Yes, as long as the (plastic) bags are isolated from the heat. Typical earthbags might not be suitable, as their thickness would make for many hours' delay in heat getting through to the surrounding space, I think the part of the wall that forms the RMH container would need to be more rammed earth than earthbags, to get proper wall thickness and heat resistance. You would want a noncombustible lining for the bell enclosure.
It could be done, but as Glenn has pointed, it will have extreme delay. With 20cm of bricks and mortar, with a metal skin inside, the rise in heat starts to be feelable by hand after 2 to 3 hours, depending on how cold the bell was.
Plus, i have to point out, that if you don't use it as a bell wall, but a bench, heat might travel faster to the ground, than to the face of the wall. Which would be counter productive.
Thanks! I have only seen relatively small RMH, so I am seeking to learn if large scale is feasible. One of the reasons I am looking into this is that if the RMH is actually a wall between two rooms, both rooms/sides of the house will benefit. More useful, is if it is one continuous wall that serves upstairs and downstairs. I am especially interested in the wall between the master bedroom and the living room/kitchen area.
Let me tell ya a story about a man named Jed. Poor mountain man with a tiny ad:
montana community seeking 20 people who are gardeners or want to be gardeners