Another make: I added the new doors and planned overhangs to my SketchUp drawing of the cabin, to see where the shadows will fall.
I’ve been studying up on the ideal percent of south-facing glass relative to floor square footage*, and the ideal percent of thermal mass relative to south facing glass and daily temperature cycles.
Apparently, mass is most effective in climates where you need more cooling than heating, and where the nights are significantly cooler than the days.**
In Joshua Tree our average nighttime temps are more than 20 degrees cooler than our daytime temps, and we do more cooling than heating, so I think means interior thermal mass makes good sense. Since we have no slab, we plan to add mass by using two layers of drywall and/or thick earthen plaster on the walls and ceiling.
*12% is the number I see most, but is that for a heating or cooling dominant climate? Here we use cooling from April to October, so we want deeper overhangs than a more temperate climate. Given that, maybe more south-facing glass is ok?
** One source indicated that night time temps needed to be at least 10 degrees lower than your thermostat setting for thermal mass to be effective for cooling, but that seems arbitrary. What if you don’t have a thermostat?