BASIX Certificates for New South Wales
BASIX is the certificate every new home and major renovation in New South Wales needs for planning approval. We prepare it using the simulation method, which means full NatHERS modelling of your actual design, so you keep the windows, orientation and roof you want and still meet the higher standards.
What is BASIX?
BASIX, the Building Sustainability Index, is the New South Wales planning tool that sets minimum sustainability standards for new homes and major renovations. Introduced on 1 July 2004, it was the first scheme of its kind in Australia.
It is a legal requirement under the Environmental Planning and Assessment Act 1979 and the State Environmental Planning Policy (Sustainable Buildings) 2022. Every BASIX building must show, before it receives development approval, that it meets targets for water, energy and thermal comfort. The proof is a BASIX certificate, lodged with your development application or complying development certificate.
When you need a BASIX certificate
You need a BASIX certificate for:
- Any new residential dwelling, including houses, duplexes, townhouses and apartments.
- Alterations and additions valued at 50,000 dollars or more.
- Certain swimming pools and spas, generally those above 40,000 litres.
Because BASIX is part of the planning approval, the certificate must be in place before your development application or complying development certificate can be determined.
The four parts of a BASIX assessment
- Water
Targets to cut mains water use through efficient taps, showers and toilets, rainwater tanks and reuse systems. - Thermal comfort
A minimum building shell performance, now aligned to a 7 star NatHERS rating, expressed as caps on the energy needed to heat and cool the home. - Energy
Targets to reduce greenhouse gas emissions from hot water, appliances, lighting and heating or cooling, often met with efficient electric systems and rooftop solar. - Materials
Since October 2023, projects calculate and report the embodied emissions of key building materials. There is no pass or fail cap yet, but the data must be recorded.
The higher standards since October 2023
On 1 October 2023, New South Wales lifted the BASIX standards to align with the National Construction Code 2022. The thermal performance minimum rose from an average of 5.5 to 6 stars up to 7 stars on the NatHERS scale. The energy and greenhouse gas targets increased by roughly 7 to 11 percent, depending on location and dwelling type, and a new materials index was introduced.
The higher standards apply across the state, with limited exceptions for homes in the North Coast climate zones (9, 10 and 11) and apartment buildings up to five storeys. The transition period for building contracts signed before the change has now ended, so the higher standards apply to current projects.
Two ways to meet the thermal target, and why simulation wins
BASIX gives you two pathways for the thermal comfort section, and the choice has a real effect on your design.
- The DIY method
This uses the BASIX tool's built-in assumptions. It is quick, but conservative, and it often forces compromises to pass, such as smaller windows, lighter roof colours and extra insulation. - The simulation method
This uses full NatHERS modelling by an accredited assessor. Your actual design is modelled in accredited software for your site and climate, which usually unlocks far more design freedom: larger windows, your preferred orientation, even dark roofs, while still meeting the higher 7 star standard.
For most architecturally designed homes, the simulation method is the difference between redrawing your plans and keeping the design you want. As accredited NatHERS assessors, this is the pathway we run for you.
How we prepare your BASIX certificate
- Send your plans. Floor plans, elevations, sections, a window schedule and your specifications.
- We model the thermal performance. Full NatHERS simulation for your exact site and climate zone.
- We complete water, energy and materials. We optimise each section to meet target with the least cost and design impact.
- You receive your certificate. A BASIX certificate ready to lodge with your development application or complying development certificate.
Available remotely for projects right across New South Wales.
BASIX or NatHERS, what is the difference?
They are related but not the same. NatHERS is the national method for rating a home's thermal performance and Whole of Home energy use. BASIX is the New South Wales planning scheme that uses a NatHERS star rating for its thermal section, then adds water, energy and materials requirements on top.
In most other states, a NatHERS certificate is lodged directly for compliance. In New South Wales, the NatHERS result feeds into BASIX, and it is the BASIX certificate that the planning system requires. We handle both, so your NSW project is covered end to end.
Planning to build outside NSW as well? Our new home NatHERS assessments cover the rest of Australia. See the New Homes page for the standard NatHERS pathway.
Frequently asked questions
What is a BASIX certificate?
A BASIX certificate is the official document that shows a new home or major renovation in New South Wales meets the state's minimum standards for water, energy and thermal comfort. It is generated through the NSW Government's BASIX tool and lodged with your development application or complying development certificate.
Do I need a BASIX certificate?
If you are building a new home or carrying out alterations and additions worth 50,000 dollars or more anywhere in NSW, then yes. BASIX is part of the planning approval process, so the certificate is required before your application can be determined.
When is BASIX required for a renovation?
BASIX applies to alterations and additions valued at 50,000 dollars or more. Below that threshold a certificate is generally not required, though the project may still need to meet other building requirements.
Does BASIX apply to swimming pools?
Yes. Certain swimming pools and spas attached to a dwelling require BASIX consideration, generally those with a capacity above 40,000 litres. We can confirm whether your pool triggers a requirement.
What does BASIX measure?
Four things: water efficiency, thermal comfort, energy and greenhouse gas emissions, and, since October 2023, the embodied emissions of building materials. Your design must meet set targets for water, energy and thermal comfort to pass.
What thermal standard does BASIX require now?
Since 1 October 2023, new homes must reach a minimum 7 star thermal performance rating on the NatHERS scale, up from the previous average of 5.5 to 6 stars. This aligns BASIX with the National Construction Code 2022.
What changed in the October 2023 BASIX update?
The thermal standard rose to 7 stars NatHERS, the energy and greenhouse gas targets increased by roughly 7 to 11 percent depending on location and dwelling type, and a new materials index was introduced to record the embodied emissions of construction materials.
What is the difference between the DIY and simulation methods?
The DIY method uses the BASIX tool's built-in assumptions and is quick but conservative, often forcing compromises like smaller windows or lighter roofs. The simulation method uses full NatHERS modelling by an accredited assessor, which usually gives far more design freedom while still meeting the standard.
Why use the simulation (NatHERS) method?
Because it models your actual design rather than relying on conservative defaults. That typically unlocks larger windows, your preferred orientation and even dark roofs, while still reaching the 7 star standard. For most architecturally designed homes it is the difference between keeping your design and redrawing it.
Is BASIX the same as a NatHERS rating?
No, but they are connected. NatHERS is the national thermal and Whole of Home rating method. BASIX is the NSW planning scheme that uses a NatHERS star rating for its thermal section and adds water, energy and materials requirements. In NSW it is the BASIX certificate that the planning system requires.
Who can prepare a BASIX certificate?
Anyone can generate a basic certificate through the DIY method, but the simulation pathway must be carried out by an accredited NatHERS assessor. Using an accredited assessor also gives you the design flexibility and the best chance of a smooth approval.
How long is a BASIX certificate valid?
A BASIX certificate is valid for three months from the date it is issued, so it needs to be lodged with your development application or complying development certificate within that window. It can be revised later in the assessment if the design changes.
Can I still use a dark roof under the new standards?
Often yes, if you use the simulation method. Dark roofs can still be modelled, though you will usually need to strengthen other parts of the design, such as insulation or glazing, to offset the extra heat and still meet the standard.
Are there exemptions from the higher BASIX standards?
The higher standards apply across NSW, with limited exceptions. Homes in the North Coast climate zones (9, 10 and 11) and apartment buildings up to five storeys were held at the earlier standards. We can confirm which standard applies to your project.
How do I lodge my BASIX certificate?
The certificate is submitted as part of your development application or complying development certificate. Once your design meets all targets, we issue the certificate ready for you or your certifier to lodge with the consent authority.
Can a BASIX assessment be done remotely?
Yes. BASIX is based on your plans and specifications, so we can prepare the certificate remotely for projects anywhere in New South Wales without needing to visit the site.
What is the materials index?
Introduced in October 2023, the materials index records the embodied emissions of key building materials in your project. There is currently no pass or fail cap, but the information must be calculated and reported as part of the certificate.
How much does a BASIX certificate cost?
It depends on the size and complexity of the design and the number of dwellings. Send us your plans and we will provide a clear, fixed quote before any work begins.
Get your BASIX certificate sorted early
The earlier we model your design, the more freedom you have to meet the standards without costly changes. Send us your plans for a fixed quote and a clear timeframe.