Reframing Metal Building Climate Response: Opportunities for Leadership

by Marcy Marro | December 1, 2022 12:00 am

I had the pleasure of speaking at METALCON 2022[1] in October, followed a few weeks later by attending the Greenbuild International Conference[2], and I would like to share a few insights from both events that are relevant to the metal building industry’s climate response. I presented a session titled Understanding Embodied Carbon, and it was great to see several other presentations on the topic, as well as expo vendors and participants discussing this subject. One sentiment I heard expressed is that the metal building industry is losing out to mass timber and asking what can be done to compete. That may be the wrong question to ask, and I propose a reframing of the opportunity.

It is true that mass timber is gaining popularity as a low-carbon building technology, and that bio-based materials not only reduce embodied carbon in construction but can also be net-carbon positive, as much of the carbon dioxide (CO₂) taken in by living forests remains stored in the wood materials for a long time. However, there are limitations to mass timber’s potential, including:

• There is a limited quantity of commercially viable forest land, and it will take time to put more land into production and wait for trees to reach harvest maturity. Mass timber is an option for many, but not all building projects, and overreliance on it may lead to unsustainable forestry practices that will undermine its benefits.
• Only about 50 to 60% of the CO₂ taken in by forests remains in the harvested wood products. Some of the carbon is held in the soil rather than the trees, and is released when trees are harvested, and only a portion of each tree is useful for long-lived lumber, with branches and bark (slash) burned or left to decompose after harvest, and mill waste (sawdust and scrap) often going into short-lived pulp and paper products.
• It is difficult to predict the end-of-life fate of mass timber materials, but some portion will be downcycled into non-structural wood materials, rather than reused or recycled back into mass timber elements. It is reasonable to assume that some of the stored carbon will be released when a mass timber building is demolished.

Given all this, and the reality that all buildings need multiple types of materials to make complete structural and enclosure systems, metal building materials are clearly not going away. This is why the question we need to be asking is: how can the metal building industry take a leadership role in creating a low-carbon, circular economy with the materials it manufactures?

The steel industry is collectively one of the three largest global producers of carbon dioxide. On average, the production of a ton of steel emits approximately 1.85 tons of carbon dioxide. The aluminum industry has a smaller total carbon footprint, but on average is more carbon intensive by weight than steel. Thanks to the increased use of scrap steel and electric arc furnaces (EAF) in the U.S., domestic steel tends to have a lower carbon footprint than steel produced in other industrialized nations. Similarly, aluminum produced in North America has lower embodied carbon, primarily due to hydroelectric powered smelters rather than the fossil fuels more commonly used in other countries.

Metal is highly recyclable and readily manufactured with recycled content. Much of the steel produced in the U.S. has a recycled content of 90% or higher and approximately 36% of aluminum is derived from recycled aluminum. However, the average recycling rate of steel is 69% and for aluminum the rate is lower. This means there is still a significant quantity of carbon-intensive material ending up in landfills. There is room for improvement at both ends of this life cycle.

The question we need to be asking is: how can the metal building industry take a leadership role in creating a low-carbon, circular economy with the materials it manufactures?

Rather than looking over its shoulders at the growing mass timber industry, the metal building industry should be introspective, looking for ways to reduce its carbon footprint, enhance its other environmental benefits, and meet emerging demands. These demands include voluntary commitments that investors and developers, and their design and construction teams, are making to low-carbon building standards, as well and new “buy clean” purchasing mandates like those implemented by California and Colorado and anticipated from the U.S. General Services Administration (GSA), and other state and local governments. The Securities and Exchange Commission (SEC) has pending rules for publicly traded entities to report carbon emissions, including Scope 3 emissions that encompass their value chains (including up-stream material suppliers). All of this will require primary and secondary manufacturers of metal building materials and products to measure and report carbon emissions, and ultimately to reduce their carbon footprints to gain competitive advantage.

Some of the steps the metal building industry can take include:

• Increasing efficiency and the use of renewable energy in the primary raw material processing and manufacturing, including direct use of renewable energy and the use of renewably produced hydrogen. Nucor’s ECONIQ net zero carbon steel provides one example of what this might look like.
• Supporting efforts to increase scrap metal recovery in all waste streams, from food and beverage containers to building demolition, as well as pursuing innovations to increase the recycled content of new material manufacturing. This might even include exploring the feasibility of mining landfills for raw materials.
• Investing in manufacturing and distribution efficiency, waste reduction, and the use of renewable energy in the production and delivery of finished building products. This includes going up-stream to encourage embodied carbon reductions by raw material suppliers and looking down-stream at waste reduction in construction processes.

The question is not: is metal better or worse than wood as a building material? As speakers at COP27 have emphasized, climate change presents an existential threat to humanity. Time is of the essence and all solutions are needed as quickly as possible to reduce greenhouse gas emissions. The metal building industry has an important role to play in creating and maintaining a low-carbon, sustainable and resilient built environment.

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Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect and consultant with over 35 years of experience in sustainable building design. He is director of sustainability with Intertek Building Science Solutions in Portland, Ore. To learn more, follow Scott on LinkedIn at www.linkedin.com/in/alanscottfaia/[3].

Source URL: https://www.metalarchitecture.com/articles/reframing-metal-building-climate-response-opportunities-for-leadership/

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