Model-based estimating utilizes a 3D model, rather than traditional 2D drawings, to extract quantities and develop a project cost estimate. It is also commonly referred to as 5D Building Information Modeling (BIM).
Understanding Model-Based Estimating
Model-based estimating represents a significant shift from traditional methods of cost estimation in construction and other industries. Instead of manually measuring lengths, areas, and volumes from 2D drawings, estimators leverage the data-rich environment of a 3D model. This offers several advantages, including increased accuracy, speed, and collaboration.
Key Aspects of Model-Based Estimating:
- 3D Model as the Foundation: The core of this approach is a detailed 3D model of the project, containing geometric information and associated data about each element (e.g., material, size, performance characteristics).
- Quantity Extraction: Specialized software automatically extracts quantities from the 3D model. This eliminates the need for manual measurements and reduces the risk of errors.
- Cost Data Integration: Cost information is linked to the model elements. This allows the estimator to quickly calculate the cost of materials, labor, and equipment based on the extracted quantities.
- 5D BIM: The term "5D BIM" refers to the integration of cost data (4D) and schedule (5D) with the 3D model. Model-based estimating is a key component of 5D BIM.
- Real-time Updates: As the model evolves during the design and construction phases, the cost estimate can be automatically updated, providing real-time insights into the project's financial implications.
Benefits of Model-Based Estimating:
- Improved Accuracy: Automation reduces human error and ensures consistent measurements.
- Increased Efficiency: Quantity takeoff is significantly faster compared to manual methods.
- Enhanced Collaboration: The 3D model serves as a central source of information, facilitating communication and collaboration among project stakeholders.
- Better Cost Control: Real-time cost updates enable proactive cost management throughout the project lifecycle.
- Reduced Risk: Early identification of potential cost overruns allows for timely corrective actions.
Example:
Imagine estimating the cost of concrete for a building foundation. Using traditional methods, an estimator would manually measure the lengths and widths of the foundation walls from 2D drawings, calculate the volume, and then apply a unit cost for concrete. With model-based estimating, the estimator can simply select the foundation element in the 3D model, and the software will automatically extract the concrete volume and calculate the total cost based on pre-defined cost parameters.
