How does BIM accomplish cost estimation? This question has been frequently asked by students, and until now, the editor of the BIM Building Training Network has not provided a direct answer. Today, the editor will share insights gathered from expert consultations and personal summaries, aiming to inspire cost engineers.
From the perspective of professional division of labor, it is clear that architects do not typically consider cost requirements when using BIM models for design. They also do not limit the BIM model to include only the information necessary for cost estimation. Consequently, there are two approaches for cost professionals to prepare estimates based on BIM models:
First, cost estimators can add specialized information required for cost estimation directly to the BIM model provided by the designer. Second, they can extract existing project information from the BIM model or link it with existing cost data. These two methods together form a BIM-based cost information model, commonly referred to as CBIM or Cost BIM.
The advantage of the first method lies in the high integration between design data and cost information. Design changes can automatically update cost estimates, and conversely, cost-driven changes—such as selecting alternative products—can be reflected back into the design model. However, this approach faces challenges: BIM models tend to grow large and may exceed hardware capabilities. It also demands intense collaboration among design, construction, cost, and other stakeholders. Both software implementation and personnel workflows require significant effort.
The second method is comparatively easier to implement, both in terms of software solutions and operational workflows. However, its drawback is the need for manual management and coordination whenever cost changes stem from design modifications, or when cost considerations lead to design changes. Establishing an effective communication bridge between design and cost teams is essential.
Overall, BIM and cost estimation complement each other well. BIM can greatly reduce the workload of cost professionals and enhance efficiency. Still, cost professionals should not limit themselves to simply budgeting and quantity takeoff; embracing the full potential of BIM is key to maximizing its benefits.
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