Selecting & Prioritizing Emission Factors

The selection and prioritization of emission factors represent critical steps in establishing a credible and transparent greenhouse gas (GHG) emissions inventory. In accordance with the principles of the GHG Protocol, organizations are encouraged to adopt the most accurate calculation methods feasible, given their data availability and resource constraints. This pragmatic stance acknowledges that while some entities have access to detailed, supplier-specific data, others may rely on more generic factors.

BeWo’s methodology leverages ERP-derived data and advanced data processing techniques, aiming to employ the highest possible degree of calculation accuracy. By progressively refining data inputs and factor selections, organizations can continuously improve the quality and reliability of their reported emissions—particularly within Scope 3, where data granularity often poses greater challenges.

Estimation Approach Prioritization

The GHG Protocol accommodates multiple calculation approaches. At BeWo, we implement a structured hierarchy, selecting the most specific and accurate methods first and resorting to more generic approximations only when necessary:

Estimation Approach	Accuracy / Priority	Data Form (Units)
Supplier-based	1 (Highest)	Supplier-specific CO2e data
Product-based	2	Physical units (kg, liters, kWh, etc.)
Activity-based	3	Activity-relevant units (km, kg, kWh, etc.)
Spend-based	4 (Lowest)	Monetary units (EUR, USD, DKK, etc.)

Each method corresponds to different data availability scenarios. Higher-priority methods (supplier- and product-based) yield more precise results, while activity- and spend-based methods ensure completeness when more specific data is unavailable.

Supplier-Based Calculations (Priority 1)

Supplier-based calculations utilize direct CO2e statements provided by suppliers. These statements should disclose the methodologies and emission factors used, enabling robust verification and alignment with the GHG Protocol’s recommendations.

• Requirements:

  • Supplier-provided CO2e figures integrated into purchase documentation (e.g., invoices).
  • Transparent methodological notes confirming that calculations align with recognized standards.

• Advantages:

  • Minimizes uncertainty, as data reflects actual supplier practices and product attributes.
  • Ensures high alignment between operational realities and reported emissions.

Product-Based Calculations (Priority 2)

Product-based calculations rely on product-specific emission factors derived from lifecycle assessments (LCAs) or Environmental Product Declarations (EPDs). LCAs are often published in databases aligned with the the Product Environmental Footprint (PEF) framework.

• Requirements:

  • Clear identification of the product in the ERP system.
  • Availability of a corresponding product-level emission factor (LCA/EPD).
  • Matching units between the emission factor and the purchased quantity.

• Advantages:

  • More tailored than activity-based or spend-based approaches.
  • Reflects specific product characteristics and supply chain nuances.

note

The emission factors available on the platform from LCAs and EPDs incorporate only the fossil-based portion of the Global Warming Potential (GWP), excluding biogenic carbon components to ensure alignment with standard carbon accounting practices.

For a more in-depth explanation of LCAs and EPDs, refer to the article on LCA & EPD in our e-learn library.

Activity-Based Calculations (Priority 3)

Activity-based calculations employ average emission factors tied to activities or product categories (e.g., kg of steel, liters of fuel, kWh of electricity). While less specific than supplier- or product-based methods, these factors are widely documented and support meaningful comparisons over time.

• Requirements:

  • Identification of a relevant activity or product category from ERP data.
  • Corresponding activity-based emission factor available in recognized public databases.
  • Unit alignment (e.g., liters of fuel, km traveled, kWh consumed).

• Advantages:

  • Broad applicability when detailed supplier or product data is lacking.
  • Facilitates trend analysis, capturing the impact of strategic changes in material usage or procurement strategies.

Spend-Based Calculations (Priority 4)

Spend-based calculations estimate emissions by applying an emission factor to the monetary value of purchases. Although they ensure completeness when no other method is applicable, they are inherently less precise. Factors such as price fluctuations, discounts, and varying product qualities introduce greater uncertainty.

• Requirements:

  • Monetary value of the purchase from ERP data.
  • Suitable spend-based emission factor correlating expenditure with typical industry emissions.

• Advantages and Limitations:

  • Guarantees completeness, preventing omission of material emission sources.
  • Less accurate due to the indirect nature of the spend-to-emissions relationship.
  • Not recommended for Scope 1 & 2, where more specific methods are typically feasible.

Ensuring Alignment with the GHG Protocol

All emission factors employed within the BeWo platform are selected with attention to GHG Protocol principles. This includes ensuring that biogenic carbon is not conflated with fossil-derived GWP in LCAs and EPDs. For Scope 1 and Scope 2 inventories, higher-tier methods (e.g., product-based or activity-based) are strongly advised to ensure compliance with established standards and to maintain the integrity of reported data.

Continuous Improvement and Transparency

As suppliers begin providing more detailed CO2e statements or organizations gain access to product-specific emission factors, it is possible to transition from lower-priority (e.g., spend-based) to higher-priority methods (supplier- or product-based). Documenting these improvements and maintaining transparency about any remaining limitations reinforces credibility and auditability.

Auditors and stakeholders can thus verify that the chosen emission factors reflect the most accurate and applicable data available, ultimately enhancing trust in the reported emissions figures.

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By systematically selecting and prioritizing emission factors, BeWo’s methodology adheres to the GHG Protocol’s pragmatic guidance. This structured hierarchy ensures that organizations produce credible, meaningful emissions inventories that evolve in precision over time, reflecting genuine operational insights and fostering stakeholder confidence in sustainability reporting.