Building Sustainability Index (BASIX) requirements can vary significantly depending on whether a project is a new home, renovation or extension.
While both project types may require BASIX assessments in NSW, the compliance pathway, documentation requirements and thermal performance expectations can differ considerably between developments.
Understanding these differences early in the design process can help reduce approval delays, redesigns and unexpected compliance issues later in the project.
New residential dwellings in NSW generally require a full BASIX assessment covering:
New homes are typically assessed as complete building systems. This means the orientation, glazing, insulation, construction materials, ventilation and hot water systems all contribute to the final BASIX outcome.
Thermal comfort requirements for new homes are often more comprehensive, requiring detailed assessment of:
Because the entire dwelling is being assessed, early passive design decisions can significantly influence compliance outcomes.
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Alterations and additions are assessed differently from new homes because only the proposed works are generally considered within the BASIX assessment scope.
Depending on the project size and approval pathway, BASIX requirements may focus more specifically on the new or modified areas of the dwelling rather than the entire house.
This can include areas such as:
In many renovation projects, achieving thermal comfort compliance can become more complex due to existing building limitations, orientation constraints or existing glazing conditions.
Older homes may also require design adjustments to improve compliance performance without significantly impacting the existing structure.
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Whether the project is a new home or renovation, early-stage BASIX planning can often help reduce redesigns and streamline the approval process.
Working through thermal comfort, glazing performance and energy efficiency considerations early in the design phase can help improve compliance outcomes while supporting long-term residential comfort and efficiency.
Projects that leave BASIX considerations until late in the approval process may require additional glazing upgrades, insulation changes or redesigns to achieve compliance targets.
Explore more BASIX guidance and residential compliance resources:
To read more about BASIX click here.