Life Cycle Assessment

Several of the other methods described so far have addressed each of the components of a product's life cycle. There is however a specific process called Life Cycle Assessment (LCA) with a standardized set of steps and output in the form of environmental impact measures. In fact, life cycle assessment is part of the ISO 14000 (environmental management) standards, and is specifically addressed by ISO 14040:2006 and 14044:2006.

LCA is defined as "an objective process to evaluate the environmental burdens associated with a product, process, or activity by identifying energy and materials used and wastes released to the environment, and to evaluate and implement opportunities to affect environmental improvements."[1] Performing a full LCA requires significant expertise and effort. There are many resources available that go into much more detail about the process than this guide covers.[2] However, it is useful to at least be familiar with the four major steps of the standardized LCA process:

1. Goal and Scope Definition – What are we trying to learn?
2. Life Cycle Inventory (LCI) – What's embedded in the product?
3. Life Cycle Impact Assessment (LCIA) – What effects does it have?
4. Data Interpretation – What does it all mean?

 

 

Goal & Scope Definition

As with other assessments, the first step involves clarifying the purpose and extent of the LCA. This entails formally determining the functional unit, impacts of interest, and system boundary—elements from our "First Choice".

While LCA "light" approaches have been described above, a "full" LCA includes actual primary environmental impact data gathered once the product's full lifecycle has been determined. Such detailed LCAs take, on average, three months[3] and cost $10,000-$60,000[4], and are only possible to complete once the product is in use and has gone through all stages of its life cycle. This increased accuracy is worth it for benchmarking or external reporting (such as green marketing) purposes.

Inventory Analysis

The next phase entails creating a list of all of the components of the products life cycle that fall within the defined system boundary. It has three major steps:

1. Construct a process flowchart that shows the following:

• Raw materials
• Mfg processes
• Transports
• Uses
• Waste management

2. Collect data for:

• Material inputs
• Products and byproducts
• Solid waste, air and water emissions

3. Calculate the amounts of each in relation to the functional unit

Essentially, this is the process flow diagram—with detailed mass and energy values attached—that Tom and Priscilla sketched out. The resulting Life Cycle Inventory (LCI) provides a breakdown of all of the energy and materials involved in a product's system at a level of detail that provides a basis for evaluation.

Impact Assessment

Once a detailed LCI is created, environmental impacts can be ascribed to its parts, and if desired to the whole system. There are four steps to the Life Cycle Impact Assessment (LCIA) process, the first two of which are considered mandatory, while the last two are optional.[5]

1.Classification

Classification involves assigning specific environmental impacts to each component of the LCI. It is here where decisions made during the scope and goal phase about what environmental impact categories are of interest come into play.

2. Characterization

Once the impact categories have been identified, conversion factors – generally known as characterization or equivalency factors – use formulas to convert the LCI results into directly comparable impact indicators as described in the Measurements section above.

3. Normalization (optional)

Some practitioners choose to normalize the impact assessment by scaling the data by a reference factor, such as the region's per capita environmental burden. This helps to clarify the relative impact of a substance in a given context. For instance, if global warming contributions are already high in the context in which the product is being assessed, a reference factor would normalize whatever the product's global warming contributions are in order to clarify its relative impacts.

4. Weighting (optional)

The pros and cons of weighting were described in the Measurements section above.

Interpretation

Although listed fourth, life cycle interpretation actually occurs throughout the whole LCA. It involves the ongoing process of clarifying, quantifying, checking, and evaluating the information used by, and resulting from, the life cycle inventory (LCI) and impact assessment (LCIA) phases. The standard that covers the LCA process, ISO 14044, gives two main objectives:

1. Analyze results, reach conclusions, explain limitations, and provide recommendations based on the findings of the preceding phases of the LCA, and to report the results of the life cycle interpretation in a transparent manner.

2. Provide a readily understandable, complete, and consistent presentation of the results of an LCA study, in accordance with the goal and scope of the study.

To achieve these objectives, the ISO standard states that interpretation should cover at least three major elements.

1. Identification of the significant issues based on the LCI and LCIA. Which life cycle stages or components stand out as major contributors to overall impact? What are the anomalies?

2. Evaluation which considers completeness, sensitivity, and consistency checks. Is all the information needed for interpretation present in the LCI and LCIA? How reliable is the information related to any identified significant issues? How much do changes in such factors influence the overall results? Are all of the assumptions, data, characterization factors, etc. that were used in the assessment consistent internally and with the overall goal and scope of the LCA?

3. Conclusions, recommendations, and reporting. As discussed in later sections of this guide, a great deal of an LCA's value depends on how its results are communicated to people involved in making relevant decisions, whether other designers, engineers, management, marketers, or other parts of the supply chain.

It is very important to note that no matter how carefully assembled, analyzed, assessed, and measured, LCAs are never the "real" answer. They require interpretation, which is turn requires transparency and judgment. The data sources, assumptions, and all other relevant information needs to be transparent to decision makers so that they can understand the full context of the results of the life cycle inventory assessment. Deciding among design options is not as easy as just comparing LCIA numbers, whether single- or multi-factor, weighted or not. LCIA results can be a source of insights, but do not stand alone in guiding product development choices. Engineers will need to take them in the context of the other attributes they are trying to optimize, including cost, manufacturability, performance, and so on. In addition, there are myriad other factors guiding product development decisions not covered by LCAs, including social impacts and acceptance, pricing, political agendas, and regulations.

LCA and the Three Choices

1. Impacts – Any
2. Scope – All life cycle stages
3. Metrics – Measurements from actual product life cycle, supported by data tables

 

"Whew, I never knew environmental assessment was such a complex world!" breathed Tom.

"Well, we've already decided that we wanted to use measurements for our Third Choice, the one on metrics. If only there were a handy table to show us what Tools were available to us now, given our three choices."

A Handy Table of Tools for the Three Choices

 

 

	Choice 1: Impacts	Choice 2: Scope	Choice 3: Metrics
Intuition	Any	Visible stages	Comments, checkmarks, scores
Product Scorecards	Any	Set boundary, usually product mfg and assembly	Checkmarks, scores
Conceptual Life Cycle Thinking	Any (but usually not specific)	All lifecycle stages	Scores
Qualitative LCA	Any	All lifecycle stages	Scores
Life Cycle-Based Design Assessment	Any	All lifecycle stages	Measurements (secondary data)
Life Cycle Assessment (LCA)	Any	All lifecycle stages	Measurements (primary data)

 

 

"It looks like what I need is a Life Cycle-Based Design Assessment," said Priscilla. "Since I already have my model in SolidWorks, it makes sense for me to use Sustainability."

"I do too," said Tom. "So I'll start out in SolidWorks Sustainability too. But if I want to use my results in marketing, I'll eventually need to do an LCA to verify the results."

 

 

 

[1] Society of Environmental Toxicology and Chemistry (SETAC), 1990

 

[2] See for instance "Life Cycle Assessment: Principles and Practice," Scientific Applications International Corporation, EPA/600/R-06/060 (May 2006)

 

[3] "A full (internal) LCA study takes 8-16 weeks to complete." http://www.industrial-ecology.com/services/lifecycleassessment.html

 

[4] B Resource Guide: Conducting a Life Cycle Assessment (LCA), Feb. 2008, p. 6. http://www.bcorporation.net/resources/bcorp/documents/B%20Resources%20-%20Conducting%20a%20Life%20Cycle%20Assessment%20(LCA).pdf

 

[5] As dictated by the ISO 14044 standard

<<< Previous: Life Cycle-Based Design Assessment	>>> Next: Chapter 5: So What? (Interperting The Results)