ESG Simple – Methodology

Basis of the ESG Simple core emission factor catalogue
Contents

1. Objective

The ESG Simple Emission Core is a compact, scientifically grounded and fully transparent catalogue of emission factors developed specifically for small and medium-sized enterprises (SMEs). It covers more than 98% of typical SME emissions and enables reliable reporting without complex specialist databases.
The Emission Core is complemented by a NACE extension in order to represent sector-specific emission factors in a targeted way, without unnecessarily broadening the core catalog.

2. Scientific data basis

All factors are derived from publicly accessible, scientifically recognised sources:
  • UBA (Germany – fuels, energy, district heating)
  • EEA / AIB (European energy and electricity data)
  • EMBER (national electricity mix emission factors by country and year)
  • DEFRA (UK Government GHG Conversion Factors)
  • IPCC (AR5 / AR6, GWP100 values)
  • ÖKOBAUDAT (construction materials)
  • EPA WARM (waste and recycling)
Only sources that are available without a paid licence are used.

3. Methodological principles

GWP100 standard (100-year global warming potential, IPCC)
All CO₂e values are based on GWP100 according to the IPCC (AR5 or AR6, depending on the data source). This ensures compatibility with ESRS E1, the GHG Protocol and ISO 14064-1.
Standardised units
  • kg CO₂e per kg, litre, kWh, m³, tkm or pkm
  • for services: kg CO₂e per EUR
This minimises misuse and facilitates auditing.
System boundaries
  • cradle-to-gate for materials
  • cradle-to-grave for waste / transport
  • gate-to-gate for energy and fuels
The system boundary of each factor is clearly documented.
For location-based electricity emissions (Scope 2), ESG Simple uses national electricity mix emission factors from a central grid mix catalogue. The relevant year is the year in which the reporting period ends. If no factor is available for a country for that year, the most recent available factor for the same country prior to or equal to the reporting year is used. If this is also unavailable, a fallback to the EU electricity mix is applied using the same logic.

4. Catalogue structure

All factors are assigned to a clear classification system:
  • electricity – electricity, district heating, PV credits
  • fuels – fuels, mobile and stationary combustion
  • transport – passenger and freight transport (pkm, tkm)
  • materials – standard materials such as paper, plastics, glass, metals, concrete, wood
  • waste – recycling, incineration, landfill
  • water – water / wastewater
  • refrigerants – refrigerants (IPCC)
  • services – services
  • investments – capital goods (proxy methodology)
  • other – special cases
The catalogue is therefore both GHG-compatible and intuitive to use for SMEs.

5. Versioning and updates

Updates
The core catalogue is regularly reviewed and updated whenever new scientific findings, revised emission factors or relevant data updates become available.
Audit-proof metadata
Each factor contains:
  • Source
  • Version year
  • GWP basis
  • System boundary
  • Valid-from / valid-to
All versions remain permanently accessible, ensuring reproducibility of historical reports.