea that buying a piece of software is the answer to adopting a new business / design strategy.

BIM is a methodology and a working process as much as it is a purchasing decision. Revit is currently the market leading BIM software and it does help facilitate this methodology if properly utilised but so would products from Bentley, Graphisoft and a myriad of other developers — even Microsoft Excel has a part to play. Each tool has ardent fans and fervent detractors and each has benefits and failures, none of which we will be looking at here.

The pros and cons of each platform need to be understood in the context of the unique office environment and the requirements therein. Best avoid the soapbox preachers from any one camp and remember to speak to the whole supply chain.

Industry drivers

Often the biggest driver for BIM adoption is the government, as it often represents the largest client with the weight to force technology and process adoption.

National governments across Europe, in particular in Scandinavia and the UK, plus various States in the US, have made progressively stronger announcements regarding BIM in recent years, many mandating the use of BIM methodology on all public works. Most follow a similar vein to the UK approach, which has initially dictated that from 2016 onwards, a Level 2 BIM methodology is mandated on all centrally procured public construction projects with IFC and COBie as the exchange formats for hand-over. These are very achievable targets in the short to medium-term but it is anticipated that as the market progresses and meets these objectives, the bar will be moved higher.

It is not that every design practice intends on winning public work, nor should a practice that precludes such work ignore this information as the effort and researching undertaken to validate this government decision has given the private sector the confidence boost it needed to move in the same direction. It is no longer early-adopter technology but something with a proven track record and a strong future.

In addition to the political drivers, the technological improvement in both hardware and software associated with BIM is driving the market forwards. The efficiency gains that can be made in adopting even a fraction of the features of BIM software can justify the often steep purchase and implementation cost.

These savings cannot be assumed however and the benefits promised by the chosen BIM software should be carefully reviewed against the associated expense of delivery in the traditional workflow; or the added financial benefit or delivering a new service.

Educational institutions have access to pretty much all the software they need but they rightly have a tendency to only adopt the technology which supports or enhances the message being taught in the wider curriculum. Software is rarely the topic of the course but usually just a means of delivering the expected result. BIM methodology transcends this and is both a delivery mechanism and a topic worthy of academic study. Many colleges and universities are now offering qualifications in BIM methodology and the principles form a core of many design courses.

Understanding of the benefits to be had from a BIM-committed supply chain is growing in the UK. Communication is a key aspect of BIM, and better communication through multiple representations of a problem or design intent, allows for a better understanding of a given scenario.

The impact of any proposed solutions is seen on all surrounding objects, therefore allowing for more informed decisions and various options can be reviewed and discussed in order to reach the best result with full understanding of the costs and rewards of each alternative.

This is why the contractor and the client can expect a more streamlined and efficient design process, which in turn is why many of them are mandating BIM on all future projects — a trend which has been accelerated by the government pronouncement to the same effect.

With energy prices expected to rocket in the coming decades, the existing building stock is coming under ever closer scrutiny. Older, less efficient structures are being assessed and options being explored and priced to renovate or replace.

Many of these inefficient buildings are owned and maintained by public bodies such as councils, universities and hospitals, and with limited budgets available in the public sector, this task has to be performed with intelligence and as much self-sufficiency as possible. BIM does have a large part to play in the survey and assessment as well as the development of refurbishment options or replacement opportunities.

The construction sector will emerge from the current financial squeeze in a leaner, more robust form. Those companies that survive and form the vanguard of the next boom will demonstrate an awareness of this cultural change and be fully conversant in the technologies, methodologies, implications and workflows of BIM.

What dimension?

For the practical purposes of BIM, there are six ‘D’s that have relative industry agreement:

  • 1D A Point
  • 2D Line Drawing

  • 3D Modelled Solids and Surfaces
  • 4D Time and Sequence
  • 5D Costing
  • 6D Building Lifecycle Management and Facilities Management

The above will have a greater or lesser involvement in your BIM workflow, depending upon your discipline and choice, but also on the demands of the clients and project stakeholders.

BIM data produced by an architect can often be used by engineers in analysis applications; quantity surveyors in cost estimating; contractors in the planning and construction phase; and ultimately used as the basis of a facilities management handover, but all of these uses may have implications on the way that a model is constructed and the type, style and formatting of information that is collated and compiled. These requirements may mean additional work to the model or even efforts that run contrary to the requirements of others.

This statement may seem contrary but in truth, the model that is produced by the concept architect at the commencement of the design is a very different model containing vastly different objects to the one which is used as an facilities management tool at the end. It is neither possible nor cost-effective to encompass all possible uses into an element from the outset, but most BIM workflows allow for the easy swapping of components and the addition of new meta-data to suit a new usage.

Is BIM relevant to me?

You may be thinking that BIM is only really of interest to architects and engineers, possibly contractors as well. Certainly those parties may chose to take on BIM and make it a core aspect of their business because it can improve the quality and efficiency of their delivery.

But they are not the only people to whom BIM is relevant. For those in less obvious sectors, the decision to get involved in BIM can be simplified with a succession of questions leading to the most appropriate solution:

  • Issue A: You need to be aware of BIM and where it is being adopted, above and below you in the supply chain
  • Action: Keep asking questions
  • Issue B: It may be pertinent to supply BIM data as a sales initiative either in maintaining current position or gaining new market share
  • Action: The most cost effective solution is to contract out building the components as the cost of maintaining the software and skills in-house would be hard to justify
  • Issue C: Building BIM skills internally would be relevant and cost-effective in order to interact with the supply chain and the manufacturing or maintenance process
  • Action: Define a BIM Strategy, choose a primary software format and train or hire BIM-ready personnel
  • Issue D: BIM methodology can deliver demonstrable efficiency gains internally
  • Action: An adoption strategy with return on investment should be strongly considered and regularly reassessed in the future if the numbers do not yet stack up
  • Issue E: Full collaborative BIM involving the transfer and reuse of electronic data with one or more stakeholders makes adoption essential
  • Action: A thorough software adoption and training strategy should be budgeted and planned

The diagram below is intended to lead through to one of the suggested solutions listed above.

BIM terminology and principles

Here we explore some common Building Information Modelling (BIM) terms and take a look at the wider implications in preparing data that may be used in design, construction and maintenance.

The single building model

The single building model relates to the idea that all stakeholders participate in the editing of one single file, adding their work and elements to a central pool.

It is a common misconception that the concept of BIM and the idea of a Single Building Model are the same. This is also one of the biggest fears for insurance underwriters who see a free-for-all where every stakeholder is working on one shared file, adding and modifying the elements, with other trades working around them, potentially getting in the way and accidentally making changes.

It raises serious questions regarding the ownership of elements and associated permissions and liabilities, only some of which are answered by the technology. A lot of these issues currently have to be handled through trust and management and are a potential hotbed of disagreement and blame.

The Single Building Model is at this point, a fallacy, both from a technological perspective and from a cultural perspective. The software and hardware would preclude all but the smallest commercial projects, and the contractual environment within the supply chain is not ready for the required workflows.

Case studies are available demonstrating the concept of a single file, worked on by all parties, but this has been in limited and controlled circumstances, on small-scale buildings. Given the right hardware and software, it is feasible to do, but that does not make it right or advisable.


It is impractical to suggest that any organisation will take a single step to go from reliance upon 2D drawings using CAD to a full collaborative BIM workflow. In fact there are four defined levels of BIM adoption:

  • Level 0: 2D CAD
  • Level 1: 3D CAD
  • Level 2: Siloed BIM
  • Level 3: Collaborative BIM

As can be seen in the above graphic, there is overlap between the levels of CAD and BIM use and there is a natural process of ascendancy that is commonly followed during the adoption of BIM.

Level 1 — Is it CAD or BIM?

It is not uncommon to find that software such as Revit, ArchiCAD or other BIM-capable applications are used to deliver drawings, but all BIM aspects are effectively ignored in the process. This is no better than 3D CAD and the model is used purely for aesthetic and graphical interrogation, effectively missing the ‘I’ out of the acronym and leaving a Building Model.

This generally occurs when there is a lack of understanding and training and usually stems from a decision — forced or otherwise — to adopt BIM and thinking that the price of this adoption is the cost of a software licence.

It is a common mistake to imagine that because a company is staffed with intelligent users, they will be able to train themselves and get on with it. Whilst this may be true, in terms of replicating old processes and getting the new software to ‘fit-in’, it does not allow those users to realise the benefits of the new workflows that deliver the real return on the investment. You can only search for help if you know what to search for.

Big BIM and little BIM

So having decided to use the missing ‘I’ and add information to the modelled elements, users move firmly into the BIM ecosystem. But adopting BIM-capable software and methodologies for in-house production of deliverables is only the first step in BIM and although the benefits of doing so are measurable, it is only when BIM data is transferred between stakeholders and used in a collaborative sense that the full capabilities are realised.

Level 2 — Siloed BIM

Level 2 BIM is often referred to as Siloed BIM or Little BIM, so called because BIM is used in isolation of outside circumstances. This is not necessarily an indication that the software is badly-used or under-performing, but is often seen as a means to an end in terms of production, alteration and management of drawings and is often the first step in a BIM implementation — learning to walk.

Often various stakeholders use BIM for their own purposes in-house and yet are unaware of how others on the project are preparing documentation for the client or contractor. Each party delivers a set of drawings and instructions as per the contractual deliverables, whether they use the latest BIM tools or not.

Level 3 — Collaborative BIM

Also known as Collaborative BIM, iBIM or Big BIM, this is the ideal to which we should aspire as an industry.

It does not dictate that all parties utilise the same software platform, but that electronic communication between platforms is fully explored and exploited.

Ideally, data is regularly passed between all parties and frequent meetings see the collation of the virtual building design incorporating all disciplines.Such meetings would identify clashes and assign resolution of issues.

Each team should have access to the BIM data of other parties as a backdrop to their design activity and the client or contractor would be able to see and interact with the process.

The final deliverable of the workflow would be a fully laden 3D model containing all associated meta-data. The production of drawings might still be required by construction workers but need no longer be an integral aspect of design delivery.



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