Building verandahs basically means you will exclude the sun year round - which is fine in a tropical/hot climate, but not good in temperate/cool or cold climates where passive solar means winter sun getting to your windows and heating the inside.
I also see you are going a framed floor and framed walls - I am not sure what region you are building in - but will be interested to see how your your NatHERS (Six star) rating goes - I have a bad feeling this might be a real sticking point for this design. I would suggest you get an assessor onto this before going to engineering or working drawings..don't treat it as a check off before going to CDC - with this design it might prove to be more involved than you suspect.