Ha, I read 'the $50 and up underground house' 4 years ago, sitting by the lower door in the Abbey, hiding out from the heatwave and thick forest fire smoke!
The place is certainly transformed from when I saw it!
Looks like a great bit of reading to start off your time in the abbey.
'Theoretically this level of creeping Orwellian dynamics should ramp up our awareness, but what happens instead is that each alert becomes less and less effective because we're incredibly stupid.' - Jerry Holkins
Inge, we hypothesize that an earthen floor over concrete might work all right, so long as the floor doesn’t get damp (like in a basement). But I don’t know how your landlord would react if you have a rented apartment!