There are two major innovation challenges facing the construction industry. One is the integration of technology and cloud-based management systems to improve productivity. The other is addressing the carbon impact of everything that goes into the construction of buildings.
Building and construction account for 40 per cent of the world’s total carbon emissions, much higher than the 25 per cent traced to the transportation sector’s fuel combustion. Of construction’s 40 per cent contribution, almost one third comes from building operations. The remainder is what is called embodied carbon (EC).
What is EC? It’s most easily defined as the total GHGs resulting from the manufacturing of materials and components, the construction process, and the end-of-life consequences at time of demolition. Overall, this is often referred to as the “carbon footprint” revealed through a researched Life Cycle Analysis (LCA). Add operational and EC together and you have a building’s complete lifecycle carbon footprint.
Initiatives around the world to improve energy efficiency will see the GHGs associated with building operations dropping significantly over the next decade. But that’s only part of the total carbon story. Increased emphasis will need to be placed on EC as operational carbons decline.
Mass Timber Construction is widely promoted as construction’s solution to EC. Trees are highly efficient at absorbing and retaining carbon, whereas concrete and steel are seen as fearsome carbon emitters.
Nevertheless, concrete and steel have been the two most basic and important construction materials for a long time. That’s not likely to change in any significant way.
The truth is, wood’s true carbon LCA is often hidden in green washing promotions. In the meantime, the concrete industry has made tremendous strides, not only with manufacturing processes but with technologies that actually capture carbon from industrial sites, just as trees capture carbon from the air, and then turn that carbon into a strengthening agent that locks it in place for perhaps centuries. In fact, the prospect of zero-carbon concrete is very real within the next two decades.
What about steel?
In an article written by a marketing coalition called Steel for Life, the industry says it has long advocated a “cradle-to-grave” approach with its products, and using steel well past the originally intended purpose.
“Steel has exceptional circular economy credentials as it is typically either reused or recycled,” they say. “Steel almost never adds to the construction and demolition waste sent to landfill.” In fact, Steel for Life claims that a “highly developed and highly efficient” recovery infrastructure has been in place “for decades.”
Steel for Life cites some impressive U.K. full cycle efforts.
“Current recovery rates from demolition sites in the U.K. are 99 per cent for structural steelwork and, on average, 96 per cent for all steel construction products.”
That in turn allows the industry to claim a recycled content of 60 per cent of structural steel used in the U.K. and over 55 per cent across the European steel industry as a whole. The American Institute of Steel Construction (AISC) claims similar levels of success.
“Structural steel produced in the United States contains 93 per cent recycled steel scrap, on average. At the end of a building’s life, 98 per cent of all structural steel is recycled back into new steel products, with no loss of its physical properties. As such, structural steel isn’t just recycled but ‘multi-cycled,’ as it can be recycled over and over and over again.”
At the same time, the industry feels it needs to develop more comprehensive studies based on data offering full LCAs to verify its claim that “structural steel is the premier green construction material.”
The AISC also believes, “the construction industry has to move up the waste management hierarchy and reuse buildings and their constituent parts.”
A full understanding of the ECs associated with construction requires looking beyond the hype and researching the measured and proven carbon impacts of wood, concrete and steel in order to reach correct material decisions for any given project.
John Bleasby is a Coldwater, Ont.-based freelance writer. Send comments and Inside Innovation column ideas to firstname.lastname@example.org.