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Building Matters

Introducing the Embodied Carbon in Construction Calculator (EC3)

The University of Washington Carbon Leadership Forum introduces new software for measuring embodied carbon in buildings

The Skanska Urbani residential block in Nya Hovås, Sweden. Skanska has made a commitment to measuring the embodied carbon footprint for each of its new projects over a certain size with EC3. Image courtesy of Skanska.

In 2018, the Intergovernmental Panel on Climate Change (IPCC) decreed that 1.5°C is the threshold below which the planet must stay to avoid the worst climate impacts. Scientists warned that to hold global warming to this level, we must cut greenhouse gas emissions roughly in half by 2030 and to zero by 2050. Given that buildings generate nearly 40% of annual global carbon emissions, according to think tank Architecture 2030, it makes sense to use three main strategies to cut our contribution: repurpose existing buildings, cut operating emissions, and build with low-carbon and carbon-storing materials.

Today’s green building industry is increasingly concerned with embodied carbon.* Fortunately, it is now measurable, and LEED project teams are encouraged to account for it. The Materials and Resources (MR) credits are designed to address this critical area. They focus on minimizing the environmental penalties associated with the extraction, processing, transportation, maintenance, and disposal of building materials—in other words, the MR category considers the entire life cycle of the components going into a building.

Measuring tools

Tools for conducting Life-Cycle Assessments (LCAs) include Environmental Product Declarations (EPDs) and material ingredient reporting tools, like Health Product Declarations. Manufacturer transparency around product content and production requirements gives architects, engineers, and contractors the ability to set informed specifications. In short, EPDs are a means for sourcing vetted products for lower-carbon projects.

Of particular interest in the MR category is the Procurement of Low-Carbon Construction Materials pilot credit, the goal of which is to reduce embodied carbon. Toward that end, the University of Washington/Carbon Leadership Forum launched the Embodied Carbon in Construction Calculator (EC3) tool.

Originally developed by Skanska and C Change Labs, EC3 was incubated by the Carbon Leadership Forum and nearly 50 industry partners until its public launch at Greenbuild 2019, at which time the nonprofit Building Transparency was founded to house EC3. Its mission is to provide open-access data on embodied carbon and the tools necessary for the industry to make low-carbon building materials selections.

Stacy Smedley, executive director of Building Transparency and co-creator of EC3, explains that the tool has two parts: the engine or database of digitized EPDs and the user interface that allows people to search and sort those EPDs and compare manufacturers and products to find lower-carbon options. “We were trying to create, essentially, the Google of EPDs,” Smedley says of the free, cloud-based software, which now has over 19,000 registered users in 70 countries.

EC3 interface
The EC3 interface showing material selection. Image courtesy of Building Transparency.

The EC3 database is generated from EPDs covering the production stage of a product’s life cycle. LEED’s low-carbon procurement credit ties to everything that is free and openly available in the tool, which has the function of exporting a LEED-compliant report—a formatted Excel file populated with the required data and ready to upload and share. (LEED teams earn one point for attempting the credit and another point for achieving a 30% or higher reduction in carbon.)

“It helps people see which manufacturers are leading, from a carbon perspective,” Smedley explains. “This is something architects and builders look at first. It can be the basis for [determining] specs.” Searches can be narrowed to LEED’s procurement pilot credit requirements, limiting the results to suitable materials.

“We can’t—and shouldn’t—expect all professionals looking at embodied carbon at the project and product level to be using building information modeling (BIM)–based products,” Smedley continues, noting that EC3 offers users the ability to manually enter building material quantities, even if they don’t have a building model.

Asked about feedback from the software’s pilot partners—among them architecture firms Perkins&Will and ZGF—Smedley says it has been well received, but there are always requests for more categories. “Now that they have access to data, they want more of it,” she says.

There’s interest in additional information on emissions derived from transportation and construction sites, as well as end-of-life possibilities, meaning products’ recyclability or biodegradability. Smedley’s team is currently working on additional tools to provide that data. There are also plans to serve the residential sector; Building Transparency is collaborating with a developer in Colorado, Thrive Home Builders, which is striving to build net zero–carbon residences.

For those interested in exploring EC3, registration is free, and there are YouTube video tutorials on using the software. Smedley encourages people to explore its functionalities, which include granular subsets of data (and, in time, will cover many more categories than are publicly available at present—from mix-specific concrete to air barriers to data cabling and steel openings).

For people looking to get a general sense of a project’s emissions profile, Smedley says, “It’s basically the same four clicks for choosing materials—once you see it, you understand how easy it is.”

Real-world applications

As a pilot partner, ZGF’s Marty Brennan has tested EC3 on a LEED project. “From my perspective—and you’d likely hear the same from other architects, general contractors, and structural engineers—EC3 is a game changer because it is free, cloud-based, and user- and process-friendly,” he says.

Brennan appreciates carbon accounting software tools as a means for bringing together an entire team around that consideration. He says cloud-based design and carbon modeling go hand in hand, and any tool that can eliminate the need for researching hundreds of individual EPDs to make product comparisons is a benefit. He values the ability to quickly get a robust picture of a project’s cradle-to-gate embodied carbon. He makes the point, too, that energy modeling requires a level of expertise that most design firms don’t have, but that they are capable of carbon modeling. “It’s totally in our court,” he says.

Net-zero-carbon home
Thrive Home Builders in Colorado is working with Building Transparency to build net zero–carbon single-family homes. Image credit: Thrive Home Builders

ZGF’s piloting efforts include using Building Transparency’s new, open-access version of Tally (a popular LCA app that is not product-specific): the Tally Climate Action Tool (tallyCAT). According to BuildingGreen, tallyCAT leverages the capabilities of Tally and the EC3 database of EPDs within BIM programs like Revit—centralizing capabilities that have previously been separate.

“Having a plug-in to connect a BIM Revit model to EC3 is powerful because it supports templates to avoid starting from scratch every time,” Brennan explains. “Take wall assemblies—say we have five we commonly use; we are starting to build those as templates and have the EC3 metadata in the template to be able to start each project with that intelligence. The more we can simplify and automate, the better, and it brings the costs down.”

ZGF has been focusing on tenant improvements and interiors because they typically get changed out every 10 to 15 years, which has a big carbon impact—one that can eclipse the structural embodied carbon. The firm is in favor of mass timber and biogenic carbon and is looking for ways to sequester carbon in buildings, too.

In other words, ZGF wants to go beyond up-front carbon emissions. As more companies look to do the same, Building Transparency’s software is being designed to answer their needs. Or, as Brennan puts it, “All this plays well into the EC3 framework—they build tools that make bridges.”

Pathways to reduction

USGBC’s LEED director, Wes Sullens, agrees the conversation around embodied carbon is exploding. He views the new Procurement of Low-Carbon Construction Materials credit as a direct response to the factors fueling that conversation.

“When we developed this credit, we were intending for the design of buildings to be informed by LCAs,” he says. “The whole theory of LCA is design change. And the theory of EC3 is competing among products and materials to find the best in class.”

Sullens notes that the LEED credit rewards teams for gathering emissions-related information and encourages transparency. He sees EC3 as a necessary and “disruptive” technology, in that it allows easy access to data that blends LCAs and EPDs.

“There’s no hard line between LCAs and EPDs in terms of working on projects. It’s an evolution,” he says. “And EC3 is disrupting the paradigm. It’s directionally accurate. It may not be the most precise tool yet, but it is allowing people to make decisions about lowering their embodied carbon footprint.”

There are currently 80 projects that have registered for the Procurement of Low-Carbon Construction Materials credit, and six projects that have achieved it. As promising as that is, it’s an enormous challenge to get the entire building industry on board to count greenhouse gas emissions during the planning phase. However, new policies, LEED credits, and tools like EC3 offer pathways to reduction.

*The term “embodied carbon” can be misleading and is often misunderstood as stored carbon. A more accurate description is up-front carbon emissions because they are emitted during the excavation of raw materials and production of materials that will go into a building i.e., the carbon has already been released into the atmosphere before the structure is built.


Kiley Jacques is senior editor at Green Building Advisor. This article originally appeared in the Tools and Tech department of USGBC+ magazine’s spring 2022 issue.


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