Here is my ten point interpretation of BIM...
1. Most importantly, BIM is not a technology. It is a process. This is possibly the most important aspect to understand. BIM applies to all aspects of the construction of a building, from the design, the estimating, the supply chain, the delivery of goods during the build, the build process, the resource allocation, the productivity requirements to meet targets and on in to the post-handover phase through Facilities and Asset Management.
2. Aspects of BIM are enabled through various technology platforms. There are several providers of technology which supports architectural tools plus the addition of intelligent information against the model. Examples include Autodesk Revit, Graphisoft ArchiCAD 17, 12d Model and Synchro Professional.
3. BIM has several implementation levels:Level 0: CAD using drawings, lines, arcs, text, etc.
- Level 1: 2D & 3D using models, objects plus file based collaboration
- Level 2: BIMs plus file based collaboration and library management for models and objects and
- Level 3: iBIM, Lifestyle Management, common dictionaries, data and processes underpinned by integrated and interoperable data through web services
Level 2 BIM is often seen as the minimum standard to achieve. These levels are also split in to A and B, e.g. 2A and 2B which denotes the directionality of information sharing, i.e. one-way or multi-way. Here are two diagrams explaining the differences:
Figure 2 - Adapted from CRC for Construction Innovation 2009, p.13
4. Industry Foundation Classes (IFC) and COBie are standards used to share information. IFCs describe building and construction industry data. It is a platform neutral, open file format developed by buildingSMART to facilitate interoperability in the architecture, engineering and construction (AEC) industry. COBie is a data format for the publication of a subset of building model information focused on delivering building information and not geometric modelling. It is closely associated with BIM and is typically exchanged using XML. These formats enable BIM interoperability and all BIM software is able to consume this information. Most are able to write it, enabling the sharing of information, even at Level 2 BIM to be easily achieved. External software such as Safe Software Feature Manipulation Engine (FME) is able to transform from IFC and COBie to other formats. This represents the beginnings of full integration possibilities between BIM and GIS.
5. BIM is so much more than just a detailed 3D model of a building. The concept is most easily explained by the term build 4 times which means build three times in the model and once on the ground. The accuracy of the model combined with animations and fly-throughs allow contractors to access the design layout before the build takes place and make alterations. This means that when the build takes place, there are fewer errors and far less rework needed. This moves the construction procurement process from design and build to design build by bringing the construction team in to the design process rather than them simply having to respond to a tender for construction after the design has been completed.6. Parametric Modelling is a key principle of BIM. Essentially this means that everything in the model is connected to everything else. If you move the location of a wall, the elements attached to the wall also move. If you change the volume of a floor, the quantities of material needed to lay the floor alter. If you move ducting in the ceiling, all aspects associated with the ducting update and conflicts are highlighted. This is also true for BIMs that have been developed independently and brought together in a collaborative BIM environment. This allows organisations who may be controlling different elements of the build to benefit from one another as aspects of the model are altered through the process. Change once, benefit many times.
7. The 'D' elements of BIM relate to the information associated with the model.
- 4D relates to scheduling information; when will an element be built. With this information you can enable just-in-time (JIT) delivery of materials to site. This in turn has an impact on transportation, making it more efficient, and reduces storage issues as materials are delivered and immediately installed.
- 5D relates to the estimating and cost aspects of the building. Each element within the building model has a cost associated with it. This allows for detailed analysis to be done regarding budgets. It also allows the delivery team to make accurate predictions regarding how much needs to be done at any given time in order to meet the construction targets.
- 6D covers the sustainability targets for a building allowing information such as energy use, sustainability from a materials and management point of view to be understood and Leadership in Energy and Environmental Design (LEED) tracking to be performed.
- 7D is the "as-built" BIM model which is important as part of the handover process to the building owner. This model is a fundamental part of the ROI for BIM as it provide accurate Facilities Management (FM) and Asset Management (AM). Each part within the building will have a lifespan and in the event of replacement, the easy identification of parts ensures that these processes may be performed efficiently.
The outcomes from having this information are impressing detail regarding all aspects of the construction project. By the very nature of the BIM model, this information is already there, you simply have to ask for the output you need whether that is a financial plan or a resource plan.
8. BIM enables new procurement processes to take place which deliver certainty to all parties involved. A typical process might look like this:
- The design and construction teams are selected
- The design work is done and is reviewed by the construction team and other subject matter experts. This review identifies areas of rework.
- This process iterates 2 more times, the result is the best possible design.
- Generic objects may have been used for materials and/or equipment; these may now be replaced by specific models conforming to the IFC classes with known materials, costs and supply chain information associated with them. In this way, the full cost of the building, the suppliers and supply chain costs of materials and the installation methodology is known by everyone involved.
- The work can now start on site using the BIM to direct the build. Technology assists in the build by presenting the BIM information in the field as construction takes place. JIT delivery of materials keeps building efficient.
The UK have appointed a "Head of BIM" within the Cabinet Office. David Philp's role is to accelerate the adoption of BIM and mandate its use.
10. The result of BIM is impressive ROI figures:
Figure 5 - Taken from BluEnt
- 20% reduction in build costs (buy 4, get one free!)
- 33% reduction is costs over the lifetime of the building
- 47% to 65% reduction in conflicts and re-work during construction
- 44% to 59% increase in the overall project quality
- 35% to 43% reduction in risk, better predictability of outcomes
- 34% to 40% better performing completed infrastructure
- 32% to 38% improvement in review and approval cycles
Figure 6 - Taken from UK Government Cabinet Office BIM Strategy Paper
Exerted from Neil Calvert's post on www.spatialiq.co.nz