Life Cycle Assessment (LCA) is a method for quantifying the potential environmental impacts of the complete lifespan of a good, product or a service – from raw material extraction, through manufacturing and use, to final disposal and recycling. This way the risk to shift environmental burdens between life cycle stages is avoided. Moreover, LCA provides an environmental profile of the product for more than only one impact category (e.g. carbon footprint). The different impact categories that we apply in greenzero are explained below.

LCA helps to focus on the most significant environmental impacts as the company develops and evaluates sustainability programs and policies; it also assists in informing product decisions to reduce the environmental impact from design and materials to manufacturing. LCA results are used to support engagement with external stakeholders to reduce the impact of materials and consumer care.

Life-LCA is a concept, developed by Görmer et al. (2019) and based on the classic product LCA method. It focus on human beings instead of products as a new study object. Life-LCA is a two-dimensional method that covers both, the human life cycle (dimension 1) and the life cycle of the consumed products (dimension 2). The approach raises the environmental awareness of people by making their specific environmental impacts comprehensively measurable and thus, tangible. Life-LCA applies the same impact assessment approach as the classic product LCA, based on several impact categories.

What is an impact category?

Emissions to the different compartments of the environment (water, soil, air) occur in each and every step of product’s life cycle. During the course of an LCA study, large amount of emissions data is collected: emissions from the raw material extraction, products manufacturing, energy and waste production, etc. These emissions come in different shapes and formats.

An impact category (or LCIA* category) groups different emissions into one effect on the environment. This is done by assignment of the emission results to the respective category (a step called classification) and calculating category indicator results by converting the emissions to a common unit with the help of characterization factors (a step called characterization).

An impact category groups complex data into accessible numbers – numbers that give a concrete picture of what the impact actually is.

*LCIA – Life Cycle Impact Assessment

Overview of the
impact categories we use

In the current LCA world, there are many categories that give indication on different impacts on the environment, as well as on the human health. They are in different state of methodological development, so their robustness differs as well. In our model, we stick to a limited number of categories that we consider as most scientifically-robust and relevant for our tool:

Climate Change

This is one of the most well-known impact categories. It measures the potential for global temperatures increase, due to emissions of CO2 and other greenhouse gases (GHGs) to air. GHGs mostly result from combustion processes (e.g. transport, energy production, etc.), but also from industry and agriculture. It is measured in [kg CO2-eq.] (kilograms of carbon dioxide equivalents).


This impact category gives an indication for the potential environmental damage to soils and water bodies due to the release of acidifying gases such as nitrogen oxides (NOx) and sulfur oxides (SOx). Such gases are usually emitted by combustion processes, especially when sulfur-reach fuels (like coal) are burned. Furthermore, emissions of ammonia (NH3) from agriculture is also a significant contributor to this category. Acidification is measured in [kg SO2-eq.].


The Eutrophication indicates the enrichment of water bodies with nutritional elements. This is caused by the emission of nitrogen or phosphor containing compounds that are often contained for example in fertilizers used in agriculture. This enrichment of nutrition in water causes the rapid growth and reproduction of phytoplankton leading to algae bloom that consumes the oxygen in the water, leaving none for other marine or freshwater life and blocks sunlight from photosynthetic underwater plants. Eutrophication is measured in [kg PO4 3−-eq.]

Photochemical Ozone Creation

This category is an indicator of emissions of gases that affect the creation of photochemical ozone in the lower atmospheric levels, catalyzed by sunlight. This is the well-known smog in bigger cities with busy car traffic. Emissions of volatile organic compounds (VOCs) and NOx from the exhaust gases of vehicles result in the formation of ozone molecules that damage crops and lead to asthma and other respiratory complaints in humans. This impact category is measured in [kg C2H4 -eq.].

Ozone Depletion

Ozone in the lower atmospheric levels where people can breath is not desired. On the contrary, ozone in the higher level of the atmosphere, i.e. in the stratosphere, keeps the planet from dangerous UV radiation. Ozone depletion gives the indication of emissions to air that cause the thinning of the stratospheric ozone layer (or the “enlargement” of the so called “ozone hole”). The depletion of the stratospheric ozone is considered not an urgent and pressing environmental issue anymore in the recent years, to due to banning the global use of ozone-damaging substances, mainly applicable in the refrigeration industry. Ozone depletion is measured in [kg CFC-11-eq.]

Water use

Freshwater scarcity has become a major concern worldwide. The reasons are the increasing demand due to continued population growth and new consumption patterns, industrial development, dependence on single supply sources, depletion and pollution of groundwater as well as hydrological and climate changes. This indicator assesses the potential of water deprivation, to either humans or ecosystems, building on the assumption that the less water remaining available per area, the more likely another user will be deprived. It is measured in [m3 world eq.]

Resource use (minerals and metals)

This category gives the potential for depletion of abiotic resources. It specifically adresses the extraction of non-renewable, abiotic, natural resources, such as different minerals and metals (but not fossil fuels). These resources are used in almost every electrical product in our daily lives and the current digital era is unthinkable without the use of such rare-earth and noble metals and minerals. Their depletion, however, is very much dependent on the current technologies for extraction, reuse and recycling. Resource depletion potential is measured in [kg Sb eq.]