BASIX Requirements

When Does BASIX Apply?

The Building Sustainability Index (BASIX) is a mandatory requirement under State Environmental Planning Policy (Building Sustainability Index: BASIX) 2004. It applies to all residential development across New South Wales, regardless of location, council area, or project value (above the minimum thresholds). Understanding whether your project triggers BASIX is the first step in the compliance process.

Development Types That Require BASIX

BASIX applies to the following residential development types in NSW:

New Residential Buildings

All new residential buildings require a BASIX Certificate, regardless of size or value. This includes:

• Detached houses (single dwellings)
• Semi-detached houses and terrace homes
• Townhouses and villa units
• Dual occupancies (attached and detached)
• Residential flat buildings (apartments)
• Secondary dwellings (granny flats)
• Boarding houses, group homes, and seniors housing

Alterations and Additions

BASIX applies to alterations and additions to existing residential buildings where the estimated cost of the work is $50,000 or more. The cost threshold is based on the total estimated cost of the building work, not including demolition, site preparation, or landscaping. The BASIX assessment applies to the new work and any significantly altered portions of the existing building.

Swimming Pools and Spas

Swimming pools and spa pools with a capacity of 40,000 litres or more require a BASIX Certificate. The assessment focuses on water efficiency (including pool covers and water-efficient backwash systems) and energy efficiency (pump sizing, solar heating where applicable). Pools below 40,000 litres are exempt from BASIX.

What Triggers a BASIX Assessment?

A BASIX Certificate is triggered whenever a Development Application (DA) or Complying Development Certificate (CDC) is lodged for residential development that falls within the scope outlined above. Specifically, BASIX is triggered when:

• A DA is lodged for new residential construction or alterations valued at $50,000+
• A CDC is applied for under the relevant State Environmental Planning Policies
• A modification to an existing approval results in changes that affect BASIX commitments
• A new pool or spa over 40,000 litres is proposed as part of a development application

BASIX Exemptions

While BASIX has broad application, certain development types and circumstances may be exempt:

• Heritage-listed properties — buildings listed on the State Heritage Register or identified as heritage items in a Local Environmental Plan may be exempt or have modified requirements where BASIX compliance would compromise heritage significance
• Minor alterations — renovations with an estimated cost below $50,000 are exempt from BASIX
• Small pools and spas — pools and spas with a capacity under 40,000 litres do not require BASIX
• Non-residential development — purely commercial, industrial, and retail development is not subject to BASIX (but must comply with NCC Section J)
• Temporary structures — certain temporary residential structures may be exempt

If you are unsure whether your project is exempt, we can connect you with an accredited assessor who can provide definitive advice based on your specific circumstances.

BASIX Target Scores

BASIX sets minimum target scores across three sustainability indices that your project must achieve. These targets have been progressively increased since BASIX was introduced in 2004:

Water Target

The water target requires a 40% reduction in potable water consumption compared to the average pre-BASIX NSW home. This applies to all residential development types. Meeting this target typically involves water-efficient fixtures (WELS-rated taps, showerheads, and toilets), rainwater tanks connected to appropriate end uses, and water-efficient landscaping.

Thermal Comfort Target

The thermal comfort target varies by climate zone and dwelling type. Recent updates have aligned BASIX thermal targets more closely with NatHERS 7-star equivalent performance. The target measures the annual heating and cooling loads of the building envelope, rewarding designs that maintain comfortable temperatures through passive design strategies including orientation, insulation, glazing selection, shading, and natural ventilation.

Energy Target

The energy target requires a reduction in greenhouse gas emissions from operational energy use. The specific reduction percentage varies by dwelling type but typically ranges from 25% to 50% compared to the benchmark. This covers heating, cooling, hot water, lighting, ventilation, and pool/spa equipment. Solar panels, heat pump hot water systems, and energy-efficient appliances are common strategies for meeting this target.

Recent Changes to BASIX

The NSW Government has made several significant changes to BASIX in recent years to align with national energy efficiency goals and the updated National Construction Code:

• Increased thermal targets — alignment with NCC 2022 has raised the bar for building envelope performance, effectively requiring NatHERS 7-star equivalent thermal performance for most new dwellings
• Updated energy benchmarks — energy targets have been recalibrated to reflect current building practices and available technologies
• Electrification incentives — the BASIX tool now more favourably scores all-electric homes with heat pump hot water and no gas connection, reflecting the shift toward electrification
• Solar panel recognition — rooftop solar PV continues to be an effective strategy for meeting energy targets, with the tool recognising current panel efficiencies
• Multi-unit methodology — assessment methodology for multi-unit developments has been refined to better account for shared walls, common areas, and diverse unit orientations

These changes mean that projects designed to older BASIX targets may not meet current requirements. If your project has been in design for an extended period, it is worth confirming with an accredited assessor that your current plans meet the latest BASIX targets before lodging your DA.