Internal Walls straw bale and earth bag

I had an idea to use both straw bales and earth bags for an internals on a passive solar house.

Effectively it would be a straw bale (for insulative properties) 'sandwiched' between earthbags (for thermal mass). So a cross section of the walls would be  Earth bad - Straw bale - Earthbag.

Aside from having ridiculously thick walls, are their any good reasons Not to do this?

I question the need to insulate thermal mass walls

On the north side where the sun doesn't hit. More insulation is a good idea. The rest of the place is a thermal battery. Consider a greenhouse room on the south side for thermal gain.

Fair enough, but the OP was talking about internal walls I believe.

From my perspective, all thermal mass NEEDS to be insulated, if not it ends up at chilly ambient temperature all year round. A house that is constantly -10c degrees would suck.

Edit: sorry I just saw the 'internal walls' description. John has a point, not much need to insulate interior walls unless they have a thermal bridge to the outside.