Because each of the 16 PEF indicators measures a different type of environmental impact, and a material rarely performs better on all of them. A change that reduces one impact can increase another. This is called burden shifting, and it is expected in the Material Simulator results, not an error.
How to read the Δ%
The Δ% column shows how much the Alternative differs from the Base on each indicator:
| Δ% | Meaning | Colour |
|---|---|---|
| Negative (for example, -54,4%) | The Alternative has a lower impact than the Base: a saving | Green |
| Positive (for example, +17,2%) | The Alternative has a higher impact than the Base | Red |
The Best badge
The Best badge marks up to 3 indicators with the highest savings, where the Alternative reduces the impact the most compared with the Base. Only indicators with a saving can get it, so if fewer than 3 indicators improve, only those are marked. It points to where the Alternative improves most. It doesn’t mean the Alternative is better overall: other indicators in the same comparison can be worse.
Why the indicators differ
The indicators fall into five areas:
| Area | Indicators |
|---|---|
| Climate Change | Global warming |
| Water | Water scarcity |
| Natural Resources | Resource use, fossils · Resource use, minerals and metals · Land use |
| Ecosystems | Acidification · Eutrophication, marine · Eutrophication, terrestrial · Eutrophication, freshwater · Ecotoxicity, freshwater |
| Human Health | Ozone depletion · Human toxicity, cancer · Human toxicity, non-cancer · Particulate matter · Ionising radiation · Photochemical ozone formation |
How to read the comparison
- Identify the indicators that matter most for your decision.
- Read the Δ% together with the Base and Alternative values. Δ% is relative to the Base, so a small Base value can give a very large percentage.
- Check all areas before concluding. A saving on one row doesn’t mean a saving overall.
- Describe the comparison by indicator. Avoid summarising it as “Material A is better”.
- Remember that the results include only raw material extraction (leather also includes tanning). Differences in later stages, such as processing, finishing or manufacturing, are not part of the comparison. This matters when you compare leather with another material: the leather result already includes a processing step that the other material’s result doesn’t.