BIM Software Tip: Use a detailed schedule to accurately extract the actual area of curtain wall panels in the Revit curtain wall system.
When it comes to obtaining the true area of curtain wall panels in a detailed schedule, Revit’s built-in “Area” parameter unfortunately does not provide accurate results. Many users have resorted to formulas to calculate this area, but these formulas become impractical or impossible to apply for irregularly shaped panels. I have also experimented with Dynamo scripts and various plugins, but none have fully resolved the issue.
Recently, I discovered a solution that requires no formulas, plugins, or coding—just pure native Revit functionality. However, be aware that this method involves working around a couple of quirks in Revit. The general workflow is to color the faces you want to measure within the panel family by assigning materials, then load the family into the project and generate a material takeoff schedule. This schedule will provide the actual area for each panel. To ensure accuracy, keep in mind these two crucial points:
- Change the family category of the curtain wall panel to Window;
- After coloring the faces that need their area calculated by material, also assign materials to the parent elements of those faces. You don’t necessarily need to color these parent elements; just select them and assign any material.
Why is this necessary? The first point addresses a known bug in Revit, and the second appears to be another quirk related to material assignments. This approach is equally accurate and applicable in the following cases:
- The area obtained by cutting elements in the project reflects the actual post-cut area of those elements. Revit’s built-in area calculation is quite reliable in this context.
- Adaptive components and other conventional models. Essentially, any model where you can color surfaces by material should work with this method.
Does changing the curtain wall panel family category to Window have any drawbacks? One known issue is that Dynamo’s CurtainPanel.ByElement node (used to retrieve all curtain wall panels) will generate errors when the category is changed. Without changing the category, you might consider dividing the material volume by the panel thickness to estimate the area. However, this approach is less precise overall.
I believe Revit’s original intention in allowing material color assignments was to enable the calculation of specific surface areas. Unfortunately, due to what seems like a programming oversight, extracting material areas from curtain wall panels in detailed schedules incorrectly equates to the panel’s area. This bug still persists in Revit 2016.
So far, I have not found a way to obtain an accurate area without changing the panel family category to Window. If you know of a better method to achieve this, please share it.
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