BASIX Requirements Explained: A Guide for NSW Homeowners & Builders
BASIX is mandatory for NSW residential development. It sets targets for energy, thermal comfort and water that your project must meet to gain approval.
BASIX – the Building Sustainability Index – is one of the first compliance hurdles for any residential project in New South Wales. Here’s what it covers, who needs it, and how to get one.
What is BASIX?
BASIX is a NSW Government scheme that ensures new homes and major renovations are designed to be more sustainable. Every relevant project must obtain a BASIX Certificate demonstrating it meets the state’s targets in three areas.
The three BASIX targets
| Area | What it measures |
|---|---|
| Energy | Reduction in greenhouse gas emissions through efficient design, appliances and systems. |
| Thermal comfort | How well the building fabric keeps the home comfortable – usually demonstrated with a NatHERS assessment. |
| Water | Reduction in potable water use via efficient fixtures, rainwater tanks and landscaping. |
Who needs a BASIX Certificate?
- New dwellings – houses, dual occupancies, townhouses and apartments.
- Alterations and additions at or above the cost threshold.
- Swimming pools and spas over 40,000 litres.
- Both DA (Development Application) and CDC (Complying Development Certificate) pathways.
How the BASIX process works
- Your assessor enters the project details into the NSW Planning Portal BASIX tool.
- The design is tested against the energy, thermal comfort and water targets.
- Commitments are optimised so they’re practical and affordable to build.
- A BASIX Certificate is issued, listing the commitments that must appear on your plans and be delivered on site.
How much does BASIX cost?
Fees depend on dwelling type and complexity. A single dwelling is usually a flat fee; multi-dwelling and mixed-use projects are quoted per project. The bigger cost to watch is the build commitments themselves – which is why optimising them early matters.
Tips to pass BASIX without overspending
- Get advice at concept stage – orientation and window decisions are cheapest to change early.
- Prepare BASIX and NatHERS together so the documents align.
- Choose efficient fixtures and a good hot water system – they move the energy score significantly.
- Use shading and glazing smartly rather than defaulting to expensive double glazing everywhere.
Frequently asked questions
How long is a BASIX Certificate valid? Three months from issue for lodgement. It can be re-issued if needed.
Do I need NatHERS as well? Usually yes – the thermal comfort target is most reliably met via a NatHERS assessment.
Ready to start? See our BASIX service or request a quote.
BASIX & NatHERS specialists, a division of Contrive Consultants. We help NSW homeowners and builders achieve energy-efficient, compliant homes.