Commentary: Life Cycle Assessment

Lead Author: Dr. Jim Bowyer

Publish date: 07.01.2008


Is Its Potential Being Overstated?


This past month Dovetail received a letter from a reader who conveyed a view that the potential benefits of Life Cycle Assessment (LCA) in green building design may be overstated. He said, in part:


“. . . while I think that developing LCA research is important (and I work with an architecture firm that seeks this information from our product reps) I think it is starting to become overstated what it can actually accomplish. The qualifiers of ‘scientific' and ‘3 rd party certification' have a certain uncritical acceptance that I am uncomfortable with. They do not convey the muddy mess that implementing LCA analyses in a built project can actually become. LCA analyses add much more complexity and dependence on software whose ‘determinations' depend on formulations largely too numerous and difficult to understand by those that would actually use it to select between materials. I think the term ‘soft science' may be more appropriate because subjective decisions are the majority when it comes to the summary weightings between the different categories of environmental impacts. And what does it mean that the Vinyl Institute, the Portland Cement Institute and other industry representatives are listed as supporters of Athena LCA software? Is this a science recognized from a third party?”


Given the possibility that others have similar questions regarding LCA, this commentary addresses the letter-writer's comments and shares a few additional observations:


The comment about uncritical acceptance of LCA is an important point. A critical view is always needed, since the results of any study, including those involving LCA, can be skewed. I recently reviewed a life cycle assessment of paper towels vs. electric hand driers that concluded that the electric driers result in lower environmental impacts. However, a close review of assumptions revealed 1) a shorter drier running time than the typical equipment setting, 2) a larger sheet size and higher basis weight for paper towels than the actual physical characteristics of the vast majority of toweling used, and 3) a higher towel use rate per person than has been documented in studies of paper towel use. When these assumptions were adjusted to more realistic values, they pointed to a conclusion exactly the reverse of that reached originally. So, it pays to be inquisitive.


Regarding the life cycle assessment issue, it is agreed that LCA can be complex. However, the complexity that you refer to is that use of LCA does not necessarily make the life of an architect or builder more complex, since user-friendly software is increasingly available. LCA does, however, bring both rigor and intellectual honesty to the process of designating environmentally preferable materials, something that is badly needed in many green building programs.


While LCA is continuing to evolve, the methodology is governed by a set of established international standards. These protocols standardize how studies are conducted and allocations of burdens made. When carried out by credible institutions and with the benefit of third-party involvement and oversight, LCA represents the best alternative to existing prescriptive and intuition-based guidelines. For example, as things now stand, there is no capacity within most green building systems to determine the carbon implications of a materials selection decision. There is likewise no capacity to determine emissions to air or water, nor any ability to consider the total consumption of energy associated with a particular building design or material selection.


As to the fact that the Vinyl Institute, the Portland Cement Association, and other industry entities are supporters of LCA software, this participation reflects the reality that the studies require industry support, including full access to industry data and facilities. Having manufacturers and competing industries involved ensures that the right questions will be asked, and that assumptions, methods, and findings will be meticulously examined and vigorously challenged when need be.


As a footnote, at a recent meeting in Southern California an individual stated that LCA could not be counted upon since it does not yet do a good job of assessing the quality of forest management. The obvious reference in this statement was to forest certification programs. However, it is important to understand that LCA was never intended to take the place of, for instance, SFI or FSC certification of wood or other standards for materials, such as low-VOC emissions standards for carpets, insulation, adhesives and/or paints.


So, is the promise of life cycle assessment being oversold? I don't believe so. We need what LCA can bring to the table. Understanding what it can and cannot do is the first step in achieving wider adoption of this incredibly useful tool. There is a need to understand and embrace this tool as rapidly as possible to provide a more rational basis for building design and materials selection.


Jim Bowyer

Director, Responsible Materials Program

July 2008