Special thanks to Jeff Hanson for the information included below; this documentation expands on yesterdays post:
Each of these Construction Types are defined when the energy model is first created. To locate these materials, navigate to the following location:
Project Browser > Mass > Conceptual Constructions
You should see categories for Mass Floors, Mass Opening, Mass Roof, Mass Shade, Mass Walls & Mass Windows and Skylights:
To edit the associated material, right-click over the construction type in the Project Browser > Type Properties > Graphical Appearance. Here you can change the material as needed.
You can see the default assignments under Analyze > Energy Settings > Conceptual Constructions
On a related note, materials containing a surface pattern do not display the pattern when assigned to a conceptual energy mass model.