The Four Phases of LCA

The LCA framework consists of four interconnected phases defined by ISO 14040. Understanding these phases is essential before conducting any LCA study.

Overview of the Four Phases

┌─────────────────────────────────────────────────────────────┐
│                                                             │
│  1. Goal & Scope    ◄────────────────────────────────────┐ │
│         │                                                │ │
│         ▼                                                │ │
│  2. Inventory Analysis (LCI)                             │ │
│         │                                    ITERATION   │ │
│         ▼                                                │ │
│  3. Impact Assessment (LCIA)                             │ │
│         │                                                │ │
│         ▼                                                │ │
│  4. Interpretation  ─────────────────────────────────────┘ │
│                                                             │
└─────────────────────────────────────────────────────────────┘

Note the iterative nature: findings in later phases often require revisiting earlier decisions.

Phase 1: Goal and Scope Definition

The foundation of any LCA study. This phase determines what you're studying and why.

Key Elements

Goal Definition:

• Intended application (decision support, marketing, policy)
• Reasons for carrying out the study
• Intended audience
• Comparative assertions (if applicable)

Scope Definition:

• Functional unit - What you're comparing (e.g., "delivering 1,000 liters of beverage")
• System boundaries - What's included and excluded
• Reference flow - Physical quantity needed to fulfill the functional unit
• Data quality requirements
• Allocation procedures
• Impact categories

System Boundary Examples

Phase 2: Life Cycle Inventory (LCI)

The data collection phase. This is typically the most time-consuming part of an LCA.

What LCI Involves

1. Flow diagram creation - Map all processes in the system
2. Data collection - Gather input/output data for each process
3. Data validation - Check data quality and consistency
4. Relating data to functional unit - Scale all flows appropriately

Types of Flows

Inputs:

• Raw materials
• Energy (electricity, fuels)
• Water
• Intermediate products

Outputs:

• Products and co-products
• Emissions to air
• Emissions to water
• Emissions to soil
• Solid waste

Handling Multi-functionality

When processes produce multiple products, you need allocation:

• Physical allocation - Based on mass, energy, or other physical properties
• Economic allocation - Based on market value
• System expansion - Avoiding allocation by expanding system boundaries
• Cut-off - Attributing burdens to the main product

Phase 3: Life Cycle Impact Assessment (LCIA)

Translating inventory data into environmental impacts.

Mandatory Elements

1. Selection of impact categories, indicators, and models
2. Classification - Assigning inventory results to impact categories
3. Characterization - Calculating category indicator results

Common Impact Categories

Optional Elements

• Normalization - Comparing to a reference (e.g., per capita impacts)
• Grouping - Sorting categories by characteristics
• Weighting - Assigning relative importance (subjective!)

Phase 4: Interpretation

Making sense of results and drawing conclusions.

Key Steps

1. Identification of significant issues
2. Evaluation through sensitivity and uncertainty analysis
3. Conclusions and recommendations

Analysis Techniques

Contribution Analysis:

• Which life cycle stages contribute most?
• Which processes are most significant?
• Which emissions dominate each impact category?

Sensitivity Analysis:

• How do results change with different assumptions?
• Which parameters most influence outcomes?

Uncertainty Analysis:

• What's the confidence in results?
• Are differences between alternatives statistically significant?

Iterative Nature

LCA is rarely linear. You'll often:

• Refine scope after preliminary results
• Collect more data for significant processes
• Adjust boundaries based on findings
• Update models as better data becomes available

Summary

The four phases of LCA provide a structured approach to environmental assessment:

1. Goal & Scope - Define what and why
2. LCI - Collect input/output data
3. LCIA - Calculate environmental impacts
4. Interpretation - Draw meaningful conclusions

Each phase builds on the previous, and the iterative process ensures robust, reliable results.

In the next lesson, we'll dive deeper into defining functional units and system boundaries.