Every material on the market today can claim to be “sustainable”. Part of the challenge is that many existing tools used to measure circularity focus on technical materials that are reused in industrial systems, making them less suited to assess bio-based materials designed to be composted.
As a result, comparing materials on circularity isn’t always straightforward:
- Should we keep using recyclable plastic for protective packaging or switch to Mycelium Packaging?
- Does replacing plastic tape with paper tape improve circularity?
- And how much do choices like printed vs. unprinted boxes matter in the big picture?
These seemingly small decisions can have a major impact on sustainability, as thousands of companies compare materials to try and align their packaging strategies with the PPWR.
To compare materials more objectively, the Ellen MacArthur Foundation developed the Material Circularity Indicator (MCI): a tool that measures how circular a product’s material flows actually are.
In this article, we use the MCI to compare the circularity of EPS and Mycelium Packaging.
Recycling can mean different things
Recycling is often treated as the default benchmark for circularity. But recycling can refer to a range of different processes depending on the material.
Take PET bottles for example. Transforming them into fleece sweaters technically counts as recycling. However, the resulting material can no longer be recycled again afterwards. This process is known as downcycling, where materials are transformed into lower-quality products that extend their lifespan before ultimate disposal.
Paper follows a similar pattern. It can be recycled several times, but each cycle shortens the fibers until they are no longer usable.
This raises two important questions that are often overlooked:
- How much material is actually collected for recycling?
- And how much of that collected material is effectively reused?
Without high collection and processing rates, materials that are theoretically recyclable still follow a largely linear path.
More broadly, circularity is not only determined by whether a material can be recycled, but also by whether all components within the system can be effectively recovered and reused. In many material processes, certain inputs are lost along the way and cannot be brought back into the loop. In the case of EPS, for example, the blowing agent used to create its structure is released into the atmosphere during production and cannot be recaptured, meaning part of the system remains inherently linear. In addition, these types of process emissions can have a significantly higher global warming potential than CO₂, further affecting the overall environmental impact.
Circularity goes beyond recycling
According to the Ellen MacArthur Foundation, a circular economy:
(1) eliminates waste and pollution
(2) regenerates nature
(3) circulates products and materials at their highest value.
Most conventional packaging systems don’t meet all three.
Even when recycling is technically possible, losses in material quality, high energy use and reliance on virgin materials mean the loop is rarely fully closed. Recycling can slow down resource depletion, but it doesn’t automatically create a circular system.
At the same time, not all materials are designed for the same type of circularity. Technical materials like plastics aim to stay within industrial systems through recycling. Bio-based materials are designed to return safely to natural systems.
This is where composting comes in, not as a secondary option, but as a fundamentally different circular pathway.
How the MCI measures circularity
The Material circularity Indicator helps make these differences visible.
It looks at:
- Inputs: what the product is made of and where the materials come from
- Outputs: what happens to the product at the end of its life
Using 17 different parameters, the tool calculates a score between 0 and 1:
- 0 = linear
- 1 = fully circular
What makes the MCI particularly useful is that it reflects real-world conditions, including imperfect collection, processing losses, and varying end-of-life scenarios.
Comparing EPS and mycelium-based packaging
As part of the ESCIB-project, the University of Gent, applied the Material Circularity Indicator (MCI) to a case study comparing EPS with our Mycelium Packaging.
Let’s take a look at the results:
For EPS:
- Best-case scenario (100% recycled): MCI ≈ 0.46
- Realistic scenarios (~50% recycling rate globally): significantly lower MCI
- Worst-case (incineration/landfill): MCI ≈ 0.1
Even under ideal conditions, EPS is only partially circular. This is largely because it depends on fossil-based inputs and inefficiency int recycling systems.
For Mycelium Packaging
- Best case (100% composted): MCI ≈ 0.94
- Incineration with energy recovery: up to 0.64
- Worst case (landfill): ≈ 0.49
Even in less optimal scenarios, it maintains a relatively high level of circularity. In fact, the worst case scenario for Mycelium Packaging is still better than the best case for EPS.
Why does Mycelium Packaging score higher?
The difference lies in how these materials are designed to flow through the system.
EPS is part of a technical cycle:
- Reliant on fossil resources
- Dependent on collection and recycling efficiency
- Vulnerable to losses that quickly make the system linear
Mycelium Packaging follows a biological cycle:
- Made from renewable, fast-growing materials
- Upfront uptake of CO2
- Designed to safely return to nature through composting
- Supports natural regeneration processes
Composting is considered circular, because CO2 is released and recaptured in a short time span. Nutrients are returned to the soil, and carbon released enters the earth’s natural carbon cycle.
What this means in practice
The comparison highlights an important shift in how we think about circularity. It considers more than whether a material can be recycled, but whether it will be. At the same time, materials designed for biological cycles should not be assessed purely through a recycling lens.
For companies making packaging decisions, the key questions become:
- What is the most realistic end-of-life scenario for this material?
- And does that pathway actually keep the material in a loop, either through recycling or by returning safely to nature?
The MCI doesn’t consider everything when it comes to circularity. For example, they don’t fully account for the energy required to keep materials in a loop, such as transport, sorting, and recycling processes. What the MCI does do is make the real-world implications of different material choices visible. And that is a necessary step towards making packaging decisions that are genuinely circular.
