LCA Terminology & Glossary: Complete Guide to Life Cycle Assessment Terms

Core LCA Concepts

Life Cycle Assessment (LCA)

A systematic, standardized methodology governed by ISO 14040 and ISO 14044 standards for quantifying the environmental impacts of a product, process, or service across its complete life cycle from raw material extraction through manufacturing, distribution, use, and end-of-life disposal.

LCA evaluates multiple impact categories including climate change, water depletion, acidification, eutrophication, human toxicity, resource depletion, and ecosystem damage. The methodology consists of four mandatory phases:

Goal and Scope Definition: Establishing study objectives, functional units, and system boundaries
Life Cycle Inventory (LCI): Compiling all inputs and outputs across the product system
Life Cycle Impact Assessment (LCIA): Converting inventory data into environmental impact indicators
Interpretation: Analyzing results to identify hotspots and improvement opportunities

Functional Unit

The quantified performance characteristic of a product system used as a reference basis in LCA studies. The functional unit defines what is being studied and provides the reference to which all inputs and outputs are related.

Examples:

"Transport of 1 tonne of goods over 1 kilometer" (logistics)
"Provide 1000 hours of illumination at 800 lumens" (lighting)
"One wear of a t-shirt" (apparel)
"10 years of residential heating in temperate climate" (HVAC systems)

Proper functional unit definition is essential for meaningful comparisons between alternative products. It must be measurable, relevant to the goal of the study, and consistent across comparative assessments.

System Boundary

The definition of which unit processes and life cycle stages are included within an LCA study. System boundaries determine which environmental impacts are captured and must be clearly stated for study transparency.

Common boundary types:

Cradle-to-Gate: Raw materials to factory gate (upstream only)
Cradle-to-Grave: Full life cycle including use and disposal
Gate-to-Gate: Single process or facility
Cradle-to-Cradle: Including recycling and closed-loop material flows

Cut-off criteria determine which minor material flows or processes can be excluded (typically < 1% of mass, energy, or environmental impact).

Life Cycle Inventory (LCI)

The second phase of LCA involving compilation and quantification of all inputs (raw materials, energy, water) and outputs (emissions to air/water/soil, waste, co-products) for all processes within the system boundary.

Data types:

Primary Data: Measured directly from specific operations (site-specific, higher quality)
Secondary Data: From LCI databases like ecoinvent, GaBi, USLCI (average industry data)

LCI databases contain thousands of pre-modeled processes for materials (steel, plastics, glass), energy (electricity grids, fuels), transportation (truck, ship, rail), and waste treatment (landfill, incineration, recycling).

Life Cycle Impact Assessment (LCIA)

The third phase of LCA where inventory data is translated into environmental impact indicators across multiple categories. LCIA methods use characterization factors to convert emissions and resource extractions into impact category indicators.

Common LCIA methods:

ReCiPe 2016: 18 midpoint categories, 3 endpoint categories
TRACI 2.1: US EPA method for North American context
CML-IA: Problem-oriented approach from Leiden University
ILCD 2011: EU-recommended method
Environmental Footprint 3.0: Official EU method for PEF/OEF

Impact categories include Global Warming Potential (kg CO₂-eq), Acidification Potential (kg SO₂-eq), Eutrophication Potential, Water Depletion, and Resource Depletion.

ISO Standards & Compliance

ISO 14040

International standard published by the International Organization for Standardization (ISO) that establishes the principles and framework for Life Cycle Assessment. ISO 14040 defines the four mandatory phases of LCA and requirements for transparency.

Key principles:

LCA must consider the entire life cycle
LCA must be iterative
LCA must be transparent
LCA must be comprehensive (multiple impact categories)
LCA results are relative to the functional unit

Compliance with ISO 14040 ensures methodological rigor and comparability across studies. Required for EPDs, eco-labels, and regulatory submissions.

ISO 14044

International standard that provides detailed technical requirements and guidelines for conducting Life Cycle Assessment studies. ISO 14044 specifies data quality requirements, allocation procedures, system boundary definitions, and critical review procedures.

Technical specifications:

Data quality indicators (temporal, geographical, technological coverage)
Allocation hierarchy and procedures
System expansion for multi-product systems
Critical review requirements for comparative assertions
Reporting format and content requirements

Studies following ISO 14044 can support comparative assertions, eco-label criteria, and Environmental Product Declarations.

ISO 14067

International standard for carbon footprint of products (CFP), providing requirements and guidelines for quantification and communication of greenhouse gas emissions throughout a product's life cycle.

ISO 14067 is based on ISO 14040/14044 but focuses specifically on climate change impact category. It includes:

Requirements for Product Carbon Footprint (PCF) calculation
Rules for communication and offsetting claims
Guidance on partial PCF (cradle-to-gate) vs. full PCF

Impact Categories & Environmental Indicators

Carbon Footprint

The total greenhouse gas emissions caused by a product, organization, event, or person, expressed as carbon dioxide equivalent (CO₂-eq). Carbon footprint is one impact category within comprehensive LCA, focusing specifically on climate change impacts.

Calculation follows GHG Protocol or ISO 14067 standards and includes:

CO₂ (carbon dioxide)
CH₄ (methane) - converted using 25-28x CO₂-eq factor
N₂O (nitrous oxide) - converted using 298x CO₂-eq factor
Fluorinated gases (HFCs, PFCs, SF₆, NF₃)

Global Warming Potential (GWP) factors convert each gas to CO₂-equivalents over 100-year timeframes based on IPCC Assessment Reports.

Global Warming Potential (GWP)

A metric for comparing the climate change impact of different greenhouse gases relative to CO₂. GWP represents the heat absorbed by a gas in the atmosphere over a specific time period (typically 100 years) relative to the heat absorbed by an equivalent mass of CO₂.

Common GWP values (100-year timeframe, IPCC AR5):

CO₂: 1 (reference)
Methane (CH₄): 28
Nitrous oxide (N₂O): 265
HFC-134a: 1,430
SF₆: 23,500

Acidification

Environmental impact category measuring the potential for emissions to cause acidification of soil and water bodies. Primarily caused by sulfur dioxide (SO₂), nitrogen oxides (NOx), and ammonia (NH₃) emissions.

Environmental effects:

Soil pH reduction affecting nutrient availability
Forest decline and crop damage
Freshwater ecosystem stress (fish mortality)
Building material degradation

Measured in kg SO₂-eq (sulfur dioxide equivalents).

Eutrophication

Nutrient enrichment of aquatic and terrestrial ecosystems caused by nitrogen (N) and phosphorus (P) compounds. Leads to excessive algae growth, oxygen depletion, and ecosystem disruption.

Types:

Freshwater Eutrophication: Primarily phosphorus-driven (kg P-eq)
Marine Eutrophication: Primarily nitrogen-driven (kg N-eq)
Terrestrial Eutrophication: Nitrogen deposition on land (mol N-eq)

Sources: Agricultural runoff (fertilizers), wastewater discharge, atmospheric deposition from combustion.

Water Depletion / Water Scarcity

Impact category measuring freshwater consumption and its contribution to regional water stress. Accounts for water withdrawn from surface or groundwater sources and not returned to the same watershed.

Measurement approaches:

Volume-based: m³ of water consumed
Scarcity-weighted: m³ H₂O-eq accounting for regional scarcity factors
AWARE method: Available Water Remaining (m³ world-eq deprived)

Regional characterization factors account for water availability differences between water-abundant and water-scarce regions.

Resource Depletion

Impact category measuring the extraction and consumption of non-renewable resources including fossil fuels (oil, gas, coal) and mineral resources (metals, minerals).

Sub-categories:

Fossil Resource Depletion: kg oil-eq (crude oil equivalents)
Mineral Resource Depletion: kg Cu-eq or kg Sb-eq (copper or antimony equivalents)

Characterization factors based on resource reserves, extraction rates, and future scarcity projections. Reflects the "surplus cost" of future extraction as high-grade deposits are depleted.

Toxicity (Human & Ecotoxicity)

Impact categories measuring potential harm to human health and ecosystems from toxic substance emissions.

Human Toxicity:

Carcinogenic: Cancer-causing effects (kg 1,4-DCB-eq)
Non-carcinogenic: Other health effects (kg 1,4-DCB-eq)

Ecotoxicity:

Freshwater ecotoxicity: Toxic effects on aquatic organisms
Marine ecotoxicity: Impacts on marine life
Terrestrial ecotoxicity: Soil organism impacts

Characterization based on toxicity factors (LC50, LD50), environmental fate, and exposure pathways.

Databases & Methodologies

ecoinvent

The world's leading database for Life Cycle Inventory data, containing over 18,000 datasets covering agriculture, energy, transport, chemicals, construction, waste management, and other industrial processes.

Maintained by the ecoinvent Centre at ETH Zurich, Switzerland. The database provides peer-reviewed, transparent data used by LCA practitioners globally.

Coverage:

Energy systems (electricity, heat, fuels)
Materials (metals, plastics, chemicals, textiles)
Transportation (road, rail, air, ship)
Agriculture and food products
Waste treatment and recycling

Current version: ecoinvent v3.9 (2023)

GaBi Database

Comprehensive LCI database developed by Sphera (formerly PE International) containing over 16,000 datasets with particular strength in industrial processes, automotive, packaging, and energy systems.

Key features:

Industry-specific datasets (automotive, electronics, construction)
Regional coverage (Europe, North America, Asia)
Material production data (steel, aluminum, plastics)
Energy and utilities data

Used alongside GaBi software or accessible through other LCA platforms. Current version: GaBi 2023.

ReCiPe Method

A widely used Life Cycle Impact Assessment methodology developed by RIVM, CML, PRé Consultants, and Radboud University. ReCiPe 2016 harmonizes midpoint and endpoint indicators.

Midpoint Indicators (18 categories):

Climate change, Ozone depletion, Ionizing radiation
Photochemical ozone formation, Particulate matter
Human toxicity (carcinogenic & non-carcinogenic)
Terrestrial, freshwater, marine acidification
Terrestrial, freshwater, marine eutrophication
Terrestrial, freshwater, marine ecotoxicity
Land use, Water consumption
Fossil resource scarcity, Mineral resource scarcity

Endpoint Indicators (3 damage categories):

Human Health: Disability-Adjusted Life Years (DALYs)
Ecosystems: Species·year loss
Resources: USD surplus cost

ReCiPe is the default LCIA method in many LCA software tools including SimaPro and openLCA.

TRACI (Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts)

Life Cycle Impact Assessment methodology developed by the US Environmental Protection Agency (EPA). TRACI 2.1 is tailored for North American environmental context.

Impact categories:

Ozone depletion
Global warming
Smog formation
Acidification
Eutrophication
Human health (carcinogenic & non-carcinogenic)
Ecotoxicity
Fossil fuel depletion

TRACI uses US-specific characterization factors and environmental fate models. Preferred for North American studies and EPA-related applications.

Environmental Standards & Regulations

Environmental Product Declaration (EPD)

A standardized, third-party verified document communicating the environmental performance of products based on LCA data. EPDs follow ISO 14025 and EN 15804 standards and product-specific Product Category Rules (PCRs).

EPD requirements:

LCA Foundation: ISO 14040/14044 compliant LCA
Product Category Rules: Follow PCRs specific to product type
Third-Party Verification: Independent critical review
Registration: Published in EPD program database

EPDs are increasingly required for green building certifications (LEED v4+, BREEAM), public procurement, and corporate supply chain transparency initiatives.

Digital Product Passport (DPP)

A mandatory digital record under the EU's Ecodesign for Sustainable Products Regulation (ESPR) documenting a product's environmental footprint, material composition, repairability, recyclability, and supply chain transparency throughout its lifecycle.

Required information:

Product Carbon Footprint (PCF) - Scope 1-3 emissions
Environmental impacts (water, energy, toxicity)
Material composition and hazardous substances
Recycled content and recyclability
Durability, repairability, and spare parts availability
Supply chain information

Implementation timeline:

First Wave (2026-2027): Textiles, furniture, electronics, tires, detergents, paints
Second Wave (2028-2030): Construction products, plastics, chemicals

LCA provides the quantitative environmental data required for DPP compliance. Companies selling covered products in EU markets must provide DPP-compliant data or face market exclusion.

ESPR (Ecodesign for Sustainable Products Regulation)

EU regulation establishing mandatory ecodesign requirements and Digital Product Passport (DPP) obligations for products sold in the European Union. Replaces and expands the previous Ecodesign Directive.

Key requirements:

Durability and repairability standards
Recycled content minimums
Design for recyclability
Digital Product Passport with environmental data
Restriction on destruction of unsold goods

Applies to almost all physical products except food, medicine, and vehicles (covered by separate regulations). Product-specific requirements being phased in 2024-2030.

GHG Protocol (Greenhouse Gas Protocol)

The most widely used international accounting tool for measuring and managing greenhouse gas emissions. Developed by World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD).

Emission Scopes:

Scope 1: Direct emissions from owned/controlled sources
Scope 2: Indirect emissions from purchased energy
Scope 3: All other indirect emissions in value chain (15 categories)

GHG Protocol provides three standards:

Corporate Standard: Organization-level accounting
Product Standard: Product-level carbon footprint (aligned with ISO 14067)
Scope 3 Standard: Value chain emissions accounting

Scope 3 Emissions

Indirect greenhouse gas emissions that occur in an organization's value chain, both upstream and downstream. The GHG Protocol defines 15 Scope 3 categories.

Upstream Categories (1-8):

Category 1: Purchased goods and services
Category 2: Capital goods
Category 3: Fuel and energy-related activities
Category 4: Upstream transportation and distribution
Category 5: Waste generated in operations
Category 6: Business travel
Category 7: Employee commuting
Category 8: Upstream leased assets

Downstream Categories (9-15):

Category 9: Downstream transportation and distribution
Category 10: Processing of sold products
Category 11: Use of sold products
Category 12: End-of-life treatment of sold products
Category 13: Downstream leased assets
Category 14: Franchises
Category 15: Investments

Scope 3 typically represents 70-90% of total corporate emissions. Product-level LCA comprehensively captures Scope 3 with greater granularity than traditional spend-based estimation.

Allocation & Advanced Concepts

Allocation

The methodological approach for partitioning environmental burdens and benefits among co-products when a process generates multiple outputs. ISO 14044 establishes an allocation hierarchy.

Allocation Hierarchy (ISO 14044):

Avoid allocation: Through subdivision or system expansion
Physical allocation: Based on physical relationships (mass, energy content, volume)
Economic allocation: Based on market value of co-products

Common allocation situations:

Multi-product manufacturing (steel + slag)
Agriculture (grain + straw)
Energy systems (electricity + heat cogeneration)
Recycling (burden sharing between product lifetimes)

Allocation procedures must be documented and justified as they significantly influence LCA results for multi-product systems.

System Expansion

An alternative to allocation where the system boundary is expanded to include additional functions provided by co-products, avoiding the need to partition burdens. Also called substitution or avoided burden approach.

Example: When a waste-to-energy plant produces both waste treatment service and electricity:

Allocation approach: Divide burdens between waste treatment and electricity based on mass or economic value
System expansion: Give credit for displacing grid electricity that would otherwise be produced

Preferred in ISO 14044 hierarchy but requires defining which products are displaced (substituted), which may be ambiguous.

Cradle-to-Grave Analysis

A comprehensive LCA approach evaluating environmental impacts from raw material extraction (cradle) through all manufacturing, transportation, use, and disposal phases until final waste treatment (grave).

Life cycle stages included:

Raw material extraction and processing
Material manufacturing (steel, plastics, etc.)
Component production
Product assembly
Packaging
Distribution and retail
Use phase (energy consumption, maintenance)
End-of-life (collection, recycling, disposal)

This full life cycle perspective reveals impacts across the entire value chain and prevents burden-shifting between stages. Required for DPP compliance and most EPDs.

Cradle-to-Gate Analysis

A partial LCA covering raw material extraction through manufacturing, ending at the factory gate. Excludes distribution, use phase, and end-of-life.

Use cases:

Business-to-business products
Intermediate materials and components
Supply chain transparency and supplier selection
EPDs for construction products (per EN 15804)

Limitations: May underestimate total impacts if use phase and disposal are significant. Not suitable for products with high energy consumption during use (appliances, vehicles).

Uncertainty Analysis

Quantitative assessment of uncertainty in LCA results arising from data variability, methodological choices, and modeling assumptions. Required for robust decision-making and comparative assertions.

Sources of uncertainty:

Parameter uncertainty: Variability in input data (energy use, emissions)
Scenario uncertainty: Alternative modeling choices (allocation, system boundary)
Model uncertainty: Impact assessment characterization factors

Methods:

Sensitivity analysis: Testing how results change with parameter variations
Monte Carlo simulation: Probabilistic analysis of combined uncertainties
Pedigree matrix: Data quality scoring

Uncertainty ranges of ±10-30% are common in LCA results. Comparative studies should ensure differences exceed uncertainty ranges.

Product & Industry Terms

Product Carbon Footprint (PCF)

The total greenhouse gas emissions associated with a specific product throughout its life cycle, expressed in kg CO₂-eq. Subset of full LCA focusing solely on climate change impact category.

PCF follows ISO 14067 and includes emissions from:

Raw material extraction and processing
Manufacturing and assembly
Transportation and distribution
Use phase (if applicable)
End-of-life disposal or recycling

Increasingly required for carbon labels, DPP compliance, and corporate Scope 3 accounting. Can be partial (cradle-to-gate) or full (cradle-to-grave).

Product Category Rules (PCR)

Standardized rules and requirements for conducting LCA and creating Environmental Product Declarations (EPDs) for specific product categories. PCRs ensure consistency and comparability within product types.

PCR specifications include:

Functional unit definition
System boundary requirements
Data quality requirements
Allocation procedures
Impact categories to report
Life cycle stages to include

Examples: PCR for construction products (EN 15804), furniture, electronics, food products, textiles.

Managed by EPD program operators (EPD International, IBU, etc.). Following PCRs enables comparability between competing products.

Circular Economy

An economic model focused on eliminating waste and maximizing resource utilization through design for durability, reuse, repair, refurbishment, remanufacturing, and recycling. Contrasts with linear "take-make-dispose" model.

Circular Economy Strategies (R-Framework):

Refuse: Prevent unnecessary production
Reduce: Increase resource efficiency
Reuse: Use products multiple times
Repair: Extend product lifetime
Refurbish: Restore products to working condition
Remanufacture: Disassemble and rebuild with new/refurbished parts
Repurpose: Use for different application
Recycle: Process materials for new products
Recover: Energy recovery from waste

LCA quantifies environmental benefits of circular strategies. ESPR/DPP regulations aim to accelerate transition to circular economy.

Software & Tools

SimaPro

Leading commercial LCA software developed by PRé Sustainability (Netherlands). Provides graphical user interface for LCA modeling with access to multiple databases and impact assessment methods.

Features:

ecoinvent, GaBi, and other database integration
ReCiPe, CML, ILCD, and other LCIA methods
Process tree visualization
Monte Carlo uncertainty analysis
Parameterized modeling

Used by consultants, academics, and in-house LCA teams. Requires training and LCA expertise. License cost: $2,500-$10,000/year depending on edition.

openLCA

Free, open-source LCA software developed by GreenDelta. Provides professional LCA functionality without license fees, supported by commercial services and database sales.

Features:

Compatible with ecoinvent, GaBi, ELCD databases
Multiple LCIA methods (ReCiPe, TRACI, CML, etc.)
Monte Carlo uncertainty analysis
Data quality assessment
Python API for automation

Popular in academia and organizations with budget constraints. Requires technical expertise and LCA knowledge.

Additional Terms

Sensitivity Analysis

A technique for testing how LCA results change when input parameters or methodological choices are varied. Identifies which factors most influence results and assesses result robustness.

Common sensitivity tests:

Alternative allocation methods
Different data sources or databases
System boundary variations
Impact assessment method selection
Key parameter variations (energy mix, transportation distance, product lifetime)

Primary Data

Site-specific, measured data collected directly from the operations being studied. Contrasts with secondary data (average or generic data from databases).

Examples of primary data:

Actual energy consumption from facility meters
Measured waste quantities
Transportation logs
Supplier-specific material data

Primary data improves accuracy but increases data collection time and cost. Hybrid approaches combine primary data for foreground system with secondary database for background (upstream) processes.

Foreground & Background System

Distinction between processes directly controlled or influenced by decision-maker (foreground) versus general economy processes (background).

Foreground System:

Processes under direct control
Product-specific operations
Typically modeled with primary data
Focus of improvement efforts

Background System:

Upstream supply chain (electricity, materials)
Generic processes (transportation, energy production)
Modeled with database (secondary) data

LCA Terminology & Glossary