Discussion abounds concerning how the construction industry needs to address its GHG emission levels. The number most often quoted quantifying the industry’s global contribution is 40 per cent. However, that needs to be broken down before potential solutions can be understood.
Of the 40 per cent total, about 11 per cent relates to what is called embodied carbon. The rest is called operational carbon, that is, the carbon caused by running buildings on a day-to-day basis. There’s tremendous focus on operational emissions, and many programs and incentives to reduce them.
That’s very important, of course. However, much less attention has been directed to embodied carbon. What is embodied carbon exactly?
Simply put, embodied carbon is everything that goes into the physical structure, from the point of its creation to the day the building is ultimately demolished. In other words, it’s the total of those cradle-to-grave carbon emissions. That includes all the carbon expended to extract materials, process them into useable products, transport them to the building site, assemble them and dispose of them decades later.
As McKinsey Global points outs, however, “embodied carbon is more difficult to measure and track than operational carbon, which is relatively simple to extrapolate from occupants’ energy bills.”
McKinsey uses the example of two steel beams that may appear identical. Yet, one was created from recycled steel in an electric-arc furnace powered by a renewable energy source. The other was forged as virgin steel from a coal-fired furnace. One was created close to the project site, while the other may have been transported across an ocean.
For those serious about reducing embodied carbons in their projects, the first step is to find a way to measure the carbon associated with each of those two steel beams.
Fortunately, “There’s an app for that.”
The Embodied Carbon in Construction Calculator (EC3) is a free, cloud-based, open-source tool that utilizes data to inform on material choices and addresses the issue of cradle-to-gate embodied carbon.
While operational carbon emissions might be generally categorized as an efficiency-first design issue, embodied carbon falls more within the domain of material procurement and assembly process. Of course, there are overlaps between the design and procurement when it comes to esthetics and material selection.
McKinsey explains the EC3 calculator allows easy access to material carbon-emissions data for products manufactured within a defined area. Integrating that data with BIM tools allows the transfer of quantitative project material data to the EC3 from the building’s digital model for detailed AEC analysis.
Ranking materials within the geographical area in terms of their carbon embodied performance drawn from Environmental Product Declarations (EPDs), the design and building teams can then determine, for example, how those identical-looking steel beams stack up against each other.
To be effective, all this should be part of the initial work undertaken by designers in consultation with project owners and considered alongside all other aspects of a building’s performance over its lifespan. By adopting a low carbon design outlook and making low carbon procurement a priority, the bar for best practices will be raised across the industry.
Obviously collaboration across all parties is required, something already demonstrated by the engineers, architects, supplier and academics who have made the EC3 available in the first place.
As McKinsey points out, “The co-operation behind EC3…serves as an important catalyst for change. EC3’s underlying data set brings together standardized material-manufacturer information, making it open and geolocated.”
This open data approach is part of the future. Combined with BIM, EC3, “connects the whole AEC value chain across project phases,” concludes McKinsey. “Together, these technologies deliver data-driven insights on a unified platform, empowering better decision-making throughout the project life cycle.”
Owners and developers must obviously be onboard from the outset. It’s their project, after all. However, in a world of increased environmental awareness, there are marketing advantages and financial returns to be gained by specifying low carbon materials and matching them with efficient designs and assembly processes.
John Bleasby is a Coldwater, Ont.-based freelance writer. Send comments and Climate and Construction column ideas to firstname.lastname@example.org.