Why are conventional Australian houses significantly less efficient and why do they end up costing so much more than Passive Houses?

Three words…minimum building code! More specifically, insufficient insulation detailing, vapour barriers that are inevitably punctured, uncontrolled thermal bridging, poor quality windows (80% of the market is single glazed!) and dated construction techniques. To summarise, poor building envelopes! To make up for these subpar practices, air-conditioners and heaters are required to make up for all of that energy loss which ends up costing homeowners each and every year.