From inventory to impact: the characterisation step
When you upload data into Root — material weights, energy consumption, transport distances — you are building what LCA practitioners call an inventory. This inventory is a list of all the physical flows associated with your product: how many kilograms of cotton, how many kWh of electricity, how many tonne-kilometres of freight.
But an inventory on its own doesn’t tell you anything about environmental impact. A kilogram of CO₂ and a kilogram of methane both appear as numbers in an inventory — but their effect on climate change is very different.
Characterisation is the step that converts inventory flows into impact scores, by applying scientifically derived conversion factors called characterisation factors.
How characterisation works
Each substance in the inventory is multiplied by its characterisation factor for a given impact category:
Impact score = Inventory flow (kg) × Characterisation factor
For example, in the climate change impact category:
1 kg CO₂ × characterisation factor of 1 = 1 kg CO₂e
1 kg CH₄ (methane) × characterisation factor of 29.8 = 29.8 kg CO₂e
1 kg N₂O × characterisation factor of 273 = 273 kg CO₂e
These factors come from IPCC assessments and are embedded in the impact assessment method Root uses — the Environmental Footprint (EF) methodology.
This process is repeated for every impact category (water scarcity, land use, particulate matter, etc.), producing a full environmental profile for your product.
Impact categories Root calculates
Root calculates impact scores across 20 EF metrics. These are the exact metrics you will see in Root's dashboards and exports:
Metric | Theme | What it measures |
Land use (agricultural) | Land & water | Impact of occupying and transforming agricultural land, affecting soil quality and biodiversity |
Water use | Land & water | Freshwater consumption weighted by local scarcity — 1 litre in an arid region counts for more than 1 litre in a water-rich one |
Carbon footprint (fossil) | Carbon | Greenhouse gas emissions from burning or processing fossil fuels (oil, gas, coal) |
Carbon footprint (biogenic) | Carbon | CO₂ and methane released from biological sources such as plant-based materials or organic waste |
Carbon footprint (FLAG) | Carbon | Emissions from Forests, Land and Agriculture — covers land-use change, deforestation, and agricultural soil processes |
Freshwater toxicity | Toxicity | Release of toxic substances into freshwater bodies, affecting aquatic ecosystems |
Marine toxicity | Toxicity | Release of toxic substances into marine environments |
Land toxicity | Toxicity | Release of toxic substances onto land, affecting soil organisms and ecosystems |
Human toxicity (carcinogenic) | Toxicity | Exposure to cancer-causing substances via air, water, or soil |
Human toxicity (non-carcinogenic) | Toxicity | Exposure to non-cancer toxic substances that affect human health |
Freshwater pollution | Pollution | Excess phosphorus entering freshwater bodies, causing algal blooms and oxygen depletion |
Marine pollution | Pollution | Excess nitrogen entering coastal and marine waters from agricultural runoff and industrial processes |
Land pollution (nutrients) | Pollution | Nitrogen deposition onto land ecosystems, altering soil chemistry and reducing biodiversity |
Land pollution (acids) | Pollution | SO₂ and NOx emissions that deposit as acid rain, damaging forests, soils, and water |
Air pollution | Air & atmosphere | Fine particle (PM2.5) emissions from combustion and industrial processes — a leading cause of premature death globally |
Smog (human health) | Air & atmosphere | Volatile organic compounds and NOx that react in sunlight to form ground-level ozone, affecting respiratory health |
Ozone depletion | Air & atmosphere | Substances that break down the stratospheric ozone layer, increasing UV radiation at ground level |
Radiation exposure | Air & atmosphere | Radioactive emissions from nuclear energy generation and certain industrial processes |
Fossil fuel | Resources | Depletion of non-renewable fossil fuel resources used as energy or feedstock |
Mineral resources | Resources | Depletion of non-renewable mineral and metal resources — particularly relevant for electronics and alloys |
All are then aggregated into the Environmental Cost Indicator (ECI) using monetisation factors — giving you a single € value that represents the total environmental cost of your product.
What this means in Root
You don’t need to do any of this manually. Root handles the full characterisation pipeline automatically:
You upload your data (BOM, utilities, transport)
Root matches your inputs to ecoinvent datasets
ecoinvent datasets contain the inventory flows (kg CO₂, kg NOx, m³ water, etc.)
Root applies EF characterisation factors to each flow
Results appear in your dashboards as impact scores per product, per material, or per facility
FAQ
Can I see the raw inventory flows behind my impact scores?
Not directly in the dashboards — Root surfaces characterised impact scores rather than raw inventory data. For a deeper breakdown, you can contact Root’s LCA team or export your data via snapshots.
Why does a material with low weight sometimes have a high impact?
Because characterisation factors vary enormously between substances. A small amount of a highly toxic or high-GWP material can dominate the impact score. This is exactly what the characterisation step reveals — and it’s one of the most valuable insights LCA provides.