Running Impact Assessment and Exporting Results

With your product system built, you're ready to calculate and analyze environmental impacts. This lesson covers openLCA's calculation capabilities, from quick results to detailed contribution analysis and Monte Carlo simulations.

Calculation Types in openLCA

openLCA offers several calculation modes, each suited to different needs:

Running a Quick Result

For a fast overview of impacts:

1. Open your product system
2. Click Calculate in the toolbar
3. Select Quick result
4. Choose your LCIA method (e.g., ReCiPe 2016 Midpoint (H))
5. Click Finish

The results window shows total impacts per category. This is useful for quick validation but doesn't show where impacts come from.

Running a Full Analysis

For contribution breakdown and hotspot identification:

1. Open your product system
2. Click Calculate → Analysis
3. Select your LCIA method
4. Click Finish

This calculation traces impacts through the entire supply chain, enabling detailed analysis.

Impact Analysis Tab

The main results table shows:

• Impact category (e.g., Global Warming Potential)
• Total value
• Unit (e.g., kg CO₂ eq)

Click any category to see process contributions.

Process Contribution View

After clicking a category:

1. A bar chart shows top contributing processes
2. Sort by contribution percentage
3. Expand processes to see their inputs' contributions

Example finding: "Electricity production (coal) contributes 45% of GWP, followed by ceramic firing (28%)."

Upstream and Downstream Analysis

openLCA can trace impacts in both directions:

Upstream analysis: What processes in the supply chain contribute to this process's impacts?

Downstream analysis: Where does this process's output ultimately go?

Access these via right-click on any process in results.

Understanding the Contribution Tree

The contribution tree provides hierarchical impact breakdown:

1. In results, go to the Contribution tree tab
2. The root node shows total impact
3. Expand nodes to see contributions from linked processes
4. Continue expanding to trace impacts to their source

This reveals the supply chain structure and where interventions would be most effective.

Creating Sankey Diagrams

Sankey diagrams visualize material and impact flows:

1. In results, go to the Sankey diagram tab
2. Select an impact category
3. Set a cut-off percentage (e.g., show flows contributing >1%)
4. The diagram shows flows sized by contribution

Interpreting Sankey Diagrams

• Wider bands indicate larger contributions
• Colors typically indicate flow direction or type
• Node size reflects process importance

Export these diagrams for reports:

1. Right-click the diagram
2. Select Export as image
3. Choose format (PNG, SVG)

Comparing Multiple Systems

To compare alternatives (e.g., ceramic mug vs. paper cups):

Method 1: Project Comparison

1. Create a Project (right-click → New project)
2. Add your product systems as variants
3. Set equivalent functional units for each
4. Calculate the project
5. View side-by-side results

Method 2: Manual Comparison

1. Calculate each system separately
2. Export results to Excel
3. Create comparison charts externally

Project comparison is more convenient but has fewer visualization options.

Running Monte Carlo Simulation

Monte Carlo simulation quantifies how uncertainty in inputs affects results:

Setup Requirements

Before running Monte Carlo:

1. Add uncertainty distributions to key inputs
2. Define distributions for parameters
3. Ensure your model has uncertainty data

Running the Simulation

1. Open your product system
2. Click Calculate → Monte Carlo simulation
3. Select LCIA method
4. Set number of iterations (1,000-10,000 typical)
5. Click Finish

Note: This can take hours for complex systems with many iterations.

Interpreting Monte Carlo Results

Results show distributions rather than single values:

• Mean: Average result across simulations
• Standard deviation: Spread of results
• Confidence intervals: e.g., 95% of results fall between X and Y
• Histograms: Visual distribution shape

Sensitivity Analysis

Test how results change when you vary assumptions:

Parameter Variation

1. Create parameters for key inputs (e.g., electricity_use, transport_distance)
2. Calculate a baseline
3. Modify parameters and recalculate
4. Compare results

Scenario Analysis

Create multiple scenarios:

1. In your process, use Parameters for key values
2. Define scenarios with different parameter sets:
   • Scenario A: Average transport distance
   • Scenario B: Maximum transport distance
   • Scenario C: Minimum transport distance
3. Calculate each and compare

Documenting Sensitivity

Create a table showing:

This identifies which inputs most influence results.

Exporting Results

Excel Export

The most common export for further analysis:

1. With results open, go to File → Export
2. Select Excel
3. Choose what to include:
   • Impact results
   • Inventory results
   • Contributions
4. Click Export

The Excel file contains multiple sheets with structured data.

HTML Report

For standalone reports:

1. Go to File → Export → HTML report
2. Select report options
3. Export generates a self-contained HTML file

This can be shared with stakeholders who don't have openLCA.

JSON-LD Export

For data exchange with other systems:

1. Right-click your product system
2. Select Export → JSON-LD
3. Choose included elements

JSON-LD files can be imported into other openLCA instances or compatible tools.

Image Exports

Export visualizations for presentations:

1. Right-click diagrams (Sankey, model graph)
2. Select Export as image
3. Choose format and resolution

Creating Professional Reports

Essential Report Elements

A complete LCA report includes:

1. Executive summary with key findings
2. Goal and scope documentation
3. System description with model graph
4. Impact results by category
5. Hotspot analysis with contribution charts
6. Sensitivity analysis results
7. Interpretation and recommendations
8. Limitations and assumptions

Using openLCA Reports

openLCA has built-in reporting:

1. Create a Report (right-click → New report)
2. Link your project/product system
3. Select report sections
4. Add commentary and interpretation
5. Export as HTML or PDF

External Reporting

For more control, export data and create reports in:

• Microsoft Word/PowerPoint
• LaTeX for academic papers
• Business intelligence tools
• Custom visualization libraries

Troubleshooting Calculation Issues

No Results

• Verify LCIA method is properly imported
• Check that elementary flows map to characterization factors
• Ensure product system is fully linked

Unexpected Values

• Check unit consistency (kg vs. ton, kWh vs. MJ)
• Verify allocation settings
• Look for circular references

Slow Calculations

• Reduce Monte Carlo iterations for testing
• Use cut-offs to simplify complex systems
• Ensure adequate memory allocation

Key Takeaways

1. Quick results validate models; full analysis reveals hotspots
2. Monte Carlo quantifies uncertainty—don't rely on point estimates alone
3. Sensitivity analysis identifies which inputs matter most
4. Export to Excel for flexible post-processing
5. Document your methods and assumptions for reproducibility

Practice Exercise

Using your coffee mug model:

1. Run a full analysis and identify the top three GWP contributors
2. Add uncertainty distributions to three key inputs
3. Run Monte Carlo (500 iterations) and compare mean vs. median
4. Export results and create a one-page summary showing:
   • Total GWP with confidence interval
   • Top contributors as a pie chart
   • One key recommendation for reducing impacts

What's Next?

You now have core openLCA skills for building and analyzing LCA models. The final lesson in this track provides a comprehensive resource list of LCA software providers and database sources to expand your toolkit.

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Resources

• openLCA Results Interpretation Guide
• Monte Carlo in LCA