After having reviewed the report entitled Assessment of Technical Basis for a PVC-Related Materials Credit in LEED, the following comments are submitted for your consideration. Before I begin, I would like to acknowledge the obvious effort put forth by the members of the TSAC to complete this large scope of work. It is a thankless job to be sure.
That being said, the analysis documented by the report leaves much to be desired. The extensive reliance of the study on secondary data and assumptions is disappointing, and the relative lack of transparency debilitating, making it difficult to determine even basic aspects of the research. There also appears to be a lack of consistency in the way issues were handled throughout the study (e.g., exclusion of data or the assumption of default parameters), some of which are pointed out below. Overall, the quality of the report along with the reliance of the study on convenient assumptions and secondary data do much to undermine the confidence and credibility of the analysis. Neither the risk assessment nor the LCA would pass a peer review process as presented.
Life-Cycle Assessment
There are several aspects of the life-cycle assessment portion of the study that are troubling. The following are comments regarding the life-cycle portion of the analysis.
1) The report, as released, is insufficiently documented to allow consideration of the results in any meaningful manner. Widely accepted guidance has been established by the International Standards Organization (e.g., ISO 14040+) and the scientific community to standardize practices and ensure the quality and transparency of LCAs. These standards require that a scoping process be undertaken that, among other things, states clearly the system to be analyzed, the functional unit, system boundaries, data acceptance criteria, data allocation procedures, etc. The communication of this information ensures that the process is open and transparent and that the results and the inherent trade-offs analyzed can be properly understood and interpreted, protecting against the misuse and misunderstanding of the study. It also protects the integrity of the study against the insertion of bias by those performing the analysis. The report clearly falls short of this standard, as pointed out below:
Nowhere in the report are system boundaries for the analyses defined or discussed. It is entirely unclear what processes are included in the analyses and which are not. Some detail regarding product manufacturing is provided in a discussion of alternatives in Appendix B, but this detail is both inconsistent and incomplete. No detail on processes for other life-cycle stages are presented, nor are suitable diagrams defining the scope and boundaries of the analysis.
Secondary data contained within Simapro and BEES were used for the study. Data quality for such secondary sources can vary widely, but tend to be poor as they often are incomplete and contain assumptions and uncertainty that exert an inconsistent affect across alternatives. Some of these inconsistencies are noted and described in Appendix B. While the use of such databases is an unfortunate necessity in LCA for many upstream and end-of-life processes, LCAs based primarily on secondary data are typically referred to as screening-level LCAs to both acknowledge and communicate the relative uncertainty in the data and resulting conclusions. This LCA clearly falls well within that category.
In addition, secondary data sets within the same lifecycle stage likely have different process boundaries. For instance, an upstream tin mining data set might include inventory from the both the mining and smelting processes, while an upstream iron mining data set might not include the smelting process, but instead include transportation. These differences should be reported and the data quality assessed, as required in ISO14041.
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