Bim adds an extra dimension
Political advisers may be pushing building information modelling, but is the industry ready?
Although the use of virtual 3D building information modelling (bim) has been widespread in the aircraft and automotive industries for many years, the construction industry has been slow to take it up. Paul Morell, the government’s chief construction adviser, recently urged a move to the adoption of bim to reduce cost and add value to public sector building procurement.
Today, architects routinely use 3D modelling to provide rendered views and walk-throughs of design work in progress. It is essential for pitching ideas and communicating with clients. In addition, 3D modelling is often used at the production information stage for structural design and analysis, cladding packages or the detailed resolution of specific 3D geometries. However, these uses of 3D are often bolt-on additions to production information, which usually remains as a set of 2D abstractions of the building in plan, section and elevation. Such 2D information requires a combination of overlay techniques and human skills in coordinating and interpreting the information thoughout the construction process.
Bim aims to be fundamentally different, in that its approach is to use a virtual 3D model of the entire project, from which all 2D and 3D information is generated. This can vary from conventional 2D plans, sections, elevations and component schedules through to clientfriendly visualisations and computer-aided manufacturing (cam) models.
The concept is that, since all the information stems from a single 3D model, it is all spatially consistent and coordination errors can be eliminated so that the client can have updated 3D visualisations as soon as any changes are made. The completed 3D model is also seen as the ideal vehicle for the repository of as-built information for facilities management over the lifecycle of the building.
So how does it stand up in practice? As a concept, Bim has been around for a long time. I remember being shown the then in-development, now defunct, Gable software at Sheffield University more than 20 years ago. Leading software houses currently have their own particular flavours – Autodesk’s Revit, Bentley’s Architecture v8i and Graphisoft’s Archicad. However, bim is yet to transform the UK construction industry.
The organisation Constructing Excellence in the Built Environment is apparently due to publish a report recommending the use of bim in building procurement.
The real-world usage of bim doesn’t always match the theoretical ideal
The flavour of UK bim usage is indicated by five bim deployment case studies that they published earlier this year (http://tinyurl.com/2vdqf8a).
The five illustrated projects were spread across health, education, commercial and scientific sectors with contract values from £30 million to more than £300 million and all completed within the last five years. They indicate that the key benefits derive from the single source of information leading to better “first fit” spatial integration. This seems to be particularly the case in detailing between different design disciplines. These advantages are credited as leading to reduced requests for information from the construction team, fewer changes by the design team and consequent reductions of up to 10% of the overall budget.
However, what is also apparent is that the real-world usage of bim doesn’t always match the theoretical ideal. Despite the adoption of bim on projects, not all parties take it on. Even where professionals subscribe to the use of bim, internal design development work is often still executed in 2D.
The single most specific virtue of bim – the use of a single, central information source – does seem to create its own issues. On the micro-level, difficulties seem to arise when changes to the single, central bim model made by one party are inadequately flagged up to other team members. While, on the broader level, parties to the process have concerns about ownership, access and design liability for the single design model. This seems to act as a restraint on its effective transfer from design team, to construction team and end-user client.
Bim is undoubtedly a powerful tool in the armoury of the building designer, but is it a panacea for taming the construction procurement process? Unlikely. It is easy to find examples of how the use of bim has saved time and money on construction projects, but architecture is more than the sum of the resolution of envelope, services and structure clashes.
For many, bim remains just one tool among many. Encouraging a much overdue increase in its usage amongst architects is desirable, but is the imposition of it on the design process from the client side really going to be the best way of achieving this?
Hugh Davies is a co-founder of IT consultant Lomas Davies
Vox pop: should bim be adopted for the public procurement process?
Rachel Shaw, director, Architecture PLB
We are about to launch our first project using Revit. Our aim is to produce coordinated information more efficiently, freeing up additional time to spend on achieving high-quality design. While we currently use 3D models as a communication and presentation tool, the opportunities offered by an intelligent model incorporating detailed information are far greater. In addition to facilitating easier co-ordination across the design team, the virtual building will provide a tool to constantly interrogate all aspects of the design, allowing adjustments and changes to be incorporated swiftly.
Ben Addy, director, Moxon Architects
The fact that, in terms of geometry alone, bim requires the use of a 3D work space across the team means it is something to be welcomed. The price tag doesn’t faze me much as it seems reasonable to assume that the potential of the various platforms will grow rapidly over time. As with the adoption of special effects software in certain practices 15 or so years ago – something that is now more or less universal – it would make sense to start working in this way sooner rather than later. Ultimately, what counts is the building. I would bet that, while bim will hardly improve architecture, it has the potential to improve the way architects work.