This article is part of the Getting started with BIM series brought to you in association with Graphisoft.
Building Information Modelling aka BIM – the phrase on everyone’s lips, from fan boys full of jargon to naysayers calling it a fad. Whatever you might think of BIM, the reality is that the future of construction lies in a holistic, digital approach to the built environment, and the next step towards that future is BIM.
The 'I' in BIM
So, what is Building Information Modelling? Well, the building part is pretty self-explanatory, and we’re all familiar with the journey from physical, scaled models to digital representations and then from two dimensions to three. So we have those sussed. But what does the information element of the term mean exactly? That’s what we hope to make a bit clearer in this article. But, before we do that, let’s talk a little bit about BIM as a whole; what it is, and what it is not.
BIM is not unique
Information modelling is not unique to construction. A range of other disciplines follow (some for years) the idea of adding and refining information up front to help avoid errors and generate efficiencies. This includes automotive manufacturing, oil and gas drilling and production, and aerospace engineering.
It is not proprietary
In a BIM process data owners share responsibility to ensure that data is open, accurate and accessible across the asset’s lifecycle – from cradle to grave. This is quite a change for an industry used to working in silos.
It is not just 3D
A large number of designers are now using 3D models to generate 2D documentation; however, contrary to some belief, just working in or with 3D isn’t “doing BIM”. Neither is investing in and using certain software packages. These things are integral to BIM, but they aren’t BIM. No, there is far more to it than that, and that more involves a process that combines geometry and information for use in a collaborative effort to create a complete, living picture of an asset; a picture that continues to evolve long after construction is complete.
BIM is a process
So, what BIM does is provide a digital description that incorporates every aspect of an asset. What BIM is is a cradle to grave process in which information is created and then managed across the asset lifecycle – before, during, and long after construction.
From beginning to end, the BIM process is also a collaborative effort: design team members work to eliminate clashes between structure and services prior to the project going to site; owners, architects and contractors work proactively to ensure that every element fits and performs the way it’s supposed to; and the facilities management team ensures the best functionality and life value of the asset until its demolition.
It’s a data revolution
BIM is also something of a data revolution that changes the way we share information and collaborate on projects. It is part of the wider digital revolution that has seen music and film reduced to digital information available for download. Where previously documents such as drawings, schedules and specifications were written, now they’re being digitally generated from well-structured information models. The end game is to embrace a way of working that sees that digital information flow from inception through to demolition – providing efficiency and accuracy savings all along the way.
And it’s rich with information
While traditional design focusses on graphic representation, it is missing the data that represents the deeper elements of information; the primary, secondary and tertiary information that uses behavioural data to predicts how individual elements and the asset as a whole will perform. This includes information like when components were installed, anticipated replacement times, estimated energy performances, etc., and this is the kind of information detail that is inherent to the BIM process.
To provide this information, a model relies upon what are called BIM objects. What are they? Well, in short, they’re visual representations of information – defining a product, defining its geometry, representing physical characteristics, providing behaviour data. Visually, BIM objects are recognizable in their appearance and behavioural elements. This allows the user to position an object to determine if it will work as intended and discover any problems or clashes much earlier on in the process.
There are two types of BIM objects. Components are fixed in size and shape. Component objects include things like boilers, air conditioning units, windows and doors. Layered objects are not geometrically fixed, and they include things like carpets, and walls and ceilings.
To ensure that the information underpinning the BIM process is correct is a big challenge. Key to that task is ensuring that the BIM objects used provide secondary and tertiary properties that define more than just physical geometry in order to create an overall model that can be analysed. For example, if the BIM objects representing the walls and doors of a space consistently including a fire rating property, then the model can be analysed for a fire strategy. The same principles apply other properties such as energy efficiency, durability, acoustic and structural performance – of the building as a whole and the individual elements and spaces within it.
The structure of the information is also important. A BIM model is a living design, so objects must be easily added, removed, and moved around. Integration of this new information must be simple, without the need for re-keying or converting information into new formats. This requires a common data environment with a standardised hierarchical data structure.
The right information
To ensure that the correct information underpins the BIM process is a big challenge. Most important is the need to ensure that the BIM objects used have properties that define more than just their corresponding physical object’s geometry. This then allows the overall building model to be analysed.
As an example: If the lighting objects in a building information model include detailed geometry and material properties, they can be analysed for energy performance and then broken out into a detailed lighting model where lighting levels, shadow placement, etc. can be analysed to ensure visual comfort. The same principles apply for all of a building’s properties – such as acoustic performance, durability and structural performance of the building as a whole or the spaces and/or elements within the building.
If BIM is to truly work as a digital flow of information from building design through to operation, then the correct information of physical products must be represented within the model, and a logical information structure must be created to allow construction and facilities management professionals to consistently add new and revised data to the model.
Collaboration and interoperability is key
Just think; if every object was created to with different property standards then this would be an impossible task. So, just like a BIM project requires us to step out of silos and work collaboratively in a common data environment, the software used on that BIM project must be based in the same digital language.
There is not one software provider that delivers tools for briefing, design, specification, construction and maintenance, and nor should there be. Just as construction professionals must collaborate, so must software providers. One way that this can be achieved is through software extensions that link data flows together and through sharing data to open international standard formats.
The glue that holds it all together
At the heart of the BIM process are the standards, which includes the PAS 1192 series, COBie (Construction Operations Building Information Exchange), and product data templates. The right software has these elements baked into by default and provides updates at logical stages in the production process.
So, the I in BIM
So we’ve determined that a successful BIM project is one that is rich with information. To achieve that level of information requires collaboration at every stage from design through to operation. It requires manufacturers providing information in a structured digital format so that their objects can be easily added to the model. And, it requires software interoperability.
The end result of all of this is better design, better construction coordination, more accurate and complete information at handover, and the financial rewards that goes with all of those things.
BIM requires a lot more of work upfront; however, in the long run, it’s worth it.
