Dr. Troy Coyle

Dr. Troy Coyle, CEO at the Heavy Engineering Research Association (HERA), and a constructsteel affiliated member shares insights on the use of steel as a sustainable construction material.

As part of a series of Q&As, constructsteel is interviewing experts within the construction sector on aspects of steel’s performance and sustainability in the built environment.

Sustainability, particularly reducing carbon emissions, in construction is a hot topic in New Zealand. Government-led initiatives, such as Building for Climate Change, are directing change within the sector. This framework proposes to set mandatory reporting and measurement requirements for whole-of-life carbon emissions, including from the materials used in construction, the construction process, construction waste, and the disposal of a building at the end of its life, which will form part of the NZ Building Code and associated regulations.

In recent years, it has become noticeable that the New Zealand government procurement has been placing a stronger focus on carbon, with the timber lobby pushing for a “Timber First” approach for all government buildings. The steel and concrete industries have had to respond, reaffirming that professionals, such as architects and engineers, and not politicians should be determining the best material for the required application. It is our view that procurement decisions should be made based on evidence and not on an assumption that timber is automatically preferable. It is also not the role of the government to be a material specifier, albeit specifying appropriate sustainability outcomes is reasonable.

Initially, much of the conversations and government white papers focused on embodied carbon versus lifecycle carbon, placing timber at an advantage over steel. Embodied carbon only considers carbon at the point in time that a building is built, while lifecycle carbon also considers carbon that is emitted during operations and at the end of life of a building. Of course, if net carbon reductions are the objective, life cycle carbon is key and requires significant diligence, education and advocacy from the sector broadly, including from life cycle analysis (LCA) experts.

As means of shifting this erroneous focus on embodied carbon in comparisons between steel and timber, HERA has developed the world’s first comprehensive carbon offsetting program for steel products used in New Zealand. The calculator was independently developed and is based on LCA data and preferably EPD data. It covers steel products ranging from roll-formed roofing and cladding, reinforcing, light gauge and heavy structural steel, and stainless steel. It currently covers carbon from cradle to erection. Early-stage industry indicators of relative construction costs of timber versus steel design are suggesting that the zero carbon steel option will come in 30-80% more affordable than the timber option.

In efforts to further extend this to a cradle-to-cradle approach, HERA has also commissioned work to determine steel scrap recycling levels in New Zealand. This independent report identified that 72% of scrap in New Zealand is recycled. A figure that is likely to be higher for construction steel (we estimate approximately 85%), which we are in the process of determining. The scrap is currently sent offshore for recycling and has an associated 1050kg/t carbon equivalent reduction, a value that increases as the recycling levels also increase due to reduced landfills.

Interestingly, HERA conducted comprehensive market research across the New Zealand population and found some significant misunderstandings about the sustainability credentials of steel. Probably the most concerning was that more New Zealanders thought that timber was more recycled than steel, whereas timber recycling levels are likely to be close to zero due to Building Code requirements for timber treatment, making it toxic and therefore of limited use at end of life.

Currently, HERA is also in the process of developing Australasia’s first material passport, which will involve research to identify roadblocks and barriers to the reuse of structural steel. It will also investigate the role of a data platform in facilitating steel reuse. Then a material passport decision-making framework will be developed. The aim is to facilitate the reuse and repurposing of steel, adding more value in terms of steel’s role in the circular economy.

HERA also recently commissioned an assessment of the economic impacts of adopting Construction 4.0 (Industry 4.0 adapted to the construction sector) in New Zealand. The study showed that Construction 4.0 adoption would lead to a 0.5 to 1.0% increase in GDP, worth $1.2 to $2.5 billion within 5 years. HERA has already developed capability in Fabrication 4.0 (through our fab4.0lab), and now we are looking to develop capability in Sustainability 4.0 as part of our broader Construction 4.0 research program.

In addition to the HERA led initiatives in New Zealand, the Sustainable Steel Council has developed a certification program based on Aotearoa New Zealand’s Living Standards Framework (LSF). This means that at least 70% of structural steel volume is now coming from certified members and the steel industry was the first in New Zealand to use the framework to assess its economic contribution to the nation. The LSF looks at sustainability in terms of intergenerational wellbeing across four capitals: financial, human, social, and natural. New Zealand’s steel industry has used the LSF as the basis for developing the Aotearoa Steel Industry Transformation Plan, with New Zealand Steel and many of the steel industry associations already on board.

HERA is thrilled to have joined constructsteel’s international network, and we are really looking forward to sharing access to emerging research and approaches to improving and evaluating the sustainability credentials of steel. We are also keen to connect with like-minded organisations to develop best-practice initiatives and coordinate information sharing across the globe.