BASIX Certificate NSW: Requirements and How to Get One

If you're building a new home or undertaking a major renovation in New South Wales, you'll need a BASIX certificate before you can get development approval. BASIX (Building Sustainability Index) is a NSW Government planning tool that ensures new homes meet specific sustainability targets for energy, water, and thermal comfort. This guide explains what's required, how the process works, and what it costs.

What Is BASIX?

BASIX is a web-based assessment tool that measures the potential performance of a residential building against sustainability targets. It was introduced in 2004 and applies to all new residential buildings and significant alterations/additions in NSW. A BASIX certificate is a mandatory document that must be submitted with your DA or CDC application.

BASIX assesses three areas:

• Water: Reduction in potable (mains) water consumption compared to a benchmark
• Energy: Reduction in greenhouse gas emissions from energy use compared to a benchmark
• Thermal comfort: The building must meet a minimum NatHERS (Nationwide House Energy Rating Scheme) star rating

Current BASIX Targets (2026)

BASIX targets have been progressively tightened. The current targets for new single dwellings in Sydney metropolitan areas are:

Category	Target	What It Means
Water	40% reduction	The home must use 40% less mains water than the benchmark through water-efficient fixtures, rainwater tanks, and landscaping
Energy	50–55% reduction	The home must produce 50–55% fewer greenhouse gas emissions than the benchmark through efficient appliances, solar PV, and building design
Thermal Comfort	Varies by climate zone	Must meet NatHERS requirements — effectively a minimum 7-star rating under NCC 2025

Note: Targets vary by location within NSW. Regional areas may have different targets. Check the BASIX website for your specific postcode.

What You Need to Meet BASIX Targets

Water Target

Common strategies to meet the 40% water reduction target:

• Rainwater tank: A 2,000–5,000 litre tank connected to toilets and laundry is typically required. This alone can achieve a 15–25% reduction.
• Water-efficient fixtures: Low-flow showerheads (WELS 3-star minimum), dual-flush toilets (WELS 4-star), water-efficient taps
• Efficient irrigation: Drip irrigation systems, drought-tolerant landscaping
• Water-efficient appliances: Dishwashers and washing machines with high WELS ratings

Energy Target

Common strategies to meet the energy reduction target:

• Solar PV system: A 5–6.6kW solar system is now effectively required for most new homes to meet the energy target. This is the single biggest contributor to meeting the target.
• Heat pump hot water: Significantly more efficient than gas or electric resistance hot water
• LED lighting throughout: Standard requirement
• Efficient heating/cooling: Reverse-cycle air conditioning with high energy star ratings
• No gas connection: All-electric homes score better than dual-fuel homes. The trend toward all-electric is being driven partly by BASIX targets.

Thermal Comfort Target

Meeting the thermal comfort target requires good building design:

• Appropriate insulation levels (ceiling R5.0+, walls R2.5+, underfloor as required)
• Double glazing in most cases
• Correct window orientation (maximise north-facing glazing, minimise west-facing)
• Adequate eaves or shading for summer sun control
• Good sealing of the building envelope

How to Get a BASIX Certificate

The process is straightforward but requires specific information about your proposed building:

1. Prepare your design: You need floor plans, elevations, and specifications of major systems (hot water, heating/cooling, lighting, water fixtures).
2. Engage an assessor or do it yourself: BASIX assessments can be done by your architect, designer, energy assessor, or you can complete the online tool yourself (though this requires technical knowledge).
3. Complete the BASIX tool: Go to basix.nsw.gov.au and enter your project details — location, building type, floor area, construction materials, glazing, insulation, appliances, solar PV, water tank, and fixtures.
4. Review the results: The tool shows whether you pass or fail each target. If you fail, adjust your specifications and re-run until you pass.
5. Generate the certificate: Once all three targets are met, pay the fee and generate the BASIX certificate.
6. Submit with your application: Include the BASIX certificate with your DA or CDC application.

BASIX Certificate Cost

• BASIX online tool fee: Currently $62 for a single dwelling (set by the NSW Government)
• Professional assessor fee: $300–$800 if you engage a NatHERS assessor or building designer to complete the BASIX assessment for you
• NatHERS assessment: $500–$1,200 for the thermal modelling required to demonstrate compliance with the thermal comfort target

Total cost for a professional BASIX assessment including NatHERS: approximately $800–$2,000.

Common BASIX Issues and Solutions

Problem: Failing the energy target. The most common solution is to increase the size of the solar PV system. Adding 1–2kW of additional panels is often cheaper than redesigning the building or upgrading appliances.

Problem: Failing the water target. Increase your rainwater tank size or connect it to more fixtures (toilets + laundry + garden). A 3,000–5,000 litre tank connected to all three typically meets the target.

Problem: Failing the thermal comfort target. This usually requires design changes — better insulation, improved glazing, adjusted window sizing or orientation, or adding eaves. These changes are best made early in the design process.

BASIX and Your Builder

If you're using a volume builder, their standard designs are typically pre-assessed for BASIX compliance — ask for their BASIX report. If you're going custom, ensure your architect or designer includes BASIX compliance as a design requirement from the outset, not as an afterthought.

For more guidance on sustainability requirements for your KDR project, search your suburb on AusBuildCircle.com — our AI tool includes BASIX and NCC 2025 considerations in the feasibility analysis.