The design process can be compared to the process of growing up, where the progression is gradual but continuous. Imagine having to start over with just a vague idea of what we had learned before at major stages of our development. Clearly the process would be slower and less efficient.
It is important to understand the different stages of the design process to appreciate potential problems. The traditional process uses a variety of software tools including schematic (basic layout only), 2D (plans and elevations), 3D (representation of plans and elevations in three dimensions) or BIM (3D models defining volumetric, material and ‘smart’ component detail).
The design process is commonly described as a progression through five stages, or, if BIM tools are used, one model with five coordination reviews.
The five stages are:
- spatial design – early or concept design intended as an overview of the project where design/cost alternatives can be considered;
- preliminary construction design – a model that defines basic quantities, areas and volumes;
- construction design – products to be used are defined in generic form;
- product design – specific products are defined;
- and maintenance design – also referred to as the ‘as-built’ design, representing how the project was actually built.
To successfully complete the design process, various professionals are involved, each creating his own design, which will impact on the others. hence, when designs are transferred between the multiple disciplines, some data is lost or misinterpreted. At each phase of the design, data has to be re-entered, creating further possibilities for information loss. Designs also have to be co-ordinated in such a way to ensure that trades do not overlap with their products or services.
Integrated project delivery
The good news is that there are processes and technologies that are primarily designed to tackle such a problem. however, these require a re-think on the way we work when using traditional methods.
Using building information modelling (BIM) processes and tools, it is possible to complete the five key stages of design in a single federated model. Models may originate with the client, architect, structural engineer, civil engineer, building services engineering, contractor, sub-contractors, suppliers and so on. A federated model is an assembly of these distinct models to create a single, complete model of the building.
Moving from one stage of design to the next in the BIM environment has been described as ‘model progression’ but the process is now more accurately defined as integrated project delivery (IPD).
IPD gives operatives the opportunity to work in a single environment with the objectives of improving efficiency and eliminating errors.
The American Institute of Architects defines IPD as a project delivery approach that “integrates people, systems, business structures and practices into a process that collaboratively harnesses the talents and insights of all participants to optimise project results, increase value to the owner, reduce waste, and maximise efficiency through all phases of design, fabrication, and construction”. In all cases, integrated projects are uniquely distinguished by highly-effective collaboration among the owner, the primed designer, and the prime constructor, commencing at early design and continuing through to project handover.”
The UK Government Construction Strategy published in May 2011, states that the ‘..Government will require fully collaborative 3D BIM (with all project and asset information, documentation and data being electronic) as a minimum by 2016’. This will represent a minimum requirement for Level 2 BIM on centrally-procured public projects. Level 2 is the creation of a managed 3D environment with data attached, but created in separate, distinct discipline models (federated models).
IPD uses a single federated BIM model throughout the five stages. The more advanced BIM tools have a greater capacity for interoperability, which is the ability to automatically transfer data between tools. This is achieved by the individual vendors developing communication links, or by using newly emerging standards such as the industry foundation class (IFC) protocols developed by BuildingSMART International.
IPD treats the five stages of the design process as the design progression of a single federated model:
- The spatial model, also known as the mass model, is a stage where the basic model defines the project in a series of zones, which can represent, for example rooms, floors, wings or entire buildings. each will have very high level quantity data defined by areas or volumes. As the model is ‘manipulated’ to create various design views, the quantities update automatically. By attaching equally high-level cost and planning data to the quantities, the resulting cost and construction time implications of the alternative designs can be easily determined. This significantly reduces the time taken to reach the best solution.
- The preliminary construction model defines basic quantities, areas and volumes. At this stage, with the design concept agreed, it is possible to start adding detail to the existing spatial model. The key products used in construction have not been defined, but are represented by elements that can follow the project programme and official specifications. At this stage, the model is used to conduct a ‘constructability analysis’ and to coordinate between trades. This model can be issued to structural and MEP (mechanical, electrical and plumbing) consultants and if they are also using BIM technologies, the data can be transmitted directly or in 3D IFC format.
- The construction model defines products to be used in generic form, like steel partition. The progression continues in the same model and the construction elements are now presented as product types. The resulting automatic quantity take-offs take this additional detail into consideration. At this stage, the data, or IFC files, are returned from the structural and MeP consultants and integrated into the model for more detailed coordination and quantification. The drawings are produced automatically from the model to facilitate the application for building permits. Overall, the construction model increases the accuracy of the project, improves workflow and reduces RFIs (requests for information).
- The product model is the stage where the progression continues with specific products defined, for example, Paroc steel wall. In this stage, the actual components – and exact quantities – that will be required, supplied and erected by the constructors and product suppliers are indicated, recorded and archived in a single environment.
- The maintenance model, also referred to as the ‘as-built’ model, represents how the project was actually built. The product model is updated to reflect any changes during the construction phase and when construction is complete, the model is handed over to the facility managers who now have a complete record of the construction, which facilitates production of the detailed manuals required to implement maintenance programmes.
When to Use IPD
Integrated Project Delivery is a reaction to the extensive collaboration required for today’s complex projects that must be influenced by tiers of people in multiple organisations. IPD is still relatively new and there is a tendency to adjust the approach with each new project.
The key firms selected for the project form a core team that includes the Owner, the Architect, the Engineer, the Construction Manager although it may include other key players also. They typically sign a single, multi-party contract with the Owner and form one or more management steering committees. The core team establishes a set of project goals — cost, time and quality and sometimes other conditions including the use of minority firms, community relations and safety. Profits and bonuses are usually shared by the core team and are usually earned based on the achievement of the project goals. There is emphasis placed on Lean construction, BIM, PMIS and continuous
IPD appears to make consummate sense:
- For unique, complex, prestige projects where the need for collaboration is high
- When there are apt to be changes during project delivery
- Where participation of top leadership from the core project teams is likely
- When the Owner is a knowledgeable hands-on manager
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