Population growth and increased urbanization point to continued high levels of construction activity around the world for decades to come. That presents a global GHG challenge.
According to the World Green Building Council (WGBC), “Building and construction are responsible for 39 per cent of all carbon emissions in the world.”
The construction process itself is responsible for 11 per cent of that, described by the WGBC as, “embodied carbon emissions, or ‘upfront’ carbon that is associated with materials and construction processes throughout the whole building life cycle.”
Concrete is the most widely used material in construction. It is therefore no surprise that the industry is in the crosshairs of environmental groups and governments are serious about carbon reduction.
The industry is well aware. In fact, North American producers responded enthusiastically to the 2011 “Challenge for Products” initiative created by Architecture 2030, a non-profit, non-partisan and independent organization seeking to reduce construction-related energy consumption and GHG emissions.
Specifically, the National Ready Mix Concrete Association (NRMCA) began publishing its carbon footprint benchmarks in 2014. The NRMCA has also argued against prescriptive-based specifications that tend to drive up carbon intensity. Instead, the NRMCA promotes performance-based specifications. One measure of the NRCMA’s progress has been the more efficient use of Portland cement, resulting in a reported 20-per-cent carbon footprint reduction associated with ready mix.
More recently, the concrete industry has embraced the cloud-based, open-access Embodied Carbon in Construction Calculator (EC3). This data-driven tool uses the construction industry’s database of Environmental Product Declarations (EPD), allowing architects, engineers, owners, contractors, building material suppliers and policymakers to easily evaluate Embodied Carbon (EC) in project specifications.
The EC3 Calculator is the creation of The Carbon Leadership Forum (CLF), an industry-academic collaboration hosted by the University of Washington focused on reducing the embodied carbon in building materials. The American Concrete Institute Foundation is an association partner.
According to the Forum, the EC3 tool “allows for supply chain-specific analysis of embodied carbon data, utilizing the first searchable and sortable database of all United States and Canadian EPDs for concrete, steel, wood, glass, aluminum, insulation, gypsum, carpet and ceiling tiles. The technology is revolutionizing the review of material or product environmental metrics by creating digital EPDs and translating all declarations into that form for viewing and analyzing project data.”
Leading concrete manufacturers like the concept of the digital EPD library. They say the EC3 tool does not require extra steps beyond the normal on-demand EPDs currently being created. More importantly, producers can now feed concrete mix designs into the EC3, thereby becoming active members in project design processes.
Data from more than 600 buildings analyzed by global engineering firm Thornton Tomasetti has identified a market-driven trend towards supplementary cementitious materials. They also found a measurable reduction in EC over the past 10 years using hollow core concrete planks and voided slabs, for example. Overall, their research points to higher levels of EC reduction in concrete structures versus those built from steel.
The study demonstrates the innovation and progress made by the concrete industry, and the need to better understand the transition required in order to achieve a low-carbon infrastructure. In a paper published by the University of Leeds (U.K.), Phil Purnell and Leon Black wrote that “much current work on eCO2 underestimates the complexity of its relationship with concrete mix design.”
Purnell and Black identify the savings possible through the increased use of pulverized fuel ash (PFA) rather than cement, the incorporation of superplasticizers, and the use of crushed aggregate rather than rounded stone. “Concrete is a complex composite. Its wide palette of engineering properties — compressive strength, workability, permeability, chemical resistance, etc. — is under the nominal control of the structural designer, rather than the materials supplier. Any notion that concrete has a single, easily defined eCO2 is clearly deficient.”
The integration of concrete mix design with project design now possible through the EC3 tool is allowing the industry to play an active role in EC reduction, rather than being an easy target for criticism.
John Bleasby is a Coldwater, Ont. based freelance writer. Send comments and Inside Innovation column ideas to editor@dailycommercialnews.com.
Recent Comments
comments for this post are closed