Life Cycle Impact Assessment (LCIA)

Life Cycle Impact Assessment (LCIA) is the third phase of a Life Cycle Assessment (LCA) under ISO 14044. It converts the flows recorded in the Life Cycle Inventory (LCI) (materials, energy, water and emissions) into quantitative environmental impact indicators. In practice, it translates tonnes of CO2, grams of NOx or cubic metres of water into understandable impact categories such as climate change, resource depletion or water scarcity, so that eco-design improvements can be compared and prioritised.

Objectives of LCIA

• Understand the magnitude and relevance of the potential impacts associated with a product or process.
• Identify the critical hotspots where reduction actions will be most effective.
• Assess alternatives in materials, energy or logistics under a common metric.
• Communicate results in Environmental Product Declarations (EPDs), CSRD reports or Digital Product Passports (DPPs).

Main stages according to ISO 14044

1. Selection of impact categories: climate change, water scarcity (AWARE), acidification, eutrophication, toxicity, resource depletion and others.
2. Classification: assign each inventory flow to the relevant categories (CO2 to climate change, NOx to acidification).
3. Characterisation: multiply each flow by a characterisation factor (GWP100, acidification potential, eutrophication potential, AWARE) and sum to obtain total contributions.
4. (Optional) Normalisation: express results relative to reference loads (for example, the annual per-capita footprint in Europe).
5. (Optional) Weighting: apply weights to aggregate categories into a single index based on scientific or policy relevance.
6. Interpretation: analyse uncertainty, sensitivity and consistency with the goal and scope.

Most widely used LCIA methods

• IPCC GWP100 for climate change.
• ReCiPe 2016 (18 midpoint categories plus endpoint damage indicators).
• EF 3.1, the European Commission method used for the Product Environmental Footprint (PEF).
• TRACI 2.1 (US EPA).
• CML-IA Baseline (Leiden University).
• AWARE for the scarcity-adjusted water footprint.
• USEtox for human toxicity and ecotoxicity.

Characterisation factors: CO2 and water examples

• CO2 to GWP100: 1 kg CO2e per kg CO2.
• Biogenic CH4 to GWP100: about 27 kg CO2e per kg CH4 (IPCC AR6); fossil methane is higher (about 29.8).
• N2O to GWP100: 273 kg CO2e per kg N2O (IPCC AR6).
• Water consumption: in a water-stressed basin the AWARE factor can be well above 20, so each cubic metre consumed is multiplied accordingly to express the result in cubic metres of water-scarcity equivalent.

Compatible tools and software

• SimaPro, OpenLCA, GaBi, Brightway2 and One Click LCA with databases such as ecoinvent, EF 3.1 or Agri-footprint.
• Cloud LCA services and APIs from providers such as Ecochain or GreenDelta.
• BIM plug-ins integrating ReCiPe and ILCD methods for the construction sector.

Best practices

• Method and goal consistency: use ReCiPe for general comparisons and EF 3.1 for EPDs under PEF category rules.
• Transparency: clearly state the factors used and their update year (IPCC AR6 versus AR5).
• Sensitivity analysis: vary key flows by around 20% to test robustness.
• External critical review for publicly disclosed studies.
• Avoid double counting between blue water use and water-scarcity indicators.

Synergies with regulations and standards

• ESPR Regulation: supports product impact disclosure through the Digital Product Passport.
• ISO 14068-1: carbon-neutrality claims require LCIA evidence of real emission reductions.
• LEED and BREEAM: LCA credits and impact reductions against reference scenarios.
• CSRD and ESRS E1 to E5: quantified disclosure of key environmental impact categories.

Emerging challenges

• Dynamic LCA: incorporating temporal variations in electricity mixes and climate conditions.
• Social impacts (S-LCA): integrating the social dimension with environmental LCIA.
• Data interoperability: shared ontologies and APIs for reliable data exchange.
• Combined footprints: simultaneous accounting of carbon, water and biodiversity without overlaps.

Life Cycle Impact Assessment turns raw inventory data into actionable indicators for decision-making. Choosing appropriate methods, being transparent and addressing uncertainty are the pillars of a robust LCIA that supports both sustainable innovation and regulatory compliance. At Manglai we help companies measure their carbon footprint and prepare their sustainability reporting. Discover how Manglai can help you.