Calculate surface area of a Mass Element in AutoCAD Architecture

I got an email with the question how to achieve this on a very complex Mass Element and here is one solution how it can be done.

To get the surface area of a Mass Element use ConvertTo3dSolids (or select the Mass Element, right click and select Convert To>3D Solid) to convert to a 3DSolid and then use the Area command with the Object option and select the 3D Solid.