BASIX Certificate & Residential Rebuilding Project: Things To Consider

BASIX Certificate & Residential Rebuilding Project

If you’re planning to knock down and rebuild a home or residential structure in New South Wales, Australia, you’ll need to obtain a BASIX certificate. 

This certificate is a mandatory requirement for all new homes and major renovations, and it ensures that any residential structure meets the state’s thermal comfort, water and energy efficiency standards.

In this blog post, we’ll take a closer look at the BASIX certificate NSW and how it fits into the picture when you’re planning a knockdown and rebuild project.

What is a residential rebuilt project?

When contemplating a new home, there’s a revolutionary option that ensures the occupants don’t bid farewell to your cherished neighbourhood: the knockdown rebuild. 

  • This innovative approach involves the complete demolition of an existing property, followed by the meticulous clearing and preparation of the land. 
  • Subsequently, a brand new home is constructed to cater to the evolving needs of your family.
  • The process enables occupants to design a home that reflects their preferences, accommodates their family’s requirements, and seamlessly integrates with the surroundings they’ve grown fond of over the years.

According to data from the Housing Industry of Australia (HIA), an impressive one-third of all new detached homes in the country are now the result of a knockdown rebuild. 

This surge signifies a shift in homeowners’ preferences, showcasing a growing inclination towards investing both time and resources into creating personalised, modern living spaces within the familiarity of established neighbourhoods.

In recent years, the trend of knockdown rebuilds has gained substantial traction in Australia. So, if you’re a builder or architect in Australia, you might be taking up rebuilding projects. But without a BASIX certificate, you can’t proceed with rebuilding a home. So, let’s take a look at what BASIX is.  

What is a BASIX certificate?

A BASIX certificate is a document that certifies that your new home or major renovation meets the minimum water and energy efficiency and thermal comfort standards set by the NSW government. 

These standards are designed to help reduce greenhouse gas emissions, promote potable water conservation and create more sustainable homes. 

To obtain a BASIX certificate, you’ll need to have your home assessed by an accredited BASIX assessor. The assessor will calculate your home’s predicted energy and water rating, which is a measure of how efficient your home is likely to be. 

If your home meets the minimum energy and water rating requirements, you’ll be issued with a BASIX certificate. Additionally, you need to obtain a NatHERS certificate to demonstrate thermal comfort efficiency in the BASIX thermal comfort section. 

BASIX Certificate Elements To Consider While Rebuilding a Home


To optimise energy efficiency and year-round comfort, it’s crucial to leverage the sun’s movement.

  • In summer, shield northern windows from intense midday sun using eaves or window hoods. Minimise or shade eastern and western windows to counter the harsh afternoon sun. 
  • In winter, design north-facing windows to capture sunlight and warmth, reducing the need for excessive heating.
  • Aligning the longest house axis east-west maximises winter sun exposure while minimising summer sun exposure. 
  • Position living areas and kitchens north/northeast, service areas west/southwest, and studies/bedrooms to the south.

For homes with non-ideal orientations, narrow blocks, or significant shading, skilful design integrating landscape elements is crucial. For commercial buildings, the JV3 assessment is ideal to attain sustainability goals. 

Wrapping and Insulation 

Insulating your home is a smart and cost-effective way to save on heating and cooling. While upgrading windows can be expensive, prioritising insulation provides long-lasting benefits.

  • Understanding R-ratings helps assess insulation effectiveness. Higher R-ratings mean better performance, which is essential for achieving 7-star ratings on your NatHERS certificate.
  • Don’t forget neglected areas like garages and spaces between levels; insulating them boosts overall energy efficiency.
  • Balancing wall thickness is crucial. Thicker walls provide better insulation, but architects find ways to optimise thickness without sacrificing space.
  • Solutions like thermal breaks or extra insulation around metal frames are effective but may increase costs.
  • Strategically placing windows and using advanced glazing technologies help achieve NatHERS 7-star ratings by harnessing natural light while minimising heat transfer.
  • For energy-efficient lighting, be cautious with downlights. Improper installation can compromise insulation. Using insulation covers for downlights mitigates their impact on energy efficiency.

Ceiling fans 

Ceiling fans are an often-overlooked and cost-effective cooling solution for homes.  

  • They’re more energy-efficient than air conditioning, allowing you to set your thermostat higher and significantly save on bills. 
  • Ceiling fans also circulate air, preventing stagnant air, moisture build-up, and issues like mould.
  • In terms of interior design, ceiling fans come in various styles to complement your decor. They can be a statement piece, adding visual interest and personality to a room. 
  • LED lighting options provide both accent lighting and comfort for relaxation or work areas.

Lighter Roof Colours

From October 1, the NSW Building Sustainability Index (BASIX) plans to implement stricter requirements for new homes to obtain a BASIX certificate, including the use of lighter roof colours. 

Using lighter colours in home design offers several advantages:

  • Reduce urban heat island effect: Lighter roofs reflect more sunlight and absorb less heat, alleviating the urban heat island effect.
  • Improve energy efficiency: Lighter roofs decrease heat transfer into a home, lowering cooling costs and enhancing energy efficiency.
  • Increase comfort: Lighter roofs create a more comfortable indoor environment by reducing heat absorption, especially in hot summer months.
  • Extend roof life: Lighter roofs tend to last longer due to reduced thermal stress and UV damage compared to darker roofs.

Balancing Low Carbon Materials and Operational Technologies

To tackle climate change, the construction industry is working to minimise the carbon footprint of new homes. 

This involves decisions on budget allocation between low-carbon materials and operational footprint-reducing technologies like solar and batteries.

Low Carbon Materials

  • Choosing materials like recycled or locally sourced options cuts a home’s embodied carbon, lowering energy use and emissions. 
  • Sustainable practices like efficient insulation enhance ongoing energy efficiency. While low-carbon materials may have higher upfront costs, collaboration is crucial for budget balancing.

Operational Footprint Technologies

Investing in technologies such as solar panels and batteries decreases a home’s ongoing carbon footprint. 

  • Solar panels use renewable energy, reducing reliance on fossil fuels. 
  • Although these technologies require upfront investment, government incentives and savings make them increasingly appealing. 
  • Despite initial costs, advancements and economies of scale benefit these technologies over time.

Wrapping up

Whether you need a JV3 assessment or BASIX certification, it is recommended that you collaborate with a renowned building consultant for the best outcomes. 


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