If you are planning any residential construction or major renovation in NSW, you will need to understand BASIX requirements. The Building Sustainability Index (BASIX) is a mandatory environmental assessment tool that applies to most residential development in New South Wales, designed to deliver water and energy savings while improving thermal comfort.
What is BASIX?
BASIX stands for Building Sustainability Index. It was introduced by the NSW Government in 2004 to ensure new homes and renovations meet minimum sustainability standards. BASIX assesses three key areas:
Water consumption: Targeting a 40% reduction compared to typical homes. Energy consumption: Targeting reductions in heating and cooling loads. Thermal comfort: Ensuring homes maintain comfortable temperatures with minimal energy use.
When is BASIX Required?
A BASIX Certificate is required for most residential developments in NSW, including all new homes and dwelling houses, granny flats (secondary dwellings), dual occupancies and duplexes, multi-unit residential developments, alterations and additions over $50,000 in value, and swimming pools and spa pools (separate certificate).
There are some exemptions, including heritage buildings and certain types of alterations, but these are limited.
BASIX Target Scores
To obtain a BASIX Certificate, your project must achieve minimum target scores in water and energy/thermal comfort. The specific targets vary depending on type of development (house, unit, alteration), climate zone (Sydney is in Climate Zone 5 - Warm Temperate), and whether it is a new building or alteration.
For new houses in Sydney, typical targets are: Water: 40 points (40% reduction), Thermal Comfort: Pass requirements for heating and cooling loads, Energy: Varies but typically requires significant reduction in energy consumption.
Common BASIX Commitments
Water Efficiency: 3-star WELS rated taps and showerheads, dual flush toilets (4/3 star WELS rating), rainwater tanks connected to toilets, laundry, or external taps, water-efficient dishwashers and washing machines, and flow restrictors on fixtures.
Energy and Thermal Comfort: Insulation in walls, ceilings, and floors (specific R-values), energy-efficient glazing (appropriate glass selection), external shading devices on windows, light-colored roofing materials, sealing gaps and draft-proofing, energy-efficient hot water systems (heat pump or solar), and LED lighting throughout.
The BASIX Assessment Process
The BASIX assessment is conducted using an online tool provided by the NSW Government. The process involves:
Initial Design: We design your project with BASIX requirements in mind from the start. Data Entry: Detailed information about the design is entered into the BASIX tool. Score Calculation: The system calculates water and energy scores based on commitments. Optimization: If targets are not met, we adjust design features and commitments. Certificate Generation: Once targets are achieved, a BASIX Certificate is issued. Lodgement: The certificate must be submitted with your DA or CDC application.
Impact on Design and Cost
BASIX requirements do influence design decisions and can affect project costs. However, when incorporated thoughtfully from the beginning, the impact is manageable.
Good passive design—proper orientation, appropriate glazing, and effective shading—can achieve BASIX compliance with minimal additional cost while creating more comfortable, efficient homes.
Need help navigating BASIX requirements? Contact us for design guidance that meets sustainability targets efficiently.
Need help navigating BASIX requirements? Contact us for design guidance that meets sustainability targets efficiently.