Ladybug with Rhino Inside


I would like to make Ladybug and Honeybee studies with geometries exported with Rhino.Inside.
The problem is that when I export the walls, I get 6-sided brep, which makes sense, but I would like to have only one surface per wall so that the calculations are not too long.
So my question is how to export with Rhino.Inside only one surface of a wall.

Thank you all for your answers.