I have been installing radiant heat in a huge house in los altos hills. strawbale construction earth/lime plaster, i'm installing radiant heat in slab in the basement, in gybcrete on second story and thermal board on the third.
it has been great to see professional contractors use these alternative materials. the lime plasterers are especially cool. lime is amazing stuff. it cracked like hell on the first application but within 24 hours they came back with a spray bottle with water & a little filler and repaired every crack. then in 10 days or so they put on the 2nd coat only a few slight hairline cracks arose. likewize within 24hours they sprayed & troweled out all the cracks. none of which were in the same spot as the previous cracks had been. finally i'm going down to see the color coat this next week.
the house is enourmous, easily cost 3 million to build. it seems odd to take a grass-roots construction method taken to this extreeme. i'm sure it isn't saving him any money but (in my opinion) it will be a very cool example of what can be done with natural materials.
this shows the gybcrete pour it went on like leveling compound (soupy) and was hard within 90 min. just on the left is the initial scrach-coat over the strawbales.