Hi everyone,

I'm wondering how best to simplify a model when considering structural
concrete columns.
My modelling is in the context of the LEED whole building energy modelling.
So I'm concerned with accuracy as much as acceptability by the LEED
reviewers. I've read the ASHRAE 90.1 user's manual but didn't find a
satisfactory answer.

Here's an example:

----
wall | | wall
-------| |------
| |
----
concrete column

I can see 3 options for simplifying, each with its own issues:

1. Make the external surface of the column at the same level of the
surrounding walls and model the column surface as having its true thickness
. The issue is that it alters the area of the space inside and doesn't
account for the shading effect of the column.

2. Follow the internal boundary of the column, which introduces 3 surfaces.
Not sure what construction thickness to assign to these surfaces. This
preserves the internal space area but alters the shading effect of the
column.

3. Follow the external boundary of the column. This also introduces 3
surfaces. Not sure what construction thickness to assign to these surfaces
either. It preserves the shading effect of the column but alters the area
of the internal space.

I'm leaning towards option 1. What do you think? Are they other better
options I overlooked?

Of course, things get a bit more complicated when the walls either side are
not aligned or in the same plan...

Thanks!
Patrick