Calculate Quantities: Space Surfaces

Calculate Quantities: Space Surfaces tool measures space surface quantities based on the object 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.

Here are the settings specific to the Calculate Quantities: Space Surfaces tool.

Spaces

Spaces define the space objects you want to include in the calculations. By default, the tool takes in all the space objects. Then again, many times the space objects are used for different kinds of purposes other than representing rooms: gross areas, building volumes, apartments, service areas... Usually, you want to restrict the calculation only to the space objects for which you need the quantities.

Bounding Objects

Space surface measurements are done by projecting the bounding elements' geometry onto the surfaces of the space objects' geometry. Bounding Objects defines which building elements should be used in this projection. In principle, you could include all the building elements here. However, usually you only want to calculate or create derived objects based on some specific building elements, like walls, windows, doors, ceilings, and slabs. The default value includes all the objects from the most common object classes. If you want to restrict the calculation to, for example, some specific kinds of walls, then first create a group for them and pass it to the Bounding Objects.

Max Distance from Space Surface

Max Distance from Space Surface is the maximum distance between the bounding building element and the space surface its geometry is projected to. If the bounding element is farther away from the space surface than the maximum distance, it is not included in the calculation. You want to keep this setting reasonably small. Both because this is a good way to make sure that you only get the surfaces you need, and because extra calculations can hurt the performance.

Max Angle to Space Surface

Only the surfaces from the bounding elements, which are inline with the space surface are included to the calculation. You want to keep this number small, so that no extra surfaces are created, but not zero either, so that there is a little room for inaccuracies in the modeling of the geometry and the placement of the objects. BIM models are created by humans, they are not perfect.

Create Virtual Surfaces

It is not quaranteed that the whole surface of the space object is covered by bounding building elements. Maybe the model is like that. Or maybe you filtered some bounding building elements from the calculations. With the Create Virtual Surfaces you can decide whether to create surface objects for these 'empty' area of the space surface. Whether you need them or not, depends on your use case. The derived virtual surface objects don't have connection to any building element, only to the space object.

Clip Space Side Surfaces

In addition to just calculating the basic area, with this option, you can decide how the area is limited in vertical direction. For example, if you are calculating the area for a wall within a space, which has tiling only to a certain level, you could limit the area to that height.

Clip Height

The height of the clipping is set with the Clip Height parameter. Note that the height can even be larger than the actual space object. This way you could calculate the area above a lowered ceiling, even if the actual space object has not been modeled that high.

Quantities

Calculate Quantities: Space Surfaces tool calculates the quantities of the projections of the bounding elements to the space surface. The areas are always net areas. If you need to calculate the gross surface areas of the space objects, use the Calculate Quantities: Surface Areas tool. 

Area Sides Net

Areas of the bounding elements projected to the space object’s side surfaces.

The Area Sides Net takes into account the openings in the bounding objects. Note that if you need the opening area for the space surface, then use the Area Opening Element.

If you create derived objects for space-side areas, then the geometry represents the intersection of the space surface and the bounding elements.

Area Top Net

Areas of the bounding elements projected to the space object’s top surfaces.

Area Bottom Net

Areas of the bounding elements projected to the space object’s Bottom surfaces.

Area Opening Element

Areas of the openings in the bounding elements, projected to the space object’s surfaces.