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Understanding System Boundaries in Life Cycle Assessment

What are System Boundaries?

System boundaries are crucial for Life Cycle Assessments (LCA). They define what processes and stages across a product's life cycle are considered in the assessment and which are not. Think of it like knowing the breakdown of the total cost of a product, such as delivery fees and taxes. Without this complete picture, it’s hard to understand the true cost.

In LCAs, clearly defined system boundaries help reduce uncertainty. Most methodologies and standards require these boundaries to be explicitly stated in reports. However, misunderstandings can still arise if the boundaries aren’t clearly communicated, similar to how unexpected fees can surprise online shoppers.

What to Look Out For

Sometimes, studies set narrow system boundaries to focus on specific aspects. For instance, a food producer might compare two types of plastic for bottles, assuming other factors like ingredients and shelf life remain constant. This makes it easier to understand the impact of the plastic alone. While it’s easy to mistake this for a comprehensive assessment of the entire product lifecycle, it’s important to not view the relative reduction of a specific aspect, as the relative reduction of the whole. 

Consider an analogy: if one product is £1 and another is £2, but both have a £10 delivery fee, the price difference is much smaller when you include the fee. Similarly, LCA results can be misleading if the system boundaries don’t account for the entire lifecycle. Other studies might omit the use phase of a product, which can bias the results. 

Products that shift final production steps to consumers might appear more environmentally friendly than they are, if the use phase is not within the system boundaries. Always check the system boundaries when comparing the outcomes of LCA studies.

PEF Requirements for System Boundaries

The EU’s Product Environmental Footprint (PEF) methodology sets comprehensive standards for LCA system boundaries:

"The system boundary shall be defined following a general supply-chain logic, including all stages from raw material acquisition and pre-processing, production of the main product, product distribution and storage, use stage and end of life treatment of the product (if appropriate)."

It includes all stages from raw material acquisition to end-of-life treatment, ensuring a holistic view. However, some exclusions are standardised, such as for intermediate products like B2B apple juice concentrate, which is sold upstream to be used as part of a consumer product, where the use and end-of-life stages are excluded. 

The thinking there is, that these will be covered in the final product’s LCA and this way, the intermediate products calculated impact can directly be plugged into the latter’s assessment, to avoid double counting. The important aspect here is, that the final product still covers the whole lifecycle including that of the intermediate products’ sourcing and manufacturing while a manufacturer has information about the ingredients they purchase. 

Of Cradles, Gates, and Graves

While the System Boundaries also define what to consider along the path of a product’s life, a terminology and concept that people are more and more familiar with is that of start-to-end point of an assessment. Common terms include:

  1. Cradle-to-Gate - This means that an assessment covers the flow from the sourcing of the raw materials (cradle) to the factory gate where a customer or distributor picks the product up. 
  2. Cradle-to-Customer - This describes the same as the above, but includes the distribution to the customer. This is for example applied in PEF for intermediate products where the customer processes that product further. 
  3. Cradle-to-Shelf - This is similar to the one above, and starts from the sourcing of the materials but extends into the shelf at the supermarket.
  4. Cradle-to-Fork - This is a term that is sometimes used in the context of food, where the preparation of it is included in the system boundaries.
  5. Cradle-to-Grave This, too, starts with the sourcing of the materials but covers the whole life cycle to the disposal of the packaging and food waste at the consumer's'. This is applied in PEF for final products.

System Boundaries Blog Diagram  (2)


System boundaries are fundamental to LCAs, defining the scope and influencing the results. Misunderstandings can occur if these boundaries aren’t clear, but standardised frameworks like PEF help mitigate this. 

At Sustained aim provide clear and understandable reports using PEF, you can find out more about why we use PEF in this blog. If you'd like to test automated LCA for your one your products, sign up for a free 2 week trial.