Sustainable building materials and methods are top-of-mind in today’s construction industry. While there are many sustainable building materials to choose from during design, wood is naturally a superior choice for developers, designers, and builders interested in lowering the environmental impact of their projects. [For all images, See PDF or View in Full Issue.]
An essential part of sustainable construction is transparency into the environmental impact of building materials selected for the project. Transparency into the effects of building material manufacturing processes may be achieved through Environmental Product Declarations or EPDs. Unlike product evaluation reports that evaluate properties for building code compliance, such as structural strength, durability, or fire resistance, EPDs are currently voluntary, independently verified reports that document the measurement of environmental impacts across a building material’s life cycle. A building material’s life cycle may be measured as:
- “Cradle-to-gate” (for the production stage only) or,
- “Cradle-to-grave” (for the production, construction, use in a building, and end-of-life stages).
EPDs are based on Life Cycle Assessments or LCA studies conducted per ISO standards. Specific rules for evaluating similar building materials are found in Product Category Rules or PCRs. PCRs are in turn developed by independent program operators such as ASTM International, SCS Global Services, UL Solutions, and BRE. This alphabet soup can be confusing, but the core deliverable is the EPD that designers use for making decisions on building materials. EPDs may be building material manufacturer and product-specific or part of an industry-wide EPD with environmental impacts averaged across multiple manufacturers and locations. There are numerous directories that list verified EPDs, including:
- Environmental Product Declarations – Certification – Products & Services (astm.org),
- Certified Green Products Guide | SCS Global Services,
- SPOT – Sustainable Product Database (ul.com),
- Impact (bregroup.com).
MiTek now has EPDs in place and ready to use to support our customers and the building industry.
Environmental impacts measured in an LCA and reported in an EPD include the potential for:
- global warming,
- acidification (absorption of CO2 into bodies of water),
- eutrophication (increase of nutrients in bodies of water leading to excessive plant and algae growth),
- smog creation,
- ozone depletion,
- abiotic resource depletion (diminishing availability of non-living natural resources).
These potential impacts interest environmental scientists, the most notable being global warming potential due to greenhouse gas (GHG) emissions. GHG includes embodied carbon in building materials, measured in kilograms of carbon dioxide equivalent or “CO2e”. The CO2e may be used to calculate the embodied carbon of building materials for a designated unit of measure in the EPD, such as a metric ton or cubic meter of material. For instance, the carbon footprint of a wood truss package could be calculated by summing the kgCO2e contributions of all the dimensional lumber by volume, connector plates by mass, and the energy used during truss production.
Embodied carbon is becoming more significant for the construction industry as jurisdictions introduce and enforce regulations for using building materials with lower embodied carbon. Some examples of embodied carbon regulations include:
- California Assembly Bill No. 2446,
- General Services Administration (GSA) Low Embodied Carbon Program,
- U.S. Federal Buy Clean Initiative.
The common thread in these regulations is the goal of reducing GHG emissions and decarbonizing the building stock over the coming decades through lower embodied and operational carbon.
EPDs may also be used in whole building LCA and voluntary green building programs such as:
- Leadership in Energy and Environmental Design (LEED) by the U.S. Green Building Council,
- National Green Building Standard (ICC 700) by the International Code Council,
- Green Globes™ by Green Building Initiative,
- Living Building Challenge™ by the International Living Future Institute,
- Building Research Establishment Environmental Assessment Method (BREEAM®) by BRE.
These voluntary green building programs go beyond the building code requirements we are more familiar with and incentivize green building design using materials with EPDs.
As mentioned at the outset, wood is a sustainable building material and helpful from an environmental standpoint as it sequesters or stores carbon. Other traditional building materials such as concrete, masonry, and steel have higher embodied carbon levels through their production, yet steel has a significant environmental benefit due to its recyclability. The American Wood Council (AWC) has developed EPDs for softwood lumber and engineered wood products, which can be found at https://awc.org/sustainability/epd-tb. In July 2024, the Environmental Protection Agency (EPA) also awarded significant financial grants to AWC, ICC, and other building material associations under its Reducing Embodied Greenhouse Gas Emissions for Construction Materials and Products program. This will prime the pump for development of even more PCRs and EPDs for wood and other sustainable building products over the coming years.
Environmental transparency of building materials provides a unique value to the construction industry, enabling smart decisions for sustainable design. The demand for building material EPDs will continue to grow as the need for more sustainable building methods become paramount.