What is a Life Cycle Assessment (LCA)?

January 5, 2023by circuvate

What is a Life Cycle Assessment ?

Life Cycle Assessment (LCA) is a tool that’s growing in importance as companies and other actors such as governments and NGOs look to quantify and communicate environmental impact. For example, a startup company may commission an LCA study to demonstrate to their investors or customers the environmental impact of their product or innovation, especially if they aim to pitch it as “sustainable” or “environmental friendly”.

Life cycle assessment can be applied, for example, to individual products, to a material, a production process, or even a specific activity. In general, we can say that a life cycle assessment (LCA) is an in-depth analysis of the environmental impact of a product or process, which collects all the inputs and outputs to a defined “system”, and converts it into one or multiple metrics of some relevance to the environment. There are many potentially relevant metrics, with the most common being the so called “Global Warming Potential” (i.e. the emission of greenhouse gases) but other factors such as water usage, impact on human health, or measure of eco-toxicity and many others are commonly used.

In this article we will take a look at LCA, its importance, the different stages of the LCA process, and some common challenges and limitations.

Why is LCA important?

In addition to communicating the environmental impact of a product or process, LCA can also be used to find particular “hotspots” in the life-cycle, enabling companies to figure out where to focus their optimisation efforts. For example, it may become apparent from conducting an LCA that the materials used in a product are the main chunk of the environmental impact, meaning they could then focus their efforts on sourcing, for example, recycled or bio-based alternatives – or by reducing the amount of materials in the product. However, it could also be the case that the packaging, or the transportation involved in its life cycle is more important part of its overall environmental impact. These hotspots can only be identified by undertaking an LCA study.

LCA could also be used to make comparisons with other products or within a certain product group. For example, policymakers have commissioned life cycle assessment studies in the past to compare the impact of alternatives to plastics bags. Equally, a company may commission a comparative LCA study to display how its product is more environmental friendly than a competing alternative.

Finally, data drawn from LCA studies support a range of other tools, systems and certifications in various industries. For example, the EPD (environmental product declaration) system used in the construction sector, various carbon or net zero standards (i.e. Carbon Trust) and the developing Product Environmental Footprint (PEF) tool from the EU. The role of LCA in these tools and systems is only expected to grow over time, and will become all but required in certain sectors and product groups in the future.

The Stages of a Life Cycle Assessment

LCA is a structured, systematic process that follows four main stages: goal and scope definition, inventory analysis, impact assessment, and interpretation. These 4 stages are defined by the ISO 14044 standard, which provides a common framework for LCA studies.

1. Goal and scope definition

The first stage of LCA is to figure out what is being looked at and what the boundaries of the assessment will be. This involves identifying the specific product, process, or activity that will be evaluated, as well as the scope of the assessment. For example, the scope of an LCA study on a T-Shirt commissioned by a fashion brand might include the entire supply chain from cotton cultivation to disposal, including its use (ie. laundering) by the consumer. This is called a “Cradle-to-grave” study. On the other hand, an LCA study conducted by the manufacturer of a textile material used in the same T-Shirt might choose to only go as far as their “factory gate”, which means excluding further manufacturing into clothes, its use by consumers and the end-of-life disposal, since these things are the responsibility of their customers (who are clothing manufacturers).

2. Inventory analysis

The second stage of LCA is inventory analysis, which involves collecting data on the inputs and outputs of the product, process, or activity being evaluated. This includes data on the raw materials and energy used, as well as the emissions, waste, and other direct inputs and outputs to and from the environment.

3. Impact assessment

The third stage of LCA is impact assessment, which involves evaluating the environmental impacts of the product, process, or activity based on the data collected in the inventory analysis. This typically involves assigning environmental impact categories, such as climate change, ozone depletion, or aquatic eco-toxicity, to the inputs and outputs of the system being evaluated.

4. Interpretation

The final stage of LCA is interpretation, which involves analysing the results of the impact assessment and drawing conclusions about the environmental performance of the product, process, or activity being evaluated. This may involve comparing the environmental impacts of different options, identifying potential improvements, and making recommendations for action. Typically, a “sensitivity analysis” may be conducted in this stage, which would evaluate how the results of the study could change with respect to key variables or assumptions used. A good interpretation will also highlight weaknesses and limitations of the study and the conclusions that can be drawn in light of the initial goal and scope defined.

Challenges and Limitations of LCA

Despite its many benefits, Life Cycle Assessment as a field is not without its own particular challenges and limitations. Some of the common challenges and limitations of LCA are:

  • Data availability: LCA relies on accurate and comprehensive data on the inputs and outputs of the product, process, or activity being evaluated. However, data can be hard to come by and may not be available for all stages of the life cycle. This is especially true of early stage innovations, which may lack data on parts of the process.
  • Data quality: In addition to data availability, the quality of the data is also important. Data may be uncertain, incomplete, or inconsistent, or out of date, which can affect the accuracy and reliability of the LCA results.
  • Boundary setting: The boundary of the LCA, which defines the scope of the assessment, is a critical factor in determining the results of the LCA. However, setting the boundary of the assessment can be difficult and subjective, and the choice of boundary can affect the results. Different studies conducted with different boundaries are not easily compared.
  • Impact categories: LCA involves assigning environmental impact categories, such as climate change or aquatic ecotoxicity, to the inputs and outputs of the system being evaluated. However, different LCA models may use different sets of impact categories, which can make it difficult to compare the results of different studies.
  • Functional units: LCA typically evaluates the environmental impact of a product or process per unit of a specific “functional unit”. For example, in the T-Shirt example, the functional unit could be “per t-shirt”, “per 50 wears of a t-shirt” or “per kg of t-shirts sold”, which would all lead to radically different impact assessment results. However, choosing an appropriate functional unit can be challenging and subjective, and depends on the stated scope and goal of the study.
  • Normalization and weighting: LCA results are often normalized and weighted to allow for comparisons between different impact categories and different systems. This is often used to provide a “single indicator” of the total environmental impact across all categories (some example include ReCiPe points, Impact 2003+ and Eco-Cost). However, normalization and weighting can be subjective, and the choice of normalization and weighting factors can affect the LCA results.


LCA is a powerful tool for understanding the environmental impact of a product, process, or activity. LCA can help us, for example, to identify and evaluate the potential environmental impacts at different life cycle stages, and can help companies and other stakeholders make informed decisions about products and production processes. However, a LCA study always requires interpretation.

It may often be the case in a comparative study, for example, that different impact assessment metrics are at odds: perhaps one alternative has higher carbon footprint, but the other has higher water usage and causes more soil acidification. Which course of action is preferred? This is a decision which, at the end of the day, can only be based on subjective values, even though the LCA study itself aims to be as objective as possible. LCA is, in the end, a tool to support human decision making.

Having said this, conducting or commissioning an LCA study is a worthwhile endeavour if solid data and science is needed to support environmental or sustainability related decision making. In the next article in this series, we will delve into the life-cycle assessment options for impact focused startups: how does one go about performing or commissioning an LCA study?

Author: Dr. Ashley Holding, Principal Consultant @ Circuvate 

Are you an impact-focused company looking to communicate and improve the environmental potential of your product, process, or service? Get in touch to see how Circuvate can help you.