Building model rendered in Autodesk 3DS Max

Building Information Modelling - DNA for buildings

Building Information Modelling (BIM) is the software-based method of mapping every aspect of a built structure's equivalent to DNA, from initial design and construction to refurbishments and eventual destruction.

The arrival of information management systems means that efficient, low-cost, just-in-time manufacturing processes are now standard across multiple industrial sectors.

The construction sector, however, is different: it is saddled with inefficient IT management processes. Whereas industrial production often has a single manufacturer overseeing the whole process throughout the supply chain, construction must contend with a gaggle of project groups, sub-contractors and many other stakeholders contributing to the outcome of each individually-designed project.

Finally, though, it seems that there may be change on the horizon for the construction sector, with the growing adoption of 'building information modelling' (BIM). BIM is generally defined as a digital representation of physical and functional characteristics of a facility.

BIM provides a shared knowledge resource for information about a facility forming a reliable basis for decisions during its lifecycle - from, according to the US National BIM Standard, its earliest conception to its demolition.

Software vendors have been offering BIM products for years, but its adoption by the construction industry has been relatively slow and disjointed. This is set to change now that the UK government has properly endorsed BIM, following recommendations from an inquiry led by its chief construction adviser, Paul Morrell.

As a result, the Cabinet Office published the 'Construction Strategy' in May 2011. This states that: "Government will require fully collaborative 3D BIM (with all project and asset information, documentation and data being electronic) as a minimum by 2016".

This requirement will apply to all government-procured construction projects valued at more than £50m. The government expects BIM ultimately to cut overall construction costs by up to 20 per cent by speeding-up building projects, reducing wasteful processes and instilling smoother joint working between project partners.

BIM is claimed to be used in around 70 per cent of architecture projects. The number of construction firms practising BIM is growing rapidly, according to McGraw Hill's 2010 Smart Market Report, which says BIM is also used by almost 50 per cent of infrastructure civil engineering projects.

Gary Ross, BIM innovation associate director at infrastructure consultancy Capita Symonds, feels that BIM now offers a major opportunity for different parties involved in a construction project - architects, buildings services engineers, various services contractors, facilities managers, to name a few - to work collaboratively to accelerate processes, and reduce waste and costs.

"In the past, for example, consulting engineers had to over-engineer everything in order to obtain customer satisfaction," Ross suggests. "With BIM the project team can interrogate the models and ask if they are meeting the requirements. And an informed client can ask the question, is this job being over-engineered?"

BIM definitions

Although standard definitions of BIM's capacity and scope are theoretically well-defined and documented, it remains essentially an open methodology. Software vendors such as Autodesk, Bentley, and Graphisoft have developed their own proprietary versions of BIM. This makes a single definition of BIM difficult; however, the following extended description from Autodesk captures most of the basics:

"[BIM]'solutions create and operate on digital databases for collaboration, manage change throughout those databases so that a change to any part of the database is coordinated in all other parts, and capture and preserve information for reuse by additional industry-specific applications.

"The building industry has traditionally illustrated building projects through drawings and added information over those illustrations via notes and specifications. CAD technology automated that process, and object-oriented CAD extended the idea of adding information to illustrations and graphics into software. The results of earlier manual drafting, graphics CAD systems, and object-oriented CAD systems were identical: the creation of graphic abstractions of the intended building design.

"The principles of BIM turn this relationship around. BIM applications start with the idea of capturing and managing information about the building, and then present that information back as conventional illustrations or in any other appropriate way. A building information model captures building information at the moment of creation, stores and manages it in a building information database, and makes it available for use and reuse at every other point in the project. Drawings become a view into the database that describes the building itself."

So, in essence, BIM is an 'intelligent', model-based process that provides insight for creating and managing building and infrastructure projects faster, more economically, and with less environmental impact. 3D software enables and support this process. "A BIM model is a collection of linked data 'objects', with each object representing a constituent part of a structure, be it a window, wall or item of mechanical plant," explains Professor Tim Dwyer of the Bartlett School of Architecture, Building, Environmental Design & Planning at University College London. BIM can also include other dimensions of a construction project - for example, time factors (sometimes referred to as 4D BIM), cost factors (5D) and project lifecycle management (6D).

Dwyer stresses that BIM is also crucially about the finished building's operations (overseen by facilities managers) and its whole-lifecycle performance. "A building will typically be in use for around 75 years, and so the real benefit of BIM is the amount of resources - whether it be money spent or the size of carbon footprints - that can be saved by applying BIM from the design stage right through to the end of the building's life," he explains.

Software and hardware variants

How are software vendors responding to the challenge of creating the tools to facilitate this process? And where is this potentially revolutionary trend leaving traditional CAD/CAM providers? A range of different BIM packages are now available in this still-developing marketplace. Autodesk's range of Revit products vies with those from Bentley, such as AECOsim, while Graphisoft's offers include ArchiCAD and Nemetschek's include VectorWorks.

Other vendors such as Tekla and Solibri provide tools to enable aggregation and interoperation of different solutions. In short, there's a lot of different bits of software out there, so prospective BIM users need to do a lot of market analysis and homework when evaluating the options. In moves to further enhance their BIM offerings, some of the bigger vendors have acquired or partnered with smaller software companies. For example, in June 2012 Autodesk acquired US vendor Vela Systems, which provides cloud and mobile software for on-site construction professionals. Autodesk has since launched its new Autodesk Cloud product, voguishly called BIM 360.

Yet despite such jostling among the high-end firms it looks like there is still scope for small and medium-sized vendors to win a slice of the BIM market. The wide range of BIM objects that are needed for the components, services, and architecture that go into a new building are far from complete, and are not likely to be made available from a single proprietary BIM vendor.

Some BIM experts might argue that the development of BIM would suffer from one major vendor becoming a dominant force. To keep moving forward on BIM development, there needs to be room for a wide range of providers, including arriviste developers.

When it comes to the hardware, the picture is much simpler. According to information from vendors and users, BIM can be supported on all the main operating- and server systems (Microsoft Windows, Linux, UNIX, and Apple). BIM users with older hardware may have to upgrade the RAM and graphics cards on their hardware to accommodate the software - but BIM software vendors usually offer advice on hardware specifications and operating-system specifications needed for their products. A server may be needed for the database that is at the 'collaborative' heart of BIM - the holding and sharing of object data.

However, when it comes to sharing data-intensive BIM data on networks, while local area networks (LANs) can cope with trafficking the very big datasets that BIM projects are certain to generate, transiting that data across wide-area network connections may prove more challenging, admits Autodesk. But the company says there are solutions that can optimise WAN capabilities to make this possible.

Prohibitive costs

For smaller companies needing to acquire BIM software licences, meanwhile, the costs may seem prohibitively high - running into several thousand pounds for group licences. In addition, there are the costs of training staff to use the systems, and also to ensure that the BIM data meets required standards.

IT managers within a typical enterprise may well see the benefits of being able to import and exporting BIM data if this done using a common data format. Translating BIM objects into a format that can be openly shared between building project team members - and other stakeholders in the construction scheme - is'at the heart of truly collaborative BIMs.

Providing different professionals with software tools to create BIM models to suit each of their needs is one thing; but creating all the data in a format that can be shared and used collaboratively right across the supply chain is quite another. "Technology providers have different slants that favour their product offering," says David Jellings of the Open BIM Network, an independent, information-sharing body. "We need BIM models that are created in the same way, using shared protocols. We need a common data format for sharing BIM data."

One common data format that is gaining ground in UK construction is the Industry Foundation Classes (IFC) model, a non-proprietary, open specification developed by an international industry body, called BuildingSMART, whose members include a range of software companies. IFC enables the importing and exporting of BIM data by users of different proprietary software packages. The IFC format is in the process of becoming an official International Standard, ISO/IS 16739, according to BuildingSMART. It defines IFC as "a standard for building information models, not for drawings. It enables [professionals] to exchange information about building structures, elements, spaces and other objects in a BIM. 3D and 2D shape, properties and attributes, parameters and relationships - for example, connectivity."

IFC files use the STEP (standard for the exchange of product model data) physical file format. STEP is an ASCII file format using EXPRESS modelling language. STEP was developed to represent manufacturing products throughout their lifecycle in 3D objects. The files can be run as .ifcXML and .ifcZIP files. IFC toolkits are also available to support different languages (such as C++, C#, Java, VB), says BuildingSMART.

File exchange compatibility

As previously mentioned, one difficulty that BIM users may face is not being able to exchange the huge BIM object files between different geographically-dispersed locations. Cloud-computing platforms can be used for examining models, but they do not have the capacity for authoring models, according to Jellings. However, if users simply want to exchange files containing only changes made to models, then the transfer is manageable, he says. It is clear that IFC, which is widely used in the US and Scandinavia, is emerging as a strong candidate for providing an international data standard for BIM. Its success may well depend on the software vendors, who are criticised by some in the industry for offering tools that don't make it easy to import and export IFC using their proprietary software.

The government's 2016 deadline points to what some might regard as a 'BIM-lite' version of the concept (although the Cabinet Office labels it 'Level 2 BIM'). This version involves creating 3D CAD data and applying a proprietary BIM tool to share this information using proprietary interface tools. A number of companies in the construction say are applying BIM Level 2. At the same time iBIM (Level 3 and above) has the objective of sharing data across the whole project for the whole-lifecycle management of the building; but the starting point is to have a fully accessible and open process, with data sharing processes that can work easily and readily with IFC standards.

Whether this will be achievable with the current state of proprietary BIM products on the market - despite the interface tools provided - remains to be seen. As the Open BIM Network's David Jellings puts it, "In construction, we need a collaborative process that mirrors what manufacturing has been doing for 30 years - and that process must drive the technology, not the other way round, as it is now." BIM software vendors "need to be developing what industry needs - which is, to have fully open and accessible systems," he adds.

Some vendors contacted by E&T were not able to respond to invitations to comment on these claims, although Autodesk says that its Building Design Suite and Infrastructure Design Suite specifically address the need for interoperability.

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