Most of the sustainable material comparison rely on life
cycle assessment, or LCA. It is a legitimate scientific method for this
particular assessment.
Higg Materials Sustainability Index is the clearest
real-world example as it is a rating tool used by more than 100 major apparel
brands to compare the environmental impact of different fabrics. In June 2022,
Norway’s Consumer Authority concluded that a retailer’s use of Higg data to
market an organic cotton T-shirt as producing far less pollution than
conventional cotton was likely false and misleading. It warned brands against
using the index for consumer-facing environmental claims.
The core problem wasn’t fraud.
The regulators found that the claims referred to an average
industry data for a fibre type rather than the actual environmental performance
of the specific finished product being sold. It basically meant that the
comparison done was real but not just of the thing consumer assumed it was
measuring.
Within weeks, the organization behind the index paused its
consumer-facing scorecards worldwide while it reviewed its methodology, and the
episode became a case study about how a technically valid metric can still
mislead when the wrong scope gets attached to it.
Same Two Materials Can Win Different Comparisons
Academic researchers have pointed this exact issue for
years.
A comparative LCA framework study noted that current
practice around defining what is actually being measured which is known as
functional unit, is inconsistent with LCA’s own guidelines. The type of
functional unit chosen can meaningfully change which material appears more
sustainable (Furberg et al., 2022).
A 2026 review of over 50 peer-reviewed life cycle studies on
bio-based materials reached a similar conclusion that simply stating on the
label “bio-based” does not necessarily indicate a lower environmental
footprint. Since, the results depend on methodological choices such as how
emissions are modelled, how carbon storage in plants is accounted, and how
land-use change is handled (El Bachawati et al., 2026).
In practical terms, it means a study measuring carbon
emissions per kilograms of fibre can produce the opposite ranking from a study
measuring water use per garment, or emissions per wear over a product’s
lifetime. Neither study is necessarily wrong. They are simply answering
different questions while appearing to answer the same one.
Even when the comparison sticks to carbon emissions
consistently, it can still miss the bigger picture.
A fibre can score well on greenhouse gas emissions per ton
produced while scoring poorly on water depletion, biodiversity loss, or what
happens to the material after disposal, categories many popular comparisons
simply leave out. Synthetic fibres, for instance, often perform competitively
on emissions metrics measured only up to the factory gate, while contributing
heavily to ocean microplastic pollution once garments are washed and eventually
discarded. It is an impact that a cradle-to-gate carbon comparison never
captures at all.
What Fair Comparison Requires
A trustworthy material comparison should specify exactly
what unit is being compared, a kilogram of fibre, a finished garment, or a
garment’s full useful life. And it should state which environmental categories
are included and which are left out.
If a claim mentions only one number, like emissions or water
use, treat it as one data point and not the whole verdict. As the question here
is that whether the material is built to answer the thing you’re actually
asking.
Frequently Asked Questions
What is a ‘functional unit’ in a sustainability
comparison?
It is the specific quantity being measured and compared,
such as one kilogram of fibre, one finished garment, or one garment worn for
its useful life. Choosing a different functional unit can change which material
looks more sustainable, even using the same underlying data.
Why was the Higg Index banned from being used in
marketing?
Norway’s Consumer Authority found that a brand used the
index’s average, fibre-level data to make specific claims about an individual
product’s environmental impact, which it ruled was likely mislead consumers.
Does a low carbon footprint mean a material is
sustainable overall?
Not necessarily. Carbon emissions are only one environmental
category. A material can score well on emissions while performing poorly on
water use, biodiversity impact, or end-of-life pollution, so a single-metric
claim doesn’t capture the full picture.
References
El Bachawati, M., Belarbi, Y. E., El Zakhem, H., &
Belarbi, R. (2026). Life cycle assessment of sustainable materials: A
comprehensive analysis of methodological asymmetries and environmental
trade-offs. Buildings, 16(7), 1385. https://doi.org/10.3390/buildings16071385
Furberg, A., Arvidsson, R., & Molander, S. (2022). A
practice-based framework for defining functional units in comparative life
cycle assessments of materials. Journal of Industrial Ecology, 26(3),
921-935. https://doi.org/10.1111/jiec.13218
Onn, N. (2023, June 4). Why we should be constructive about
the Higg Index, not shame it. Medium. https://cleonajah.medium.com/why-we-should-be-constructive-about-the-higg-index-not-shame-it-f36fabba63fc
