practical life cycle assessment through streamlining

Practical Life Cycle Assessment through Streamlining

Keith A. Weitz and Aar t i S h a m

Life cycle assessment (LCA) provides a concept,framework, and method to identi& and evaluate the environmental burdens of products and processes. An ongoing concern of companies trying to implement LCA is the value of L a in supporting actual decisions versus the resources and time needed to conduct a “fun” L a . In response to these concerns, there has been a lot of activity sur- rounding the “stream1ining”of LCA to keep it more manageable yet provide useful and acceptably accurate results. This article explores the concept of streamlining, discusses whereand how streamlining decisions can be made in an L a , and presents issues related to conducting more streamlined LCAs. Due to the wide variety of purposes and scenarios in which LCAs are conducted, it is difficult to devise a one-size-fits-all method for streamlining. Instead, we have focused on pre- senting thestreamlining options in the context of major decision points that are common to most LCAs.

I L C A is intended to be a comprehensive evaluation of the environmental burdens and impacts of products and processes on a system-wide, cradle-to-grave basis. This definition has represented more of an ideal rather than a practical guide. In practice, every application of LCA is more or less an approximation of this ideal. Any LCA that has been conducted to date falls along a range of comprehensiveness and detail as illustrated in Exhibit 1. There is no hard distinction between what constitutes a “full” LCA and a “streamlined” LCA. In- stead, there are many different LCAs, each unique in its level of comprehensiveness, detail, and scope. In fact, there are multiple characteristics that define any particular LCA, as shown in Exhibit 2.

However, there is a point at which an intended LCA can be reduced so narrowly that it no longer addresses the life cycle concepts it intended to capture. Based on discussions at the EPA-sponsored Confer- ence on Streamlining LCA,’ in order for a

study to be considered an LCA, the study team should at a minimum consider, either quantitatively and/or qualitatively, the fol- lowing elements:

All life cycle stages (raw materials through final disposal) Releases to all media (air, water, land) Impacts to the environment and human health

THE GOAL AND SCOPE DEFINITION PROCESS

Streamlining can be thought of as an inherent element of the goal and scope definition process. As the study team evaluates and decides what to include and excIude from the LCA, they are, in effect, streamlining.2 Defining the goal of the LCA entails identifying the intended use(s) of the results, the type of analysis needed, and the manner in which results are to be presented. Defining the scope of the LCA entails identifying what, how much, and to

CCC 1088-1913/98/070481-07 0 1998 John Wiley &Sons, Inc ENVIRONMENTAL QUALITY MANAGEMENT / Summer 1998 / 81

Exhibit 1. Range of LCA Practice

A range of LCA practice exists between conducting a full "idealized" LCA and othertypes of environmental assessments (e.9.. process waste assessment, "gate to gate" assessment) that are nottraditionally considered LCAs. Al l LCAs to date have not been full LCAs but rather fall within a range of practical LCA.

what level of detail and quality information is collected for different life cycle components, environmental releases, and impacts to the environment and human health. A clearly defined goal and scope and a thorough understanding of the system under study provides the groundwork needed for considering streamlining options.

The key challenge to the study team is to ensure that the choice of streamlining options is consistent with the study goal and that the subsequent results will be adequate to support that goal. Goal and

Exhibit 2. The Many Dimensions of LCA

scope definition can be considered a process to determine what needs to be in the LCA to begin with rather than starting from a full-scale LCA and determining what can be eliminated.3

Prior to the decision to streamline an LCA in some manner, it is important to first consider some key factors that may be significantly affected by streamlining. Due to the variety of purposes and scenarios in which LCAs are conducted, it is difficult to devise a "one-size-fits-all" set of streamlining options. Instead, we have identified and discussed different streamlining op-

Peer Review

A Life Cycle System Boundaries Stages

4 Environmental Media

Available Data Categories

V Impact Methods

LCA streamlining decisions occur for multiple aspects of the study. Each of these aspects can be thought to comprise many dimensions, as illustrated here. For example, the study might only be concerned with a limited number of impact categroies, but may analyze these categories using reltively complex methods. Other studies may be focused on obtaining a more general evaluation of the all-impact categories using more simplistic methods. These types of decisions make every LCA unique.

82 / Summer 1998 / ENVIRONMENTAL QUALITY MANAGEMENT Keith A. Weitz and Aarti Sharma

tions in the context of decision points that are common to most LCAs. Examples of common decision points were developed by drawing from information about LCA characteristics and decision steps provided in Environmental Life Cycle Asse~smen t .~ These example decision points are listed and summarized below.

What type of analysis is required to meet studygoals? The appropriate level of rigor and comprehensiveness needs to be identified by the study team so that the results will be consistent with the goal of the study. The more clearly the goal can be defined, the more likely the study team will be able to identify the type of analysis needed and, thus, appropriate streamlining options. For example, if the goal of the LCA is to support a public purchasing decision, then perhaps a more rigorous and quantitative analysis is needed and some streamlining options will be less appropriate. If, on the other hand, the goal is to get a general overview of potential life cycle environmental issues for internal purposes, then perhaps a more rough and qualitative analysis will suffice.

How are the study results intended to be used? The degree of rigor required in general investigations or more qualitative studies is usually less and enables searching for valid streamlining methods. Semi-quantitative or qualitative information might suffice when information is to be used primarily for fur- ther development of corporate goals and environmental strategies. Streamlining also can be considered as an option when obtaining rough estimates of differences is more the priority than scrutiny of each individual LCA. Studies that aim to analyze very specific questions can be targeted toward devel- oping the information necessary to answer the questions. For example, in using LCA for a design application, the study team may decide to eliminate life cycle components that are not affected by the new design.

Who is the intended audience or context for the study results? If the study is used internally rather than to substantiate

external product or marketing claims, it is more likely that streamlining options can be chosen. This is because steamlining options are typically more controversial and undergo greater scrutiny, requiring more documentation and precision. Also, an internal study may justify removal of certain pieces of the life cycle over which internal decisionmakers do not have direct control. If some pieces of data are to be released externally, the detail to be provided, sensitivity of results, and purpose can all play a role in determining whether or not streamlining can be detrimental to project objectives.

How narrowly defined is the product or process under study? A company that wants to improve its own production system would require more detailed information specific to its own operation as well as those upstream and downstream life cycle components for which it can have direct influence. A company that wants to compare several vendors would need information specific to those vendors. A comparison of two generic products, for example, would permit use of industry- level or more generic averages. Studies of generic categories of products or materials often can be streamlined because they are not amenable to being precisely quantified.

What is the role of recycling for one or more products being studied? Comparing virgin products to recycled or reused products must be done with great care because the product systems will have very different structures. A virgin product system generally will have relatively larger upstream and downstream burdens. A recycled product system often (but not always] is dominated by product recovery, cleaning and washing, or transportation processes. In addition, closed loop recycled systems greatly reduce upstream effects and, thus, removing these stages would affect results, especially when comparing with virgin systems. Open loop recycled systems also reduce upstream effects, although generally by smaller amounts. Thus, selection of a streamlining

The more clearly the goal can be defined, the more likely the study team will be able to identify the type of analysis needed and, thus, appropriate streamlining options.

Practical Life Cycle Assessment through Streamlining ENVIRONMENTAL QUALITY MANAGEMENT / Summer 1998 / 83

~

The streamlining options should be

chosen through intelligent choices

based on objectives and limitations of the

study itself.

option must consider these differences in product system structure. If upstream stages are removed in a study comparing virgin and recycled products, the comparative advantages of the recycling system in the upstream stages are lost.

How dominant is the manufacturing stage (operations) in the life cycle of the product being studied? If the manufacturing stage of the life cycle has significantly greater amounts of inputs and outputs as compared with other stages, then streamlining options such as eliminating other stages of the life cycle may not have as great an impact on conclusions. However, this aspect may not play as important a role if a comparison is being made between two or more products that both have dominant manufacturing stages.

What is the life of the products (in the useheuse stage) being studied? Durable products can typically be expected to have greater amounts of inputs and outputs as- sociated with the useheuse stage of the life cycle as compared to consumable products. If similar characteristics can be found among durable products, certain portions of the life cycle could be highlighted for study. Consumables, in general, can be expected to have higher flows in the upstream stages. Thus, certain types of streamlining options may be chosen if your study compares consumables alone or durables alone. However, this becomes harder when comparing consumables and durables, as streamlining by removal of certain stages could eliminate the advantages of one product group or mask the dis- advantages of another.

What is the acceptable level for data quality or uncertainty? Any level of streamlining will inevitably add uncertainty to LCA results and there is currently no established methodology to measure this uncertainty. Potentially important components of an LCA may be unknow- ingly omitted in the process of streamlining and could affect overall conclusions. However, if a study has more general goals

and a higher threshold for uncertainty, based on how the study results would be used, there could be streamlining options available. Additional issues also need to be addressed, such as the ability of the study to handle secondary data that do not permit aggregation or comparison (due to differences in the way the data were collected by the different studies).

What i s the study team’s overall level of knowledge about the product orprocess being studied? The more the study team knows about the product or process under study, the more confidence they can have in making streamlining decisions. For example, knowledge that two alternatives use the same types and quantities of certain raw materials might justify their exclu- sion. If enough data are available to complete a rough LCA using preliminary data, a sensitivity analysis can be performed to help determine avenues for streamlining based on goals and objectives of the study and dominant or key components identified in the preliminary study. On the other hand, if there are several data gaps, ana- lysts will need to determine if the level of data available is sufficient to meet the study goals and objectives. If not, some alternative and less complex method of analysis may be preferable. Streamlining should not be the default just because of lack of data. Rather, the streamlining options should be chosen through intelligent choices based on objectives and limitations of the study itself.

Appropriate streamlining options, based on key LCA decision points as sug- gested above, need to be identified and evaluated based on their relationship to the goals of the study. Exhibit 3 provides an example of how the streamlining decision points discussed above could be presented on a streamlining decision matrix. A check-mark in any box would reflect the appropriateness of streamlining for each particular option or decision point.

The different decision points need to be looked at collectively and the effective-

84 / Summer 1998 / ENVlRONMENTALQUALlTY MANAGEMENT Keith A. Weitz and Aarti Sharma

Exhibit 3. Summary of Streamlining Appropriateness

Example Decision Points

Whattype of analysis is required?

Who is the intended audience?

How are study results intended to be used?

How narrow is the product or process under study defined?

To what extent are recycled or reused materials a factor?

How dominant is the manufacturing stage in the life cycle of the product under study?

Is the product under study a durable or consumable product?

What is the acceptable leve for uncertainty related with data?

How much does the study team know aboutthe product or process under study?

More Opportunity for Streamlining

Roug h/Qualitative

0

Internal U

ScopinglScreeningl Identify hot spots

0

Generic material group 0

Virgin OR recycled/ reused products

0

Very dominant a

Very durable Long-use phase

R

High 0

High knowledge of all life-cycle stages

0

ness of the streamlining process cannot be judged on the basis of a single decision point. For example, in a comparison of virgin and recycled systems, removal of downstream stages may not affect comparative rankings significantly. However, if objectives go beyond comparative rankings to assessing environmental burdens throughout the life cycle, eliminating the downstream stages, for example, may ex- clude some environmental impacts that are unique to recycled systems-that have comparatively high burdens in the downstream stages.

It is also important to ask why the LCA is being streamlined and whether the results will adequately address the defined

4 * Relative Difference/ Semi-quantitative

0

Internal and external U

Product Design/ Process Design/

Purchasing 0

General producttype 0

Virgin AND reused products

0

Somewhat dominant 0

Consumables Short-use phase

0

Medium 0

High knowledge of some life-cycle stages

0

Less Opportunity for Streamlining

Rigorous/Qualitative

0

External U

Marketing/Labeling/ Public policy

0

Company specific product 0

Virgin AND recycled products

0

Not dominant 0

Durables and consumables/ Variable-use phases

0

Low cl

Low knowledge

U

goals and end-use objectives. For example, if your end-use objective is to compare two products to determine superiority of one over another in the entire life cycle, then it makes sense to limit the streamlining process as much as possible. It is also important to ask whether your study actually needs the rigor of LCA. This is especially true if you are interested only in a certain piece of the life cycle, in which case an environmental or pollution prevention audit or some other analytical technique may suffice. The manner in which you plan to analyze the LCA results is also an important consideration. For example, if you plan to do a detailed impact assessment, then the data collected will have to


Appropriate use of streamlining ideally

requires the study team to be able to

reasonably characterize major

processes within the life cycle and subsequently estimate their significance.

be of the type and quality that will allow such analysis.

THE RISK OF STREAMLINING In recent research we conducted with

Franklin Associates, Ltd. ,5 various streamlining options were applied to a set of 26 LCA case studies and the results compared. The findings from this effort led us to the conclusion that streamlining can be problematic if not done carefully. Most streamlining options tested gave incorrect ranking of products at least half of the time or more, as compared to the more complete LCAs. This level of consistency is unac- ceptable given that the primary application of LCAs is to make comparative assertions between alternative product systems. Com- mon practice dictates that success requires a process that will give correct conclusions at least 80 percent of the time, with 90 to 95 percent being preferable.

As part of the process of evaluating each of the streamlining options, a search was made for principles and guidelines for performing streamlined LCAs that could be applied to new product groups for which there is limited knowledge, but that would yield results of acceptable quality.

The most successful streamlining option appears to be the traditional “sensitivity analysis” approach. This requires development of a complete flow diagram of the entire product system to be studied, with materials flow quantities in place. Each process can then be represented by the best data available. If primary data are not available, secondary data, or even generic data from commercial databases can be used. A good overview of publicly available data (mostly European), existing case studies, and private databases can be found at the Ecosite Internet site at: http:// www.ecosite.co.uk/.

With preliminary data in hand, a rough life-cycle inventory, covering all major life- cycle stages, can be constructed. Sensitiv- ity analysis can then be applied to identify the key life-cycle components. In this pro-

cess, each inventory entry is examined and the percent contribution of each process to the total is calculated. For those processes that contribute a large percentage of the total (by mass), the best data possible should be used. Generic data or estimates will not be sufficient. For those processes that contribute very little to the total (e.g., less than 1 percent), estimates or surrogates are acceptable. This process also leads to an analysis of product system structure, which is also an aid to selecting valid streamlining methods.

CONCLUSIONS Due to cost and time considerations of

conducting a full LCA, and objectives of the sponsoring organization, it is apparent that the streamlining of LCA will continue and great care must be taken in doing so. A systematic and logical analysis based on detailed knowledge of the product systems can help indicate when a given streamlining approach might work. Streamlining will always introduce the risk of obtaining a result that is different from that of a full LCA. However, if some level of risk is acceptable, there are some general rules that can be followed to select a streamlining method that will reduce the risk of serious error. Appropriate use of streamlining ideally requires the study team to be able to reasonably characterize major processes within the life cycle and subsequently estimate their significance. This information can then be used in conjunction with the defined study goals to determine specific study characteristics (data quality, level of impact assessment, level of peer review, etc.) that will be used to identify streamlining options. Detailed knowledge of the product system is necessary to make appropriate streamlining choices; expert judgment will always be a factor in produc- ing valid results from streamlined LCAs.

NOTES 1. Research Triangle Institute, ”Streamlining Life Cycle As-

sessment Conference Proceedings,” Conference report prepared for EPA, NRMRL, Cincinnati, OH, 1997.

86 / Summer 1998 / ENVIRONMENTAL QUALITY MANAGEMENT Keith A. Weitz and Aarti Sharma

2. Society of Environmental Toxicology and Chemistry, 4. Mary Ann Curran, EnvironmentalLife Cycle Assessment, "Streamlining Environmental Life Cycle Assessment:

liminary draft report prepared by the SETAC LCA Stream- lining Workgroup, Pensicola, FL, 1997.

New York: McGraw- Hill, 1997.

sessment: Concepts, Evaluation of Methods and Recom- mendations," Draft report prepared for EPA, NRMRL, Cin-

Report ofthe SETAC LCA Streamlining Workgroup," Pre- 5. Research Triangle Institute, "Streamlining Life Cycle As-

3. Id. cinnati, OH.

Keith A. Weitz and Aarti Sharma are environmental scientists in the Center for Environmental Analysis at the Research Triangle Institute, a North Carolina-based independent nonprofit organization performing research in many disciplines for government, industry, and other clients throughout the United States and abroad. The Insti- tute conducts research that responds to priorities in medicine and pharmaceuticals, public health, advanced technologies, environmental protection, and public policies. They both conduct research in the areas of life-cycle assessment, pollution prevention, environmental accounting, and industrial ecology. Comments about this article can be sent to Keith A. Weitz, Center for Environmental Analysis, Research Triangle Institute, 3040 Cornwallis Road, Research Triangle Park, NC 27709, Phone: 919-541-6973, e-mail: [email protected].

Although the research described in this article has been funded wholly by the U S . Environmental Protection Agency through cooperative agreement CR823018 to the Research Triangle Institute, it has not been subjected to Agency review. Therefore, it does not necessarily reflect the views of the U.S. Environmental Protection Agency.


practical life cycle assessment through streamlining

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