BASIX Newsletter December 2025

Welcome to the second edition of BASIX News with updates on the BASIX tool and requirements.

BASIX Energy 100 homes

The NSW Government has legislated ambitious emissions reduction targets for NSW: a 50% reduction in greenhouse gas emissions by 2030 (compared to 2005 levels), and net zero emissions by 2050. The built environment plays a key role in achieving these goals.

Under BASIX, developers and designers can reduce a new home’s emissions by reaching a BASIX energy score of 100. This can only be achieved by all-electric homes powered by rooftop solar. To date, over 7,000 BASIX certificates have been issued for BASIX Energy 100 homes. We encourage developers and designers to explore cost-effective ways to reduce emissions in their designs.

NSW Housing Pattern Book

The NSW Government has launched 9 new architect-designed patterns for mid-rise apartments as the next phase of the NSW Housing Pattern Book. The Pattern Book designs also come with a streamlined planning pathway (noting that a BASIX certificate is still required).

Each design includes technical drawings, general guidance to support NatHERS and BASIX assessments, and a step-by-step guide to prepare a planning application. For more information or to purchase a pattern visit the NSW Housing Pattern Book website.

Explainer – Is a BASIX certificate always required for alterations and additions?

Planning regulations require a BASIX certificate for all alterations and additions to an existing BASIX building (such as residential premises) that cost $50,000 or more. This applies regardless of the nature of the alterations.

The online BASIX tool can be used to do the assessment and create a BASIX certificate. The initial part of the assessment requires you to answer a series of ‘yes’ / ‘no’ questions about the scope of the alterations (for example, are you installing a new hot water system or installing any new or altered lighting fixtures, floors, walls, ceilings, windows or skylights). It also asks you to provide the existing and proposed floor area.

If you answer ‘no’ to all of the questions and the floor area is unchanged, you will generate a BASIX certificate that has no BASIX commitments. Project examples where this may apply include verandas, covered unenclosed outdoor areas, or brickwork repairs.

However, in most cases, you will answer 'yes' to one or more of these questions. The BASIX tool then directs you to provide further details, and the BASIX certificate you generate will include some BASIX commitments relating to these details.

By completing the BASIX assessment and answering these questions for every alteration and addition costing $50,000 or more, it ensures that the development is assessed correctly.

Housekeeping amendments to legislation – embodied emissions

The NSW Government recently amended the legislation governing BASIX (the Sustainable Building State Environmental Planning Policy 2022) to clarify that if you are doing an alteration or addition and need a BASIX certificate, you do not have to calculate the embodied emissions of the materials you use. This is only required for new residential development. This has always been the policy intent, and the legislation has now been updated to clarify this.

Explainer – How does BASIX apply to a secondary dwelling, including granny flats

A secondary dwelling is defined under the planning legislation as a self-contained dwelling that:

(a) is established in conjunction with another dwelling (the principal dwelling), and 
(b) is on the same lot of land as the principal dwelling, and 
(c) is located within, or is attached to, or is separate from, the principal dwelling.

It is important to note that if there is an existing principal dwelling on the site, and you are building a new granny flat, or converting non-habitable space (for example, a garage or a shed) into a new dwelling, you must assess the new development as a new single dwelling house. This is not considered alterations and additions to an existing BASIX building. In these cases, the BASIX standards for new dwellings apply, and not the standards for alterations and additions.

The Secondary Dwelling (Granny Flat or Bedsitter) Help Note provides further guidance.

Contact us with your BASIX enquiries

To ensure that the BASIX team receives all your enquiries, please always include ‘BASIX’ in the subject line when emailing us.

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