Low carbon design

Carbon confusion and the need for guidance and clarity.

There is significant confusion in the market about the embodied carbon at the different stages of a building’s life. Carbon calculators are emerging prolifically, but they only tell a one-dimensional story about CO₂ equivalent emissions per mass of particular products, with a focus on either the Cradle to Gate or Cradle to Practical Completion, i.e. Module A emissions, or if they do extend to modules C and D, there is very little available data to populate these, and where data is available, the underpinning assumptions can be open to question.

This is in spite of MBIE’s commitments to consider and target opportunities to realise the whole of life (i.e. Modules A-D) carbon reductions and announcements that relate to the Building Act being modified to better report and focus on Modules B and C. Thus, by having a better understanding of the source and contribution of the embodied carbon from each Module and consideration of how design influences choice of material and vice-versa, can it be possible to design a truly carbon efficient sustainable building. This will identify the nexus between material choice and design; that goes beyond a carbon calculator being utilised at a belated stage of its design, when it is too late to implement the necessary carbon reductions.

This is a broader set of considerations than what simply comparing building materials using a carbon calculator would provide. It includes, for example, designing for re-use, designing for waste minimisation, evolving how we manage service life, the quality of that service life, and designing for reduced maintenance and longer lifetimes.

This will enable increased:

1. Awareness of the need to choose materials and designs that reduce the carbon footprint of our buildings; and
2. The framework and tools to actually then choose the materials and designs that will lead to carbon reductions, while producing high-quality buildings.

Materials agnostic. Design guidance framework.

This is a material and typology agnostic design guidance framework (“the Framework”) that can be used by the sector as a template for preparing design guidance to achieve the lowest embodied carbon.

The Framework is intended to be broadly applicable across materials, building typologies, and systems, enabling consistent, low-carbon design approaches without the need to start from first principles.

This Framework is evidence-based, considers whole-of-life impacts (Modules A-D of EN 15978:2011), and encourages a cradle-to-cradle approach – setting the stage for future advancements in dynamic LCA approaches. 

This framework was focused on:

1. Creating a practical and clear roadmap to navigate circular and low-carbon strategies visually for both new and existing buildings, as well as understand how these concepts integrate.
2. Simplifying the overview of Life Cycle Assessment (LCA) and circularity to cut through the complexity to enable confident assessment of whole-of-life carbon impacts.
3. Providing actionable strategies that can be apply immediately to achieve low-carbon circular design. 
4. Delivering a template for preparing specific design guidance to help create specific design strategies to achieve the lowest whole-of-life embodied carbon and material or system circularity in projects. 

Low carbon design framework rōpū

Putting the framework to the test.

Building on the framework, this design guide was focused on providing targeted strategies to reduce embodied carbon in typical low-rise building typologies, with Stage 1 pilot case study based on steel, steel-concrete, steel-timber materials.

This work supports the adoption of circular economy principles in commercial buildings, while maintaining design integrity and function – improving adaptability, future resilience and design optimisation. 

The resulting guide:

1. Demonstrated that design and specification decisions can halve carbon emissions – sometimes more.
2. Outlined design strategies for longevity and disassembly, with a focus on extending building life and improving adaptability.
3. Offered material and system-level guidance on superstructures, highlighting how material choices impact whole-of-life carbon outcomes.
4. Delivered design for circularity guidance, outlining how to reduce waste and support material reuse through smarter planning.
5. Highlighted approaches to reduce operational carbon, including thermal efficiency strategies and integration of technologies such as heat pumps.

Design guidance rōpū

Addressing critical knowledge gaps.

This report outlines identified research priorities – including insights from industry experts, literature reviews, and peer feedback. It also identifies opportunities for collaboration, critical knowledge gaps that will need to be addressed in the future, and pathways for innovation in terms of emerging materials, technologies and methodologies.

Research gap rōpū

Reduce embodied carbon. Steel specification in NZ.

This technical report offers evidence-based guidance for specifying structural steel that supports emissions reduction, material circularity, and low-carbon design across the construction sector.

Steel plays a critical role in the built environment — but how it’s specified can determine its environmental impact for decades to come.

It introduces benchmarking tools and specification guidelines, including Environmental Product Declarations (EPDs), to help professionals make informed decisions that align with sustainability goals. The report also explores the integration of steel reuse and outlines strategies to incentivise decarbonisation across the supply chain.

The resulting guide:

1. Clarified benchmarks and definitions that distinguish low-carbon steel, aligning structural performance with environmental responsibility.
2. Guided users through carbon benchmarking methods using Environmental Product Declarations (EPDs), Worldsteel data, and global standards.
3. Provided step-by-step specification guidance to help professionals select high-performance, low-carbon steel aligned with project sustainability goals.
4. Outlined strategies for decarbonisation, including annual carbon reduction targets and the use of high-strength steels to minimise material demand.
5. Highlighted the value of steel reuse in supporting circular design, reducing waste, and adding character to new builds.

Steel specification rōpū