@NunavutBirder, I expected wall thickness to be at least twice as thick. That high ceiling... All the heat goes up. Is it so small, that there is no need to focus so much on efficiency?
@rudolfsciemins it has 2x6 walls with R20 insulation. Plenty thick enough and an efficient heater. The ceiling is high for a different efficiency, the efficiency of space. It accommodates a loft.