Growing interest in sustainable materials

This Issue This is a part of the Building for climate change feature

By - , Build 188

The embodied impacts of building materials used in construction are under the spotlight. As the focus turns to reducing carbon emissions, there is an impetus to consider the sustainability of materials used.

Table 1: Sustainability attributes of building materials

OUR GLOBAL economic growth has been intimately linked with increased material use. Every year, we transform more than 100 billion tonnes of raw material into products. Of this total, an estimated 30–50% of materials go into producing building materials, and less than 10% cycles back into the economy at the end of its life. Put another way, today, the global economy is only 8.6% circular.

Aside from their impact on resource use, building materials are also significant sources of emissions. For years, the construction sector has reasonably successfully focused on operational impacts – for example, energy for lighting, heating, cooling, ventilating systems and appliances.

Focus on embodied impacts of materials

However, as the building industry increasingly heads towards net zero, the embodied impacts of the materials used in construction and operation practices have come to represent an ever-increasing proportion of their footprint. In response, policy makers are starting to explore how these might be addressed, as we have seen with the Ministry of Business, Innovation and Employment exploring a whole-of-life embodied carbon emissions reduction framework.

Then there are the human impacts of the materials we use. We are part of, and dependent on, global trade and supply chains. The International Labour Organization estimates that over 40 million people are in some form of slavery today. Some 24.9 million people are in forced labour, of whom 16 million people are exploited in the private sector through domestic work, agriculture and construction roles.

With building materials closely linked to all three of these hot topics – circular economy, carbon reduction and modern slavery – it’s no surprise that more people are asking what sustainable products are, how to identify them and how to accelerate their adoption.

What are sustainable construction materials?

As with so many sustainability questions, the answer isn’t simple. Just because a product is (or claims to be) low carbon, made of recycled materials or ethically sourced, it doesn’t mean it’s sustainable. Answering the question requires a more holistic view that considers a broad set of principles and indicators (see Table 1).

Table 1: Sustainability attributes of building materials

Finding sustainable materials and buildings

There is a wide range of product assessment frameworks, ecolabels and certification schemes, many of which cover building materials.

LCA widely used

Among these, one of the most used methods in the sector is life cycle assessment (LCA) which is a key method for measuring and comparing the environmental impact of products, building systems and whole buildings. The benefits of using LCA include providing scientific and quantified information for decision making that covers the whole of life across a range of environmental impacts.

On a whole-of-building scale, lessons can be learned from whole-of-building LCAs:

  • Planning – identifying alternatives to avoid new constructions where possible is by far the most effective way to reduce and avoid impacts.
  • Design – building less by maximising use of existing assets and building new assets with adaptive reuse in mind is the second most effective way to reduce and avoid impacts.
  • Construction – building smarter by optimising material usage, selecting low embodied carbon materials, ecolabelling certified products and suppliers offering product stewardship and take-back programmes.
  • Operations and maintenance – eliminating waste and optimising reuse, repair and recycling of used products and materials from maintenance, refurbishment and repairs.

Leading rating tools such as Green Star have been instrumental in driving the uptake and use of LCA for whole building and product assessments and unearthing the lessons learned above. There are now several commercial tools available to cost-effectively conduct project-specific LCAs.

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EPDs for products

On a product level, there are over 10,000 verified environmental product declarations (EPDs) for construction products registered globally, providing comprehensive and comparable LCA-based environmental information and data, including embodied carbon. EPD Australasia registers and publishes EPDs and climate declarations for New Zealand and Australian product suppliers.

Using EPDs from manufacturers can assist in significant impact reductions. For example, there are options for low embodied carbon materials available in the market across material categories such as concrete, steel, bricks and carpet to name a few. These materials demonstrate carbon reductions of approximately 30–90%, without using carbon offsets.

Everyone can play a part

Sustainable materials are fast becoming the next frontier for improving sustainability, particularly in relation to decarbonising the built environment. Often seen as the domain of architects and specifiers, the truth is that there is a role to be played in every part of the construction industry’s value chain and across all stages of asset development:

  • Planners and regulators can set policy frameworks that require the use of sustainable materials and thresholds for key metrics such as embodied carbon rates.
  • Investors and asset owners should put in place sustainable material targets, including for embodied carbon, and look for opportunities to work with the finance community to drive embodied carbon reductions. A recent study by the Clean Energy Finance Corporation described the low embodied carbon market as a billion-dollar opportunity.
  • Developers and construction companies can also put in place ambitious targets. To support them, they can build sustainable materials into the entire construction cycle, with a particular emphasis on planning and design. Engage with suppliers and develop collaborative partnerships with those that can offer sustainable materials.
  • Designers and engineers can ensure projects look at the whole-of-life implications of material and design choices, including environmentally sustainable design (ESD), and proactively specify certified and low embodied carbon materials. This includes using LCA as a design tool rather than a tick box exercise.
  • Building material manufacturers and suppliers can seek appropriate certifications and publish third-party-verified performance data. Look for opportunities to make relevant data easy to find as part of company profiles on materials databases.
  • Rating tool providers can continue to incentivise both suppliers and customers of sustainable materials by incorporating credits that reward good material selection, low embodied carbon construction and circular economy outcomes. Ensure these measures are holistic rather than a single-issue focus.
  • Procurement teams can establish tendering criteria that evaluate, reward and drive low-carbon product and material selection and mandate provision of certifications and labels such as EPDs. Clearly communicate expectations to your supply chains.

Contributing to the decade of action

While focus on sustainable materials is growing, there is a long way to go. The potential, though, is massive if we can get it right. With such a large proportion of global resource use accounted for by the built environment, even small changes can multiply to generate huge impacts.

If the whole industry can come together, there is the opportunity to make a dramatic contribution to creating a low-carbon circular economy with a strong story on human rights – and with it should come significant economic benefits.

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Table 1: Sustainability attributes of building materials