A Life Cycle Assessment is defined as the systematic analysis of the potential environmental impacts of products during their entire life cycles.
During a Life Cycle Assessment, the potential environmental impacts are evaluated throughout the entire life cycle of a product (production, distribution, use and end-of-life phases). This also includes the upstream and downstream processes associated with the production (e.g., production of raw, auxiliary and operating materials) and with the disposal (e.g., waste incineration).
Environmental impacts cover all relevant inputs from the environment (e.g., ores and crude oil) as well as emissions into air, water and soil (e.g., carbon dioxide and nitrogen oxides). The International Organization for Standardization provides guidelines and requirements for conducting a Life Cycle Assessment according to ISO 14040 and 14044.
The Main Phases of Life Cycle Assessment
Goal & Scope Definition
The product or service to be assessed is defined, a functional basis for comparison is chosen and the required level of detail is defined. A goal is then set in accordance with science, including objective, application and audience. It is determined whether or not there will be a critical review of that goal.
An inventory analysis of extractions from and releases into the environment is performed. The final inventory lists all inputs and outputs associated with the life cycle of a product or service.
The potential effects of the resource use and emissions generated are grouped and quantified into a limited number of impact categories which may then be weighted for importance.
The results are discussed in terms of contributions, robustness, data quality, and limitations, and the opportunities to reduce the impact of the product(s) or service(s) on the environment are systematically evaluated.
Life Cycle Assessment Terminology
Description of the activities within the product’s life cycle phases that are included and excluded from consideration.
The entirety of all activities within the system boundary that provides the functional unit.
Reference unit for scaling the product system based on the function provided; all further assessments are carried out based on this unit. Examples include 100 pairs of hands dried (e.g., for paper towels and electric hand dryers), 1 liter of coffee brewed (e.g., for coffee machines), 1,000 pages printed (e.g., for office printers), or 1 ton-kilometer (e.g., for freight transport).
Amount of product needed to provide the functional unit, expressed in mass or energy. For LCAs that assesses intermediate products or raw materials without a specified end use, the reference flow may double as the functional unit (e.g., 1 ton of metal A or chemical B).
Life Cycle Inventory Analysis (LCI)
Assembly and quantification of inputs (resource and energy flows) and outputs (emissions and other releases) into and out of the product system that cross the system boundary.
Life Cycle Impact Assessment (LCIA)
Evaluation of potential environmental impacts based on LCI analysis results using a comprehensive selection of impact categories.
Discussing and evaluating the findings of the LCI and LCIA results to arrive at a conclusion and to identify existing improvement potentials.
Documenting the LCA study in a comprehensive and transparent manner in accordance with ISO 14044 requirements.
Conformity assessment by one or more independent expert(s) to confirm adherence to the requirements of ISO 14044 which greatly increases the credibility of the study.
- Climate change (a.k.a. global warming, 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.
- Eutrophication (a.k.a. overfertilization) – Eutrophication covers all potential impacts of excessively high levels of macronutrients, the most important of which nitrogen (N) and phosphorus (P). Nutrient enrichment can cause an undesirable shift in species composition and elevated biomass production in both aquatic and terrestrial ecosystems (e.g., potentially toxic algal blooms). In aquatic ecosystems increased biomass production may lead to depressed oxygen levels, because of the additional consumption of oxygen in biomass decomposition.
- Acidification – 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.
- Smog formation (a.k.a. photochemical ozone creation) – 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 (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 such as 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.
- Ozone depletion – A measure of air emissions that contribute to the depletion of the stratospheric ozone layer (i.e., 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.
How Is Data Collected for Life Cycle Assessment?
What is the chain of events leading up to a complete LCA study?
The flow chart of the system to be analyzed, provided by the client.
On the basis of the flow chart, a data collection questionnaire is developed for analyzing the material and energy flows of the process cycle.
The client collects data (with external support, if necessary).
A life cycle inventory model is created from the collected data (e.g., using the GaBi Software).
Evaluation and interpretation
The developed model is evaluated regarding its potential environmental impacts.
Critical review (optional)
A critical review confirms ISO conformity and increases the reliability and credibility of the study.
What are the requisites for data quality?
- Correct units and their reference values (base year, production units etc.)
- Reference to a single, well-defined functional unit
- Adequate precision and accuracy
- Completeness in terms of relevant material and energy flows as well as processes
What are the options for collecting data?
- Data collection based on a “black box“ process for multiple process steps at once
- Data collection for each individual process step separately
- Anything in-between these two