BASIX Certificate

What Is a BASIX Certificate?

The Building Sustainability Index (BASIX) is a NSW Government initiative that ensures all new residential buildings and significant alterations meet mandatory sustainability targets. Introduced in 2004, BASIX is one of Australia's most established building sustainability schemes and applies to every residential development across New South Wales.

A BASIX Certificate is the official document generated once your project design meets all required sustainability targets. This certificate must be submitted alongside your Development Application (DA) or Complying Development Certificate (CDC) before construction can begin.

Who Needs a BASIX Certificate?

BASIX applies to all residential development types across NSW, including:

• New single dwellings — houses, townhouses, and terrace homes
• Multi-unit developments — apartments, dual occupancies, and residential flat buildings
• Alterations and additions — with an estimated cost of $50,000 or more
• Swimming pools and spas — with a capacity of 40,000 litres or more

Whether you are building a single home in suburban Sydney or a 200-unit apartment complex in Newcastle, a valid BASIX Certificate is mandatory before your project can receive development consent.

The Three BASIX Sustainability Indices

BASIX evaluates your project across three key sustainability areas, each with specific target scores that must be met:

1. Thermal Comfort

The thermal comfort index measures how well your building maintains comfortable indoor temperatures without excessive reliance on mechanical heating and cooling. It considers insulation, glazing, orientation, shading, and ventilation. Target scores vary by climate zone but typically require a reduction in heating and cooling loads compared to a benchmark building.

2. Water

The water index targets a 40% reduction in potable water consumption compared to the pre-BASIX average NSW home. This is achieved through water-efficient fixtures, rainwater tanks, and landscaping choices. Specific commitments such as dual-flush toilets, WELS-rated tapware, and rainwater collection systems contribute to meeting this target.

3. Energy

The energy index requires a reduction in greenhouse gas emissions from energy consumption. This covers heating, cooling, hot water, lighting, and pool/spa equipment. Solar panels, heat pump hot water systems, LED lighting, and efficient appliances all contribute to meeting the energy target.

BASIX Certificate Process

When you reach out through our service, here is what to expect:

1. Submit your enquiry — provide your project details, location, and architectural plans
2. Get matched with an assessor — we connect you with an accredited BASIX consultant suited to your project type and location
3. Assessment and optimisation — your assessor reviews plans, enters data into the BASIX tool, and optimises your design to meet all targets
4. Receive your certificate — once all indices pass, your BASIX Certificate is generated and provided for submission with your DA or CDC
5. Ongoing support — if plans change during construction, your assessor can prepare an amended BASIX Certificate

BASIX Certificate Cost

BASIX Certificate costs vary depending on the complexity of your project:

• Single dwelling: $600 – $900
• Dual occupancy: $800 – $1,200
• Multi-unit development: $1,200 – $2,000+
• Alterations and additions: $500 – $800

For a detailed breakdown of costs by project type, visit our BASIX Certificate cost guide.

Turnaround Time

Standard BASIX assessments are typically completed within 3-5 business days once your assessor has received all required plans and documentation. Many consultants in our network offer express turnaround within 1-2 business days for an additional fee. Multi-unit and complex developments may require 1-2 weeks depending on the number of unit types and design complexity.