You can define a SITE from a selection of faces / surfaces
at the top level of the model.
The site-element is a cube /3d-space built around this selection.
You will have to enter a name for the site, while some automatic check routines will try to avoid double-naming (hopefully successfully

)
Site-Cubes are saved on a site layer.
The Site-layer is normally invisible. It will be swiched to visible when you start the tool and hidden again by other tools.
AREAL3D - buildings will then detect the cube during the calculation process ( >> report generator) for the FSI-calculation.
At this stage of the project this tool is very simple and needs further development,
but it already gives you a basic information about the site.
Important: Buildings must be completely inside a site ! The routine always calculates the whole building area! If you right-click on the SITE-cube, some options are available:

Example of a site:
