Introduction
If you are an architect, building designer, builder, planner or property consultant working on residential developments in New South Wales, understanding BASIX multi dwelling requirements is not optional — it is a legal obligation embedded in the NSW planning system. The Building Sustainability Index (BASIX) is a NSW Government online assessment tool administered by the Department of Planning, Housing and Infrastructure. It sets mandatory sustainability targets for all new residential buildings, including townhouses, dual occupancies, and Class 2 apartment buildings. Whether you are lodging a Development Application (DA) or a Complying Development Certificate (CDC), a valid BASIX certificate is a non-negotiable prerequisite. In this guide, we break down what BASIX multi dwelling compliance means in practice, how the assessment works, and what each project type needs to do to meet BASIX requirements in NSW
What Is BASIX Multi Dwelling and Who Does It Apply To?
According to the NSW Planning Portal, BASIX applies to all new multiple home developments in NSW. This includes units, townhouse rows, villa units, and subdivisions. The BASIX multi dwelling pathway is specifically designed to address the complexity of larger residential developments — particularly those with common areas such as car parks, lifts, shared gardens, and communal services that consume significant amounts of water and energy.
A project falls under the BASIX multi dwelling tool if it:
- Involves more than one dwelling on the same parcel of land
- Includes common property or services shared with other new or existing development
- Comprises a residential flat building (generally three or more units to be strata titled)
- Includes two or more terrace houses, row houses, or semi-detached houses
- Contains two or more detached or attached houses, including villa units and dual occupancy dwellings with shared infrastructure
- Involves several single dwellings on land subject to subdivision into separate lots
Understanding this classification is the first step toward achieving BASIX compliance correctly. Misclassifying your project type can lead to delays in planning approval and costly redesigns.
Three Pillars of BASIX Compliance for Multi-Dwelling Projects
BASIX Multi Dwelling: Specific Requirements by Development Type
The BASIX Assessment Process: Step by Step
Updated BASIX Standards from October 2023: What Changed?
Related Resources
Conclusion
Navigating BASIX multi dwelling requirements demands technical expertise, early engagement, and a thorough understanding of the three assessment pillars. From the first sketch to DA lodgement, embedding BASIX compliance into the design process — rather than treating it as a box-ticking exercise at the documentation stage — is the most effective way to avoid costly redesigns and project delays. For the most authoritative and up-to-date guidance on BASIX standards and BASIX requirements in NSW, always consult the NSW Planning Portal BASIX page and the BASIX assessment tool. If your project requires a NatHERS-accredited thermal comfort assessment or a full BASIX certificate for a multi-dwelling development, engage a qualified energy assessor or environmental consultant experienced in NSW residential sustainability compliance.
FAQs
BASIX multi dwelling compliance means that any NSW residential development involving two or more dwellings, or including common property, must complete a sustainability assessment through the BASIX online tool and obtain a BASIX certificate before lodging a DA or CDC. The assessment measures water efficiency, energy efficiency, and thermal comfort against government-set BASIX standards. All three targets must be achieved for the BASIX certificate to be issued.
Yes. All new BASIX multi dwelling developments in NSW — including townhouses, dual occupancies, villa units, and apartment buildings — require a valid BASIX certificate as a condition of planning approval. A BASIX certificate must be submitted with every DA or CDC lodged through the NSW Planning Portal. Without it, the application cannot proceed.
BASIX requirements for townhouses and apartments include meeting water efficiency targets (typically a 40% reduction in potable water use), energy efficiency targets (aligned with NCC 2022, with emissions reductions varying by climate zone), and a minimum 7-star NatHERS thermal comfort rating per dwelling. BASIX compliance for apartments additionally requires assessment of all common property energy and water use, including lifts, car parks, shared pools, and communal gardens. These BASIX standards apply to each individual unit within the development.
For dual occupancy projects, BASIX multi dwelling requirements apply when two dwellings exist on the same lot, particularly where common services or infrastructure are shared. A single BASIX certificate covers both dwellings, with each dwelling assessed individually for thermal comfort using NatHERS-accredited simulation software. Water and energy inputs capture shared systems. Achieving BASIX compliance for dual occupancies requires the same three-target framework as any multi-dwelling project.
The BASIX assessment process for multi-dwelling projects involves: registering on the BASIX tool, entering project details (dwelling type, number of dwellings, common area data), engaging an accredited NatHERS assessor for thermal modelling, entering construction material data (materials index), and meeting all water, energy and thermal comfort targets. Once all BASIX requirements are satisfied, a BASIX certificate is generated and lodged with the DA or CDC. The process must be completed before development approval is sought.
Yes. BASIX compliance for BASIX multi dwelling projects is more complex than for single dwellings. Key differences include: the DIY thermal comfort method cannot be used (a NatHERS-accredited assessor is mandatory); the assessment captures common property energy and water use; and each dwelling within the development must individually meet BASIX standards. Managing varied unit orientations, sizes and configurations — all while meeting BASIX requirements — demands early-stage integration of sustainability into the design process.
BASIX standards in NSW are the mandatory sustainability performance benchmarks set by the NSW Government for all new residential buildings. They are administered under the Environmental Planning and Assessment Act 1979 and SEPP (Sustainable Buildings) 2022. BASIX standards were significantly updated on 1 October 2023, raising thermal performance minimums to 7 stars NatHERS, tightening energy emissions targets in line with NCC 2022, and introducing an embodied carbon materials index. These BASIX standards apply to all new residential buildings across NSW, with limited exceptions for certain climate zones and building heights. For the most current BASIX requirements, always refer to the NSW Planning Portal.