Is it necessary to have triple glazed windows in a Passive House in Australia?

It really depends on your location and thus the climate. All Passive House’s must be designed and tested using the specialist software PHPP and you might find, on occasion, that it is possible to use very high performance double glazing in some instances. If you do use double glazing, however, be aware that you will probably experience some thermal discomfort on very cold winter nights in mountainous regions whilst sitting close to such windows due to the temperature difference that will inevitably arise between the internal surface of the glass and the surrounding living space.