GUIDEBOOK · CEA-4 APP TRAINING

Emissions

Emissions

Overview

Calculates greenhouse gas emissions for each building and district plant across the full building lifecycle. Produces both lifecycle emissions (embodied + operational over the building’s lifespan) and operational emissions (hourly emissions from energy system operation).

What It Calculates

Embodied (Production) Emissions (kgCO2e):

• Building envelope construction (walls, roof, floor, windows)
• Technical systems (HVAC equipment)
• PV/PVT/SC panel manufacturing (if configured)

Operational Emissions (kgCO2e):

• Per energy carrier (grid electricity, natural gas, oil, coal, wood)
• Per service (space heating, space cooling, DHW, electricity)
• District heating and district cooling (including pumping)
• Hourly timesteps (8,760 hours)

Biogenic Carbon (kgCO2e, negative):

• Carbon stored in timber and bio-based building materials

Demolition Emissions (kgCO2e):

• End-of-life processing at the building’s demolition year

Maintenance and Repair Emissions (kgCO2e):

• Estimated as a fraction of production emissions, not modelled from a schedule
• Charged once per installed generation, on each component’s own replacement cycle

Solar Offset Emissions (kgCO2e, negative):

• Grid emissions avoided by on-site PV/PVT/SC generation

Lifecycle Timeline:

• Year-by-year emissions from construction year through demolition
• Supports grid decarbonisation projections

Scope: which lifecycle stages are included

CEA reports against the EN 15978 lifecycle module framework. Knowing which modules are covered matters when comparing CEA results with a whole-life carbon assessment produced elsewhere — a smaller CEA total may simply reflect a narrower boundary.

Two points worth reading carefully:

demolition is C2-C4, not C1. The underlying material data covers transport, waste processing and disposal, but not the energy of deconstruction itself. The category name is broader than the modules behind it.

Maintenance (B2) and repair (B3) are estimates, not simulations. CEA has no maintenance schedules, so both are taken as a proportion of production emissions, following RICS (2017) and as adopted by Singapore’s Green Mark Version 7 Cn Technical Guide (Table 16):

Both defaults are deliberately conservative. RICS states B2 against A1-A5, but CEA models only A1-A3, so the fraction is applied to a smaller base. Neither figure carries a frequency term, so CEA charges the allowance once per installed generation rather than annually.

Set either fraction to 0 to exclude that module entirely.

Prerequisites

• Final Energy completed for the what-if scenario
• Solar radiation data (for PV-related embodied emissions)
• Zone geometry and building properties

Key Parameters

How to Use

1. Run Final Energy first for the what-if scenario

2. Run Emissions:

   • Navigate to Life Cycle Analysis
   • Select Emissions
   • Select the what-if scenario
   • Optionally configure grid decarbonisation trajectory
   • Click Run

3. Processing time: 2-10 minutes for typical districts

Output Files

All outputs are under {scenario}/outputs/data/analysis/{what-if-name}/emissions/:

Understanding Results

• Buildings using DH/DC show zero operational emissions at building level; actual emissions appear on the plant row as district heating/cooling emissions
• emissions_buildings.csv contains lifecycle totals (operation column sums the full lifecycle, not a single year)
• Timeline files show year-by-year breakdown, useful for tracking trajectories toward net-zero
• Grid decarbonisation linearly interpolates emission factors between reference and target years, reducing operational grid emissions over time

Troubleshooting

Plot - Lifecycle Emissions

Overview

Creates stacked bar charts showing total lifecycle emissions per building, combining embodied, operational, biogenic, demolition, and solar offset categories.

What It Shows

• Positive bars: operational emissions by service + embodied (production, demolition)
• Negative bars: biogenic carbon, PV/PVT/SC offsets
• Title includes the lifecycle year range (e.g. “CEA-4 Lifecycle Emissions (1926 - 2088)”)
• Net-zero buildings show positive and negative bars roughly equal

Key Parameters

Legend Labels

Plot - Emission Timeline

Overview

Visualises how cumulative emissions evolve over time across the district, tracking the trajectory from construction through demolition.

What It Shows

• Cumulative stacked area chart over the lifecycle year range
• Construction spikes (embodied), steady operational accumulation, demolition at end-of-life

Example

Cumulative emission timeline showing district emissions over the building lifecycle:

Key Parameters

Plot - Operational Emissions

Overview

Creates bar charts of operational emissions from energy system operation, with breakdowns by service and/or energy carrier.

What It Shows

• Per-building operational emissions (annual or time-series)
• Breakdown by service or by carrier
• Solar offset emissions (shown as negative)

Example

Operational emissions by energy carrier (percentage breakdown per building):

Key Parameters

Related Features

• Final Energy - Prerequisite (must run first)
• System Costs - Economic analysis of the same what-if scenario
• Heat Rejection - Environmental heat impact
• Visualisation - Additional plotting tools

<- Back: Final Energy | Back to Index | Next: System Costs ->

Source: view raw on GitHub ↗