In a nutshell:
- Jan 1, 2020 - all concrete purchases required to have EPD
- April, 2021 - establish GWP threshold
- Jan 1, 2022 - all concrete EPDs required to meet GWP threshold
In a nutshell:
Thanks Jordan. If you don’t mind me asking, where are the city’s GWP thresholds described, and do you know how they are defined? Does this concept expand beyond concrete mix/ portland cement? Appr ciate any clarifications you may be able to make!
Hi there. The GWP thresholds won’t be established until April 2021. The thresholds will likley be infomed by much of the same data that was used to set the Marin County thresholds. Things like:
Unlike Buy Clean CA, the formula for setting the threshold is not laid out in the policy. Instead, it will be based on a variety of sources and the best available information at the time. Hope this helps!
When setting limits, I strongly recommend using the EC3 tool (buildingtransparency.org) to choose limits based on performance specs. The point is minimum CO2e per unit stuff held up in the air for 75 years, not minimum CO2e per cubic yard!
I’m not sure I follow.
Like the Marin County building code, the City of Portland’s thresholds will likely be maximum acceptable GWP/yd3 by strength class. We’ll certainly use EC3 as a reference point, since the tool does a great job of displaying the range of what’s possible in your local market based on published EPDs.
However, since concrete application (foundation vs. PT slab) of the same strength mix changes the potential to reduce GWP, we’ll need to take a broad range of applications in mind when establishing an upper GWP threshold. I don’t think it will be as easy as just choosing the 20th percentile in EC3 (termed “achievable”) and applying that to all mixes within a certain strength class since the policy will cover literally any use of concrete within a strength class.
Please do let me know if I missed a critical feature in EC3 I’ve yet to explore or understand.
Jordan, I think you’re making a good point about something EPDs (and therefore EC3) isn’t tracking right now, and should: concrete application. The key question is, how do we understand which concrete(s) are for which application? How do you usually go about this? Is this based on exposure classes (F1/S2 etc) or something else?