BASIX is a New South Wales residential sustainability assessment used within the planning and development approval pathway. Where it applies, the project must complete the relevant assessment and carry the resulting certificate commitments into the design and construction documentation.

Green Star Homes is a separate voluntary certification framework administered by the Green Building Council of Australia. It is structured for eligible volume home builders delivering repeatable home designs or residential product ranges.

A NSW home may therefore require BASIX regardless of whether Green Star Homes certification is being pursued. The two pathways can be coordinated, but neither replaces the other. For full pathway guidance, visit the Green Star Homes Knowledge Hub and the BASIX assessment page.

The phrase failing BASIX is commonly used when a residential assessment has not yet achieved the water, energy or thermal performance requirements applying to the project. It may also refer more broadly to an incomplete assessment that cannot yet generate a Certificate.

In most cases, this is a design and documentation stage rather than a final refusal. The assessor reviews the result, identifies the part of the assessment requiring attention and determines whether the issue comes from incorrect information, an unresolved specification or a genuine performance shortfall.

This guide explains what happens next. For a broader explanation of BASIX targets, documentation and the NSW submission pathway, visit the BASIX Knowledge Hub.

A project that does not initially achieve its required BASIX outcome does not necessarily need a complete redesign. In many cases, the result can be improved through a targeted review of the assumptions, specifications or design elements affecting the relevant assessment component.

The important first step is diagnosis. Water, energy and thermal comfort respond to different inputs, and a change that improves one part of the assessment may have little effect on another. Repeatedly upgrading unrelated products can increase project cost without resolving the actual constraint.

This guide focuses specifically on how BASIX outcomes can be refined through a structured design process. For the wider assessment, certification and NSW submission pathway, visit the BASIX Knowledge Hub.

Uncontrolled air leakage can allow conditioned air to escape and external air to enter through gaps, penetrations and construction junctions. This can create draughts, reduce temperature stability and weaken the practical benefit of insulation and efficient heating or cooling systems.

Within a BASIX thermal comfort assessment using NatHERS software, air movement is represented through standardised modelling assumptions and inputs for relevant openings and penetrations. The assessment does not ordinarily measure the completed home’s actual whole-building leakage rate.

This guide explains that distinction. For the wider BASIX targets, documentation and NSW submission pathway, visit the BASIX Knowledge Hub.

Orientation is one of the fundamental inputs shaping residential thermal performance. It influences the solar exposure of walls and windows, the usefulness of winter sunlight, the risk of summer overheating and the effectiveness of different shading arrangements.

Within a BASIX thermal comfort assessment, orientation does not operate as a standalone compliance item. Its effect is expressed through the interaction between the building layout, glazing, shading, insulation, thermal mass, ventilation and the project’s climate conditions.

This guide focuses specifically on that relationship. For the wider BASIX process, targets and NSW submission pathway, visit the BASIX Knowledge Hub.