Life cycle thinking

Life cycle impact assessment

After the inventory analysis comes the third phase of the LCA, the Life Cycle Impact Assessment (LCIA). Here, inventory data are linked to environmental impacts. This phase aims at understanding and evaluating the environmental impacts of a product system. 

LCIA includes three important steps on the way to obtaining the results (ISO, 2006):

• The selection of impact categories, category indicators and characterisation models,

• Classification: assigning inventory results to relevant impact categories. 

• Conversion of LCI results into common units, e.g., the characterisation factor 'Global Warming Potential' (GWP, kg of CO2-eq to air) is used in the impact category for climate change. This approach simplifies the evaluation of a environmental impacts across different substances and categories (Hauschild et al., 2013).

Additionally, additional steps may be needed to prepare the results, such as normalisation and weighting (depending on the goal).

Impact categories

In Life Cycle Impact Assessment (LCIA), we look at various impact categories which are aspects of the environment and human health affected by a product's life cycle. Special models calculate indicators that represent the environmental or health stress for each unit of emission or resource use within each category. This allows us to compare different emissions, resource use, and product options across these indicators. The results can be expressed as midpoint indicators which report a common environmental impact for all contributing substances. This is how we can use a single measure of CO2-equivalents to represent climate change and not require the GWP of each individual substance for example. Further data processing can aggregate the output into endpoint indicators, which include natural resources, ecosystem quality, and human health (Hauschild et al., 2013).

Midpoint indicators

Midpoint indicators help us focus on singular environmental issues, providing a detailed view of the problems arising at intermediate stages in the cause-effect chain. By honing in on these midpoint impacts, LCIA allows for a deeper understanding of how certain emissions or resource consumption contribute to environmental challenges, Some common impact categories include the following:

Endpoint indicators

Endpoint indicators mark the final part of the cause-and-effect sequence and consolidate environmental effects into broader 'areas of protection' (EC, 2010; Finnveden et al., 2009). Areas of protection represent key environmental aspects that society aims to protect or sustain (Hauschild et al., 2013; Bruijn et al., 2002). The main areas of protection typically include:

These areas of protection are used to organise and categorise the various environmental impacts identified during LCIA. They help decision-makers and stakeholders understand the significance of these impacts and make informed choices to minimise or mitigate them. The selection of specific indicators may vary depending on the goals and scope of the LCA study. 

Impact assessment methods

LCIA methods evaluate the impact of either emissions, resource use, or a combination of both. Emission-based models include the Intergovernmental Panel on Climate Change (IPCC), resource-based methods like Cumulative Exergy Extraction from the Natural Environment (CEENE), or a hybrid approach such as ReCiPe and Environmental Footprint Method (Dewulf et al., 2007; Huijbregts et al. 2017; IPCC, 2019). Furthermore, the European Commission has encouraged the use of standardised methods for assessing and communicating environmental performance, leading to the development of unified approaches for evaluating products and organisations (Pelletier et al., 2014).

PEF methodology and environmental impact categories: The Product Environmental Footprint (PEF) methodology ensures that essential environmental impact categories and life cycle activities relevant to specific product categories are considered comprehensively (European Commission, 2022).

OEF methodology and holistic assessment: The Organisation's Environmental Footprint (OEF) methodology extends its scope to encompass organisational activities in their entirety, including supply chain operations. These methodologies are structured with general requirements and principles, partly derived from ISO standards and the ILCD Handbook, with the primary goal of standardising environmental assessments for products. This standardisation aims to facilitate easier comparisons of study results related to the same products or sectors (European Commission, 2022).