FAQs on Life Cycle Assessment

This article collects the most common questions and answers about life cycle assessment. Discover the simplified glossary for LCA.

Short and to the point questions and answers on life cycle assessment.

What is the history of stroke?

The first environmental assessments were carried out as early as 1969 following an initial awareness of the environment and the understanding of the finite dimension of our resources. The first environmental impact analysis was commissioned by Coca-Cola in the United States. At that time called Resource and Environmental Profile Analysis, the objective was to compare the environmental impacts of returnable glass bottles with several other types of packaging over their life cycles. The multiplication of studies during the 1980s and the inappropriate use of LCA by companies to promote their products through false claims led to the need to standardize the method. In the 1990s, the European scientific community mobilized to develop the LCA standardization process. It was during this decade that the methodology evolved. LCA became more complex and required the development of software and databases. In 1997, the ISO 14040 standard was published by the International Organization for Standardization, generalizing the LCA methodology internationally.

How to do a life cycle assessment?

Four main steps structure the realization of an LCA:

• Definition of the objectives and scope of the study
• Realization of the life cycle inventory
• Evaluation of the impacts
• Interpretation of the results

To know the details of these steps, consult this article.

What does an LCA report look like?

An LCA report is structured around the four main stages of the study and follows the ISO 14040/44 standards. Examples of LCA reports: LCA report comparing electric and thermal vehicles - ADEME LCA report on denim pants - Bio Intelligence Service LCA report on hydrogen - ADEME

What is the point of doing an LCA?

LCA is the most advanced tool for the global evaluation of the potential impacts of a product on the environment. This tool allows to identify precisely the impacts of a product with a multi-criteria approach over its entire life cycle. From this environmental assessment, it is possible to compare two solutions (with equal quality of service) in order to select the most respectful for the preservation of the planet. Another interest of LCA is the identification of impact transfers. Thanks to this type of study, we can become aware that an environmental gain at one stage of the life cycle can have negative consequences on another stage. LCA can also be used to communicate with the public. Moreover, it is considered as a major decision support tool in the realization of eco-design and public policies (waste management plan, eco-labeling criteria...).

What is impact transfer?

Impact transfer occurs when:

• An environmental improvement achieved in one stage of the life cycle leads to negative effects in another stage of the life cycle

• An environmental improvement achieved on one impact indicator leads to negative effects on another indicator

For example, an electric car pollutes less during the use phase than a combustion car, but more during other stages of the life cycle (extraction of raw materials, manufacturing and end of life). Similarly, the switch to electric cars reduces the indicators related to the greenhouse effect and the consumption of non-renewable energy, but increases the impacts related to acidification and toxicity (see diagram). We can underline here that impact transfers are common in eco-design. They are difficult to avoid but it is essential to identify and control them. They can be identified by carrying out environmental assessments.

What is an LCA indicator?

LCA indicators allow to characterize environmental impacts. They are calculated during life cycle analyses. They are also called criteria or environmental impact indicators. There are more than 50 LCA indicators that can be calculated with the same life cycle inventory (for the same product). The best known impact indicators are :

• Climate change or greenhouse effect (expressed in kg CO2 eq.)

This indicator refers to the integrated global warming potential over 100 years due to greenhouse gas emissions.

• Depletion of mineral and/or fossil resources (expressed in kg Sb eq)

This criterion quantifies the depletion of natural resources. The precariousness of the resource is included.

• Acidification of air, soil and water (expressed in mole eq. H+)

This indicator concerns the quantity of acid substances in the lower atmosphere. These emissions cause acid rain that disturbs forest and aquatic ecosystems.

• Eutrophication of fresh water (expressed in kg P-eq)

This criterion characterizes the enrichment of an aquatic environment in nutrients. A too consequent contribution can cause the asphyxiation of the aquatic ecosystems.

• Photochemical ozone formation (expressed in kg eq. NMVOC)

This indicator is related to the formation of ozone from primary pollutants. Human and plant health is affected by this gas. The availability of impact criteria depends on the LCA software and the characterization methods chosen. It is recommended to make a selection beforehand to study the most relevant indicators for each type of product.

What is the critical review of an LCA?

When external communication of the results of an LCA is envisaged, the report and the synthesis must be critically reviewed by an independent expert. In case of product comparison during the study, a panel of several experts must compose the critical review committee. This panel must be competent in the sector of activity concerned and in LCA. The realization of a critical review allows the ISO certification of the study. The objective is therefore to give credibility to an LCA study. The critical review ensures that the construction of the study follows the rules of the ISO 14044 standard. It verifies that:

• The methods used follow the ISO 14044 standard and are scientifically and technically relevant

• The data used are consistent with the objectives of the study

• The interpretations respect the identified limitations and meet the objectives of the study

• The transparency and consistency of the report

Depending on the type of study and its importance, it can be carried out as the analysis progresses or at its end.

How to establish the scope of an LCA?

The field of study or scope of an LCA must be precise and contain the following elements:

• The functions of the studied system
• The functional unit
• The scope of the study
• The assumptions made
• The limitations of the study
• The choice of impact categories selected, the calculation and interpretation methodologies
• Initial data quality requirements
• The type of critical review
• The format of the specific study report

In an LCA, the perimeter of the study or system boundaries encompass all phases of the product's life cycle. On the other hand, it should be noted that the functional unit is in fact the unit of measurement used to make the final comparisons. This step also consists of selecting the right indicators for the study in relation to the subject under study.

What is sensitivity analysis?

Sensitivity analysis occurs in the fourth step of an LCA (the interpretation). During this step, the results of the LCA are analyzed. The objective is to identify the parameters that have a strong influence and those that have a weak influence on the impact criteria. The more known and accurate the high influence parameters are, the smaller the uncertainty in the results. Conversely, low-influence data require less precision and can even be characterized by an order of magnitude because they vary the results only slightly. Sensitivity analyses thus make it possible to refine the interpretation and evaluate the robustness of the results. On the other hand, the identification of parameters with a strong influence is useful for the research of technical solutions that can reduce the impacts of the studied product.

What are the limitations of LCA?

The limitations of LCA are multiple:

• Only quantitative impact criteria are measured

Examples of aspects not taken into account: noise, odors, toxicity of the products emitted, time, impacts on the landscape, light pollution...

• The results of an LCA depend on the initial assumptions, which may be poorly calibrated or even erroneous

This is why it is necessary to ask a set of relevant questions before embarking on a life cycle assessment.

• Interpretation of the results can be difficult for actors outside of LCA

Only LCA experts can properly use the data and software to interpret and software to interpret the LCA results in the best possible way.

• The method requires a lot of time, energy and skills

It is therefore difficult to implement in SMEs.

What are the conclusions of an LCA?

The conclusions of an LCA precisely identify the impacts of a product with a multi-criteria approach over its entire life cycle. They are only valid for the specific scenario(s) studied. They depend on the assumptions made.

Conclusion

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