City Energy Analyst (CEA)

GUIDEBOOK · CEA-4 APP TRAINING

Import & Export

Import & Export

This category contains features for exchanging data between CEA and external applications, as well as generating summary reports.

Export to Rhino/Grasshopper

Overview

Exports CEA files into Rhino/Grasshopper-ready format, allowing you to visualise and further process CEA geometry and results in Rhinoceros 3D and Grasshopper.

When to Use

  • Visualising building geometry in 3D
  • Further geometric analysis in Rhino/Grasshopper
  • Integrating CEA workflows with architectural design tools
  • Using cea4gh (CEA for Grasshopper) plugin

Required Inputs

  • Zone geometry: Building footprints with geometry data

Key Parameters

  • Include zone: Export zone building geometries. Keep this on — it also carries the typology information and the shapefile the others are geo-referenced against.
  • Include site: Export the polygon drawn in the Create Scenario wizard, if any
  • Include surroundings: Export surrounding building geometries
  • Include streets: Export street network
  • Include trees: Export tree geometries
  • Network name: Choose an existing network layout to export. Leave it empty to skip networks entirely. Both the district heating and district cooling networks are exported if they exist for the layout you pick — there is no separate DH/DC switch.

How to Use

  1. Open the CEA-4 App and navigate to Import & Export
  2. Select Export to Rhino/Grasshopper
  3. Configure which elements to export:
    • Select zone buildings (typically always enabled)
    • Optionally include site, surroundings, streets, trees
    • Pick a network layout if you want the thermal networks exported, or leave it empty
  4. Click Run
  5. Find exported files at: 
    {CEA Project}/{Current Scenario}/export/rhino/from_cea/

Output Files

The feature exports CSV files containing geometric coordinates:

  • zone.csv - Main zone building geometries
  • site.csv - Site boundary (if exists)
  • surroundings.csv - Surrounding buildings (if exists)
  • streets.csv - Street network (if exists)
  • trees.csv - Tree geometries (if exists)
  • DH_edges.csv / DH_nodes.csv - District heating network (if exists)
  • DC_edges.csv / DC_nodes.csv - District cooling network (if exists)

All coordinates are standardised to a projected coordinate system for use in Rhino/Grasshopper.

Next Steps

After exporting:

  1. Download cea4gh (CEA for Grasshopper) from https://www.cityenergyanalyst.com/cea4gh
  2. Use the cea4gh Grasshopper components to import the exported CSV files into Rhino
  3. Visualise and analyse your urban energy model in 3D

Tips

  • Export all available geometry layers for complete visualisation
  • The coordinate system is automatically reprojected for optimal use in Rhino
  • Use this feature to create presentation materials and 3D visualisations

Troubleshooting

Issue: Export folder is empty

  • Solution: Ensure you have valid zone geometry in your scenario

Issue: Missing network files

  • Solution: Run Thermal Network Part 1 (layout) before exporting networks

Import from Rhino/Grasshopper

Overview

Imports Rhino/Grasshopper-generated files back into CEA, allowing you to use external design tools to create or modify building geometry before CEA analysis.

When to Use

  • Creating new building geometries in Rhino/Grasshopper
  • Modifying existing geometries with architectural design tools
  • Preparing complex urban morphologies
  • Integrating architectural design workflows with CEA analysis

Prerequisites

  • cea4gh installed and configured
  • Scenario created using cea4gh in Grasshopper
  • Current CEA scenario matches the cea4gh-generated scenario

How to Use

  1. In Rhino/Grasshopper:

  2. In CEA-4 App:

    • Ensure the current scenario is the one generated by cea4gh
    • Navigate to Import & Export
    • Select Import from Rhino/Grasshopper
    • Set the parameters below
    • Click Run

Key Parameters

A scenario arriving from Grasshopper has geometry but none of the supporting data. Rather than make you rebuild it, the import can copy that across from a scenario you already have.

  • Reference scenario name: the scenario you originally exported with Export to Rhino/Grasshopper. The three options below copy from it. The current scenario is not offered.
  • Copy database: bring the reference scenario’s database across. This also runs the Archetypes Mapper, so the imported buildings come back with their envelope, HVAC, comfort, loads and supply populated.
  • Copy terrain: bring the terrain file across. Use this only when every building in the new scenario — surroundings included — falls inside the reference scenario’s terrain.
  • Copy weather: bring the weather file across.

What Gets Imported

The feature imports:

  • Building footprint geometries
  • Building heights
  • Building properties (if assigned in Grasshopper)
  • Site boundaries
  • Surroundings (context buildings)

Next Steps

After importing:

  1. Verify imported geometry using the 3D viewer in CEA-4 App
  2. Use Archetypes Mapper to assign building properties if not already set
  3. Continue with standard CEA workflow (Solar Radiation → Demand → Analysis)

Tips

  • Always use cea4gh to ensure CEA-compatible geometry
  • Verify that building footprints are valid polygons (no self-intersections)
  • Ensure buildings have positive heights
  • Name buildings systematically (e.g., B001, B002, etc.)

Troubleshooting

Issue: Import fails with geometry errors

  • Solution: Verify geometry validity in Grasshopper using cea4gh validation components

Issue: “Scenario mismatch” error

  • Solution: Ensure the active CEA scenario matches the one created by cea4gh

Issue: Missing building properties

  • Solution: Assign properties in Grasshopper, or use Archetypes Mapper after import

Export Results to CSV (Summary and Analytics)

Overview

Generates CSV files containing aggregated CEA results for custom analysis, reporting, and data exchange. This feature provides flexible data export by building, time period, and metric.

When to Use

  • Creating custom reports and dashboards
  • Performing statistical analysis in Excel, Python, or R
  • Comparing scenarios side-by-side
  • Generating data for publications and presentations
  • Integrating CEA results with other software tools

Required Inputs

  • Zone geometry: Building footprints
  • Analysis results: At least one completed CEA analysis (e.g., demand, solar, emissions)

Key Parameters

  • Building filter: Select specific buildings or all buildings
  • Time aggregation: Hourly, daily, monthly, or yearly summaries
  • Metrics: Choose which results to export (demand, emissions, costs, solar, etc.)

How to Use

  1. Complete at least one CEA analysis (e.g., Energy Demand, Emissions, PV assessment)
  2. Navigate to Import & Export
  3. Select Export Results to CSV (Summary & Analytics)
  4. Configure export options:
    • Select buildings to include (or use “All buildings”)
    • Choose time aggregation level (hourly/daily/monthly/yearly)
    • Select metrics to export
  5. Click Run
  6. Find exported CSV files in: 
    {CEA Project}/{Current Scenario}/outputs/data/exports/

Output Structure

The feature generates structured CSV files with:

  • Building-level aggregations
  • Time-series data (if selected)
  • Summary statistics
  • Customised metric columns based on selection

Example output columns:

  • Name - Building identifier
  • GFA_m2 - Gross floor area
  • Qhs_MWhyr - Annual space heating demand
  • Qcs_MWhyr - Annual space cooling demand
  • E_MWhyr - Annual electricity demand
  • Additional columns based on available results

Use Cases

Scenario Comparison

  1. Export results for Scenario A
  2. Export results for Scenario B
  3. Compare CSV files in Excel or Python

Custom Reporting

  1. Export all metrics for selected buildings
  2. Import into Excel/PowerBI
  3. Create custom charts and pivot tables

Statistical Analysis

  1. Export hourly time-series data
  2. Analyse in Python/R
  3. Perform statistical tests and regressions

Tips

  • Export yearly summaries for high-level comparisons
  • Export hourly data for detailed temporal analysis
  • Use building filters to focus on specific building types
  • Combine with Excel pivot tables for flexible reporting

Troubleshooting

Issue: Empty export files

  • Solution: Ensure you have completed at least one CEA analysis before exporting

Issue: Missing metrics in export

  • Solution: Some metrics only appear after specific analyses (e.g., PV data requires PV analysis)

Issue: Too large file for hourly data

  • Solution: Use daily or monthly aggregation, or filter to fewer buildings

Common Workflows

Workflow 1: CEA to Rhino Visualisation

  1. Complete CEA analysis (demand, solar, emissions)
  2. Export to Rhino/Grasshopper with all layers
  3. Open exported files in Rhino using cea4gh
  4. Create 3D visualisations and renderings

Workflow 2: Rhino to CEA Analysis

  1. Design building geometry in Rhino/Grasshopper
  2. Use cea4gh to export CEA-compatible scenario
  3. Import from Rhino/Grasshopper in CEA-4 App
  4. Run standard CEA analysis workflow

Workflow 3: Results Export for Custom Analysis

  1. Complete CEA analyses
  2. Export Results to CSV with desired metrics
  3. Perform custom analysis in Excel, Python, or R
  4. Create custom reports and visualisations

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