Calculate Quantities: Openings

Calculate Quantities: Openings tool measures opening object quantities based on the object geometry. Openings are a special kind of objects in IFC models, which are not usually visualized in 3D, although they do have 3D geometry.

Simplebim calculates quantities based on the geometry of objects. Because of this, it doesn’t matter which model author tool was used for creating the models or who made them. Simplebim always calculates the quantities with the same logic in a consistent way. Thus, quantities are comparable between different models and even between different projects. In other words, Simplebim calculates standardized quantities.

Quantities are calculated both for object instances and container objects. For example, a wall can either be an instance with a single geometry or it can be an assembly with several child objects, each of which has its own geometry and thus also its own quantities.

Quantities can be calculated for objects from any object class. So the wall doesn’t have to be modeled as a wall, and you can still calculate the quantity you need for it.

Settings

There are six different tools for calculating quantities. They all share common settings, which you can find in the Calculate Quantities: Dimensions article.

Objects with Openings

Since the opening objects are not visible in the basic Simplebim as 3D objects or object class instances. So you need to access them through their parent objects, for example, walls or slabs, or windows and doors. 

Objects with Openings should include the objects that are connected to the openings you want to calculate. 

The connections for the derived objects are created to the filling that the opening element relates to, for example, a window or door. Empty openings, which are not related to any fillings, are connected to the parent building element, for example, the wall or slab.

Quantities

Opening elements are a special feature in BIM models. Usually, they are not explicitly visible in the viewers. The same applies to Simplebim. However, if they are in the IFC model, they can be used for quantity calculation. This depends on how the model is created in the model author tool.

Area Opening Element

The area of an opening element that is related to, for example, windows or doors. Note this can be different from the area of the actual product within the opening, for example, a window or door.

If you want to calculate the area of a window or door, use the Calculate Quantities: Shadow Areas tool and the Area Shadow Net instead. Which one you choose depends on whether you need to take into account the mounting allowance or not. Area Shadow does not take into account the mounting allowance. Area Opening Element does. Note whether or not these two are different, depends on how the model is created by the designer. Whether the designer has modeled the mounting allowance or not.

Dimension Height Opening

So-called fills, for example, doors and windows, have two different heights. One for the opening and one for the actual fill (product). To measure the fill height, use Height dimension of the Calculate Quantities: Dimensions tool. To measure the opening height, use Dimension Height Opening.

Whether these two are different depends on how the model is created. If the opening is modeled with the so-called mounting allowance, then these two dimensions are different. In this case, you can choose the one you need for your QTO.

Dimension Width Opening

So-called fills, for example, doors and windows, have two different widths. One for the opening and one for the actual fill (product). To measure the fill width, use the Shortest dimension of the Calculate Quantities: Dimensions tool. To measure the opening width, use the Dimension Width Opening.

Whether these two are different depends on how the model is created. If the opening is modeled with the so-called mounting allowance, then these two dimensions are different. In this case, you can choose the one you need for your QTO.

Dimension Length Frame Opening

This is a derived measure for your convenience. It is calculated with the formula: 2 * Height Opening + Width Opening.

The Frame Opening is only calculated for the fills, like doors and windows.

Perimeter Opening

This is a derived measure for your convenience. It is calculated with the formula: 2 * Height Opening + 2 * Width Opening.

Note to measure the fill (door or window) perimeter, use the Perimeter Shadow Outer.