Ty Morrison wrote:This should be obvious to me, but the cold has apparently affected my brain. Are Wofati 0.8 and Allerton Abbey one and the same?
nope, 0.7 = Allerton Abbey.
Using my modeling skills, I have built a concept model to illustrate the simplicity of the concept.
I made these diagrams to help others visualize the concept.
some comments:
The insulating qualities of earth while a part of the equation, are not the reason to use earth at all. The main consideration is storage and rate of heat travel. That is, it would be easy to have more heat storage in a smaller volume (water for example). Also note the there is generally a layer of material above the earth for the purpose of insulating and water sealing to keep the earth dry. Heat travels by more means than one and earth umbrellas rely on all of them. Earth that has been heated at the hottest times of year in a trombe wall will be emitted quite soon and probably before it is needed/wanted. heated earth 12 feet away from the dwelling will let it's heat take as much as 6 months to reach the dwelling and start releasing that heat to the interior. So earth has the quality of cheap, but massive heat storage, but also slow heat release without manual intervention with the right design.
This concept is scalable from small to large. Trombe walls are way more complicated than straw-bale, too. But they might have some advantages in digger designs with bigger budgets.
I don't know that I would put a trombe wall on the south side. It is hard to know what would work best with that.
It is (another) interesting coincidence, that the materials on hand seem to be the best materials for the job.