Impact Categories (LCA) – The complete overview

Learn what environmental impact categories are useful for and which impact categories there are in the scientific method Life Cycle Assessment (LCA).

Footprinting & LCA

In the time of environmental impact evaluation, impact categories play a pivotal role in translating complex Greenhouse Gas (GHG) emissions into actionable insights.

Actionable is a very important aspect here. Environmental sciences are immensely complex. Thus, when companies try to become more sustainable, they have to define what they mean by that.

What are impact categories in LCA and what is their role?

An impact category groups different emissions into one effect on the environment. These emissions come in different shapes and formats since the emissions from harvesting raw materials are very different from the emissions from producing electricity.

This is where impact categories come into place. During the Life Cycle Impact Assessment (LCIA) of an LCA, we try to unite these different emissions into actionable numbers. Meaning: that different emissions that cause the same impact- are converted into one unit that translates into one impact category.

For example, the impact category ‘climate change’ is expressed in kg CO₂ equivalents (kg CO₂-eq). However, other greenhouse gas emissions than carbon emissions (CO₂) also cause climate change, such as methane (CH₄), or laughing gas (N₂O).

By expressing these other GHG emissions with different measuring units in kg CO₂ equivalents. An impact category makes it possible to come to a single metric for climate change.

Which impact categories should you measure?

The short answer: all of them!

The long answer: Climate change could have catastrophic outcomes for humanity – therefore it is rightly a focus of much sustainability reporting and a crucial consideration for sustainably-minded consumers. However, other impact categories are there for a reason. Human toxicity, air pollution (particulate matter), or ozone depletion are no fun either! Your particular product might have unusually high impacts in any category. Therefore, focus on reducing the environmental impacts that matter most in YOUR case!

Luckily, you don’t have to choose which category to assess. An LCA gives you the results of all categories (the complete environmental footprint) measured by your assessment method. In this way, you can find out which categories need your attention most. Also, an LCA warns you of environmental tradeoffs  (e.g. a design measure that decreases climate impacts but increases toxicity impacts) in advance. This way, you can still choose to prioritize climate impact, while also being aware of the impact on other categories.

Thus, don’t fall into a tunnel vision on carbon emissions. Use LCA software like Ecochain Mobius and Helix to calculate the complete environmental footprint – with no extra work involved!


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Environmental impact categories – The overview

This table gives you an overview of the 15 environmental impact categories, which unit they are measured in, and what they describe.

The 15 categories and indicators are all taken from the EN15804 (A1+A2) standard for LCA’s in the construction sector. Other impact assessment methods (such as the PEF 3.0) exist as well, which use slightly different categories. However, EN15804 +A2 gives a good general overview.

Good to note: the EN15804 standard was updated to EN15804 + A2 (2019). This resulted in quite some other changes. Find these new adaptations here.

Table 1. Environmental impacts

Impact Category / Indicator Unit Description
Climate change – total, fossil, biogenic, and land use kg CO2-eq Indicator of potential global warming due to emissions of greenhouse gases to the air. Divided into 3 subcategories based on the emission source: (1) fossil resources, (2) bio-based resources, and (3) land use change.
Ozone depletion kg CFC-11-eq Indicator of emissions to air that causes the destruction of the stratospheric ozone layer
Acidification kg mol H+ Indicator of the potential acidification of soils and water due to the release of gases such as nitrogen oxides and sulfur oxides
Eutrophication – freshwater kg PO4-eq indicator of the enrichment of the freshwater ecosystem with nutritional elements, due to the emission of nitrogen or phosphor-containing compounds
Eutrophication – marine Kg N-eq Indicator of the enrichment of the marine ecosystem with nutritional elements, due to the emission of nitrogen-containing compounds.
Eutrophication – terrestrial mol N-eq Indicator of the enrichment of the terrestrial ecosystem with nutritional elements, due to the emission of nitrogen-containing compounds.
Photochemical ozone formation kg NMVOC-eq Indicators of emissions of gases that affect the creation of photochemical ozone in the lower atmosphere (smog) catalyzed by sunlight.
Depletion of abiotic resources – minerals and metals kg Sb-eq Indicator of the depletion of natural non-fossil resources.
Depletion of abiotic resources – fossil fuels MJ, net calorific value Indicator of the depletion of natural fossil fuel resources.
Human toxicity – cancer, non-cancer CTUh Impact on humans of toxic substances emitted to the environment. Divided into non-cancer and cancer-related toxic substances.
Eco-toxicity (freshwater) CTUe Impact on freshwater organisms of toxic substances emitted to the environment.
Water use m3 world eq. deprived Indicator of the relative amount of water used, based on regionalized water scarcity factors.
Land use Dimensionless Measure of the changes in soil quality (Biotic production, Erosion resistance, Mechanical filtration).
Ionizing radiation, human health kBq U-235 Damage to human health and ecosystems linked to the emissions of radionuclides.
Particulate matter emissions Disease incidence Indicator of the potential incidence of disease due to particulate matter emissions


Author image Luc  Hillege
Luc Hillege

Hi! I'm Luc - Product Manager at Ecochain. I ensure the development of our software solutions is aligned with the needs and requirements of our customers. My main objective: to deliver valuable technology that allows our customers to measure their Product's Environmental Footprint (LCA).

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