Unit of Measure (UoM) - TX
'Unit of Measure (UoM) refers to the unit in which an environmental indicator or quantitative measure is expressed. It defines the scale and type of the result value, such as kilograms of CO₂-equivalent or megajoules of energy.
Unit of Measures are essential for ensuring comparability, validity, and consistency across all data domains, Commerce & Operations, Health, Safety Sustainability data exchange using the IMDE model.
Purpose
The Unit of Measure indicates the unit of measurement for the value being reported, independently of what it is reported *per* (e.g., per kilogram or per piece). It answers the question: “What is the quantity expressed in?”. The per unit is the Unit of Declaration (UoD). Examples price UoM is $, and the the UoD can be per kg, per piece or per Supply Chain Unit ([[1]])
Examples
Common UoMs used for environmental impact indicators are shown below, along with standardized or recommended keys:
| UoM | Key | Description | Indicator Example |
|---|---|---|---|
| kg CO₂eq | kgCO2eq | Kilogram of carbon dioxide equivalent | Climate Change / Carbon Footprint |
| m³ | m3 | Cubic meter of freshwater | Water Use |
| MJ | MJ | Megajoule (energy unit) | Primary Energy Demand |
| kg Sb eq | kgSbeq | Kilogram of antimony equivalent | Resource Depletion (Abiotic Resources) |
| kg PM2.5 eq | kgPM25eq | Kilogram of fine particulate matter equivalent | Air Pollution (Particulate Matter) |
| kg SO₂ eq | kgSO2eq | Kilogram of sulfur dioxide equivalent | Acidification |
| mol H⁺ eq | molHplusEq | Moles of hydrogen ion equivalent | Acidification Potential |
| kg N eq | kgNeq | Kilogram of nitrogen equivalent | Eutrophication (Terrestrial) |
| kg P eq | kgPeq | Kilogram of phosphorus equivalent | Eutrophication (Freshwater) |
| CTUe | CTUe | Comparative Toxic Unit for ecosystems | Ecotoxicity |
| CTUh | CTUh | Comparative Toxic Unit for humans | Human Toxicity |
Note: Keys follow commonly used abbreviations in ILCD/PEF datasets and ISO unit symbols where applicable. Compound units such as “kg CO₂eq” or “kg Sb eq” reflect impact-specific normalization factors used in LCA characterization models.
Characteristics
- May be expressed as standard SI units (e.g., kg, m³, MJ)
- May be expressed as derived or compound units (e.g., kg CO₂eq, MJ primary energy, kg Sb eq)
- Units should be consistent with international LCA standards (e.g., ILCD, PEF, EN 15804)
Use in IMDE
The UoM is part of the environmental impact declaration structure in IMDE and is applied per Indicator:
- Example:
* EnvironmentalImpactIndicator: CFP {Climate Foot Print)
* Value: 0.98
* UoM: kgCO₂eq
* Reference Unit: kg (see Reference Unit)
This separation ensures reusability of indicators across products, geographies, and life cycle stages while preserving semantic clarity.
