Architects have always adapted their designs for the key building indicators of their time. After decades of focus on energy efficiency, embodied carbon is quickly becoming the key indicator for our next generation of buildings. Yet most of us are only beginning to understand the work of life cycle analysis (LCA), which is central to assessing the environmental impacts of building products both before, during, and after construction.
Wood and other bio-sourced building materials offer a unique potential to help the construction industry store carbon instead of emitting it. During photosynthesis, plants absorb carbon dioxide (CO2) from the atmosphere and release oxygen. When this fiber is utilized in construction, we can effectively lock away significant amounts of carbon for the life span of the building. This makes wood fundamentally different from other building materials with energy-intensive manufacturing using fossil carbon.
“With the smoke from wildfires still clouding some North American skies, there’s never been a better time to learn about biogenic carbon,” says Eli Gould, who educates architects through the non-profit Quebec Wood Export Bureau (QWEB), and manages industry-wide non-profit initiatives in BIM and carbon calculation. “It’s a humbling topic with a call for modern forestry to tackle mitigation work across a huge landscape before and not after fires. Even with all that work ahead, taking a closer look at biogenic carbon can also bring about positive education about forest ecosystems, and a reminder that we often under-report their long-term benefits.”
1 De Haro / Perkins&Will.
A quick understanding of embodied and biogenic carbon
Embodied carbon refers to the total greenhouse gas emissions associated with the extraction, processing, manufacturing, transportation, construction, use, and end-of-life disposal of a building material. It encompasses both the direct emissions from the material itself and the indirect emissions from the energy used during its life cycle.
In wood construction, embodied carbon is calculated based on the amount of wood stored in the structure. The life cycle analysts’ work also takes into account the co-products from the log that made the lumber, and the footprint of the milling, harvesting, and wood drying operations.
Biogenic carbon refers to the carbon that was captured by the whole plant (tree) during growth; not only the sawlog portion above ground but the roots, branches, and leaves or needles. A biogenic carbon calculation also starts with the volume of lumber stored in a structure, but then adds attributed data based on the dynamics of the forest ecosystem.
Steps to account for biogenic carbon after a baseline comparison has been made
Forestry verification is now a global and satellite-driven topic. North American data shows that our primary risk to forest ecosystems is not timber harvesting but encroaching development and the parcellation of land. However, the 60 years of continuous forest inventory work combined with satellite verification, shows how the North American continent is on a biogenic increase as trees continue to come back around our cities and towns, with the regrowth after past harvests, and even in the wake of catastrophic fires.
One obstacle to improved data about the life cycle of wood as a building material is not in the forest origin, but in what happens at the end of the building’s service life. The analysis turns back to the local building environment and the way that wood will be landfilled or recycled. This is often a part of the equation that a life cycle analyst is least sure about, so it is a good time for architects and owners to implement circular principles in their building design.
The Offsite Wood initiative that combines BIM tools for architects with timber industry expertise is helping pilot project architects with this topic to unlock the full circularity benefit of their buildings. The architects’ role today is a sign of hope that studios can have an impact from choosing a material, to designing for circular economies that will re-use it in the next century.
If you have any questions, would like to schedule a lunch and learn seminar for your firm, or want to know more about Offsite Wood and Carbon Fixers, write directly to info@offsitewood.org or visit the CarbonFixers landing page to sign up for beta access to the software.