Green Star

Green Star is a comprehensive, voluntary environmental rating system which rates a building against nine environmental criteria. These are:

• environmental management
• indoor environment quality
• energy efficiency
• transport
• water
• materials of construction
• land use and ecology
• greenhouse emissions
• innovation

Green Star is a change agent tool, designed to bring about a mind shift in building design and construction at the premium end of the market.

The Green Star ratings are determined by the accumulation of points in each of the nine categories. Each Green Star tool is based upon a detailed technical manual which stipulates the design and performance features necessary for point accrual in each of the categories. Points are weighted by category and, together with the addition of any innovation credits, provides the final score.

There are four eligibility criteria for a project being assessed for a Green Star rating. These are:

• space use
• spatial differentiation
• conditional requirements
• timing of certification.

The Green Star rating tools

Green Star rates a building both at its design stage and after construction. Green Star includes the following tools applicable to the following building classes:

• Green Star – Communities (version 1.1)
• Green Star – Buildings (version 1), previously Green Star – Design & As Built (v1.3);
• Green Star – Interiors (version 1.3)
• Green Star – Performance (version 2)

GBCA is continuing to develop several new ratings tools, including Green Star for Fitouts, Green Star for Communities and Green Star Homes. These are designed to deliver better outcomes for fit outs and precincts and accelerative the industry’s trajectory towards a positive built environment.

As change agents, the rating tools will evolve by the release of new versions, raising the standard necessary to achieve a rating. This is one of the significant risks to be addressed in transactional documentation.

If a project was registered or certified under Green Star – Performance (version 1) then it must be transitioned to the new version by 1 July 2025. From this date onwards, all certifications will be done using version 2. Currently a project can be registered under version 1 and then transitioned over.

The ‘design’ tools assess the environmental attributes of a prospective development based upon the design documentation submitted at about 80% design completion. The design tool relies upon computer modelling of the energy performance of the building design, using the design brief, specifications and design drawings and computer simulation. The ‘as built’ tools assess the environmental attributes of the completed development at a time within 24 months after practical completion. The materials submitted for assessment by the ‘as built’ tool include final data sheets and as built drawings

How are ratings calculated?

Ratings are determined by the accumulation of points in each of the nine categories and then weighted by category. The weightings vary depending upon the jurisdiction and local circumstances. Weighted category scores are then added together to create a category total. Innovation credits, if any, are added to the category total before issue of a total score. A list of credits for each category is available here.

For example, a score of 63 points across the categories equates to a 5 star Green Star office design rating. A score of:

• 45 to 59 equates to a 4 Star rating, or best practice
• 60 to 74 equates to a 5 Star rating, or Australian excellence
• 75 or above equates to a 6 Star rating, or world leadership

Any building awarded a 6 Star Green Star rating will have zero operational carbon emissions. This star rating is assigned to buildings which showcase world leadership in delivering sustainability outcomes. This is an evolving rating as it reflects excellence in relation to the sustainability benchmark. Given that the sustainability benchmark has been progressively rising, achieving a 6 Star Green Star Rating today requires sustainability innovation beyond what has been required in the past.

5 Star Green Star buildings will be net zero ready, and 4 Star Green Star buildings will provide a new entry point for sustainable buildings, demanding 10% less upfront and operational emissions.

How to obtain a Green Star rating and certification

The right to promote the Green Star rating relies upon formal certification by the GBCA.

The certification process involves the registration of the project, submission of material that justifies credit accumulation and the assessment by a panel of certified assessors appointed by the GBCA.

The time of registration of a project is critical, as it will determine which version of the relevant tool is used in the certification process. Contract terms should precisely specify the particular tool version and the significance of the date of registration of the project should be noted.

Fees also apply to projects pursuing a Green Star certified rating, and cover the standard Green Star certification process. The fees are based on the rating tool.