The new BASIX 7 star requirement (introduced in October 2023) marks a significant leap in building standards, pushing for higher performance in the design and construction of new homes.

While it is an exciting move forward for environmental sustainability and the comfort and health of our homes, we’re finding that it can be challenging for clients who are used to coasting through this approvals process.

This article talks about what’s changed and the options you have to continue to sail through the compliance process.

Quick summary of BASIX 7 stars

• BASIX certification is required for new homes built in NSW.
• BASIX includes a thermal comfort section, measuring the amount of heating and cooling a house needs to maintain a comfortable temperature – generally this information is created using a NatHERS thermal model and accredited assessors (like us!).
• The thermal performance requirements have changed and are now harder to achieve.
  • Heating and cooling load limits have become around 20-30% harder
  • Buildings now also have a total load limit, equivalent to NatHERS 7 stars.
• You have options! Pay attention to solar passive design basics, upgrade your building materials and get early advice in the process – particularly if you want to create a more interesting design.

Jump to our BASIX FAQs to find out more about what BASIX is and how it works.

The new requirements for BASIX: 7 stars, and heating and cooling load caps

Previously, BASIX focused solely on meeting a heating and cooling load limit, equivalent to a 5.6-star energy rating. That rating was relatively easy to achieve, particularly in more temperature coastal areas.

Under the new BASIX system, the building must (1) meet tougher heating and cooling loads and (2) meet a total load that is equivalent to a 7-star rating. The heating and cooling loads are specific to each climate region within the state, and in general they are 20-30% harder to achieve.

What does this mean in practice?

• Completing BASIX now takes longer due to more data entry and some frustrating errors in the portal as the Government rolls out the changes.
• The process is more demanding, so we recommend starting the star rating assessment early in your design process to avoid surprises.

What can you do?

Get the basics right

• Ensure that there is North-facing glass to living areas. This will reduce your build’s heating loads, as the winter sun will keep the build warm.
• Pay attention to the amount of windows – over 50% glass-to-floor ratio is going to make things challenging.

Improve the building specs

We recommend:

• R5 ceiling insulation
• R2.5 external wall insulation, including garage walls
• Under-slab and slab-edge insulation (mandatory as per NCC2022 updates–see our guide to underslab insulation)
• Double-glazed windows, at a minimum. Not all double-glazed windows are equal! Read our window comparison to find our favourites.

Do a preliminary thermal comfort model

Our recommended process for all clients is now to do two NatHERS assessments. The preliminary assessment takes place when the design is still being finalised, and the final assessment takes place at building approvals stage. Although it adds to the initial cost, there are three key reasons why this will save you time and money:

1. Design optimisation: The first assessment helps identify the most cost-effective measures to meet the energy efficiency requirements early in the design process. It allows for adjustments to the design before construction begins, potentially saving costs and time.
2. Budget management: An initial assessment can help estimate the financial impact of the energy efficiency measures required to meet the BASIX targets. It also allows you to assess if there are more affordable ways to reach compliance.
3. Compliance assurance: A preliminary assessment can act as a checkpoint to ensure the project is on track to meet the BASIX requirements.

When you work with our team, you’ll also get access to the Powerhaus app, an interactive dashboard that helps you connect design decisions with building specifications. 

Want to get started on your BASIX 7 star assessment? Simply request a quote to start working with our expert team.

BASIX FAQs

What is BASIX?

BASIX, an acronym for the Building Sustainability Index, is a scheme introduced by the government of New South Wales (NSW), Australia, to regulate the energy efficiency of residential buildings. It is designed to ensure homes are built to be more energy and water-efficient.

When apply for a building permit in NSW, you will need a BASIX certificate. The certificate has three main parts:

1. Thermal comfort (UPDATED): ensuring the building meets specific heating and cooling requirements. This section is where we undertake a thermal model and provide the modelled star rating as well as the heating and cooling loads of the building.  
2. Energy use (NEW): The energy use of the building is assessed, including lighting, heating, cooling and hot water systems.
3. Water efficiency: All water fixtures must have a minimum efficiency and water tanks installed on the property.
4. General building data (NEW): The NSW Government is now collecting a range of non-assessed building data.

What is the star rating and how is it measured?

The 7-star rating refers to a home’s overall thermal performance as assessed by the Nationwide House Energy Rating Scheme (NatHERS). It measures the energy needed to maintain comfortable heating and cooling levels, with a higher star rating indicating better thermal efficiency and less energy required.

In the BASIX portal, the thermal performance is assessed under the “simulation method”. You are required to provide the heating, cooling and total loads for the house. These numbers are calculated in line with the NatHERS thermal modelling process.

Can I complete BASIX myself?

Yes you can! Most of the BASIX sections can be completed by an engaged homeowner. However, we advise against completing the thermal comfort section using the DIY method. It is onerous and does not produce beneficial outcomes. We’re happy to complete the thermal comfort simulation section only – you can request a quote here.

What if my design can’t meet the 7-star rating?

If your initial design does not meet the 7-star requirement, you will need to make changes. Where possible, our team will suggest affordable improvements to insulation first followed by improvements to windows and design changes.

Do renovations and existing homes also need the 7-star rating?

No! You will still need a BASIX certificate; however, you will not need to meet the 7-star limits. The BASIX process for existing homes is more relaxed than for new homes.

Are there exemptions or alternative pathways to achieving the 7-star requirement?

The short answers is – no. Although the National Construction Code allows for alternative compliance in the form of a ‘Performance Solution’, the NSW Government is the only state in Australia that does not accept these.