Passive House knows that for high thermal comfort in Australia, insulation needs to deal with the Summer (radiant) condition and the Winter (conductive) condition.
Our typical approach with lightweight timber construction, is to use specialist reflective (diffusion open, breathable) building wrap externally, in combination with wood fibre or cellulose insulation systems, and paper based internal building wrap for moisture control.
We eliminate steel structurally in the building envelope, replacing with engineered timber solutions (with the support of our understanding Structural Engineer), to absoultely minimise thermal bridging. Typical Holzbau.
We also absolutely avoid Petrochemical based "Foam" insulation systems, such as Polyisocyanurates, Polyurethanes, Expanded & Extruded Polystyrene, Polyester, Fibreglass.....not even Rock or Mineral wool insulation ( as they use binders such as sodium silicates, polyesters, melamine urea formaldehyde, polyamides, furane-based resins, phenolic resin-based binders).
If you can't put in your mouth.....don't put it in your house!