BIM is a highly collaborative process that allows multiple stakeholders and AEC (Architecture, Engineering, Construction) professionals to collaborate on the planning, design, and construction of a building within one 3D model. It can also span into the operation and management of buildings using data that owners have access to. This data allows owners and stakeholders to make decisions based on pertinent information derived from the model even after the building is constructed.
To trace the history of BIM and BIM systems, we have to go back to the early days of computing and dig through the conceptual underpinnings. Computer-Aided Design and Computer-Aided Manufacturing (then machining) developed as two separate technologies roughly at the same time going into the 60s. At the time, no one foresaw that both CAM and CAD would eventually intertwine and emerge as powerful forces in the industrial world (American Machinist, 1999).In 1957, Pronto, the first commercial software Computer-Aided Manufacturing (CAM) was developed by Dr. Patrick J. Hanratty. It was a numerical control machining technology that later grew into Computer-Aided Manufacturing. A short time after that, he dabbled into computer-generated graphics and in 1961 developed DAC (Design Automated by Computer) which became the first CAM/CAD system that used interactive graphics and was used for General Motors’ complex die molds.
In 1963, the first computer-aided design (CAD) with graphical user interface, “Sketchpad”, was developed at the MIT Lincoln Labs by Ivan Sutherland. Overall, it pioneered the way for human-computer interaction and was a major breakthrough in the development of computer graphics (Sutherland, 2003). In terms of construction tech, Sketchpad gave way to solid modelling programs computational representation of geometry was further developed which allowed the ability to display and record shape information. In the 70s and 80s, the two main methods born out of this were constructive solid geometry (CSG) and boundary representation (brep). The whole design process for this necessitated an intuitive connection to the design medium and presented the challenge of commanding the computer in a simple way.The 80s came and several systems were being developed everywhere. They quite gained popularity within the industry and some were even applied to construction projects. It was in 1986 when RUCAPS (Really Universal Computer-Aided Production System) was used to assist the renovation of Heathrow Airport’s Terminal 3. It was the first CAD program in the history of BIM to be used in prefab construction (or temporal phase construction, if you want to be technical). It is regarded as a forerunner to today’s BIM software (Eastman et al, 2008).
There are a few BIM players worth mentioning here. Although having small market shares, they have made huge impacts in the world of design. In 2003, Bentley Systems developed Generative Components (GC), a BIM platform that focused on parametric flexibility and sculpting geometry that supports NURBS (non-uniform rational B-spline) surfaces. In 2006, Gehry Technologies released Digital Project, a program similar to GC. Both Digital Project and GC spawned a revolution in architectural designs. These two platforms are revolutionary, in a sense, as they can produce especially complex and provocative architectural forms, paving the way for parametricism. Patrick Schumacher coined “parametricism” and the movement of building parametric architectural structures in 2008.
The concept of BIM Levels has become the accepted definition of what criteria are required to be deemed BIM compliant, by seeing the adoption process as the next steps in a journey that has taken the industry from the drawing board to the computer and ultimately into the digital age.The process of moving the construction industry to full collaborative working will be progressive, with distinct and recognizable milestones being defined within that process, in the form of levels. These have been defined within a range from 0 to 3 and while there is some debate about the exact meaning of each level the broad concept is as follows:
In its simplest form, level 0 effectively means no collaboration. 2D CAD drafting only is utilized, mainly for Production Information. Output and distribution is via paper or electronic prints, or a mixture of both. The majority of the industry is already well ahead of this now.
This typically comprises a mixture of 3D CAD for concept work and 2D for drafting of statutory approval documentation and Production Information. CAD standards are managed to BS 1192:2007 and electronic sharing of data is carried out from a Common Data Environment (CDE), often managed by the contractor.
Level 2 BIM is distinguished by collaborative working and requires “an information exchange process which is specific to that project and coordinated between various systems and project participants”. Any CAD software the party uses must be capable of exporting to one of the common file formats such as IFC (Industry Foundation Class) or COBie (Construction Operations Building Information Exchange). This method was implemented and set as a minimum target by the UK government for all work on public-sector work.
BIM Level 3 is the only approach that fully connects the data chain from start to finish, helping to create end-toned efficiencies. In a Level 3 system, BIM data is not converted into files and emailed or sent via FTP sites to various parties. A Single Source of Truth is established, stored in a database on the cloud, and accessible by all project contributors through web services. BIM Level 3 allows data to be transacted able for construction, fabrication, and even facility management purposes, enabling open collaboration and building lifecycle management. A robust Product Lifecycle Management (PLM) system creates an efficient environment for coordinating complex Architecture, Engineering & Construction data. Adding BIM data to a PLM system creates a Building Lifecycle Management (BLM) system, which enables BIM Level 3. A single collaborative, online, project model with construction sequencing (4D), cost (5D) and project lifecycle information (6D). This is sometimes referred to as ‘iBIM’ (integrated BIM) and is intended to deliver better business outcomes.
Following this trend, the work teams have to orient themselves from the design phase to the later phases of construction and finally to those of operating the building. This involves using some protocols from the beginning, a modelling protocol from the beginning, a modelling strategy that is constructive and collaborative. Each new step in the life cycle of a project represents a new dimension of the BIM methodology. And every day new ones are created.
The 3D model contains the geometry of the building used to construct the virtual model and it serves as the basis for the assignment of information to each object of the model. From the 3D model we extract the deliverables (drawings, documentation), renderings and animations. We can also resolve conflicts between objects (Clash detection).
The 4D model incorporates to the 3D model the fourth dimension in the construction, the time. The 4D model allows you to link individual 3D objects to project execution planning, including scheduling resources and quantities, and getting the film of how the project will be built and assembled. 4D = 3D + Planning (Time)
The 5D is the cost. 3D is the relation of objects with all their geometry from which we could extract the quantities. The measurement associated with a particular unit of work, and all the information associated with it (price of material, personnel, machinery, geographical area) determine the cost. 5D integrates the design with the quantities, the planning and the calculation of costs, including THE DIMENSIONS OF BIM: planning and the calculation of costs, including the generation of bill of materials and budgets, productivity, labour costs, etc. 5D = 4D + cost
The 6D model (The Green BIM) lets us know how the project will behave before construction begins. It allows us to create variations and iterations in the envelope, the materials used, the type of fuel used to cool / heat the project, taking into account even its situation, position, orientation and many other aspects.
The 7D model it manages the life cycle of a project and its associated services. It allows the logistic and operational control of the project during the life of the building, optimizing the processes, such as inspections, repairs, maintenance, etc. The 7D model is usually delivered to the owner when a construction project is finished. The "As-Built" BIM model is populated with relevant building information such as data and details, maintenance / operation manuals, cut sheet specifications, photos, warranty data, web links to product online sources, manufacturer information and contacts etc.
Construction of a building requires efficient collaboration and information sharing between project members. Traditionally, this was done with paper drawings and documents, but new requirements such as 2D or 3D CAD (Computer-Aided Design) and facilities-management drawings increased the adoption of BIM (Building Information Modelling) for effective information sharing. The global AEC (Architectural, Engineering, and Construction) market will mature at a CAGR (compound annual growth rate) of 11.8% during the period 2017 until 2021.Open BIM solves interoperability issues by ensuring file, syntax, visualization, and semantic-level interoperability. The adoption of open BIM is relatively moderate in the current market situation. The AEC market will profit from the adoption of the technological solutions and drive the construction market into the future.The UK Government’s BIM mandate has been in place since April 2016. The mandate requires that all projects funded by central government be delivered with ‘fully collaborative 3D BIM’.
The graph below shows, year on year, the confidence levels of people’s knowledge and skills in BIM. The knowledge and skills of the industry are steadily growing. Fifty eight percent are now confident (compared to 45% in 2015), and fewer than one in five (19%) are not. This is not a rapid process, but the skills and knowledge needed for the UK to make a success of BIM are coming into place.
As BIM celebrates at least 40 years of its general concept and technology, it seems to just be realizing its massive potential to the architecture, engineering, and construction sector. We are slowly witnessing the integration of virtual design and construction with “sustainable design practices, human-computer interaction, augmented reality, cloud computing, and generative design” (Bergin, 2011). These trends are continually and rapidly influencing the evolution of BIM. It is actually an exciting time to be alive and to witness the rise of the construction tech.
The concept of LOD recognises that model elements within a model evolve at different rates throughout the design process. LOD is a means of defining the extent to which model elements have been developed, from conception in the mind of the designer through to their construction and operation. The development of information associated with model elements is as important as the development of geometry, and is integral to its LOD.
“The Level of Development (LOD) describes the minimum dimensional, spatial, quantitative, qualitative, and other data included in a Model Element to support the Authorised Uses associated with such LOD.”
The following reflects the general consensus of the most widely used LOD Definitions:
The Model Element may be graphically represented in the Model with a symbol or other generic representation, but does not satisfy the requirements for LOD 200. Information related to the Model Element (i.e. cost per square foot, tonnage of HVAC, etc.) can be derived from other Model Elements.
The Model Element is graphically represented within the Model as a generic system, object, or assembly with approximate quantities, size, shape, location, and orientation. Non-graphic information may also be attached to the Model Element.
The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of quantity, size, shape, location, and orientation. Non-graphic information may also be attached to the Model Element.
The Model Element is graphically represented within the Model as a specific system, object, or assembly in terms of quantity, size, shape, orientation, and interfaces with other building systems. Non-graphic information may also be attached to the Model Element.
The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of size, shape, location, quantity, and orientation with detailing, fabrication, assembly, and installation information. Non-graphic information may also be attached to the Model Element.
The Model Element is a field verified representation (i.e., as-built) in terms of size, shape, location, quantity, and orientation. Non-graphic information may also be attached to the Model Elements.
Parametric modelling enables the constraint features to be created such as the height of a horizontal level, which then can be linked to the height of a specific set of walls, parametrically adjusted with each other. This creates a geometry-tied dynamic database model. This evolution gave a solution to the absence of computable information. Parametric modelling allowed the industry to change drawings at multiple scales and across fragmented drawing sheets hours necessary for manual redrafting steadily decreased over time. The employment of computer technology automated long-winded tasks in all disciplines, thereby greatly improving productivity. In the early days, BIM was more of a figure of speech than actual technology computer limitations and weird user interfaces for BIM platforms ended up with 2D line drawing programs like AutoCAD and Bentley Micro station. It took quite a while to incorporate computability in design modelling.
The term 'accuracy' is often used to describe the way work conforms to a predefined standard or specification. This interpretation includes completeness of information as well as how true or accurate that information is specifying level of accuracy is something that the AECO (Architecture, Engineering, Construction and Owner/ Operator) industry has long struggled with in regards to existing conditions building documentation.The Level of Accuracy attainable is closely related to the tools, techniques and processes used to capture and represent the objects being documented. In the case of laser scanning, each scanner has stated collection accuracy. The methods and techniques used by service providers to capture scan data such as overlap, point density, noise, point spray, methods of registration and control, all affect the accuracy of the registered point cloud data.
BIM, as a whole, refers to the process of all parties involved in the construction and lifecycle management of built assets, working collaboratively and sharing data. However, the true power of BIM lives in the “I” (information). All of the information gathered from conception to completion isn’t just stored, it’s actionable. The data can be used to improve accuracy, express design intent from the office to the field, improve knowledge transfer from stakeholder to stakeholder, reduce change orders and field coordination problems, and provide insight into existing buildings for renovation projects later on.
This information in a BIM model is shared through a mutually accessible online space known as a common data environment (CDE), and the data collected is referred to as an 'Information model'. Information models can be used at all stages of a building’s life; from inception to operation and even renovations and renewals.Through BIM, the UK construction industry is undergoing its very own digital revolution. BIM is a way of working. BIM is information modelling and information management in a team environment, all team members should be working to the same standards as one another. BIM creates value from the combined efforts of people, process and technology.The geometrical or graphical data can tell us the width of a brickwork leaf and the height of the walls, at a certain point during construction it is the written word that is needed to take us to a deeper level of information. It is within this textual environment that we describe the characteristics of the brickwork itself such as density, strength and source, and it is words that are used to describe the kind and type of mortar joint and wall ties.In the context of BIM, we are actually looking at a rich information model which, aside from graphical data − such as geometry and shape − also includes non-graphical information such as performance requirements and associated documentation, presented in a specification or manual format. The written specification is not new and has been around for centuries. However, it is only now by combining these aspects of graphical and non-graphical information that we get the ‘overall picture’.
The essence of the BIM process is that it enables the creation of virtual 3D models that can be explored and manipulated, making it easier to understand the relations between spaces, materials and systems. A database generates a 3D image and creates building plans. Thus, the BIM process can build, view and test a structure in 3D. These abilities allow revisions and the assembly of accurate details. The detailed data permits design, clash detection, cost and scheduling. Each of the stages of design and construction benefit from its involvement in BIM, which generally works as follows: