There are different kinds of product life-cycles that are considered for Life Cycle Assessments, depending on how deep the study will be and its primary goals.
'Cradle-to-grave' assessment considers impacts at each stage of a product's life-cycle, from the time natural resources are extracted from the ground and processed through each subsequent stage of manufacturing, transportation, product use, and ultimately, disposal.
It is a variation of cradle-to-grave, exchanging the waste stage with a recycling process that makes it reusable for another product, essentially “closing the loop”
Cradle-to-gate only assesses a product until it leaves the factory gates before it is transported to the consumer.
Which are the impacts evaluated with Life Cycle Assessments? Here are some of the most common ones:
(a.k.a., global warming or carbon footprint) A measure of greenhouse gas emissions, such as CO2 and methane. These emissions are causing an increase in the Earth’s absorption of radiation emitted by the sun, increasing the greenhouse effect. This can in turn have adverse impacts on ecosystem health, human health and material welfare.
Depletion of water means scarcity of water which means that there is a lack of water. Water scarcity is the lack of sufficient available freshwater resources to meet water demand.
Eutrophication - marine
Indicator of the enrichment of the marine ecosystem with nutritional elements, due to the emission of nitrogen containing compounds.
Eutrophication - terrestrial
Indicator of the enrichment of the terrestrial ecosystem with nutritional elements, due to the emission of nitrogen containing compounds.
Eutrophication - freshwater
Indicator of the enrichment of the fresh water ecosystem with nutritional elements, due to the emission of nitrogen or phosphor containing compounds
A measure of emissions that cause acidifying effects to the environment. The acidification potential is a measure of a molecule’s capacity to increase the hydrogen ion (H+) concentration in the presence of water, thus decreasing the pH value (e.g., acid rain). Potential effects include fish mortality, forest decline and the deterioration of building materials.
Photochemical ozone creation
(a.k.a., Smog formation) A measure of emissions of precursors that contribute to ground level smog formation (mainly ozone O3), produced by the reaction of VOC and carbon monoxide in the presence of nitrogen oxides under the influence of UV light. Ground level ozone can be detrimental to human health and ecosystems and may also damage crops.
Particulate matter emissions
(a.k.a., dust and aerosol emissions)—A measure of particulate matter emissions and precursors to secondary particulates, such as SO2 and NOx from sources like fossil fuel combustion, wood combustion and dust particles from roads and fields. Particulate matter causes negative human health effects, including respiratory illness and an increase in overall mortality rates.
A measure of air emissions that contribute to the depletion of the stratospheric ozone layer (i.e., the ozone hole). Depletion of the ozone leads to higher levels of UVB ultraviolet rays reaching the Earth’s surface with detrimental effects on humans and plants.
The impact category ‘land use’ describes in the Life Cycle Assessment (LCA) methodology the environmental impacts of occupying, reshaping and managing land for human purposes. Land use can either be the long-term use of land (e.g. for arable farming) or changing the type of land use (e.g. from natural to urban area). The impact category ‘land use’ comprises those environmental consequences, which impact the environment due to the land use itself, for instance through the reduction of landscape elements, the planting of monocultures or artificial vegetation, or the sealing of surfaces. Important environmental consequences of land use are the decreasing availability of habitats and the decreasing diversity of wildlife species.
Ecotoxicity refers to the capability of a compound or any physical agent to show the harmful effect on both environment and organisms, for instance, fish, insects, microorganisms, wildlife, and plants.
Human toxicity refers to the disease burden attributable to exposure to chemical substances released throughout a product or service life cycle.
Depletion of abiotic resources – fossil fuels
Indicator of the depletion of natural fossil fuel resources.
Depletion of abiotic resources – minerals and metals
Indicator of the depletion of natural non-fossil resources.
A Life Cycle Assessment consists of four stages (defined in the ISO standards 14040 and 14044)
Stage 1 - LCA goal & scope definition
The goal and scope definition step ensures that your LCA is performed consistently. In this phase, you define the product that we wish to assess and choose a functional basis for comparison and define the required level of detail. Then you set a goal which determines the scope, including objective, application and audience. Lastly, you determine whether or not there has to be a critical review of that goal.
Stage 2 - Inventory analysis
In the inventory analysis, you look at all the environmental inputs and outputs associated with a product or service. Inventory analysis gives a description of material and energy flows within the product system and especially its interaction with environment, consumed raw materials, and emissions to the environment. Here you perform a data compilation and an inventory analysis of extractions from and releases into the environment.
Stage 3 - Life cycle impact assessment (LCIA)
In impact assessment, you classify resource use and emissions generated according to their potential impacts and quantify them for a limited number of impact categories, which you may then assess in terms of their relative importance for the goal of the LCA study.
Stage 4 - Interpretation
During the interpretation phase, you check that your conclusions are well-substantiated. With the above information, you discuss the results in terms of contributions, relevance, robustness, data quality and limitations, and you systematically evaluate any opportunities for reducing the negative effects of the product(s) or service(s) on the environment while avoiding burden shifting between impact categories or life cycle phases.