BASIX Requirements NSW: Certificate + 7-Star New Homes

Last Updated: September 2026. This page reflects the BASIX increases effective 1 October 2023 and the transitional period that closed on 30 September 2024. Always confirm project-specific requirements on the NSW Planning Portal or with your certifier, since standards are reviewed periodically.

BASIX, the Building Sustainability Index, is the NSW planning tool that sets water, energy and thermal comfort targets for new homes. BASIX requirements apply to new dwellings, alterations and additions valued at $50,000 or more, and to pools or spas with a capacity of 40,000 litres or more.

Every assessment covers three areas: water, energy, and thermal comfort. Since 1 October 2023, the thermal comfort target has been raised to 7-star BASIX equivalence under the Nationwide House Energy Rating Scheme (NatHERS).

At Montgomery Homes, we manage this process for our clients from the first home design conversation through to lodgment, so you're never left guessing what your certificate needs to include.

On this page:

Glossary of BASIX terms
BASIX requirements for new homes (NSW)
7-star BASIX changes: what changed on 1 October 2023
How BASIX relates to NCC 2022 and NatHERS
What's on a BASIX certificate (and what commitments mean)
How BASIX assessments are completed
DIY vs simulation method (NatHERS): which one applies
What information you'll need for a BASIX assessment
BASIX materials index (embodied emissions)
How much does a BASIX certificate cost, and how long does it take
Transitional rules and contracts timing
What if you can't meet 7-star BASIX
FAQs
Official resources

Terms you may need to know:

BASIX: The Building Sustainability Index, the NSW tool that sets water, energy and thermal comfort targets for residential development
NatHERS: The Nationwide House Energy Rating Scheme, the national framework used to rate a home's thermal performance
Thermal performance: How well a home's design and materials manage heat gain and loss, which BASIX measures via heating, cooling and total load
BASIX tool: The online system, accessed through the NSW Planning Portal, used to complete a BASIX assessment and generate a certificate
DA: Development Application, the standard council approval pathway for new homes and major renovations
CDC: Complying Development Certificate, a faster approval pathway for projects that meet set criteria
Materials index: The BASIX module that records the embodied emissions of key building materials
WELS rating: The national water efficiency rating system used for taps, showerheads and toilets

BASIX requirements for new homes in NSW

If you're building a new home in NSW, a BASIX certificate has to be lodged with your Development Application (DA) or Complying Development Certificate (CDC) before council, or your certifier can approve the build. Here's what that looks like in practice:

A BASIX assessment is required before your DA or CDC can be submitted
The output is a BASIX certificate listing your water, energy and thermal comfort commitments
Your builder or a NatHERS-accredited assessor typically completes the assessment on your behalf
Common inclusions to meet the targets include WELS-rated fixtures, a rainwater tank, ceiling and wall insulation, and appropriately sized glazing

We handle the BASIX assessment and lodgment as part of our standard process, so you don't need to chase paperwork between your designer, assessor and council.

7-star BASIX changes: what changed on 1 October 2023

The most significant update to BASIX in recent years took effect on 1 October 2023, lifting standards across thermal performance and energy, while leaving water targets largely unchanged.

#1: Thermal performance (7-star equivalent)

The thermal comfort target increased from an average of 5.5 to 6 stars up to a 7-star NatHERS equivalent rating. This means homes need better insulation, glazing and passive design to pass their assessment.

#2: Energy targets (by floor area and climate zone)

Energy standards became stricter, with greenhouse gas emission reduction targets increasing by roughly 7-11%, depending on your climate zone and dwelling type. Unlike the flat targets previously used, energy targets now vary by floor area and location.

#3: Water (largely unchanged)

Water targets stayed the same through the 2023 update. Homes still need to reduce potable water use by up to 40% compared to the pre-BASIX benchmark, mainly through WELS-rated fixtures and rainwater tank connections.

Before vs after the 1 October 2023 changes

Thermal performance	Average of 5.5 to 6 NatHERS stars	7-star NatHERS equivalent rating
Area	Before	After
Energy	Flat reduction targets regardless of floor area	Targets vary by floor area and climate zone, roughly 7 to 11% higher
Water	Up to 40% less potable water use than the pre-BASIX benchmark	Largely unchanged
Materials	No materials reporting requirement	New materials index recording embodied emissions

Heating and cooling loads, and total load caps

BASIX thermal performance is assessed using heating, cooling, and total loads. A heating load is the estimated energy needed to keep the home warm over the course of a year, while a cooling load is the estimated energy needed to keep it cool.

The total load combines both, and the cap your home needs to meet depends on its NatHERS climate zone, so the same design can have different requirements in Newcastle compared with Western Sydney.

How BASIX relates to NCC 2022 and NatHERS

As of 1 October 2023, BASIX standards are aligned with and complement the National Construction Code (NCC) 2022. In practical terms, this means the thermal and energy expectations baked into BASIX now match the national benchmark rather than sitting as a separate, NSW-only standard.

For homeowners, it means a 7-star BASIX outcome and NCC 2022 energy efficiency provisions are working toward the same result: a home that needs less heating and cooling to stay comfortable.

What's on a BASIX certificate (and what commitments mean)

A BASIX certificate lists the sustainability commitments your home must meet. These commitments become conditions of your development consent, which means your build has to match what's on the certificate, not just what's in your original concept plans.

Typical BASIX commitments (with examples)

Water	Install a rainwater tank connected to toilets and the laundry	Cuts potable water use and contributes to the water target
Area	Example commitment	Why it helps
Water	Fit taps and showerheads with a minimum WELS rating	Reduces daily water consumption without changing how fixtures are used
Energy	Install a heat pump or solar hot water system	Lowers greenhouse gas emissions from hot water, a major energy draw
Thermal	Use insulation with a specified R-value in ceilings and walls	Reduces reliance on heating and cooling to stay comfortable
Thermal	Specify glazing type and size to match orientation	Manages heat gain and loss through windows across the seasons
Materials	Record the materials used for floors, walls, ceilings and glazing	Feeds into the materials index, so embodied emissions can be tracked

How BASIX assessments are completed

Getting from plans to an approved BASIX certificate follows a fairly consistent workflow, whether you're using the DIY method or a NatHERS simulation. Here's how it works:

Gather your plans and key specifications, including floor area, orientation, glazing and fixtures
Enter these details into the BASIX tool, using either the DIY method or the NatHERS simulation
Generate your BASIX certificate once the water, energy and thermal comfort targets are met
Lodge the certificate with your DA or CDC application
Build to the commitments listed on the certificate
Provide compliance evidence if your certifier or council requests it during construction

We submit the BASIX assessment on your behalf, so this workflow happens in the background while you focus on your design and selections.

DIY vs simulation method (NatHERS): which one applies

The BASIX tool offers two paths to meet the thermal comfort target, and which one applies depends on your project's complexity.

Simple, standard designs may be eligible for the DIY method, where you enter fixed construction details directly into the BASIX tool
Complex designs, multi-dwelling projects, or homes that don't pass the DIY thermal comfort check generally need the simulation method
The simulation method requires NatHERS modelling by an accredited assessor using approved software
If you're unsure which applies, your assessor or builder can confirm this early, before your DA or CDC is prepared

A simple way to think about it: if your design is straightforward and uses standard materials, DIY may be enough. If your home has custom glazing, unusual orientation, or multiple dwellings on one site, simulation is the more likely path.

What information you'll need for a BASIX assessment

Before your assessor or builder can run a BASIX assessment, you'll need to have a few design details finalised. The main inputs are:

Total floor area of the home
Orientation of the block and the building
Window sizes and glazing types
Insulation levels for walls, ceilings and floors
The hot water system you're planning to install
Fixtures and fittings, including taps, showerheads and toilets
Appliances such as dishwashers and cooktops
Landscaping details, including any pool or spa

Having these details ready before your DA or CDC stage helps avoid delays, since incomplete information is one of the most common reasons a BASIX assessment needs to be revised.

BASIX materials index (embodied emissions), what it is and when it applies

Since 1 October 2023, BASIX assessments have included a materials index that estimates the embodied emissions of the materials used to build your home, covering floors, walls, ceilings, roof and glazing.

Embodied emissions are the greenhouse gases generated during the extraction, manufacture and transport of building materials, as distinct from the ongoing energy your home uses once it's built.

For most homeowners, this means your assessor or designer records the materials being used for these building elements as part of the standard assessment process. There's currently no pass-or-fail limit attached to this figure, as it's a reporting requirement while the NSW Government gathers data to inform future benchmarks.

You can find the official technical guidance in the Embodied Emissions Technical Note on the NSW Planning Portal.

How much does a BASIX certificate cost, and how long does it take?

Costs vary depending on your project, and the market for BASIX assessments and NatHERS modelling isn't uniform, so it's worth getting a specific quote for your design rather than relying on a single figure.

The main cost drivers are:

Project complexity, including custom glazing, raked ceilings or unusual orientations
Whether the DIY method or the NatHERS simulation applies
Whether it's a single dwelling, alterations and additions, or a multi-dwelling development
NSW Government fees for generating the certificate, which sit alongside your assessor's professional fee

Turnaround times also vary with complexity, and a straightforward single dwelling assessment is generally quicker than a multi-dwelling simulation. Building with Montgomery Homes means these costs and timing are incorporated into your overall tender, since we manage the assessment and lodgment as part of your project.

Transitional rules and contracts timing

The higher BASIX standards included a transition period for projects already underway. Eligible applicants with a building contract signed before 1 October 2023 could continue under the earlier standards, with that transition period ending on 30 September 2024.

That transition window has now closed, so any new BASIX certificate generated now needs to meet the current standards, regardless of when your project was first conceived.

If you have questions about which standards apply to an existing DA or CDC, you can always contact your dedicated Montgomery Homes team member for more clarity.

What if you can’t meet 7-star BASIX?

If your design doesn't pass its thermal comfort assessment on the first attempt, there are several levers worth working through with your designer or assessor, generally in this order:

Review shading and orientation, since small adjustments can meaningfully change heat gain
Increase insulation levels in walls, ceilings or underfloor areas
Reconsider your glazing specification, including glass type and window sizing
Improve air leakage and sealing around windows, doors and penetrations
Add ceiling fans to bedrooms and living areas to support natural ventilation

These are options to work through with your design team rather than guaranteed fixes, since every home's result depends on its specific site and layout. At Montgomery Homes, our team works through these levers with clients whose initial designs need adjustment to meet the current thermal target.

FAQs

Who needs a BASIX certificate? Anyone building a new home, making alterations or additions worth $50,000 or more, or installing a pool or spa with a capacity of 40,000 litres or more, needs a BASIX certificate before their DA or CDC can be approved.

What's on a BASIX certificate? A BASIX certificate lists your home's sustainability commitments across water, energy and thermal comfort. These become conditions of your development consent, so your build needs to match what's specified.

Should I use the DIY method or the NatHERS simulation? Simple, standard designs may qualify for the DIY method, while complex designs and most multi-dwelling projects need NatHERS simulation by an accredited assessor. Your builder or assessor can confirm which applies to your project.

Do renovations or alterations need 7-star BASIX? A BASIX certificate is still required for alterations and additions valued at $50,000 or more, but the thermal comfort pathway for existing homes differs from that for new builds. Renovation projects typically compare the proposed work against the existing dwelling's performance rather than applying a flat 7-star target, so it's worth confirming the exact pathway with your assessor.

When do the 7-star BASIX changes apply to my project? The higher standards apply to BASIX certificates generated from 1 October 2023 onward. The transition period for contracts signed before that date closed on 30 September 2024, so current projects need to meet the updated standards.

What happens if my design fails its BASIX assessment? Your assessor will usually recommend design adjustments, such as improved insulation, revised glazing or better shading, and you can revise your plans and resubmit. This is a normal part of the design process rather than a major setback.

What information do I need to provide for a BASIX assessment? You'll need your floor area, orientation, window sizes and glazing types, insulation levels, hot water system, fixtures and appliances, and landscaping details, including any pool or spa.

How much does a BASIX certificate cost, and how long does it take? Costs and timeframes depend on your project's complexity and whether the DIY or simulation method applies. Government fees and your assessor's professional fee both factor in, so it's worth getting a project-specific quote.

What is the BASIX materials index? The materials index is a reporting requirement introduced in 2023 that records the embodied emissions of key building materials, including those used for floors, walls, ceilings, and glazing. There's currently no pass-or-fail limit attached to this figure.

When don't you need BASIX? BASIX generally doesn't apply to alterations and additions under $50,000, or to non-habitable structures that don't meet the definition of a BASIX-affected dwelling. Thresholds and definitions can be specific to your project, so it's always worth confirming your exact requirements with the council before you finalise your plans.

An extra note on energy bill savings… Government estimates suggest homes meeting the higher BASIX standards could save as much as $980 a year on energy bills, though these estimates are subject to change and actual savings will vary by home and household. These figures are modelled averages rather than a guarantee for any individual build.

Building your BASIX-compliant home with Montgomery Homes

Bringing your dream home to life shouldn't mean getting lost in paperwork. Whether you're planning a single-storey stunner or a spacious two-storey home, our team manages your BASIX assessment and lodgement as part of the build process, so your certificate, your DA or CDC and your construction plans all line up.

If you're building on a sloping site, we apply the same approach to BASIX planning as we do for the rest of your new home builds, factoring in orientation and site conditions from the start.

And if you're weighing up a knockdown rebuild, we can help you understand how BASIX applies to your specific block before you commit to a design.

For homeowners looking to go beyond the minimum, our energy-efficient inclusions are worth exploring alongside your BASIX assessment, as some upgrades that support compliance also improve everyday comfort. Learn more about our inclusions and upgrades, or contact our friendly team and get the ball rolling on your BASIX-compliant build today!

Official resources & where to get more information

These are official government sources for confirming current requirements, fees and standards for your specific project:

More information from the Montgomery Homes team: