How to specify concrete that meets Green Star Buildings and Green Star Infrastructure requirements in Australia 2026
A complete 2026 guide to Green Star concrete requirements — covering embodied carbon targets, supplementary cementitious material (SCM) use, recycled content, responsible sourcing credits, EPD requirements, and mix design strategies for achieving Green Star ratings in Australia.
Practical guidance for engineers, specifiers, and project teams targeting Green Star certification through sustainable concrete specification in Australia
Green Star is Australia's leading green building rating system, administered by the Green Building Council of Australia (GBCA). Concrete — as the most widely used construction material by volume — is directly addressed across multiple Green Star credit categories including Embodied Carbon, Responsible Materials, and Innovation. Meeting Green Star concrete requirements typically involves reducing embodied carbon through SCM substitution, procuring concrete with Environmental Product Declarations (EPDs), and demonstrating responsible sourcing of cement and aggregate in 2026.
In 2026, the primary Green Star tools applicable to concrete are Green Star Buildings (for commercial, residential, and mixed-use buildings) and Green Star Infrastructure (for roads, bridges, and civil works). Both tools contain a Materials credit category that directly rewards reduced embodied carbon, use of recycled and secondary materials, Environmental Product Declarations (EPDs), and responsible sourcing of structural materials including concrete, steel, and timber. Green Star Performance also applies to existing buildings undergoing assessment.
Concrete typically accounts for 40–60% of a building's structural embodied carbon and an even higher proportion in infrastructure projects. Portland cement production generates approximately 0.83 kg CO₂ per kg, making cement the dominant embodied carbon contributor in most concrete mixes. Reducing concrete's embodied carbon — through fly ash, GGBS, and optimised mix design — combined with procurement of EPD-verified concrete, is one of the highest-impact strategies available to project teams targeting Green Star points in 2026.
The primary Green Star credit areas where concrete specification directly affects project rating outcomes
Green Star concrete requirements are not prescriptive mix specifications — the rating system does not mandate specific SCM percentages or w/c ratios. Instead, Green Star rewards measurable outcomes: lower embodied carbon (kg CO₂e per m³), verified through EPDs or LCA, and responsible procurement demonstrated through supplier documentation. This outcome-based framework gives project teams flexibility to achieve Green Star points using whichever combination of mix design, material substitution, and procurement strategy best suits the project's structural and programme requirements in 2026.
The most significant update to Green Star in recent years was the release of Green Star Buildings, which replaced the legacy Green Star — Design & As Built tool. Green Star Buildings places greater emphasis on whole-life carbon — including both embodied and operational carbon — and requires a more rigorous, tool-based approach to embodied carbon assessment than its predecessor. For project teams, this means concrete specification decisions must be integrated with a formal LCA process from early design, not treated as a documentation exercise at the end of construction. For related guidance on assessing existing concrete structures that may be retained as part of a Green Star refurbishment project, our dedicated guide provides a full technical reference.
Green Star concrete credits are earned through a combination of upfront design decisions (mix specification, EPD procurement) and post-construction documentation (delivery records, LCA confirmation). Starting the LCA and EPD process at design development stage — not post-tender — is critical to achieving maximum points.
The Embodied Carbon credit within Green Star Buildings is the highest-value credit category directly influenced by concrete specification. Points are awarded on a sliding scale based on the percentage reduction in whole-of-project embodied carbon (measured in kg CO₂e) relative to a reference building of the same type and size. Concrete typically represents the largest single opportunity to reduce whole-project embodied carbon because of its volume and the high carbon intensity of Portland cement. The key concrete strategies for maximising Embodied Carbon credit points in 2026 are detailed below.
Replacing Portland cement with fly ash (Class F or Class C) or ground granulated blast-furnace slag (GGBS) is the single most impactful strategy for reducing concrete's embodied carbon under Green Star. A 30% fly ash replacement reduces concrete GWP by approximately 20–25%. A 50% GGBS replacement can reduce GWP by 35–45%. Both are readily available from Australian suppliers in 2026, comply with AS 3582 and AS 3582.2, and produce concrete meeting standard strength and durability requirements when correctly specified. For detailed guidance, see the Air-Entrained Concrete Guide for cold-climate SCM considerations.
An EPD is a third-party verified document quantifying the environmental impacts of a product — including Global Warming Potential (GWP in kg CO₂e) — across its lifecycle. For Green Star, EPDs for concrete mixes must conform to ISO 14025 and EN 15804 (or equivalent Product Category Rules). In Australia, the EPD Australasia program is the primary EPD registry. Project-specific EPDs from the concrete supplier provide the most accurate GWP data for Green Star LCA submissions; industry-average EPDs are acceptable where project-specific data is unavailable.
Beyond SCM substitution, optimising the total binder content of concrete mixes reduces embodied carbon without compromising structural performance. Many standard concrete specifications are conservatively over-designed — specifying 400+ kg/m³ binder where 320–350 kg/m³ with a lower w/c ratio and appropriate SCM content would achieve identical strength and durability. Working with a concrete technologist at design stage to right-size mix designs across all grades used on the project can reduce whole-project concrete GWP by an additional 5–15% on top of SCM substitution benefits.
Green Star Responsible Materials credits reward the use of recycled content in structural materials. Recycled coarse aggregate (RCA) — sourced from crushed demolition concrete — can replace up to 30% of virgin coarse aggregate in non-structural applications and up to 20–25% in structural concrete under AS 2758.1-2023 limits. Using RCA reduces the demand for virgin quarried aggregate, reducing embodied carbon in the aggregate component of the mix and contributing to both the Responsible Materials and Embodied Carbon credit pathways in Green Star Buildings.
In 2026, several Australian cement manufacturers offer low-carbon blended cement products — General Purpose cement blended with 25–65% GGBS or fly ash at the grinding plant — marketed under product names such as Envisia, ECOPact, and similar. These products deliver documented lower GWP values compared to standard GP cement and are supplied with product-specific EPDs, simplifying the Green Star documentation process compared to batching plant-level SCM addition. They comply with AS 3972 and are accepted under AS 3600 for structural concrete in most exposure classes.
Geopolymer concrete — produced using fly ash or GGBS activated by an alkaline solution rather than Portland cement — can theoretically achieve near-zero embodied carbon from the binder component. In 2026, geopolymer concrete remains predominantly used in non-structural and precast applications in Australia, with structural use limited by the lack of a dedicated Australian Standard and the complexity of mix design and curing. Projects using geopolymer concrete in innovative structural applications can pursue Green Star Innovation credits, which reward approaches that go beyond current industry standard practice.
The Responsible Materials credit in Green Star Buildings rewards projects that procure structural materials — including concrete — from suppliers who can demonstrate responsible production practices. For concrete, responsible sourcing encompasses the cement supply chain, aggregate extraction, SCM sourcing, admixture manufacturing, and the batch plant operation itself. The credit uses a tiered framework: basic compliance earns a minimum score, while deeper verification of the supply chain earns additional points. Unlike the Embodied Carbon credit, Responsible Materials is largely a procurement and documentation exercise rather than a technical mix design challenge.
| Responsible Sourcing Requirement | Credit Category | Verification Method | Applies To |
|---|---|---|---|
| Environmental Management System | Responsible Materials | ISO 14001 certificate from cement / concrete supplier | Cement manufacturer, batch plant operator |
| Chain of Custody Documentation | Responsible Materials | Supplier declaration confirming material origin | Cement, SCMs, aggregate |
| EPD for Concrete Mix | Embodied Carbon + Responsible Materials | ISO 14025-compliant EPD from accredited verifier | All concrete grades used on project |
| Recycled / Secondary Content Declaration | Responsible Materials | Supplier statement of % recycled content by mass | Fly ash, GGBS, recycled aggregate |
| Quarry / Mine Certification | Responsible Materials | NATA-accredited or equivalent quarry certification | Coarse and fine aggregate suppliers |
| Responsible Sourcing Framework | Responsible Materials | GBCA-recognised framework (e.g. BES 6001, Net Positive) | Major structural material suppliers |
| Concrete Waste Management Plan | Waste | Waste tracking records: ordered, placed, wasted, recycled | Concrete contractor, batch plant |
| Admixture Safety Data Sheets | Responsible Materials (supporting) | Current SDS for all chemical admixtures used | Admixture supplier |
While Green Star does not prescribe specific mix designs, the following table provides a practical reference for typical Green Star-aligned concrete mix specifications across common structural applications in Australia 2026. These specifications are designed to balance structural compliance with AS 3600, durability requirements for typical exposure classes, and embodied carbon reduction for Green Star credit pathways. Project engineers should confirm suitability for their specific exposure class, loading, and programme requirements before adopting these as project specifications.
| Application | Grade | Typical Binder (kg/m³) | SCM Substitution | Approx GWP (kg CO₂e/m³) | vs Standard Mix |
|---|---|---|---|---|---|
| Ground floor slab (residential) | N32 | 310–340 | 25–30% fly ash | 220–250 | ~20% reduction |
| Suspended slab (commercial) | N40 | 340–380 | 30% fly ash or 40% GGBS | 230–270 | ~25% reduction |
| Columns & walls (commercial) | N40–N50 | 360–420 | 25–30% fly ash or 35% GGBS | 255–310 | ~20% reduction |
| Raft / pad footings (mass) | N32–N40 | 320–380 | 40–50% fly ash or 50–60% GGBS | 165–210 | ~35–40% reduction |
| Retaining walls | N32–N40 | 330–370 | 30–35% Class F fly ash | 215–255 | ~22% reduction |
| Marine / below-ground (aggressive) | N40–N50 | 380–440 | 30–35% Class F fly ash | 265–320 | ~18% reduction |
| High-strength structural | N65–N80 | 450–520 | 10–15% fly ash + 8% silica fume | 370–440 | ~12% reduction |
| Pavement / hardstand (civil) | N32 | 300–340 | 25–30% fly ash | 210–245 | ~20% reduction |
The GWP values in the table above are approximate indicative figures based on typical Australian concrete EPD data in 2026. Actual GWP values vary significantly between concrete suppliers, SCM sources, and geographic regions. For Green Star credit submissions, project teams must use EPD-verified GWP data from the actual concrete supplier delivering to the project — not generic industry averages, unless project-specific EPDs are genuinely unavailable. Engage the concrete supplier's technical team at tender stage to obtain mix-specific EPDs and confirm GWP figures before committing to embodied carbon targets in the Green Star submission.
Green Star Infrastructure (formerly IS Rating Scheme, now integrated under the GBCA Green Star umbrella) applies to roads, bridges, tunnels, rail, water infrastructure, and other civil works. Concrete is even more dominant in infrastructure projects than in buildings — typically representing 60–80% of total project embodied carbon. The Green Star Infrastructure Materials credit category follows similar principles to Green Star Buildings but with infrastructure-specific benchmarks, LCA methodologies, and EPD requirements. The Infrastructure Sustainability (IS) Rating Scheme administered by the Infrastructure Sustainability Council (ISC) remains widely used alongside Green Star for major civil projects in Australia in 2026 and has closely aligned materials credit requirements.
One of the most common missed opportunities in Green Star projects is leaving EPD procurement and concrete supplier engagement until after the concrete subcontract is awarded. By this stage, the structural engineer has already specified concrete grades and the contractor has priced against standard mixes. To maximise Green Star points from concrete, project teams should issue performance specifications at design development stage that include maximum GWP targets per concrete grade (e.g. "N40 suspended slab concrete: maximum 280 kg CO₂e/m³ to be verified by project-specific EPD"). This approach drives competition between concrete suppliers on sustainability credentials in addition to price, and ensures EPD data is available for the LCA model from the start of construction documentation.
Green Star Buildings rates projects on a scale from 1 Star (Certified) to 6 Stars (World Leadership), with the Embodied Carbon credit contributing an increasing proportion of total points at higher star levels. Projects targeting 4 Stars (Best Practice) or above must demonstrate measurable embodied carbon reductions across the whole project, with concrete specification forming a key part of the strategy. The following table summarises indicative concrete embodied carbon reduction targets associated with typical Green Star rating levels for commercial building projects in Australia 2026.
| Green Star Rating | Stars | Whole-Project Embodied Carbon Reduction (indicative) | Typical Concrete Strategy | EPD Required? |
|---|---|---|---|---|
| Certified | ⭐ 1 Star | Baseline only — measurement required | Embodied carbon measured; no reduction mandatory | Recommended |
| Good Practice | ⭐⭐ 2 Star | ~10% below reference | 15–20% fly ash substitution on major grades | Recommended |
| Best Practice | ⭐⭐⭐ 3–4 Star | ~20–30% below reference | 25–35% fly ash or 35–50% GGBS; EPDs for all major grades | Required |
| Australian Excellence | ⭐⭐⭐⭐⭐ 5 Star | ~40–50% below reference | Maximum SCM substitution; optimised mix design; low-carbon blended cement products | Required — project-specific |
| World Leadership | ⭐⭐⭐⭐⭐⭐ 6 Star | ~60%+ below reference | Geopolymer / ultra-low carbon; whole-system optimisation; carbon offset for residual | Required — project-specific + verified |
The Green Building Council of Australia publishes Technical Manuals for Green Star Buildings, Green Star Infrastructure, and Green Star Performance. These documents contain the precise credit requirements, documentation checklists, and calculation methodologies that project teams must follow for each credit category affecting concrete. The Technical Manuals are updated periodically — always verify you are referencing the current 2026 version when preparing Green Star submissions involving concrete embodied carbon or responsible materials claims.
Concrete Assessment Guide →Fly ash and GGBS are the two primary tools for reducing concrete embodied carbon in Green Star projects. Understanding their technical properties, dosage limits, mix design implications, and documentation requirements is essential for project engineers and specifiers. Our detailed guides on fly ash and air-entrained concrete cover the technical specification requirements that underpin successful Green Star materials credit submissions in 2026, including AS 3582 compliance and EPD procurement guidance.
Air-Entrained Concrete Guide →EPD Australasia is the primary Environmental Product Declaration program for building and construction products in Australia and New Zealand. Concrete suppliers registered with EPD Australasia publish verified EPDs for their concrete products that can be directly used in Green Star LCA submissions. When specifying concrete for Green Star projects in 2026, require that the concrete supplier is either registered with EPD Australasia or can provide an equivalent ISO 14025-compliant EPD from another recognised international program such as the International EPD System or ASTM International.
Foundations & Sub-base Guide →