The insulation is mechanically held (not show) by flexible wires to the warm side surface allowing a 1" air gap at the bottom of the joist bay. Ventilation is accomplished with screened holes in the sheathing.
Plywood was installed to "critter proof" the insulation.
With the building now fully insulated the temperature fluctuations were further reduced. Unheated or air conditioned the building is ~15* F cooler than the daytime high and 15* F warmer than the outside temperature in the mornings. The Temperature range for this trip was 45-90*F.