This section briefly outlines the basics of life cycle assessments. This discussion of the lifecycle assessment is an abridged version of “LCA 101 – Introduction to LCA” published by the US Environmental Protection Agency.

What is Life Cycle Analysis?

As environmental awareness increases, governments, industries and businesses have started to assess how their activities affect the environment. Society has become concerned about the issues of natural resource depletion and environmental degradation. The environmental performance of products and processes has become a key issue, which is why many organizations are investigating ways to minimize their effects on the environment. Many have found it advantageous to explore ways to improve their environmental performance. One such tool is called life cycle assessment (LCA). This concept considers the entire life cycle of a product.

Life cycle assessment is a "cradle-to-grave" (or “well to wheels”) approach for assessing industrial systems. "Cradle-to-grave" begins with the gathering of raw materials from the earth to create the product and ends at the point when all materials are returned to the earth. LCA evaluates all stages of a product's life from the perspective that they are interdependent, meaning that one operation leads to the next. LCA enables the estimation of the cumulative environmental impacts resulting from all stages in the product life cycle, often including impacts not considered in more traditional analyses (e.g., raw material extraction, material transportation, ultimate product disposal, etc.). By including the impacts throughout the product life cycle, LCA provides a comprehensive view of the environmental aspects of the product or process and a more accurate picture of the true environmental trade-offs in product selection.

Specifically, LCA is a technique to assess the environmental aspects and potential impacts associated with a product, process, or service, by:

• Compiling an inventory of relevant energy and material inputs and environmental releases;
• Evaluating the potential environmental impacts associated with identified inputs and releases;
• Interpreting the results to help make informed decisions.

The term "life cycle" refers to the major activities in the course of the product's life span from its manufacture, use, maintenance, and final disposal; including the raw material acquisition required to manufacture the product. The following figure illustrates the possible life cycle stages that can be considered in an LCA and the typical inputs/outputs measured.

The LCA process is a systematic, iterative, phased approach and consists of four components: goal definition and scoping, inventory analysis, impact assessment, and interpretation as illustrated in the following figure.

Goal Definition and Scoping - Goal definition and scoping is the phase of the LCA process that defines the purpose and method of including life cycle environmental impacts into the decision-making process.

The goal definition and scoping of the LCA project will determine the time and resources needed. The defined goal and scope will guide the entire process to ensure that the most meaningful results are obtained. Every decision made throughout the goal definition and scoping phase impacts either how the study will be conducted, or the relevance of the final results. The following six basic decisions should be made at the beginning of the LCA process to make effective use of time and resources:

• Define the goal of the project.
  
• Determine what type of information is needed to inform the decision-makers.
  
• Determine how the data should be organized and the results displayed.
  
• Determine what will or will not be included in the LCA.
  
• Determine the required accuracy of data.
  
• Determine ground rules for performing the work.
  

Inventory Analysis - A life cycle inventory (LCI) is a process of quantifying energy and raw material requirements, atmospheric emissions, waterborne emissions, solid wastes, and other releases for the entire life cycle of a product, process, or activity. Without an LCI, no basis exists to evaluate comparative environmental impacts or potential improvements.

In the life cycle inventory phase of an LCA, all relevant data is collected and organized. The level of accuracy and detail of the data collected is reflected throughout the remainder of the LCA process. An inventory analysis produces a list containing the quantities of pollutants released to the environment and the amount of energy and material consumed. The results can be segregated by life cycle stage, by media (air, water, land), by specific processes, or any combination thereof.

A life cycle inventory is usually completed used the following steps:

• Develop a flow diagram of the processes being evaluated,
  
• Develop a data collection plan,
  
• Collect data,
  
• Evaluate and report results.
  

Impact Assessment - The Life Cycle Impact Assessment (LCIA) phase of an LCA is the evaluation of potential human health and environmental impacts of the environmental resources and releases identified during the LCI. A LCIA attempts to establish a linkage between the product or process and its potential environmental impacts.

The key concept in this component is that of stressors. A stressor is a set of conditions that may lead to an impact. For example, if a product or process is emitting greenhouse gases, the increase of greenhouse gases in the atmosphere may contribute to global warming. Processes that result in the discharge of excess nutrients into bodies of water may lead to eutrophication. An LCIA provides a systematic procedure for classifying and characterizing these types of environmental effects. The following key steps comprise a life cycle impact assessment.

• Selection and Definition of Impact Categories - identifying relevant environmental impact categories (e.g., global warming, acidification, terrestrial toxicity).
  
• Classification - assigning LCI results to the impact categories (e.g., classifying CO2 emissions to global warming).
  
• Characterization - modeling LCI impacts within impact categories using science-based conversion factors.
  
• Evaluating and Reporting LCIA Results - gaining a better understanding of the reliability of the LCIA results.
  

Interpretation - Life cycle interpretation is a systematic technique to identify, quantify, check, and evaluate information from the results of the life cycle inventory and the life cycle impact assessment, and communicate them effectively. Life cycle interpretation is the last phase of the LCA process.

The International Organization for Standardization (ISO) has defined the following two objectives of life cycle interpretation:

• 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.
  
• 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.
  

What Are The Benefits of Conducting an LCA?

An LCA will help decision-makers select the product or process that results in the least impact to the environment. This information can be used with other factors, such as cost and performance data to select a product or process. The ability to track and document shifts in environmental impacts can help decision makers and managers fully characterize the environmental trade-offs associated with product or process alternatives. By performing an LCA, researchers can:

• Develop a systematic evaluation of the environmental consequences associated with a given product.
  
• Analyze the environmental trade-offs associated with one or more specific products/processes to help gain stakeholder (state, community, etc.) acceptance for a planned action.
  
• Quantify environmental releases to air, water, and land in relation to each life cycle stage and/or major contributing process.
  
• Assist in identifying significant shifts in environmental impacts between life cycle stages and environmental media.
  
• Assess the human and ecological effects of material consumption and environmental releases to the local community, region, and world.
  
• Compare the health and ecological impacts between two or more rival products/processes or identify the impacts of a specific product or process.
  
• Identify impacts to one or more specific environmental areas of concern.
  

Limitations of Conducting an LCA

Performing an LCA can be resource and time intensive. Depending upon how thorough an LCA the users wish to conduct, gathering the data can be problematic, and the availability of data can greatly impact the accuracy of the final results. Therefore, it is important to weigh the availability of data, the time necessary to conduct the study, and the financial resources required against the projected benefits of the LCA.

LCA will not determine which product or process is the most cost effective or works the best. Therefore, the information developed in an LCA study should be used as one component of a more comprehensive decision process assessing the trade-offs with cost and performance.