Chlupp's design borrows very, very heavily on passive house concepts.
And he uses massive amounts of insulation. He creates a large (big enough to walk in) wall cavity, and fills that with blown cellulose. I think it's on the order of twenty tons of cellulose. Not only does it insulate, but it forms a thermal mass.
Similarly for his foundation: a large sand base as I recall, then a slab, which create yet more thermal mass. The masonry stove at the building core is another, and finally a 5,000 gallon vertically-arranged water tank. This has a perforated distributor, and the idea is that he circulates water through his masonry stove and solar thermal panels whenever the output of those is warmer than the water at some point in the tank -- it tends to be ~120F near the surface, and ~40F near the bottom. The water stratifies according to temperature, and he banks his BTUs.
In our case it's something like five tons of cellulose. It's supposedly a good buffer against summer heat getting into the house but it doesn't really store heat to release it slowly when the temperature goes down again. I can imagine it works well high up north but here I think it would make it more difficult to control the temperature. It's one of the reasons why we have chosen a wood-based construction using I-joints. We do have a concrete foundation slab, screed everywhere and ceramic tiles on the ground floor.
The big stratified water tank is a well known concept but you need to have room for such a big tank. Here in Belgium space is at a premium so houses tend to be on the small side. Solar thermal panels are often connected to a tank of 500 litres or less, simply because of space constraints...
There are several possible construction models; it's a matter of selecting one that fits your local climate and your habits. Not everybody likes a stove for example.
The last couple of years we've seen a shift happening from applying the passive house concepts on new houses (pretty much a solved problem) to renovating existing ones. Here in Belgium there's a massive amount of old houses constructed before the seventies/eighties which is when they finally started putting in insulation. Now that all new houses are energy efficient it's time to tackle the massive waste in those old houses. Most people buy such an old house and start renovating so there's a lot to be gained.
In Chlupp's case, he pretty much designs his structure around the tank, it's integrated to the building core.
An alternative he points to in Europe is a community / neighborhood storage, where a thermal storage tank serves a number of homes. Another option is seasonal thermal storage using ground-base storage, where you've got suitable geology (no moving water table to whisk your heat away helps a lot), used in at least one instance in Canada. Heat is pumped in during the summer and extracted in the winter, as part of a ground-loop heat pump.
And he uses massive amounts of insulation. He creates a large (big enough to walk in) wall cavity, and fills that with blown cellulose. I think it's on the order of twenty tons of cellulose. Not only does it insulate, but it forms a thermal mass.
Similarly for his foundation: a large sand base as I recall, then a slab, which create yet more thermal mass. The masonry stove at the building core is another, and finally a 5,000 gallon vertically-arranged water tank. This has a perforated distributor, and the idea is that he circulates water through his masonry stove and solar thermal panels whenever the output of those is warmer than the water at some point in the tank -- it tends to be ~120F near the surface, and ~40F near the bottom. The water stratifies according to temperature, and he banks his BTUs.