Green Star Requirements for Building Services

What You Need to Know

Green Star is Australia's building rating system. It scores how well a building performs on energy, water, indoor air quality, and carbon. The Green Building Council of Australia (GBCA) runs the program. Green Star Buildings v1.1 is the current tool. It applies to new builds and major refits. Every mechanical, electrical, and hydraulic system in the building affects the final score.

A 4 Star rating means "Best Practice." A 5 Star rating means "Australian Excellence." A 6 Star rating means "World Leadership." The building needs at least 15 points out of 100 for 4 Stars, 35 points for 5 Stars, and 70 points for 6 Stars. All projects must also pass 10 minimum expectations before any points count.

From July 2026, the Commonwealth Government will require a minimum 4 Star Green Star rating for any government office space over $15 million.

• The building must use at least 10% less energy than the NCC Section J reference building. This is a minimum expectation, not a bonus credit. (Green Star Buildings, Energy Credit)
• Outdoor air rates must exceed AS 1668.2:2012 by at least 50% across 95% of regularly occupied areas. For offices, that means 15 L/s per person instead of the code minimum of 10 L/s per person. (Green Star Buildings, Clean Air Credit)
• Buildings targeting 5 or 6 Stars (registered after 1 January 2023) must follow the Climate Positive Pathway: fossil fuel free, highly efficient, powered by renewables, and built with lower upfront carbon. (GBCA Climate Positive Pathway)
• All standard building operations must be all-electric. Fossil fuels for emergency power must stay below 1% of total building energy. (Green Star Buildings, Energy Source Credit)
• Potable water use must be reduced using water-efficient fixtures rated under the WELS scheme. Up to 12 points are available through the Potable Water credit. (Green Star Buildings, Credit 18B)
• Upfront carbon from building materials must be cut by at least 10%. Building services equipment counts toward this under CIBSE TM65ANZ. (Green Star Buildings, Upfront Carbon Credit)
• The building must have a Zero Carbon Action Plan that lists all refrigerants, energy-consuming systems, and the carbon reduction strategy. (Green Star Buildings, Minimum Expectation)
• At least 80% of construction and demolition waste must be recycled. (Green Star Buildings, Environmental Management)

Start with the energy model. Green Star requires energy modelling that builds on the NCC Section J JV3 method. The proposed building plus all services must beat the reference building by at least 10%. The HVAC consultant and energy modeller need to work together from day one. Every assumption in the model - supply air temperatures, fan power, chiller efficiency - must match the design documents.

Ventilation drives a big part of the mechanical design. The 50% uplift over AS 1668.2 means bigger outdoor air intakes, larger AHU coils, and higher fan energy. For a 2,000 m² office floor with 200 people, you go from 2,000 L/s (code minimum) to 3,000 L/s. That increase affects duct sizes, plant room space, and cooling loads.

Water credits touch hydraulic design directly. The GBCA Potable Water Calculator scores reductions across sanitation, HVAC cooling tower water, irrigation, and fire system test water. Rainwater harvesting with a properly sized tank, low-flow WELS-rated fixtures, and closed-loop cooling systems all earn points.

The all-electric rule changes the game for heating. Gas boilers are out. Heat pumps, electric boilers, or heat recovery systems are the standard path. This affects electrical load calculations, switchboard sizing, and transformer capacity.