Hello CLF Team - What is the lowest embodied carbon CMU block available in SoCal with and without a cost premium? Thank you, Aaron
Expanding on Aaron’s question, we did a little preliminary research on CMU that might be helpful.
We’re working on a few projects likely to use CMU as the façade and vertical structure. Initially, we wanted to source lightweight block due to the improved thermal performance, but decided to compare the embodied carbon numbers of LW block against MW and NW block. Digging into the EPDs—primarily from Angelus Block’s website and EC3—we found lightweight CMU tends to have at least as much cement as a percentage of the overall mix to achieve the same compressive strength as medium and normal weight CMU. (This makes intuitive sense. Manufacturing process and volume of cement are determinant factors in strength, density is not.)
A few important caveats:
- The EPDs we looked at exclusively account for the A1-A3 product stages.
- Without a wholistic LCA it’s hard to assess if the additional cement in the block is offset by smaller foundations/footings (resulting from the lower structural weight), reduced rigid insulation in the walls, less fuel freighting the CMU to the project site, etc.
Hey @aaron.vaden-youmans! Do you intend to use for structural application or for non-structural partition walls?
For non-structural application, you might have some more flexibility. There’s a company that USGBC-LA was supporting that takes plastic waste and makes into blocks. There’s also an interesting living lab in Seattle by @ddavies (way to go Don!) that uses Prometheus blocks, but that’s pretty early stages and likely not available for commercial use today.
For structural blocks, here are a few you might track for having appropriate ASTM test data and see where they’re at with manufacuring and distribution. Carbon Built started out of UCLA research, but last I heard their plant was starting in Alabama. Perhaps others have more recent information…
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Thank you Luke! These links are great.
I’ve looked into all and waiting to hear back on the regional availability of Prometheus and Biomason blocks. Indeed, it seems CarbonBuilt is not available in our region yet.
We need these for exterior structural application in Southern California (for new rail stations).
At this point, we think our best bet is the Angelus’ CarbonKind block.
Let us know if we are missing anything in terms of innovative low-embodied carbon CMU in SoCal.
Tracking this thread!
In the past, best I’ve been able to do is pointing to the best-in-class available CMU blocks/suppliers. The Angelus CarbonKind block being a leading product we have recommended in the past.
All others seem to be in early testing stages and not yet commercially available, at least last time I reached out. @aaron.vaden-youmans in the case you hear back from Prometheus and Biomason, would you mind sharing your conclusions here?
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We have heard back from CarbonBuilt. They are currently working on expanding out West and should have product availability out of their Flagstaff producer partner’s plant towards the end of the year. Also, they have partnered with Climate Earth for their EPDs and will have a preliminary EPD ready once they have finalized their mix design and a final EPD after 12 months of data collection at the plant.
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Semi related question, has anyone updated their project documents (ie specifications), CMU division, to include language about low-embodied carbon CMU; similar to what you could do for cast-in-place concrete division 03?
We are wanting to update our specifications but struggling a bit on how to exactly since CMU is made up of both the concrete block itself, where we could use a performance spec similar to CIP concrete, and then the grout portion - which we know little about in terms of laying out GWP limits.
Any thoughts on how to actually incorporate low embodied carbon CMU on a project would be appreciated!
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