Defining correct system boundaries:
indirect and rebound effects in LCA

Session Coordinator: Sebastien Humbert

Tuesday, September 30, 2008
Part 1 : 1:30pm-3:00pm
Part 2 : 3:30pm-5:00pm

LCA is used in an attempt to capture all important impacts associated with a product, process, or service. However, the results are dependent on how the system is defined for analysis and one of the challenges associated with LCA is defining appropriate system boundaries to ensure that the results will not be biased or misleading. The treatment of indirect and rebound effects has been a particularly difficult issue to resolve. Indirect effects are caused by changes in the system at a different location or time, often resulting from the market response to changes in demand (e.g. CO2 emissions caused by deforestation triggered by an increase in demand for agricultural land due to biofuels production). Rebound effects are caused by changes in habits that are more difficult to correlate to the functional unit studied (e.g. emissions of CO2 caused by extra travelling permitted because money was saved when using a lower fuel consumption car). How does one decide when to include or exclude indirect and rebound effects? As LCA becomes increasingly used in supporting decision making process, it is important to strengthen the way this issue is tackled in practice and to suggest accepted and consistent approaches to practitioners. This session addresses this issue, first by describing the state of the art in methodology associated with indirect and rebound effects and then by presenting several relevant case studies.

1:30-1:40
What is and why are indirect and rebound effects important to LCA
Sebastien Humbert, ecointesys-life cycle systems, Lausanne, Switzerland
(presentation)

This introductory presentation contextualizes why the system definition is important, defines the terms, suggests how that will improve the science and application of LCA, what has been done and examples where differences in results occured due to lack of a clear methodology, and a non exhaustive list of key issues related to indirect and rebound effects.

Methodology (15 min presentation, 5 min questions):

1:40-2:00
How to assess the impacts of rebound effects
Mark Goedkoop, Pre Consultants, The Netherlands
(presentation)

2:00-2:20
Rebound effects of sustainable production
Bo Weidema, 2.-0 LCA consultants, Denmark
(presentation)

This presentation provides a definition and classification of rebound effects, and gives examples of the different kinds of rebound effects. In general, ignoring rebound effects leads to either under- or over-estimation of the effects of new technologies. A case study related to the improvement potentials for meat and milk products in Europe is presented. More knowledge is also required of the best ways to influence consumer behavior to convert the insights in the rebound effect into reductions in environmental impacts.

2:20-2:40
Identifying the Marginal Electricity Sources in North America: Sources of Data and Why it Matters
Pascal Lesage, Sylvatica, Montreal
Gregory A. Norris, Harvard University, Boston
(presentation)

In change-oriented (or consequential) LCA, it is necessary to include only processes that are actually affected (marginal technology). This presentation will concentrate on the identification of the marginal electricity in different North American contexts. The general procedure will be reviewed, data sources will be identified, and the importance of properly identifying the marginal electricity producer will be exemplified with a simple case study.

2:40-3:00
Extending system boundaries to capture indirect effects on LCA - An enlightening example!
Renee Michaud, Claude Belley, Edouard Clement, Rejean Samson, Manuele Margni - CIRAIG, Montreal
(presentation)

The importance of properly setting the system boundaries in LCA and its importance for decision making is discussed. An enlightening example presenting a comparative LCA between incandescent and fluorescent light bulbs is proposed. Results for three different system boundary levels are presented and discussed in relationship with their capabilities to capture direct, indirect and avoided impacts, respectively.
The results of this study demonstrated that the final answer depend on which is the marginal electricity production technology.

3:30-5:00
Effects from land use change associated with biofuels
Richard Plevin and Andrew Jones - University of California, Berkeley
(presentation)

The change of use of land in the US to produced biofuels can affect the change of use of land in other regions. This presentation presents the indirect effects associated with increasing biofuel production in the US. We examine the magnitude and uncertainty in the estimation of market-mediated land use conversion induced by the expansion of biofuels feedstock production. We develop estimates based on the output of two distinct economic models (FAPRI from Iowa State, and GTAP from Purdue University) to estimate the magnitude (in area) of the anticipated land use conversion, as well as analyzing the uncertainties in the estimation of the GHGs released from this conversion. We discuss the possible implications of our results for California's Low Carbon Fuel Standard.

3:50-4:10
Reuse of plastic shopping bags and the unintended consequences of bans and taxes
Keith Christman, Shari Jackson, Annie Walton, Mike Levy - American Chemistry
(presentation)

We do have some data on the increase in the purchase of other bags as a
result of high taxes on plastic bags in Ireland. In fact, the amount of plastic used in Ireland increased 10 percent (PIFA, 2004). While sales of plastic shopping bags declined almost 90 per cent, there was a dramatic increase in the sale of other plastic bags of 400 per cent. Basically, people buy other plastic bags to use as trash containers since plastic shopping bags are no longer available to be re-used for their trash (PIFA/Mike Kidwell Associates 2004).

4:10-4:30
Rebound Effects of Videoconference in Different Countries
Takahashi KI (NTT Energy and Environment Systems laboratories), Tsuda M, Nakamura J, Matsuno Y, Adachi Y.
(presentation)

We have evaluated the CO2 emission from videoconference in Japan considering the rebound effects. In this paper we tried to expand this idea worldwide. Considering the differences between countries we did LCA on videoconference with rebound effects in USA and in France.

4:30-4:50
The issue of allocation in indirect and rebound effects: who is responsible for these effects? Based on the case study of coal fly ash “Is the use of fly ash a wise use?"
Sebastien Humbert (University of California, Berkeley)
(presentation)

Why fly ash from coal is used in concrete instead of being dumped in landfill, its status moves from a waste to a coproduct. This can increase the economical competitivity of the coal industry and thus increase the coal part of the electricity mix. Since electricity from coal is more polluting than the average mix, the use of fly ash can be rended non-wise from an environmental perspective. This case study illustrate the importance of capturing the indirect effects when evaluating a change in the system.

4:50-5:00
Closing Remarks