Despite their relevance to cost estimation, this is not about procurement, scope management, risk management or team selection. Instead, the focus here is on the cost estimate itself, the need for it to be accurate and how accurate cost estimation can be achieved through Building Information Modeling (BIM).
The significance of overshooting budgets is not limited to projects in any particular industry or to major projects. In fact, investigation of successful projects has revealed that smaller or medium sized projects can suffer more from inaccurate budgets as they often receive less attention than larger ones.
The need for accurate cost estimation to avoid overshooting budgets
In today’s competitive construction market, the need for accurate cost estimation to avoid overshooting budgets is usually a given. Based on historical precedents, the probability of a project cost estimate being accurate is slim and so the need to improve is all the more pressing.
Proper cost estimating, cost monitoring and cost control are vital for the success of construction projects. These become more complex and challenging to achieve as projects progress so it is important to understand and compare the benefits of methods taken to achieve it.
There are several ways of achieving accurate cost estimation: collaborative procurement routes, scope management, thorough project risk analysis and organizational cultures valuing honest opinion but a key mechanism to achieving it is to use BIM from inception to completion and beyond.
Building Information Modeling
All AEC professionals have to develop graphical representations that are detailed enough to support their non-graphical documentation, without creating digital models that are too complex to update and coordinate for cost estimation purposes.
Those who implement BIM have to develop standards for representing building elements in a digital model and establish the level of detail (LOD) required relating to each project phase.
The case for linking costing applications with BIM
BIM objects data can be embedded in a digital model and further information affiliated with such objects in an external database as well.
Costing applications can harvest information from BIM objects in two ways:
- by enhancing object definitions within the model
- By using a unique identifier to link objects to more detailed information stored externally from the BIM application in a database.
The benefits and promise of automated 4D BIM costing or value-engineering applications
Construction costing requires a means to export component information from a digital model, identify its data, including quantities, and export it to a costing application.
Ideally, the exchange of data between BIM and costing applications would be bi-directional. This would allow digital models to exchange information from automated BIM costing applications but this is not currently possible. Value engineering, undertaken during the pre-construction phase, would benefit from this.
If undertaken throughout a project lifecycle, automated BIM costing exercises would hold the promise of reducing the need for value-engineering by providing decision-making processes with more accurate information, earlier in projects.
BIM based cost estimation, monitoring, and control research methodology
Cost estimation, monitoring, and control tools are important for construction projects. Some research has revealed new approaches to estimating, monitoring and controlling them for the industry.
These include a BIM-based visualization system.
BIM based visualization system
BIM based visualization systems facilitate the estimation, monitoring, and control of construction progress and are used for controlling small to medium projects.
They have two key advantages:
- They enable construction progress to be visualized along with contextual conditions.
- They provide stakeholders with a framework to easily view and evaluate construction progress.
The research emphasizes the importance of integration between project cost estimates, cost monitoring/control techniques and BIM platforms.
They are considered as an effective tool for monitoring construction projects, providing project decision-makers with a useful tool to facilitate their cost and program-related decisions.