I have a question about the reporting of the cost of concrete between these two credits.
Background:
MRc4 - Recycled Content. Concrete manufacturers provide their mix design, $/m³, volume used, etc. on the Supplementary Cementitious Materials calculator. The resulting value is entered into the cost column of the MRc4 template, and designated "SCM Cement," with a post-consumer recycled content of 100%. Therefore, the cost of the CONCRETE is not counted towards this credit, rather just the cost of the SCM cement. If the cost of the concrete was $100, and $35 was determined to be "SCM Cement," we would count $35 at 100% on our MRc4 template. Fine.
MRc5 - Regional Materials. If a product meets the extraction and manufacturing distance requirements, 100% of its material cost is included toward the total regional materials cost of the project. The $100 worth of concrete that is locally-extracted is recorded as $100 on the MRc5 template.
The issue:
If we say the cost of the concrete on a project, not an insignificant amount in most commercial buildings, is only the "SCM cement," $35 in the example per direction from MRc4, we are losing the benefit of an expensive, local material in MRc5: $35 vs. $100.
Additionally, how do we reconcile this difference when reporting our Actual Materials Cost?
Has anyone worked their way through this?
Keith Robertson
PresidentSolterre Inc.
54 thumbs up
September 18, 2015 - 10:06 am
It is fine to have two different values for concrete. The SCM value ($35 in your example) is the concrete's contribution to MRc4. The full concrete value ($100 from your example) contributes to MRc5.
It is odd that the SCM calculator requires us to report $35 at 100% recycled content instead of $100 at 35%, but that is how CaGBC set it up.
If you are tabulating the actual LEED material cost for the whole project (instead of the 45% default value) I would use the full concrete value, not the SCM value.
Eric White
Sustainability CoordinatorGroup2 Architecture Interior Design Ltd.
September 22, 2015 - 5:03 pm
Thank you for the advice, Keith. Have you submitted a project using the latter method?
I think we will be submitting a narrative explaining the $100 at 35% (rather than the $35 at 100%) for MRc4.
Keith Robertson
PresidentSolterre Inc.
54 thumbs up
September 24, 2015 - 10:19 am
I think that a narrative explaining that submission would be fine. We have submitted the other way with no questions asked. We called it "Cast-in-place concrete" in MRc5 and "SCM Cement" in MRc4