Role of 5D BIM in Construction Projects

The procurement of a construction facility deals with design, construction and operation stages where sustainability is a major requirement. Building Information Modelling (BIM), an concept, is capable of sharing information between the project team members and across the software applications which are commonly used in the procurement process of the construction facility, emphasizing the characteristics of a sustainable procurement strategy.

Building Information Modeling

The BIM is a "revolutionary concept of using computer simulation in the construction industry" which has already attracted the attention in Architecture, Engineering and Construction/ Facility Management (AEC/FM) field . Moreover, Zhiliang pointed out that BIM is designed in a way that it is capable of facilitating information sharing in a construction project, among the stakeholders in different phases in order to make better decisions. 

To date, in most of the design firms, the main focus on (BIM) implementation has been simply about the way the parametric 3D modelling software works (Mitchell, 2012). However in U.S. General Services Administration (GSA) emphasized that 3D models alone are not BIM models as geometric representation is only a part of the BIM concept, and its true concept and true intention is represented by the "I" in BIM; information. As defined by Associated General Contractors of Georgia (AGC),BIM is the development and use of a computer software model to simulate the construction and operation of a facility. 

The resulting model, a Building Information Model, is a data-rich, object-oriented, intelligent and parametric digital representation of the facility, from which views and data appropriate to various users’ needs can be extracted and analyzed to generate information that can be used to make decisions and improve the process of delivering the facility. (para.2)Moreover, Hamil highlights that the problem of silo working and badly coordinated documentation in the construction industry will be greatly reduced through the adoption of BIM, and for this to be achieved, interoperability is critical. But, Bernstein and Pittman clearly points out that poor software interoperability has long been regarded as an obstacle to industry efficiency in general and to BIM adoption in particular. Among different levels of interoperability, interoperability through open standards is considered to be the most applicable (Hamil).

Cost Modeling :

Among the critical activities for any construction project, cost modelling is a vital task to be performed throughout the lifecycle of a building project (Zhiliang) especially from inception to completion of the project. As defined by Ferry, Cost modelling is the symbolic representation of a system, expressing the content of that system in terms of the factors which influence its cost. In other words, the model attempts to represent the significant cost items of a cash flow, building or component in a form which will allow analysis and prediction of cost to be undertaken. Such a model must allow for the evaluation of changes in such factors as the design variables, construction methods, timing of events, etc. Though quantities of the building project can be extracted from BIM model, the estimating process is currently not an automatic process in BIM environment as "work must be performed which identifies and maps the objects in the CAD model to a format which traditional estimators are comfortable with Hannon. According to Bailey, even in USA though progress has been made with the use of the “Omni Class” coding system, at this stage “published documentation only provides a level of codes suitable for conceptual and early schematic models and estimates”. It should be noted that thus far 5Dmodelling is performed through the combination of BIM authoring software combined with 3rd party software for measurement and estimating.

Characteristics of Cost Modeling in BIM Environment

• Operating in a 3D-based platform obtained either from independent developing or professional BIM-based design software.
• Capable of extracting input data from IFC file.
• Since there is no enforced specification, the software follows the coding system developed by the industry association.
• Applicable for estimating from conceptual design to detail design.
• The quantity extraction is not subjected to uniform calculation rules but is based on object types and their dimensions.
• Cost estimation is based on the cost items generated by the professional and experienced cost estimators

Key Requirements of Cost Modeling in BIM

• Automatically import design result:

The estimators can make use of the design result of IFC data automatically. There is no need to manually identify the drawing and to establish the model which could eliminate manual reworks, increase speed and improve productivity.

• Interactive 3D visualization:

Users can enjoy the best performance of 3D building model navigation and object details examination. The 3D building elements and cost items are highly interactive and selectable. Support interactive data modifications.

• Intelligent match:

Building elements can be automatically linked to cost items through the intelligent judgment of the building element’s properties. This feature reduces a great deal of effort of estimators.

• Intelligent change management

If the design is changed, the next generation Construction Cost Estimation software can display changed, new, and deleted objects, and automatically update the quantities. The cost estimating can be easily adjusted. This feature helps the estimators to deal with the design change efficiently.

• Export the standard cost estimating data

Export the standard IFC data file which include building element’s dimensions, construction process and cost items data so that the downstream software, such as construction management software, information reuse software can directly use the data.