BASIX MVHR & Air Tightness NSW 2026: Complete Guide to Ventilation and Thermal Performance BASIX MVHR Air Tightness NSW 2026: Complete Guide to Ventilation and Thermal Performance Quick Answer (40-60 words): BASIX requires mechanical ventilation with heat recovery (MVHR) for airtight homes ... Air Tightness BASIX MVHR Passive House Ventilation energy efficiency nathers-certificate Jul 7, 2026