One of the things that keeps coming up when we have conversations about sustainability in our business is this: most of a building’s carbon impact is decided long before anyone pours concrete or steps on site.
In recognition of B Corp Month, this article is centred on one of the areas where we see the greatest opportunity to make a meaningful difference through our work: the influence of early project decisions on carbon outcomes in construction.
Across Aotearoa New Zealand, buildings and construction account for a significant share of national emissions when both direct and indirect impacts are considered. A BRANZ study estimates this contribution to be in the range of 15–20 percent. While the exact figure varies depending on how it is measured, the more important question is where, and when, that impact is shaped. Buildings last a long time. The decisions we make today, will continue to shape environmental impacts well into the future.
We’ve found valuable guidance on this idea in the SESOC Top Tips for Low Carbon Design. Though written primarily for structural engineers, the guidance highlights a broader truth that applies across project management, design and delivery: the biggest carbon reductions are usually achieved through early decisions about whether to build, what systems to use, and how much material is required. This all happens long before detailed design begins.
Daniel Gray, Structural Engineer and member of our Sustainability Steering Committee, sums it up simply: “Carbon is a timing issue, not just a technical one”.
You might notice that this is contrary to a common assumption that carbon reduction is something you tackle once designs are detailed, and numbers are precise. In reality, it’s often the opposite. Early in a project, at concept and preliminary design stage, we’re deciding things like structural systems, material quantities, and construction approaches. At that point, carbon estimates are rough, but the ability to change outcomes is at its highest, and if you are working in a consulting capacity, it is right here that you can have a potentially big influence. Later on, we find the numbers get more accurate, but by then most of the big decisions are already locked in.
Image from SESOC Top Tips for Low Carbon Design
Low Carbon Choices in Practice
If you’re interested in what those early choices look like in a real-life scenario, we explored this in more detail in an earlier article, published by Daniel last year. Written from a structural engineering perspective, it unpacks practical, high‑impact design strategies, from designing for disassembly and reuse, through to material‑efficient concrete solutions and smarter structural grids to show how early thinking can materially reduce embodied carbon.
Our Footprint and Our Influence
Like many organisations, we measure and work to reduce our own operational emissions. However, it is also worth recognising the scale of influence that we as building professionals have through everyday project decisions. For context, Maynard Marks’ operational footprint is approximately 224 tonnes of carbon dioxide equivalent per year, with commuting accounting for around 27 percent of that total. By comparison, the average New Zealander’s individual consumption‑based carbon footprint is estimated at around 11 to 12 tonnes per year.
On construction projects, a single early design decision can shift embodied carbon by tens of tonnes.
In some cases, that is comparable to an entire year of commuting emissions for an organisation, or the combined annual footprint of several individuals. This is not to downplay the importance of reducing operational emissions, but to highlight where professional influence can be particularly powerful.
Small Early Choices, Big Real‑World Differences
Two early‑stage examples help illustrate how much impact these decisions can have.
Scenario 1: On a larger residential project of 153 units, the foundation design required around 1,415 cubic metres of concrete. Using standard New Zealand embodied carbon factors, this equated to approximately 372 tonnes of carbon dioxide equivalent for 30 MPa concrete. Testing alternative strengths at an early stage showed that reducing the concrete strength, could lower embodied carbon by between 20 and 55 tonnes, but without changing the overall design intent.
Scenario 2: For a development of three duplex buildings, two foundation approaches were compared. A timber pole foundation solution, including timber floors, resulted in approximately 4.9 tonnes of embodied carbon for that element, compared with around 11.4 tonnes for a concrete wall foundation. The difference was roughly 6.5 tonnes, or more than a 50 percent reduction.
These projects are very different in scale, but they tell the same story: the largest carbon differences tend to come from early system choices and material quantities, rather than from fine‑tuning materials once designs are already locked in.
Making Better Decisions (Without Perfect Data)
One of the most encouraging insights that has arisen from our discussions and our work in this space is that meaningful carbon improvement does not require specialist expertise or perfect data.
Some of the most effective actions are also the simplest. For example, asking your architect, geotechnical engineer, or other project consultants, for two or three viable options early, rather than progressing a single solution, creates real choices. Including indicative embodied carbon alongside cost, performance and programme helps make trade‑offs visible. Accepting that early numbers will be imperfect, but directionally useful, allows better decisions to be made while there is still flexibility.
This does not mean undertaking a full life‑cycle assessment for every project. Early‑stage, indicative comparisons are often enough to highlight where the biggest differences lie and to guide more informed decision‑making.
Carbon as Part of Good Business
Thinking about embodied carbon early is not a separate ‘environmental exercise’. It supports better long‑term value, reduced project risk, clearer decision‑making and stronger alignment with purpose‑led business values. These are principles many organisations already prioritise, and they translate naturally into the built environment.
The key takeaway is that carbon does not need to compete with cost, programme or buildability. It can sit alongside them as part of normal early‑stage thinking. If carbon becomes one more routine question we ask at the start of a project, rather than a late‑stage check, the impact can be significant.
Interested in a Low Carbon Approach?
If you are at the early stages of a project and want to explore practical ways to compare options, including simple, indicative embodied carbon alongside cost and programme, our team can help you start that conversation early and with clarity. Contact us.
Daniel Gray | Wellington | daniel.gray@maynardmarks.co.nz
Daniel Kennett | Auckland & Christchurch | daniel.kennett@maynardmarks.co.nz
