Phil and Chris, hosts of the Green Architects’ Lounge Podcast, define and discuss embodied carbon in buildings, and make an impassioned case for understanding why this is absolutely the most urgent issue we face in the design and construction industry today—even ahead of zero-energy building—as we work together to combat a fast-approaching climate crisis.
Listen to the podcast
Embodied carbon is carbon that is emitted in the production of materials, and the building industry is responsible for 40% of global annual emissions. Buildings are the problem and the solution, and understanding the immediate impacts of embodied carbon is absolutely vital.
Phil and Chris define the critical difference between embodied and operational carbon, and explain why net-zero-energy buildings simply aren’t enough at this moment in time. They take a pass at understanding the numbers behind the issues. They also spend the second half of the podcast talking about the materials that we either must, or absolutely should not specify. Wood is good, steel and concrete are bad, but anyone in the industry knows that this doesn’t leave us with a simple puzzle to solve.
The Cocktail: The Bennett Cocktail
2 oz. Gin
¾ oz. Fresh lime juice
¾ oz. Simple syrup
2 dashes Angostura bitters
Directions: Shake all ingredients with ice to chill, then strain into a chilled glass. Garnish with a lime wheel.
- What is embodied carbon? Carbon that is emitted in the production of materials.
- 40% of global annual carbon emissions are caused by building industry.
- We need to understand eCO2e (embodied carbon emissions) vs. oCO2e (operational carbon emissions).
- What are the differences between embodied (upfront) vs. operational carbon? (11% embodied + 28% operational = 39% total)?
- We don’t have time to mess around. New zero-energy-buildings are simply not good enough to save us in time. Energy is not a proxy for carbon.
- Buildings are the problem and the solution. It’s best not to build at all, but if you must—and we must—embodied carbon emissions become critical.
How is our tribe doing already?
- For residential construction, we are doing pretty well, and it’s been a good testing ground. The nerds need to distill the data into actionable rules of thumb so the non-nerds can act.
- Commercial is the big nut to crack: 33% of embodied carbon is in the structure.
- We can’t get to net zero-carbon with a dirty grid.
- Transport of workers to the job site is the biggest source of emissions.
- Impact of the work we do is more important that personal changes we make.
- Sometimes it actually can be better to tear down and build a smaller, high performance building.
- Impacts of the construction process are 20-25% of the total.
Understanding the numbers
- Calculations now are right enough, we need action more than precision.
- Use only very round numbers—1,2,5,10,20,50,100—so they are retained.
- EPDs are the MPGs for buildings.
- How can a number be negative? Regenerative building can actually fix the environment.
Top five materials
- FSC-certified wood (all wood is not the same)
- Natural building materials (straw/hemp/wool)
- Cellulose insulation
- Cross-laminated timbers
- Wood fiberboard insulation
Bottom five materials
- Spray foam
Song of the episode
747 by Bill Callahan
Images courtesy of Chris Magwood, Endeavour Centre; Jacob Racusin, New Frameworks; Ace McArleton, New Frameworks.
The Green Architects’ Lounge hosts are Chris Briley and Philip Kaplan. Chris is a principal at BRIBURN architecture for life. Phil is a principal at Kaplan Thompson Architects. Never miss an episode and take the podcast with you! Subscribe to the Green Architects’ Lounge on iTunes or from wherever you download your podcasts. The show’s Theme Music is Zelda’s Theme by Perez Prado.
Special thanks to our sponsor Pinnacle Window Solutions!
Get building science and energy efficiency advice, plus special offers, in your inbox.