Questions that seem straightforward, such as “How can we improve the sustainability performance of our products?” or “Which product performs better?” often get the answer “It depends…” This article is an attempt to provide more insight into the complexity of environmental footprinting, also known as life cycle assessment, for non-technical professionals – to help you understand why the vague answer is often the right answer, and so you can help make sure that your study supports the decisive answers you’re looking for.

Uncertainty can creep in at any point in the four steps of a life cycle assessment:

• Goal and scope definition
• Inventory analysis
• Impact assessment
• Interpretation

Vaguely defined goal and scope

A common goal of environmental footprinting is to identify which emissions and resource uses in the life cycle of a product or organization have the highest impact and which processes are responsible for this. The outcome of such an assessment may point to, for example, methane emissions and land use in an analysis of animal products or carbon dioxide emissions from burning natural gas in an analysis of steel production. This information is then often used to identify improvement opportunities.

Another common goal is to compare the impact scores of a product with an alternative or competing products. For example, comparing different types of packaging, or comparing organic foods to conventional foods. If comparison is the goal, this is often not made explicit when designing the study. However, assessment results will very likely be used for comparison when they’ve been made public, even if the study was not intended for comparisons.

The big issue is that such comparisons are often not “fair”. The first reason for this is that study results are often unique and incomparable with other studies because the scope of the study determines many technical details. For example, the scope defines the functional unit: the exact definition of the product, its intended use and its specific quality. The scope also sets the system boundaries – which processes and phases are included and how emissions and resource uses are divided among co-products. Another choice that varies between studies is which product gets the credits for recycling. The big variation in goal and scope among studies is one important reason for saying “It depends…”

Gaps in your inventory

To make a complete inventory of all the emissions and resource uses in the life cycle of a product, you need to collect a lot of detailed data. Getting data from within your organization is one challenge, but getting primary data from material suppliers and users of your products is often not possible. LCA software packages such as SimaPro are a good source of background data, but this data is not specific to the situation and is often only weakly representative. Gaps in your inventory data can be a source of high uncertainty: another reason for saying “It depends…”

Too many impact assessment methods

Many scientific methods are available for translating the long list of emissions and resource uses into a limited list of impact indicators. What’s more, these methods are continuously being developed, due to new scientific insights and the correction of earlier mistakes. There is also an ongoing fundamental discussion about what level of indicators should be used: damage indicators which aggregate the results into three themes – human health, ecosystems and resources – or midpoint indicators, which can be up to 15 different equivalence factors – one for each environmental topic, such as climate change, particulates, human toxicity, land use, resource depletion, water scarcity, etc. The choice is a trade-off: there are too many midpoint indicators to interpret them fully, but they are scientifically more robust than the damage indicators. The choice of impact assessment method and version is another reason why the results of different studies can be unsuitable for comparison.

Everyone has an interpretation

From this brief overview of the technical complexities in environmental footprint assessments, you will understand that there are many subjective choices involved. To be able to assess these choices and interpret the results, one needs a lot of technical knowledge and experience. This work is often done by specialized technical consultants. The work of such consultants, like me, is to help the professionals we work with understand the available choices, draw reasonable conclusions, and make the right decisions.

So, what’s the point?

You might be asking yourself: “what’s the point of doing an environmental footprint while there are so many uncertainties and arbitrary choices?”. I would say that it is still an excellent tool for gaining valuable insight into the supply chain, your company’s operations and the use phase of your products. It is also a great basis for setting sustainability targets and priorities and for defining a roadmap to realize your company’s ambitions.