Life Cycle Impact Assessment (LCIA) is a phase of Life Cycle Assessment aimed at understanding and evaluating the magnitude and significance of the potential environmental Impacts for a Product system throughout the life cycle of the Product, as defined in ISO 14040 clause 3.4.
LCIA represents the interpretative phase of LCA where the compiled inventory data from the Life Cycle Inventory analysis is translated into meaningful environmental impact indicators. This phase moves beyond simply listing emissions and resource consumption to assessing what these flows actually mean for the environment and human wellbeing.
The LCIA phase transforms elementary exchanges into quantified environmental impacts through characterisation models. These models establish relationships between inventory results and impact categories such as climate change, acidification, eutrophication, human toxicity, and resource depletion. Each impact represents a causal, directional relationship between an activity and an environmental issue of concern, typically involving a significant externality.
The assessment evaluates both the magnitude (how large is the impact?) and the significance (how important is this impact relative to others or to reference levels?) of potential environmental consequences. This dual focus enables decision-makers to identify hotspots in product systems, compare alternative solutions, and prioritise improvement opportunities based on their environmental relevance.
Importantly, according to the ISO 14001 definition of environment, which encompasses air, water, land, natural resources, flora, fauna, humans, and their interrelation, LCIA includes social, biophysical, and economic impacts. This broader scope recognises that environmental assessment extends beyond purely ecological considerations to encompass human health and resource sustainability.
