Previously, I wrote an article titled “How to Calculate Quantity in BIM?” Many readers asked if there are alternative BIM quantity calculation methods based on Revit software. Here, I will introduce the steps, advantages, and disadvantages of combining Revit with QTO for quantity calculation.
QTO is a 3D-based building cost estimation software that integrates BIM models generated by Revit to produce quantity data. The combined workflow of Revit and QTO for quantity calculation involves six key steps, which are outlined below.
1. Build the BIM model: This step is the same as Step 1 in How is BIM measured? What is the process? (Based on Revit software).
2. Add project name and size parameters: This corresponds to Step 2 in the Revit-based quantity calculation process.
3. Import the BIM model into QTO: Export the BIM model created in Revit to a format compatible with QTO, then import it into QTO.
4. Filter components: Within QTO, use the work item names as search criteria to filter components. QTO will list all components associated with the selected work items.
5. Establish quantity calculation formulas: Define formulas for calculating quantities based on the filtered work items.
6. Repeat filtering and formula setup: Continue steps 4 and 5 until quantities for all work items have been calculated.
Advantages and Disadvantages of Combining Revit with QTO for Quantity Calculation
1. Flexible filtering criteria: QTO allows filtering using all parameter fields of components, including some that Revit itself cannot use as search conditions.
2. Unlimited formula creation: QTO enables calculations using various available parameters regardless of unit consistency. In contrast, Revit restricts computations to parameters with the same units.
3. No need for multiple detailed tables: QTO can calculate quantities for multiple categories together—for example, steel bars in columns and beams can be calculated at once. Revit requires separate calculations for each category, such as columns, beams, slabs, and walls.
4. 3D visualization enhances the calculation process: QTO uses 3D BIM models to visually distinguish calculated components with different colors, preventing duplicate counts. It also allows users to view the precise location of each component, reducing errors caused by unclear positioning.
5. Excel output format: QTO exports quantity calculation results in Excel format, which can be directly imported into PCCES for unit price reading.
Regarding calculation accuracy, if the same formulas and parameters are applied, quantities generated by Revit alone and those produced by Revit combined with QTO should match. However, Revit’s strict formula limitations may require adjustments during formula setup that can introduce errors.
Additionally, unlike Revit, which requires itemizing each component separately, QTO leverages work item information embedded in the Revit model as search criteria. This allows quantities to be classified and generated by budget item within a single interface, eliminating manual aggregation and providing ready-to-use engineering quantities for budgeting.
In summary, although using QTO requires model conversion, it significantly improves efficiency when handling projects with multiple components—such as steel bars existing in various columns, beams, slabs, and walls—by consolidating all results into one window and avoiding manual calculations.
That concludes the steps, advantages, and disadvantages of combining Revit with QTO for quantity calculation. I hope this article proves helpful to everyone!
Must log in before commenting!
Sign Up