What is Life Cycle Thinking (LCT)?
Life Cycle Thinking (LCT) is a way of analyzing complex problems to develop long-term solutions that minimize unintended consequences and avoidable mistakes. Recognizing that many of the grand challenges of today require a systems thinking-based approach to identify sustainable solutions, LCT incorporates the holistic evaluation of environmental, economic, and social impacts along the life cycle of a product or system.
To be successful, manufacturers could use Life Cycle Assessment to explore what kinds of materials to use to create the least impacts. With Life Cycle Costing, manufacturers would consider costs from manufacturing, and also operations, maintenance, and socialized costs of carbon over the life span of the product. Adopting a Systems Thinking approach could prevent unintended negative effects within other social or environmental sectors.
Why is it important?
To live within our planetary boundaries, we need to use our resources wisely and recognize where “hotspots” place unnecessary stress on our supply chains and new product (or building) development. Being able to quantify impacts across the life cycle of a product— including into the future and end-of-life—creates a much clearer picture for product development, sustainable investment, impact rating schemes, supply-chain management, and corporate reporting.
Glossary of Key Terms
Refer to this website (https://www.lifecycleinitiative.org/resources/life-cycle-terminology-2/) for a detailed list of definitions relevant to Life Cycle Assessment.
Fundamental Terms
Term |
Definition |
| Life Cycle | Consecutive and interlinked stages of a product system, from raw material acquisition or generation from natural resources to final disposal |
| Life Cycle Analysis (LCA) | Compilation and evaluation of the inputs, outputs and the potential environmental impacts such as climate change, acidification etc. (Refer to terms in Environmental Impact Categories) of a product system throughout its life cycle |
| Life Cycle Costing | Compilation and assessment of all costs related to a product, over its entire life cycle, from production to use, maintenance and disposal. |
| Life Cycle Impact Assessment (LCIA) | Phase of life cycle assessment aimed at understanding and evaluating the magnitude and significance of the potential environmental impacts for a product system throughout the life cycle of the product. LCIA translates emissions and resource extractions into a limited number of environmental impact scores by means of so-called characterization factors. |
| LCIA Methodologies | Methodologies for life cycle impact assessment as developed by different research teams and agencies worldwide. Methodologies differ for example in the amount and type of environmental impact categories. Commonly used methodologies include ReCiPe, CML, TRACI. All methodologies and their specifications are summarized in International Reference Life Cycle Data System (ILCD) handbooks. |
| Life Cycle Inventories | The phase of life cycle assessment where data are collected, the systems are modeled, and the life cycle inventory results are obtained |
| Life Cycle Inventories Analysis (LCI) | Phase of life cycle assessment involving the compilation and quantification of inputs and outputs for a product throughout its life cycle |
| Life Cycle Inventories Analysis Result | Outcome of a life cycle inventory analysis that catalogs the flows crossing the system boundary and provides the starting point for life cycle impact assessment |
Environmental Impact Categories
Term |
Definition |
| Environmental Impact Categories | Environmental issues (including resource depletion, emissions to air, water and soil and impacts on health) to which life cycle inventory analysis results may be assigned. |
| Acidification | Acidification is the increasing concentration of hydrogen ions (from atmospheric deposition of inorganic substances such as sulphates and nitrates) within an environment. Excess acidity in soils for example can lead to toxicological effects for flora and fauna. |
| Climate Change | This impact category measures the impact of increased greenhouse gases contributing to changes in global climate patterns |
| Ecotoxicity | Toxicological effects on the flora and fauna in the environment caused by release of chemicals |
| Eutrophication | An oversupply of macro-nutrients (phosphorous and nitrogen) to bodies of water, generally as a result of human activities (e.g. nitrogen-based fertilizers entering the waterways) which accelerate biological productivity and an undesirable accumulation of algal biomass and reduction of the oxygen content in water bodies. |
| Fine Particulate Matter | Particles of micrometer size of complex chemical composition. They can either be released/ dispersed into the air naturally (silt, volcanoes) or through human activities (mainly combustion). Particles can also form from gases including sulfur dioxide, ammonia, nitrogen oxides, and others inside the atmosphere and form an optimal surface for toxic substances to attach (adsorb). Due to their small size, particles can be inhaled and causes health problems such as respiratory distress and mortality |
| Human Toxicity | The environmental persistence and accumulation of a chemical in the human food chain, and its associated toxicity (effect) on humans |
| Land Use | Damage to ecosystems due to the effects of land transformation, occupation and relaxation |
| Ozone Depletion | Destruction of the stratospheric ozone layer by anthropogenic emissions of ozone depleting substances. Stratospheric ozone is vital for life because it reduces exposure to harmful ultraviolet radiation. |
| Photochemical Ozone Formation | Sunlight-induced chemical reactions in the atmosphere involving Nitrogen Oxides (NOx) and non-methane volatile organic compounds (NMVOCs), leading to the formation of ozone. Ozone is a health hazard to humans. |
| Resource Depletion | Includes water depletion, mineral depletion (metals and minerals extracted from mines), and fossil fuel depletion (coal, oil, natural gas). Each impact assessment methodology categorizes these resources differently. |
Terms used in Assessments/Analysis
Terms |
Definition |
| Attributional LCA | Attributional LCA describes the analysis of a single system life cycle and its subsystems. |
| Category Indicators/Impact Category Indicators | Quantifiable representation of an impact category |
| Characterization Factor | A factor which is applied to convert an LCI result to the common reference unit of the category indicator. e.g. 1 kg of methane emitted is classified under the global warming potential impact category which uses the reference unit of kg CO2eq. All emissions are converted to kg CO2eq using a characterization factor; for methane, this factor is 1 kg of methane = 25 kg CO2eq |
| Circular Economy | An economic model that involves ongoing reuse of resources through continuous recovering and regeneration |
| Consequential LCA | Consequential LCA describes how environmentally relevant flows will change in response to changes in the functional unit |
| Cradle-to-gate | The product life cycle that begins with material extraction from the earth (the cradle) and includes processing and manufacturing until the product is ready to leave the factory gate |
| Cradle-to-grave | A product life cycle that includes environmental impacts beyond the factory gate, including impacts caused during the use of the product and end of the life (disposal, reuse, recycling) |
| Cut-off Criteria | Specification of the amount of material or energy flow or the level of environmental significance associated with unit processes or product system to be excluded from a study |
| Elementary Flow | Material or energy entering the system being studied that has been drawn from the environment without previous human transformation, or material or energy leaving the system being studied that is released into the environment without subsequent human transformation |
| Environmental Hotspot | Process in life cycle of a product that causes a significant portion of the product’s (environmental or social) impacts |
| Functional Unit | Quantified performance of a product system for use as a reference unit |
| Gate-to-gate | Partial LCA scope looking at only one value-added process in the entire production chain |
| International Reference Life Cycle Data System (ILCD) | International Reference Life Cycle Data System summarizing and recommending LCIA Methodologies and Frameworks used by LCA practitioners |
| ISO 14040 Standard | Standards which describe the principles and framework for LCA |
| Intermediate Flow | Product, material or energy flow occurring between unit processes of the product system being studied |
| Normalization | This is an optional calculation of the magnitude of category indicator results relative to reference information. The purpose of normalization is for easy comparison of all impact categories as they no longer have different physical units |
| Process | Set of interrelated or interacting activities that transforms inputs into outputs |
| Production System | Collection of unit processes with elementary and product flows, performing one or more defined functions, and which models the life cycle of a product |
| Reference flow | Measure of the outputs from processes in a given product system required to fulfil the function expressed by the functional unit |
| System Boundary | Set of criteria specifying the scope of a LCA; which unit processes are part of a product system |
| Unit Process | Smallest element considered in the life cycle inventory analysis for which input and output data are quantified |
| Weighting | Converting (& aggregating) indicator results across impact categories using numerical factors based on value-choices |