Although the AGC initiative is aimed at general contractors who are responsible for the overall results of a project, it necessarily includes other parties, skilled subcontractors, and others. Their contributions—project materials, components, labor, and work practices—must be taken into account when calculating the overall carbon footprint of a project. According to the AGC Guide, for projects that prioritize carbon reduction, carbon sources must be accurately identified and responsibility assigned for tracking and mitigating them. Decarbonizing construction will therefore be an intensive collaborative effort.
In their role, subcontractors will need to assess not only their own operations for carbon contribution, but also those of suppliers who provide the equipment, components and materials used in construction. Depending on how they are designed, produced, delivered, installed and functioned, these inputs determine the project’s embodied carbon, which is the sum of greenhouse gas emissions associated with operations such as raw material extraction, material manufacturing, transportation/demolition and disposal. It is distinct from operational carbon, which is the greenhouse gases emitted from the ongoing use of the project.
Ubiquitous materials like concrete, steel, glass and wood are getting the most scrutiny for embodied carbon analysis, but many other materials could play a role as construction decarbonization advances. That could put more subcontractors under the microscope than general contractors seeking to build greener.
In a video briefing on the new guidance provided by AGC, Joe Rosa, CEO of the general contractor who helped draft the document and is chief sustainability officer at Minneapolis-based Ryan Companies, advised contractors of all types to put the greenhouse gas profile of construction inputs on their radar. Ryan works to understand the global warming potential of the materials used in its projects and has developed a list of the top 11 materials, suggesting that concerns extend beyond the bulkier materials that are the biggest contributors to greenhouse gases.
“I would encourage companies to understand the role of their products, whether it’s in a high or low carbon footprint and how it helps with the overall carbon footprint of the project,” he says. “Those kinds of differentiators are going to be important going forward. As people are really trying to show the market that they can decarbonize and help them meet their carbon targets, building relationships with subcontractors and materials manufacturers who have really thought about this and are bringing more innovative and better products to market is a great thing to do. Even if it’s not immediately listed as a top priority, it’s still a value proposition that’s worth sharing with everyone.”
