I also welcome the renewal of the dialogue. I have made some progress since
we last spoke. I am sending you (under separate cover) a paper that
discusses sustainability issues with some discussion of the weighting issues.
Sustainability issues address normalization or benchmarking. They are
independent of valuation issues which require weighting. If weighting is not
done, then valuation is by default either equal among environmental concerns
(problems, burdens) or it is at the discretion of the user. Most systems now
employed to evaluate overall building environmental performance are both at
the discretion of the user and under the implicit weighting assigned by the
methodology (BREEAM, BEPAC, LEEDS, etc.) I propose use of a system that
continues to involve the user's discretion but makes it explicit,
systematic, specific, and transparent. I would not impose my values on
others but only ask that they give an accounting of the values used in
making their environmental assessment and evaluation of a product, material,
design, or building.
I have met with Erwin Lindeijer (of the University of Amsterdam IVAM -
Insitute for the Environment). He wrote the portion of the SETAC Europe
Impact Assessment work group LCA methodology document in which weighting is
advocated. I have not heard from him that there is any resistance to the
approach he has advocated.
I currently do not see any larger data problem with weighting than with any
of many other data-dependent aspects of LCA. I do not see it as being any
more subjective than not weighting. In fact, it identifies the subjectivity
and is specific about the decisions made whereas not weighting leaves the
implicit weighting subjective and unidentified. Avoiding weighting leaves
weighting decisions to those making them without systematically establishing
them by use of a set of criteria and an explicit process for application of
those criteria.
My (still-unsubmitted) draft report for EPA contains an appendix with the
worked example from which the weights I show were derived. These are
presented only as my best effort to date for global weighting. Local or
project specific weights might differ. _EcoIndicator '95_ from PRé
consultants (Amersfoort, Netherlands) shows a worked example for the
European context. I am in the process of establishing more detailed
procedures for groups or organizations to use in developing (or adopting
existing) criteria and applying them to create their own weighting schemes.
These can be either global or local/regional/project specific. In most
cases, I believe (as does Lindeijer) that both are necessary. Thus, a
further level of weighting will be required to weight the two sets of weights.
I see no reason not to do weighting, and I am unable to understand what the
reasons are for the reluctance of U.S. LCA pracititioners to do it. Does
weighting expose the high degree of uncertainty that often accompanies or is
embedded in commercial applications of the LCA process? I believe that
identifying and handling uncertainty can and should be done rigorously (see,
for example, the very thorough and lucid treatment of the subject in M.
Granger Morgan and Max Henrion,1990, _Uncertainty_ , Cambridge University
Press, 332 pp). In fact, uncertainty is a given in this work, and must be
addressed if reliable, credible results are to be produced.
Hal Levin
At 10:17 AM 3/5/97 -0500, Joel Todd wrote:
>In his comments on Rob Watson's description of LEED, Hal raised some
>important issues concerning the application of life-cycle assessment to
>buildings. Life cycle concepts are very useful in thinking about the
>"green-ness" of various alternatives--particularly in identifying the
>trade-offs among those alternatives, since it is rare that one alternative
>is "best" on all parameters. His discussion on the inevitability of values
>entering into the assessment is absolutely correct. However, those of us
>in the U.S. who are trying to develop better LCA methodology are not quite
>as convinced as the Europeans that "normalization" is an objective and
>feasible process, given data currently available and the importance of
>local conditions on many measures. The scientists are still arguing over
>the validity of some measures and we are exploring alternatives to the
>"normalization" approach. The point is that these references are useful,
>but LCA is still under development. We should use it and start to
>incorporate its concepts into our thinking, but we should not overstate our
>capabilities.
>
>LCA It is one of many tools that help us to consider more thoroughly what
>we mean by "sustainable" or "green." Even though the developers of the
>methodology have invented an incredibly arcane jargon, it is really a
>simple concept and one that I encourage everyone to use.
>
>Hi Hal, good to be having this conversation with you again!
>
>--Joel
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