The cost case for salvaged steel looks promising even with an embryonic supply chain and a raft of logistical complexities to recover, inspect, store and then reuse structural members in new construction projects. The salvaged steel component in the mammoth restoration of Centre Block in Canada’s parliament buildings is projected to be on par with new steel on a simple cost basis, while life cycle assessment confirms more far-reaching paybacks.
“The cost to take the steel out of the building and get it ready to go back in is equal to the procurement of new steel,” Isis Bennet, a structural engineer on the project with the consulting engineering firm, WSP, told seminar attendees at the Canada Green Building Council’s recent annual conference. “That includes the deconstruction, the cleaning of the steel, the inspection and the tagging and tracking process before it goes to the fabricator to get fabricated for reinstallation.”
In its totality, the Centre Block restoration has been characterized as the most complex building rehabilitation project yet undertaken in Canada. Budgeted in the range of $4.5 to $5 billion, the federal government reports about $814 million had been spent as of March 31, 2024 on the multi-year, multi-phase project, which includes: complete interior and exterior restoration; replacement of the mechanical, electrical and fire safety systems; seismic and accessibility upgrading; installation of digital infrastructure; and newly constructed space to be known as the parliament welcome centre.
The directive to recover and reuse structural steel, where appropriate, aligns with the government’s mandate to show leadership in reducing greenhouse gas (GHG) emissions in its own portfolio of buildings. Reuse of an existing beam or column recovered from the deconstruction of another structure curtails an estimated 97 per cent of the embodied carbon involved in manufacturing a comparable item from virgin steel. In interior areas of Centre Block where demolition is necessary, crews have been cutting out recoverable lengths of steel — at approximately 50 millimetres or two inches from any bolts or connectors — to be used in subsequent construction stages.
“It is being deconstructed quite delicately. On this project, we know a lot about the steel that’s coming out of the building and we’re also the designers who are specifying the steel that’s going in, so it’s much easier for us to determine what members have the highest potential for reuse,” Bennet observed. “This is steel already owned by the client so it’s a great opportunity to put it to good use.”
She and co-panellist, Jolene Mclaughlin, vice president, climate and sustainability, with the construction contractor, EllisDon, shared their experiences on this element of the Centre Block project as part of a wider discussion on the growing uptake of salvaged building materials in new construction. Ryan Zizzo, a specialist in whole building life cycle assessment and chief executive officer of the consulting firm, Mantle Developments, joined in with insight on market trends, opportunities and challenges.
Among contributing influences, Zizzo tallied: the emergence of salvaged material trading platforms and specialized professional services such as deconstruction audits; the commercial real estate industry’s increasing pursuit of net-zero GHG emissions; and various regulatory prods and/or monetary enticements to curb emissions and waste sent to landfill.
For those on the voluntary track, LEED version 5, which was released in consultative draft form earlier this year, has an intensified emphasis on decarbonization. That comes with a new prerequisite to assess the upfront embodied carbon in “major materials” in a building’s structure, enclosure and hardscape, and a new credit, worth up to six points, for reducing embodied carbon in construction materials.
“What people may not have realized is that it’s only new material that’s being included in those limits (established in the credit). If you’re reusing used material, you can count that as zero on your embodied carbon ledger,” Zizzo advised.
For contractors and related service providers bidding and working on federal construction or retrofit projects, new expectations have been outlined in a recent update to the government’s green operations strategy. Federal departments and Crown corporations will be required to consider life cycle cost analysis for GHG reductions in determining project costs, which is to be based on a 40-year period and a shadow carbon price of $300 per tonne. As well, “recycled and lower-carbon materials, material efficiency and performance-based design” are to be employed, beginning in 2025, to achieve a 30 per cent reduction in the embodied carbon of major construction projects. The total embodied carbon of construction materials will also have to be disclosed.
Heightened reliance on life cycle analysis is expected to change how project proponents perceive value. Mclaughlin ranks it as a potential key driver of the salvaged materials market, particularly if truer costs for waste disposal are introduced.
“We know when we just look at the capital costs, our sustainability objectives don’t pay out,” she said. “It’s dirt cheap to just throw stuff out in Canada so it costs us far more to put people on the site to deconstruct than to throw it out. If we create more value in keeping that material, that starts to change the conversation.”
Standards and a more robust supply chain are identified as other essential ingredients for wider uptake of salvaged steel. Bennet recounted how the engineering team on the Centre Block project has largely forged its own way in devising specifications for removing steel, determining its suitability for reuse, and storing it in an organized way that’s secure from detrimental weather. Other early adopters have also needed to take a self-directed approach.
Vigilantly developed standardized procedures are prioritized to provide guidance, consistency and assurance for design, quality control and deconstruction/construction. In turn, that could spur more confidence to use salvaged steel and a more efficient rollout of projects.
“If each project goes about it differently, that’s a lot of hoops for someone on the contractor side to jump through. If we have a standards package, we can say: Refer to this standard; go through these steps and we’re happy with it,” Bennet said.
“If steel is tested to a standard and then goes into the materials market, we, as a contractor, know we can trust to buy that,” Mclaughlin concurred.
Bennet notes that project proponents are currently faced with fairly challenging legwork to source salvaged steel. Ideally, she would like to see building owners opening up trade links — citing one such example of University of Toronto, Scarborough acquiring steel recovered from deconstruction at the Royal Ontario Museum — and thinking more strategically about what can be gleaned from their own or their peers’ retrofit and decommissioning projects.
“There is real opportunity for portfolio owners to see the whole portfolio as a material bank,” Zizzo urged. “It’s easier to reuse your own material than buying from someone else. You can take materials from one of your buildings that might be under renovations and find ways to use it in one of your other buildings.”
