Life Cycle Assessment: A Complete Methodology Guide

What is LCA?

Life Cycle Assessment (LCA) is a systematic methodology for evaluating the environmental impacts of a product, process, or service throughout its entire lifecycle — from raw material extraction ("cradle") to end-of-life disposal ("grave").

The Four Phases

Phase 1: Goal & Scope Definition

• Define the purpose and intended audience
• Establish the functional unit (e.g., "1 kg of packaged yogurt delivered to consumer")
• Set system boundaries (cradle-to-gate, cradle-to-grave, cradle-to-cradle)
• Define allocation procedures for multi-output processes

Phase 2: Life Cycle Inventory (LCI)

• Collect data on all inputs (materials, energy) and outputs (emissions, waste)
• Sources: Primary data (measurements), secondary data (databases like ecoinvent)
• Address data quality requirements

Phase 3: Life Cycle Impact Assessment (LCIA)

• Classification: Assign LCI results to impact categories
• Characterization: Calculate category indicator results (e.g., kg CO₂ eq for GWP)
• Optional: Normalization, grouping, weighting

Phase 4: Interpretation

• Identify significant issues
• Evaluate completeness, sensitivity, and consistency
• Formulate conclusions and recommendations

Key Impact Categories

Best Practices

1. Always follow ISO 14040/14044
2. Use recognized databases
3. Document all assumptions
4. Conduct sensitivity analysis
5. Have critical review for public claims