Viewshed Modelling for Urban Development and Site Planning

The three names are often grouped together because each can influence the design and documentation of a residential development. That does not make them interchangeable. NatHERS is a residential energy-rating framework. BASIX is a New South Wales residential sustainability requirement. BESS is a Victorian planning-stage sustainable design assessment.

The correct starting point is usually the project location, building type and approval pathway. A house in New South Wales may need BASIX together with NatHERS modelling. A Victorian apartment development may need BESS at planning stage and NatHERS as a separate residential energy assessment. A Victorian commercial development may require BESS but would not use NatHERS.

This guide compares the role of each framework without replacing the detailed requirements of the individual pathways. For project-specific guidance, review the relevant council, planning authority and building approval requirements.

A building does not become a certified Passive House simply because it uses high-performance windows, additional insulation or mechanical ventilation. Certification considers whether the complete building has been modelled, designed, documented and delivered in accordance with the applicable Passive House Institute criteria.

The process is carried out through an appropriately accredited Passive House Building Certifier. The certifier independently reviews the project information and determines whether the building satisfies the requirements for the intended certification pathway.

This guide focuses specifically on how certification develops. For the wider standard, five principles and Australian climate application, see the Passive House in Australia Knowledge Hub.

A building may contain substantial insulation and high-performance windows while still losing conditioned air through gaps between construction elements. Wall-to-floor junctions, window perimeters, roof connections and service penetrations can collectively undermine the intended performance of the envelope.

Passive House design addresses this by establishing a defined airtight layer around the conditioned building volume. The layer may be formed by membranes, boards, plaster, concrete or other suitable materials, but it must remain continuous across changes in construction.

This article focuses specifically on airtight-envelope design and testing. For the wider standard, five principles, PHPP and Australian climate application, see the Passive House in Australia Knowledge Hub.