I understand how to calculate recycled content using the SCM calculation for concrete. My question is this, does this calculation affect your total material cost for the project if you're tracking actual costs? In my mind if I am only considering the cost of the Portland cement and SCM's in the credit calculation then I would only account for the cost of those materials in my total material cost for the project, i.e. $7.50/cy total material cost vs. $85.00/cy total cost.
Or, am I calculating the recycled content using the SCM calculation and applying that dollar amount against the total material cost. For example, at $85.00/cy total cost, I'm paying $10/cy for portland and 20% fly ash. This equates to $1.00/cy of recycled content. For 100cy I have $100 recycled content. Do I apply that $100 against the total cost of $8500 or an adjusted material cost of $1000?
Hopefully you're not as confused as I am. I am on a project that will place approximately 25K cy of concrete some with SCM's some without. So this portion of the total material cost could be quite large.
Thanks for any assistance!
Eric Shamp
Associate Vice PresidentCannonDesign
68 thumbs up
February 27, 2011 - 8:44 pm
William, I think we need some clarification of terms. The "total material cost" is just what it sounds like: the total material cost for all project materials, whether those materials are compliant with LEED criteria or not. It is the denominator in the calculation of the project's total recycled content cost value. It does not vary, no matter whether you use the SCM approach or not.
However, the "assembly cost" of a particular assembly is obviously just the cost of a discrete assembly. In the case of the SCM calculation for concrete, we essentially consider the cementitious materials to be a separate "assembly" from the non-cementitious materials. We know that the recycled content of an assembly is determined by the percentage of recycled content (by weight) multiplied by the assembly cost. The problem with using the standard assembly calculations on concrete is that while the weight of cementitious materials is quite low compared to the entire concrete assembly, its cost is quite high. That cost is then "diluted" by the enormous weight of the non-cementitious material.
So, by treating the cementitious material as a separate assembly from the aggregates, fines, admixtures, and water, we can capture a greater percentage of the flyash recycled content cost value.
So, that's the very long answer. The very short answer is: for the purpose of the cementitious material "assembly" used in the SCM calculation, the assembly cost is $1000. In the total project material cost, however, you use $8500. If you happened to have recycled content in your aggregate, that would be a different "assembly", with an assembly cost of $7500.
Patty Lloyd
Director of SustainabilityLeopardo Companies, Inc.
13 thumbs up
December 28, 2011 - 1:59 pm
So my question would be in utlizing the LEED online template how would you show the SCM? For the materials cost you would only put the total dollar value of the cementious materials and then the recycled content of just the cementious materials? The remainder of the concrete cost, which isn't recycled content then just is part of your total materials cost?
Tim Crowley
LEED AP / Founderwww.BCdesignbuild.com
60 thumbs up
October 11, 2012 - 2:50 pm
Patricia - I was just reviewing your thread about concrete SCM. I think that the answer to your last question, posted on Dec 28, 2011 is YES, but I would like to get someone else to weigh in on this issue.