How to combine lofted surfaces into a solid

I am trying to loft 3 surfaces into a closed box so I can then input the information into honeybee for future analysis.
But I am quite confused about which component to use for combining them into a closed surface.
Can someone help please?loft to (154.3 KB)

IMHO, you are using Loft too much in unnecessary places.

loft to (149.4 KB)

Thank you very much!!!

Just note that you might run into trouble when running an analysis on curved geometry.
See, for example,