Traditional design methods have relied heavily on physical models for evaluation. However, today’s designers increasingly prefer digital design tools. Both approaches offer unique advantages and remain essential depending on the context. Since design plans frequently change, establishing a 2D spatial area, asset quantities, and a BIM 3D model enables continuous control over project budgets and scope, ensuring consistent design quality.
Here are three common budgeting methods based on BIM models:
1. Extract quantities from the BIM model—usually exported as an Excel file—and input these figures into professional budgeting software. Most of these programs require specific Excel templates and careful coordination during the modeling process to ensure accuracy.
2. Use third-party intermediary software that integrates directly with BIM tools for budgeting purposes. These solutions typically calculate labor and material costs by grouping objects and referencing unit price databases like R.S. Means for detailed cost estimation.
3. Utilize specialized BIM quantity extraction software that reads model data directly and automatically generates quantity takeoffs and budgets. Examples include Autodesk QTO, Exactal CostX, Innovaya, and Vico Takeoff Manager, each offering different capabilities for managing components and construction quantities.
The American Institute of Architects (AIA) introduces the concept of Model Progress Specification, which defines varying levels of detail or levels of development (LOD) based on the task at hand—whether modeling analysis, project management, or budgeting. As construction projects progress, the BIM model’s data becomes more comprehensive, and the LOD correspondingly increases.
In China, recent BIM research has largely concentrated on design clash detection. Less attention has been given to extracting engineering quantities from BIM models, and the integration of external quantity calculation programs with unit price databases remains mostly experimental.
In summary, quantity extraction typically begins with the completed BIM model outputting design quantities. Construction drawings then define materials and work items, enabling the extraction of construction quantities. These quantities are matched with material unit prices from databases to calculate construction costs, while associated labor rates provide the foundation for project scheduling.
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