Interiors have a significant embodied carbon footprint and their churn rate is much greater than base buildings. Dr Caroline Noller of The Footprint Company lays out the situation.
Illustration by Michelle Byrnes for Indesign magazine.
The declaration of a climate emergency and the need to act to achieve net zero carbon by 2050 or earlier is now well-developed and embedded into the Australian and developed world’s governance and policy settings.
For the Australian architecture and design community the last 18 months has seen significant momentum through the actions of Architects Declare Australia; Green Building Council Australia; the Materials & Embodied Carbon Leaders’ Alliance and Federal and NSW State Government investment into extending the NABERS rating scheme to ‘embodied carbon’ within the next two years.
If I had a dollar for every architect and designer who has asked me for specific guidance on how to ‘convince’ a client to care for, or engage with, addressing embodied carbon in design, I could have retired many times over. So, it is an outstanding piece of leadership by the Australian Institute of Architects (AIA) to move to formally incorporate into professional competency requirements, the requirement to “be able to assess … embodied carbon implications of materials … to achieve net zero carbon when developing design concepts.” (National Standard for Competency for Architects, 2021 (PC35 and 39).
This renders whole-of-life carbon (inclusive of operating and materials), a minimum practice standard for which all design practices and individual practitioners must develop skill in.
It has been more than 15 years developing the sector’s capability to action operating carbon efficiency.
There is a call for an immediate 50 per cent embodied carbon reduction against ‘typical practise’, which is enormous given the level of information, resources and benchmark data presently available globally. The recent announcement of the 80,000th materials carbon declaration (across 325- odd materials labelling schemes) should be celebrated, but the reality is dire, given that globally materials market is US$1.2 trillion in scale (refer here).
Understanding where to start reduction relies on the question of, ‘What is my embodied carbon benchmark for interior projects and where is that carbon?’ As noted above, the product carbon labels are developing, as are materials carbon calculators – both of which must expand rapidly to support capacity.
Carbon measurement standards to achieve robust “benchmarks” also need work, helped along recently by the publication of the International Cost Management Standards coalition and the Low Carbon Institute measurement and reporting guide. These are critical foundations, which need industry consensus, fast.
There is a broad desire for a quick fix through simple individual material substitution (for example, timber versus concrete; steel versus aluminium). But this restricts mitigation to the end of the design chain at procurement which restricts savings to about 10 per cent. This makes benchmarks critical to understand where the carbon is across the design elements, and which are the major design strategies that can contribute the most at the earliest design stage.
The application of key design principles –
– are foundation elements to net zero embodied carbon design practice.
Let’s consider the potential of these options more closely, and the scope for reduction within the context of our net zero design principles.
For all projects, furniture (loose, workstations and chairs) and fixed joinery are the largest proportion of carbon footprint at 31-38 per cent. With very rare exception, designers’ go-to tends to be ‘new’ for any interior project.
By simply applying the first principle of build/no build, the potential to mitigate at least 20 per cent of the carbon footprint is to embrace a design approach of repurpose. The second-hand market for furniture is well-developed. But in my experience, it is rare that a designer will opt for ‘repurposed’ furniture as a key element of design – despite it generally saving cost.
Even within categories such as a task chair, there is room to mitigate carbon through considered selection. The Footprint Company recently calculated the embodied carbon in seven task chairs, all with eco-labels of some description, and a consistent design. The carbon footprint ranged between 220-80kg CO2-e per chair (which is good considering the average office task chair is 300kg CO2-e).
For the fit-out involved, selecting the lowest carbon chair could deliver more than a 70 per cent reduction as compared to the ‘benchmark’ chair, and almost 75 tonnes CO2-e in absolute terms for the subject project. That’s the same as 75 cars driving from Sydney to Melbourne five times.
Finally, floor finishes constitute about 15 per cent of the average retail interior carbon footprint. Porcelain tiling and its cement bed makes up more than 90 per cent of the impact. Tiles are expensive in cost and carbon terms. The stark reality is that their real life is a fraction of their service life (generally five to 10 years) and has a carbon impact of 300-400kg CO2-e per square metre. This, as opposed to rubber and vinyl alternatives, timbers or epoxy finishes. Making the one decision to avoid vitrified tiles or pursue the newer thin format and high recycled content alternatives will avoid 50 per cent, or more, for this element.
These are just a few small but meaningful insights into mitigation potential for interior projects. Interiors have a significant embodied carbon footprint and their churn rate is significantly greater than base buildings and subject to the vagaries of fashion and business success.
Growing capacity to facilitate mitigation in an evidenced-based approach is critical to success. The recent inclusion of credit points in GreenStar for landlords measuring and engaging tenants to address embodied carbon is to be applauded.
This, combined with the AIA leadership in competency standards, I hope will support and drive the necessary rapid transformation of the interior architecture and design sector to the net zero 2040 goal.
This article was first published in Indesign magazine, the ‘Hybrid At Work’ Issue, in early 2022. Purchase the single issue.
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