Billy asks: I am a roofing contractor that is being asked to provide an itemized list of LEED-compliant material and the associated value. The request goes also states, "If only a portion of the material is LEED-compliant, provide the total material cost and the percentage of material which meets the LEED threshold."
I have some manufacturer provided spec sheets that highlight LEED attributes, such as SRI or recycled material, but not a percentage of the material that is LEED compliant.
Does this request make sense to anyone?
Hi Billy: It sounds like you are being asked to provide the overall cost of the roofing assembly and also the percentage of LEED-relevant content. Your roofing assemblies may help building owners to gain LEED certification if the materials have recycled content and if they come from within a particular local distance radius. It’s fine if only a portion of the material is recycled or regional, as you note in your question.
The categories in LEED that may apply are Recycled Content (Materials and Resources MR Credit 4) and Regional Materials (Materials and Resources MR Credit 5). Please note that it is not the building products or assemblies that are LEED certified, but the finished building. Your roofing assemblies contribute to the LEED-readiness of the overall building.
If all you are being asked to provide is the raw data, then you can get the costs and the percentages of the recycled and regional materials from the manufacturer(s). If you are being asked to provide the actual calculated values, then you can follow the steps below.
Determine recycled content:
You will need to contact the manufacturer(s) to find out the actual percentages of recycled content in the materials that you use in your roofing assemblies. Once you have this information, you can apply these equations from the LEED V3 Green Building Design and Construction handbook to your data to determine the following information:
Equation 1 – Material’s Recycled Content
Recycled Content Value ($) = (%Postconsumer Recycled Content x Materials Cost) + 0.5 (%Preconsumer Recycled Content x Materials Cost)
Equation 2 – Project’s Recycled Content
Percentage Recycled Content = Total Recycled Content Value ($)/Total Materials Cost x 100
Equation 3 – Assembly’s Recycled Content
Assembly Recycled Content Value ($) = % Postconsumer Recycled Content/Total Assembly Weight x Assembly Cost + % Preconsumer Recycled Content/Total Assembly Weight x 0.5 x Assembly Cost
You may find these definitions helpful:
Post-Consumer Content: USGBC (or US Green Building Council) defines post-consumer recycled content as material that has been used in commercial, industrial and residential settings and that can no longer be used for its original function.
Pre-Consumer Content: - USGBC defines pre-consumer recycled content as that which was diverted from the stream of manufacturing.
Determine the percentage of regional materials:
Per the LEED V3 Green Building Design and Construction handbook, regional material must be ‘extracted, harvested or recovered, as well as manufactured, within 500 miles of the project site for a minimum of 10% or 20%, based on cost, of the total materials value.’
To determine regional material costs, use the same cost values as in the recycled content equations above. Apply the following equation:
Equation 1 – Local Materials Percentage
Percentage Local Materials – Total Cost of Local Materials/Total Materials Cost ($) x 100
I hope this helps to clarify your question. Good luck!