BASIX Certificate


The Building Sustainability Index

For homes, additions and multi units (in NSW) a BASIX Certificate is required before a Development Application is issued. Obtaining a BASIX Certificate means your design has met certain energy and water use objectives.

BASIX (The Building Sustainability Index) was introduced as part of the NSW Government’s 2004 initiative to ‘encourage sustainable residential development’ and is in effect part of the Environmental Planning and Assessment Act.

The BASIX certificate aims to help lower greenhouse gases, improve thermal comfort performance and reduce water consumption across New South Wales.

Certification is mandatory across single dwellings, multi unit developments and renovations if the cost is $50,000 or more.

BASIX - Certification Required

New residential dwellings built in NSW valued at $50,000 or more require a BASIX certificate as part of the development application stage. Properties we often prepare BASIX Certificates for include:

  • Single dwellings
  • Guest houses and grannie flats
  • Dual-occupancy
  • Pool/sauna/spa (40,000 or more litres of water)
  • Multi units
  • Villas
  • Townhouses
  • Renovations

We are here to help

BASIX is intended to be a Do-It-Yourself process for simple dwellings and extensions. However, it can get involved if you don’t pass and alternate solutions are needed. It also takes time which can be at a premium.

Class 2 buildings (multiple dwellings) and more complex Class 1 buildings (single detached home) require energy modelling. Application Solutions can help in this area.

The purpose of a BASIX Certificate is to ensure residential dwellings deliver effective water and greenhouse gas emissions reductions across NSW. BASIX does this by setting sustainability targets for water and energy use, as well as minimum building performance levels for thermal comfort of the proposed development.

The BASIX assessment requires water and energy use details of the proposed development to be entered into the online BASIX assessment tool. Proposed construction details of the building are also required for the Thermal comfort section of the assessment. At the end of the assessment, the BASIX tool will state if compliance is achieved or not. If compliance is achieved, then a BASIX certificate can be generated which includes the BASIX requirements, referred to in the certificate as “commitments”, that the development must comply with. If the development does not meet the BASIX targets, then changes will need to be made to the proposed development. If the proposed development is not passing the Thermal comfort section of the assessment, then the Simulation method can be selected to achieve compliance. The Simulation method must be undertaken by an Accredited Assessor using accredited simulation software. Application Solutions has a team of Accredited Assessors that can help you, should your development require the BASIX Simulation method.

A BASIX Certificate can be obtained by completing the online BASIX assessment. Anybody can register for a BASIX account and carry out an assessment using the online BASIX tool under the Do-it-Yourself (DIY) method. If the development doesn’t meet the BASIX DIY Thermal comfort criteria, then an Accredited Assessor will need to be engaged to carry out an assessment under the Simulation method using approved software. To help minimise the risk of not meeting the right criteria and investing in additional time and resources to reapply, contact us today.

A BASIX compliance certificate is a regulatory document that must accompany a Development Application (DA) or Complying Development Certificate (CDC) approval in NSW. A BASIX Certificate contains the BASIX requirements that a new development must achieve when approved for construction under the Environmental Planning & Assessment Act.

Anyone can generate a BASIX certificate under the Do-it-Yourself (DIY) assessment method. If the development doesn’t meet the DIY Thermal comfort criteria, then an Accredited Assessor will need to be engaged to carry out an assessment under the Simulation method using approved software.

We regularly share resources on our blog that you might find helpful with the DIY assessment. Alternatively, you can always contact us for help.

A BASIX certificate covers the water use, energy consumption and thermal comfort levels for a proposed residential dwelling development in NSW.


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Questions? Need assistance with your certification requirements? Please reach out to our friendly team.

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