Tools: Reducing the Carbon Footprint of Buildings

When designing and specifying buildings, architects and others can make a difference in the amount of embodied carbon in their projects by choosing products with a low carbon footprint. But how can we differentiate between products that do in fact contain low amounts of embodied carbon and those that contain more? One approach is to follow the procedures in green building rating systems such as LEED that include multiple credits conducting a whole building life-cycle assessment (LCA) of products.

There are a number of LCA tools on w hich LEED provides guidance for proper use. Part of the process includes the use of an environmental product declaration (EPD) for each of the main products used in a building. EPDs are prepared at the request and expense of manufacturers. However, the key point is that they are carried out by independent third parties, much the same way code-compliance testing is carried out by independent third-party organizations. For a proper disclosure to be made, EPDs first rely on a product being categorized and rules established for the proper means of comparing that product to others. Simply referred to as product category rules (PCRs), these are usually prepared by trade associations taking into account industry specific data that is common across manufactured products of a particular type (i.e., masonry, roofing, etc.)

With the LCA process and PCRs as the basis, EPDs look at the specific environmental impacts of the product being assessed over its entire life cycle. Among the common reported impacts are the amounts of carbon dioxide released into the atmosphere for each unit (square foot, cubic yard, etc.) of material or product produced. This is good information and allows a specifier to compare the differences in the impact between material types (i.e., masonry versus steel) and products (i.e., some flooring types, insulation types, etc.) as long as a complete and relevant EPD has been performed and made available for those products. While the building products and materials industry is moving in this direction, the current reality is that not all product types have PCRs and not all manufacturers have prepared EPDs for their products. Nonetheless, the best way to find lower-embodied-carbon products is to look for those that are third-party certified as carbon neutral either through EPD data or similar information.

Recognizing the limited availability of EPDs and other information available to design and construction professionals, some leaders in their respective fields have come together and developed some strategies and tools for manufacturers, architects, designers, and other building industry professionals to engage in and use as follows.

Carbon Smart Materials Palette

The not-for-profit organization Architecture 2030 offers a free online public resource called the Carbon Smart Materials Palette (www.materialspalette.org). This tool takes an attribute-based approach to embodied-carbon reductions in the built environment—that is, it identifies key attributes that contribute to a material’s embodied carbon impact. It also offers guidelines and options for emissions reductions. As a dynamic tool, The Carbon Smart Materials Palette is designed to support and complement LCAs and EPDs. It is also intended to provide highly impactful guidelines for low/no-carbon material selections and specifications. The creators do point out that this tool “is a living resource that reflects the best available knowledge and resources at this time. The palette will be updated as new technology, research, and data becomes available. The extent to which any or all of these guidelines and recommendations are realized in practice depends in large measure on their application, local conditions, and the extent to which the designer succeeds in understanding and applying them.”

Currently, the palette addresses some high-impact materials, such as concrete, steel and insulation. It also looks at wood in terms of its potential high or reduced impacts. Similarly, it looks at materials that can be considered carbon smart in that they have low carbon or even store (i.e., sequester) carbon within them. These include hemp-crete, sheep’s wool, strawbale construction, and wood.

Materials Carbon Action Network

An independent collaborative known as the Materials Carbon Action Network (materialsCAN) is comprised of “members of the global building industry that are ready to ACT on the smart prioritization of embodied carbon in building materials” (www.materialscan.org). Those members include manufacturers of ceilings, insulation, flooring, and wallboard products—some of the most common and extensively used products in building projects of all types. It also includes Gensler and Skanska representing the design and construction communities. This group aims to empower those who own, lease, design, or construct spaces with education and tools to better understand the carbon footprint of their projects, specifically through measuring the embodied carbon of specified materials. In terms of action items, materialsCAN indicates that it will 1) improve embodied carbon awareness via client, industry, and external partnerships; 2) support the creation of a methodology to enable analysis and prioritization of embodied carbon goals in specifications; and 3) highlight case studies on low-carbon, carbon-neutral, and carbon-sequestering interiors.

Lisa Conway is vice president of sustainability for the Americas at Interface, one of the founding members of materialsCAN. She points out, “When considering a newly constructed building, typically the most energy-intensive materials are concrete and steel, meaning they have the most embodied carbon. However, most projects aren’t new construction, and most renovations include new flooring. For example, with carpet, from an embodied carbon perspective, up to 100-percent recycled content nylon can be specified, which drastically reduces the carbon footprint for the product category and avoids those emissions today.”

Some of the basic principles that materialsCAN promotes to achieve carbon neutrality in buildings include concepts that architects and other design professionals may already be familiar with and can implement on all current projects, including the following.

• Reposition existing buildings.
• Reuse existing parts and pieces.
• Optimize choices: Do we need it? Do we need as much of it?
• Once decided it’s needed: What is the carbon footprint of it, and are there lower-footprint options?
• Specify for carbon reduction.
• Don’t be afraid to speak up and educate the design firm and owner as early as possible.
• Estimate carbon footprint as well as cost.
• Smart procurement: Suggest options that save emissions and don’t sacrifice performance or cost.
• Engage in policy discussions and opportunities.
• Inform, educate, and push.
• Utilize LCAs.
• Target the highest carbon impacts for footprint reductions.
• Utilize renewable energy for the manufacturing process, and same for supply chain.
• Commit to recycle carbon-intensive materials.
• Work with new product development teams to ensure carbon footprint is a consideration for development process.

Kirsten Ritchie, Gensler’s director of sustainable design, helps incorporate these principles into the firm’s design projects and is also involved with the effort to reduce embodied carbon in buildings. “We need more ways to easily influence and impact the embodied carbon footprint of our projects,” she says.

“We recently delivered a project with a 43 percent reduction in embodied carbon by replacing our typical ‘go-to’ products with lower-carbon-footprint options that still met performance and all other project criteria,” she continues. “Our hope is that with the resources provided by materialsCAN, others will be able to easily make the same improvements.”

Image Courtesy of Gensler

Specifying individual products in buildings with a lower carbon footprint can add up to dramatic reductions in the total carbon dioxide emissions embodied in a completed building project.