Life Cycle Assessment evaluates a product's environmental performance across its entire lifespan — from raw material extraction at the "cradle" stage through to disposal at "end-of-life." But the real question is: what environmental impacts actually get measured, how are they calculated, and which ones matter most?
That's where impact categories come in. They group emissions and resource flows by the type of environmental damage they cause, converting raw inventory data into meaningful, comparable indicators that sit between the Life Cycle Inventory (LCI) results and the final category endpoints.
Quantifies emissions in relation to a single, well-defined environmental problem — such as climate change or acidification — and expresses the result in one common unit. Midpoint indicators sit earlier in the cause-and-effect chain, making them more scientifically robust and easier to interpret consistently across studies.
Traces those same emissions further along the cause-and-effect chain to their ultimate damage on three broad "areas of protection": human health, ecosystem quality, and resource availability. Endpoint results are more intuitive to communicate but carry greater modeling uncertainty than midpoint results.
Also called climate change, this is the most widely recognized impact category. It converts greenhouse gas emissions into a single common unit, letting different gases be compared on equal footing.
kg CO₂ eqCaptures the potential for emissions like SO₂ and NOx to form acid rain, which damages soil, water bodies, and built structures.
kg SO₂ eqAssesses the risk of nutrient overload — typically nitrogen or phosphate — in freshwater, marine, or terrestrial ecosystems, which can trigger harmful algal blooms.
kg PO₄ / N eqEvaluates a substance's potential to break down the stratospheric ozone layer, which shields the planet from harmful UV radiation.
kg CFC-11 eqMeasures the potential harmful effects of chemical substances released during a product's life cycle on human health and on freshwater, marine or terrestrial organisms.
CTUh / CTUeCovers the consumption of finite resources such as fossil fuels and minerals, reflecting future extraction costs and scarcity pressure on non-renewable reserves.
kg Sb eq / MJCarbon footprint alone tells only part of the story. Assessing a full set of impact categories gives a rounded picture of a product's environmental footprint — covering resource depletion, human health, and ecosystem damage alongside climate change.
The categories selected for a given study depend on the product, the goal of the assessment, and the methodology applied — all governed under ISO 14044, which sets out requirements for the impact assessment phase of an LCA.
Our consultants select impact categories and characterization methods appropriate to your product, sector and target standard — whether that's a PCR-based EPD, a corporate carbon footprint, or a full ISO 14040/44 compliant LCA — modeled end-to-end in SimaPro with ecoinvent data and expert review at every stage.
From selecting the right impact categories to running a full SimaPro-based LCIA, SIPL's team can guide your study end-to-end.
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