Calculation of CO₂ Equivalent (CO₂e) Emissions from an Energy Simulation

This document explains how to calculate CO₂-equivalent emissions (CO₂e) from the results of an energy simulation.
The method aligns with ISO 52000, EN 15603, and GHG Protocol frameworks.

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📊 Required Data from the Simulation

For each energy carrier (electricity, natural gas, biomass, district heating, etc.), you need: - Final energy consumption (kWh, usually based on LHV) - (Optional) Exported energy (e.g., PV or CHP generation) - (Optional) Auxiliary information such as generator efficiencies or CHP heat/power split

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⚙️ Calculation Settings

Emission Scopes

• Scope 1: Direct on-site fuel combustion (boilers, CHP, etc.)
• Scope 2: Purchased electricity, steam, heat, or cooling
• Scope 3 (optional): Upstream emissions (extraction, transport, T&D losses)

Electricity Method

• Location-based: Average grid emission factor (annual or time-resolved)
• Market-based: Supplier-specific emission factor (residual mix)

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🧮 General Formula

For each energy carrier \(i\) and time step \(t\):

\[ \mathrm{CO_2e}_{i,t} = E_i(t) \times \mathrm{EF}_{i}^{comb}(t) + E_i(t) \times \mathrm{EF}_{i}^{upstream}(t) \]

where:
- \(E_i(t)\): energy consumption (kWh)
- \(\mathrm{EF}_{i}^{comb}\): direct combustion emission factor (kgCO₂e/kWh)
- \(\mathrm{EF}_{i}^{upstream}\): upstream emission factor (kgCO₂e/kWh)

If emissions are split by gas species (CO₂, CH₄, N₂O):

\[ \mathrm{CO_2e} = \mathrm{CO_2} + \mathrm{CH_4} \times \mathrm{GWP}_{100,CH_4} + \mathrm{N_2O} \times \mathrm{GWP}_{100,N_2O} \]

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🌍 Typical Emission Factors

Energy carrier	Emission factor (kgCO₂e/kWh)	Example source
Electricity (EU grid)	0.25	ENTSO-E 2023
Natural gas (combustion)	0.202	IPCC 2006
Natural gas (upstream)	0.025	DEFRA 2023
Biomass (solid)	0 (biogenic)	IPCC 2006

⚠️ Always use emission factors consistent in region and year.

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🔋 Handling On-Site Generation

• Self-consumed PV: reduces imported grid electricity.
• Exported PV: should not be subtracted from consumption unless the reporting framework allows it.
• CHP systems: allocate fuel emissions between heat and power using an efficiency- or substitution-based method.

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📘 Example Calculation

Energy type	Consumption (kWh)	EF (kgCO₂e/kWh)	Emissions (kgCO₂e)
Electricity (grid)	10,000	0.25	2,500
Natural gas (comb.)	5,000	0.202	1,010
Natural gas (upstream)	5,000	0.025	125
Total	—	—	3,635

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🐍 Example Python Script

import pandas as pd

# Input data (final energy in kWh)
energy = pd.Series({
    'electricity_grid': 10000,
    'natural_gas': 5000,
})

# Emission factors (kgCO2e/kWh)
EF = {
    'electricity_grid': 0.25,   # Scope 2
    'gas_combustion': 0.202,    # Scope 1
    'gas_upstream': 0.025,      # Scope 3
}

co2e = {
    'Scope2_electricity': energy['electricity_grid'] * EF['electricity_grid'],
    'Scope1_gas': energy['natural_gas'] * EF['gas_combustion'],
    'Scope3_gas_upstream': energy['natural_gas'] * EF['gas_upstream'],
}

co2e['Total'] = sum(co2e.values())
print(pd.Series(co2e).round(1))