City Energy Analyst (CEA)

GUIDEBOOK · CEA-4 APP TRAINING

Visualisation

Visualisation

Visualisation features create charts and plots to present CEA results. These tools generate publication-quality graphics for energy demand, emissions, solar potential, comfort analysis, and optimisation results.

Plot - Building Energy Demand

Overview

Creates bar charts of building energy demand results, showing heating, cooling, electricity, and hot water demand for selected buildings. This is the primary visualisation for energy demand forecasting results.

When to Use

  • After completing Energy Demand Part 2
  • Presenting building energy performance
  • Comparing energy demand across buildings
  • Supporting energy reports and presentations

What It Plots

Energy Services:

  • Space heating (Qhs)
  • Space cooling (Qcs)
  • Electricity (E) - appliances, lighting, auxiliaries
  • Domestic hot water (Qww)

Views Available (via X to plot, Y normalised by and Plot type):

  1. Per building - Totals per building, stacked or grouped by service
  2. Energy intensity - Normalised by gross or conditioned floor area
  3. Faceted - By months, seasons, construction type, or main use type
  4. District time series - Hourly, daily, monthly, seasonal, or annual totals

Prerequisites

  • Energy Demand Part 2 completed
  • Total demand file exists

Key Parameters

ParameterDescriptionOptions
Y metric to plotEnd-use services to showelectricity / space_heating / space_cooling / domestic_hot_water
Y metric unitUnitMWh / kWh (default) / Wh
Y normalised byNormalisationno_normalisation / gross_floor_area (default) / conditioned_floor_area
X to plotX-axis groupingbuilding (default), faceted by months, seasons, construction type, etc.
Plot typeBar chart stylebar_plot_stack (default) / bar_plot_group / bar_plot_stack_percentage
Buildings and building filtersWhich buildings to includeAll, or filter by year, construction type, use type

How to Use

  1. Complete Energy Demand Part 2

  2. Run plot generation:

    • Navigate to Visualisation
    • Select Plot - Building Energy Demand
    • Choose services (Y metric to plot), unit and normalisation
    • Choose the X-axis grouping (start with building)
    • Select buildings (or leave blank for all)
    • Choose plot type (stacked, grouped, or stacked percentage)
    • Click Run

  3. View results:

    • The interactive chart is shown in the app (not saved to the scenario folder)
    • Hover for values; zoom, pan, or download a PNG from the chart toolbar

Chart Interpretation

Annual Demand Bar Chart:

  • Height = total energy (MWh/year)
  • Colours = energy services (heating, cooling, electricity, DHW)
  • Taller bars = higher energy consumers
  • Colour distribution shows energy mix

Energy Intensity:

  • Normalises by floor area (kWh/m²/year)
  • Allows comparison regardless of building size
  • Typical ranges:
    • Low-energy buildings: 50-100 kWh/m²/year total
    • Standard buildings: 100-200 kWh/m²/year
    • Old/inefficient: >200 kWh/m²/year

Time Series:

  • Shows hourly variation over year
  • Identify peak demand periods
  • Assess load diversity
  • Support system sizing

Customisation Options

  • Colours: Customise colour scheme for energy services
  • Sorting: Sort buildings by total demand, name, or type
  • Labels: Show/hide data labels on bars
  • Legend: Position and format
  • Export: Plots are interactive HTML in the app; download a PNG from the chart toolbar. HTML files are only written when you export a canvas archive

Tips

  • Start with annual demand: Best overview of results
  • Use intensity for comparisons: Fairer comparison across building sizes
  • Filter by type: Group similar buildings for clearer insights
  • Time series for validation: Check if patterns make sense

Troubleshooting

Issue: No plots generated

  • Solution: Ensure Energy Demand Part 2 completed successfully
  • Solution: Check Total_demand.csv exists

Issue: Charts show unexpected values

  • Solution: Validate demand calculation results first
  • Solution: Check units (MWh vs kWh)

Plot - Energy by Carrier

See Final Energy > Plot - Energy by Carrier for full documentation.

Bar charts of final energy consumption by carrier (grid, gas, oil, coal, wood) for buildings and plants under a what-if scenario.

Plot - Lifecycle Emissions

See Emissions > Plot - Lifecycle Emissions for full documentation.

Stacked bar charts showing total lifecycle emissions per building (embodied + operational + biogenic + solar offsets). Title includes the lifecycle year range.

Plot - Emission Timeline

See Emissions > Plot - Emission Timeline for full documentation.

Cumulative stacked area chart showing how district emissions evolve from construction through demolition.

Plot - Operational Emissions

See Emissions > Plot - Operational Emissions for full documentation.

Bar charts of operational emissions by service or energy carrier, with solar offset as negative bars.

Plot - System Cost Sankey

See System Costs > Plot - System Cost Sankey for full documentation.

Sankey diagram showing cost flows from components through services to total costs, with annualised or total CAPEX views.

Plot - Anthropogenic Heat Rejection

See Heat Rejection > Plot - Anthropogenic Heat Rejection for full documentation.

Bar charts of waste heat rejected to the environment by buildings and district plants.

Plot - Solar Technology

Overview

Creates bar charts of solar energy technology potential (PV, PVT, solar collectors), showing electricity and heat generation capacity for buildings.

When to Use

  • After running renewable energy assessments
  • Presenting solar potential results
  • Supporting solar investment decisions
  • Comparing solar technologies

What It Plots

Solar Technologies:

  • PV: Electricity generation (MWh/year, kWp capacity)
  • PVT: Electricity + heat generation
  • Solar collectors: Heat generation (MWh/year)

Views:

  1. By surface - Roofs and north/east/south/west walls (Y metric to plot)
  2. Normalised - Per gross floor area or per installed panel area of each surface
  3. Per building or district time series - Via X to plot

Prerequisites

How to Use

  1. Complete solar assessments (PV, PVT, and/or SC)

  2. Generate plots:

    • Navigate to Visualisation
    • Select Plot - Solar Technology
    • Choose surfaces (Y metric to plot), unit and normalisation
    • Choose the X-axis grouping
    • Click Run

  3. Output: The interactive chart is shown in the app (not saved to the scenario folder). See Saving and Sharing Plots.

Chart Interpretation

Annual Generation:

  • Compares total output by technology
  • PV: Electricity only
  • PVT: Electricity + heat (show both)
  • SC: Heat only

Comparison Across Buildings:

  • Identifies buildings with best solar potential
  • Accounts for shading, orientation, available area

Technology Trade-offs:

  • PV: Maximum electricity, no heat
  • PVT: Balanced electricity + heat, lower electrical efficiency
  • SC: Maximum heat, no electricity

Tips

  • Normalise by area: Use kWh/m² for fair comparison
  • Show both capacity and yield: Capacity = size, yield = performance
  • Highlight best performers: Identify buildings for priority installation

Plot - Building Comfort Chart

Overview

Plots comfort and discomfort hours for buildings based on thermal comfort analysis from energy demand calculations. Shows when indoor conditions meet or fail to meet comfort criteria.

When to Use

  • After Energy Demand calculation
  • Assessing indoor environmental quality
  • Evaluating HVAC system performance
  • Supporting comfort-based design decisions

What It Plots

Comfort Metrics:

  • Total comfort hours (hours/year within setpoint ranges)
  • Discomfort hours (hours/year outside ranges)
    • Too hot
    • Too cold
  • By building and by zone (if multi-zone)

Comfort Standards:

  • Based on setpoints in indoor_comfort.csv
  • Typically ASHRAE 55 or EN 15251 criteria
  • Adaptive comfort models (if configured)

Prerequisites

  • Energy Demand Part 2 completed
  • Comfort setpoints defined in indoor_comfort.csv

How to Use

  1. Complete Energy Demand calculation

  2. Generate comfort plots:

    • Navigate to Visualisation
    • Select Plot - Building Comfort Chart
    • Select buildings
    • Click Run

  3. Output: The interactive chart is shown in the app (not saved to the scenario folder). See Saving and Sharing Plots.

Chart Types

Annual Comfort Hours:

  • Stacked bar showing comfort/discomfort split
  • Goal: Minimise discomfort hours

Discomfort Breakdown:

  • Too hot vs too cold
  • Seasonal patterns

Comfort vs Outdoor Temperature:

  • Scatter plots showing indoor-outdoor relationship

Interpretation

Acceptable Discomfort:

  • Category I (best): <10% discomfort (< 876 hours)
  • Category II (standard): 10-20% discomfort (876-1,752 hours)
  • Category III (acceptable): 20-30% discomfort (1,752-2,628 hours)

  • 30% discomfort: Unacceptable

Typical Patterns:

  • Free-running buildings: More discomfort but acceptable
  • Fully conditioned: Minimal discomfort, high energy use
  • Balance: Moderate comfort, moderate energy

Tips

  • Compare comfort vs energy: High comfort often means high energy
  • Seasonal analysis: Identify summer overheating or winter underheating
  • Validate HVAC sizing: Excessive discomfort suggests undersized systems

Plot - Pareto Front

Overview

Plots Pareto frontiers from optimisation results, visualising trade-offs between competing objectives (cost, emissions, energy).

When to Use

What It Plots

Optimisation Objectives:

  • The objective functions selected when the optimisation was run (cost, GHG_emissions, system_energy_demand, anthropogenic_heat)
  • One 2D scatter plot per pair of objectives
  • An additional 3D plot when three objectives were optimised

Points on Chart:

  • Pareto optimal solutions: Non-dominated solutions (on frontier)
  • Dominated solutions: Worse on all objectives (not shown or greyed)
  • Reference solutions: Baseline, current state

Prerequisites

  • District Supply System Optimisation completed

Key Parameters

None besides the scenario. The axes follow the objective functions of the optimisation run.

How to Use

  1. Complete District Supply System Optimisation

  2. Generate Pareto plot:

    • Navigate to Visualisation
    • Select Plot - Pareto Front
    • Click Run

  3. Output: The interactive chart is shown in the app (not saved to the scenario folder). See Saving and Sharing Plots.

Chart Interpretation

Pareto Frontier:

  • Lower-left corner: Best solutions (low cost, low emissions)
  • Horizontal movement: Cost changes with minimal emission change
  • Vertical movement: Emission changes with minimal cost change
  • No solution dominates another on frontier

Key Points on Frontier:

  1. Min cost solution: Cheapest option (often high emissions)
  2. Min emissions solution: Cleanest option (often expensive)
  3. Knee point: Best compromise (balanced cost and emissions)

Decision Making:

  • Choose solution based on priorities (budget, climate goals)
  • Trade-off rate: EUR per ton CO₂ saved
  • Carbon price implications

Customisation

  • Colour by technology: Show which technologies appear in solutions
  • Size by objective: Third objective as marker size
  • Annotate: Label key solutions

Tips

  • Show current state: Add reference point for context
  • Calculate trade-off rate: Cost increase per ton CO₂ reduction
  • Interactive plots: Hover over the plot to see solution details
  • Multiple scenarios: Overlay Pareto fronts to compare

Plot - Pathway Emission Timeline

Cumulative lifecycle emissions for one district pathway, across its state years, broken down by source. The pathway equivalent of Plot - Emission Timeline.

Requires a pathway with simulated states — see District Evolution Pathways.

Plot - Cost Breakdown

Cost breakdown for energy supply systems. Supports both baseline costs and what-if scenario costs, so it can be used before or after a what-if has been defined.

See LCA Part 2b: Costs for the underlying results.

Plot - Energy Flow Sankey

Annual energy flows for a what-if scenario as a Sankey diagram, running from energy carrier through conversion to end use. Use it to see where carriers enter the district and what they ultimately serve.

See LCA Part 1: Energy by Carrier for the underlying results.

Plot - Load Duration Curve by Component

One load duration curve per selected supply component — annual hourly loads sorted from highest to lowest. Reading the curve tells you how a component is actually used: a steep, short curve indicates peaking duty, a long flat one indicates base load.

Useful for sanity-checking sizing before reading cost results.

See LCA Part 1: Energy by Carrier for the underlying results.

Plot - Supply System

Plots the components of energy supply systems, showing what the optimisation selected.

See Energy Supply System Optimisation.

Common Visualisation Workflow

Standard Visualisation Sequence

After completing CEA analyses:

  1. Energy Demand Plots:

    • Plot - Building Energy Demand (annual and intensity)
    • Validate results before proceeding

  2. Life Cycle Analysis Plots (per what-if scenario):

  3. Renewable Energy Plots:

    • Plot - Solar Technology (if solar assessments done)

  4. Comfort Plots (optional):

    • Plot - Building Comfort Chart (verify thermal comfort)

  5. Optimisation Plots (if optimisation done):

    • Plot - Pareto Front (show trade-offs and optimal solutions)

Saving and Sharing Plots

Plots are generated on demand and shown in the app; CEA does not write plot files to the scenario folder. HTML plot files are only produced inside exported canvas archives (data/<cardId>/plot_<i>.html).

  • Image: Hover over a chart and use the camera icon in the chart toolbar to download a PNG
  • Side-by-side views: Arrange plots and maps in the Canvas Builder
  • Underlying data: Use Export Results to .csv (Summary & Analytics) to get the numbers behind a chart
  • Publication figures: CEA has no SVG or PDF export; rebuild the chart from the exported .csv in your own plotting tool

Visualisation Best Practices

Chart Design

  • Clear titles: Describe what is shown
  • Axis labels: Include units
  • Legend: Essential for multi-series charts
  • Colours: Use colour-blind-friendly palettes
  • Annotations: Highlight key findings

Data Presentation

  • Normalise when comparing: Use intensity (per m² or per capita)
  • Sort logically: By value, name, or type
  • Filter for clarity: Don’t show too many buildings (>20 becomes cluttered)
  • Aggregate when needed: Group by building type if many buildings

Storytelling with Charts

  1. Start with overview: Total demand, total emissions
  2. Break down by component: Which services dominate?
  3. Compare across buildings: Identify outliers and patterns
  4. Show time dimension: How do patterns vary over time?
  5. Present solutions: If optimisation done, show improvements

Customising Plots

Plot Parameters

Most bar-chart plot tools expose their appearance settings as parameters: plot title, axis labels, Y-axis range and step, plot type (stacked, grouped, or stacked percentage), X-axis grouping and sorting, and faceting.

Post-Processing

For publication-quality figures:

  1. Export the data with Export Results to .csv (Summary & Analytics)
  2. Recreate the chart in your own plotting tool
  3. Adjust fonts, colours, and labels as needed

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