Displaying Gross Area and Net Area for manually-drawn Spaces

[EliM]

Our office uses spaces for energos energy modeling and must draw the spaces so they are contiguous, cover the whole floor plan, and extend to the outside face of the exterior walls. We also need to display net areas that do not include the area taken up by the walls.

I have tried a couple of methods but none of them work well:

 

1) Using Auto-bound, which will display correct Net and Gross Areas for simple spaces but Auto-bound does not accommodate spaces that are not fully enclosed by walls, walls within symbols, and more complex perimeters, and it is cumbersome for each space to custom specify the gross boundary definition by identifying exterior walls where the bound should go to the outside face of the wall and interior walls where the bound should go to the wall centerline.

 

2) Displaying an approximate Net Area using the formula =(#Gross Area#) - (#Gross Perimeter# * 0.25), where the 0.25 represents an average wall thickness of 3" around the Perimeter of the space. The fundamental flaw of this approach is that wall thicknesses often vary around the perimeter of the space and some sides of the space don't have a wall at all, so the estimate is very crude. (But further I am also having trouble with the custom formula--#Gross Perimeter# is yielding a large result off by orders of magnitude from the actual perimeter, which is correctly displayed if I just add Gross Perimeter as a space label not through a custom formula.)

Short of always drawing two different polygons for each space, is there a better way to display gross and net areas when the auto-bound will not work? Is there a way with a manually-drawn space to make the subtraction areas for the net area calculation equal the area of the walls encompassed within the space?

[maxstk]

I was just typing to bump your question but figured out a solution to my own problem that may help you. 

I was trying to get just the net and gross SF of all my units in a multifamily building. My issue was that when the boundary was manually selected, the Gross function no longer worked properly and only displayed the same as the Net. 

My solution was to place the walls which would cause issues with auto boundary (in my case, all the interior walls of the apartments i.e. bedroom wall, closets etc etc) on their own Class (I duplicated the interior wall class). This allows me to turn the walls which I want to ignore off, auto bound my spaces accurately, then turn the class back on afterward. I now have accurate Gross and Net SF's. 

Might help? 

Max