A complete technical account of how VSME OS calculates greenhouse gas emissions — the data sources used, the formulas applied, and the assumptions made. Designed to satisfy auditor enquiries and ESG due diligence.
GHG Protocol
Corporate Standard
ISO 14064-1:2018
Quantification standard
EU VSME 2025/1710
Commission Recommendation
CSRD ESRS E1
Climate disclosures
All emissions in VSME OS are calculated using the standard activity-based methodology defined by the GHG Protocol:
Emissions (kgCO₂e) = Activity Data × Emission Factor
Where activity data is the quantity of a resource consumed (e.g. kWh of electricity, litres of diesel, km flown) and the emission factor converts that quantity into kg of CO₂ equivalent (kgCO₂e), accounting for all relevant greenhouse gases (CO₂, CH₄, N₂O, HFCs etc.) expressed as CO₂ equivalents using IPCC AR5 GWP100 values.
Emissions from multiple sources are summed to produce scope totals. The grand total is the sum of Scope 1 + Scope 2 (location-based) + Scope 3 emissions, expressed in kgCO₂e or tCO₂e (1 tCO₂e = 1,000 kgCO₂e).
Carbon Intensity Metrics: Where annual revenue is provided, VSME OS calculates two intensity metrics. The primary metric is kgCO₂e per million units of revenue currency (e.g. kgCO₂e / M€), aligned with ESRS E1-6 (GHG intensity of net revenues) and used for cross-supplier comparison. The secondary metric is kgCO₂e per actual EUR of revenue (4 decimal places), useful for absolute cost-of-carbon calculations. Both are shown on Page 1 of the generated report.
VSME OS uses country-specific emission factor databases rather than a single global average. The correct national database is selected automatically based on the supplier's declared country of operations. This is critical for accuracy: France's electricity grid (predominantly nuclear) has a factor of 0.052 kgCO₂e/kWh, while Poland's (predominantly coal) is 0.773 kgCO₂e/kWh — a 15× difference that would produce a fundamentally misleading report if the wrong factor were applied.
| Country / Region | Primary Database | Grid Factor (kgCO₂e/kWh) | Last Updated |
|---|---|---|---|
| France | ADEME Base Carbone 2024 | 0.052 | 2024 Q1 |
| United Kingdom | DEFRA 2025 / National Grid ESO | 0.196 | 2025 Q2 |
| Germany | Umweltbundesamt (UBA) 2023 | 0.380 | 2024 Q1 |
| Spain | MITECO / REE 2023 | 0.181 | 2024 Q1 |
| Italy | GSE Italy / IEA 2023 | 0.233 | 2024 Q1 |
| Netherlands | CBS Netherlands / IEA 2023 | 0.341 | 2024 Q1 |
| Belgium | CREG Belgium / IEA 2023 | 0.167 | 2024 Q1 |
| Sweden | Energimyndigheten 2023 | 0.013 | 2024 Q1 |
| Poland | URE / IEA 2023 | 0.773 | 2024 Q1 |
| USA | US EPA eGRID 2023 | 0.386 | 2024 Q2 |
| Canada | ECCC NIR 2023 | 0.130 | 2024 Q1 |
| Australia | Australian NGA 2023 / Clean Energy Regulator | 0.656 | 2024 Q1 |
| South Africa | DFFE / Eskom 2022 | 0.928 | 2023 Q4 |
| India | BEE / CEA 2022 | 0.708 | 2023 Q4 |
| China | NDRC / IEA 2022 | 0.581 | 2023 Q4 |
| Other (default) | IEA World Average 2023 | 0.494 | 2024 Q1 |
60+ countries are supported. For countries where national grid operators do not publish standalone emission factors, IEA World Energy Statistics 2023 averages are applied as a conservative estimate and clearly labelled as such in the report. Factors are reviewed and updated annually, typically in Q1 following national database publication cycles.
Scope 1 covers emissions from sources owned or controlled by the reporting organisation. VSME OS covers three Scope 1 categories:
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| Natural Gas | kWh | 0.244 | ADEME Base Carbone 2024 | Full lifecycle (combustion 0.205 + upstream 0.039). Conservative approach per GHG Protocol. |
| Heating Oil | litres | 3.200 | ADEME Base Carbone 2024 | Full lifecycle. Gas oil / fuel oil. |
| Propane / LPG | litres | 1.510 | ADEME Base Carbone 2024 | Full lifecycle. Liquefied petroleum gas. |
All fuel factors use ADEME Base Carbone 2024 full lifecycle methodology, which includes combustion CO₂, CH₄, N₂O (IPCC AR5 GWP100) plus upstream extraction and transport emissions. This is more conservative than DEFRA combustion-only Scope 1 factors and is the standard approach in French/EU GHG accounting.
Covers fuel used in vehicles owned or leased by the company (fleet vehicles). Employee personal vehicles reimbursed per km are reported in Scope 3.
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| Diesel (fleet) | litres | 3.160 | ADEME Base Carbone 2024 | Full lifecycle incl. upstream extraction and transport. |
| Petrol / Gasoline | litres | 2.800 | ADEME Base Carbone 2024 | Full lifecycle incl. upstream extraction and transport. |
Refrigerant leaks are high-impact Scope 1 emissions due to the very high Global Warming Potential (GWP) of hydrofluorocarbons. Factors are GWP100 values from IPCC Fifth Assessment Report (AR5, 2013), which is the current standard required by UNFCCC and GHG Protocol.
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| R410A | kg | 2,088 | IPCC AR5 GWP100 | Common AC refrigerant. 50% R32 + 50% R125. |
| R32 | kg | 675 | IPCC AR5 GWP100 | Newer AC refrigerant, lower GWP than R410A |
| R134a | kg | 1,430 | IPCC AR5 GWP100 | Vehicle and light commercial AC |
| R404A | kg | 3,922 | IPCC AR5 GWP100 | Commercial refrigeration. EU F-Gas phase-out. |
EU F-Gas Regulation Note: R404A is being phased out under EU Regulation 517/2014. Organisations using R404A should be planning transition to lower-GWP alternatives. Reporting refrigerant top-ups is legally required for systems ≥3 tonnes CO₂e charge under EU F-Gas Regulation.
Scope 2 covers emissions from purchased electricity, heat, steam, and cooling. VSME OS implements both GHG Protocol Scope 2 methods as required by CSRD ESRS E1:
Uses the average emission factor for the national or regional electricity grid in the country where the energy was consumed. See Section 2 for the full country-specific factor table. This is the default method and the one most commonly required by buyers for Scope 3 Category 3 reporting.
Uses the emission factor from the specific energy contract or certificate:
Both methods are reported in the generated PDF. CSRD ESRS E1-6 requires both to be disclosed. The location-based figure is typically used for Scope 3 Category 3 (buyer's upstream energy) calculations by the buyer.
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| District Heating | kWh | Country-specific | Euroheat & Power 2023 | Derived from country grid mix and typical plant efficiency |
| District Cooling | kWh | Country-specific | IEA methodology | Grid factor ÷ Coefficient of Performance (COP 3.5) |
Scope 3 covers indirect emissions in a company's value chain. VSME OS currently covers Category 6 (Business Travel) and Category 7 (Employee Commuting), which together represent the most material Scope 3 sources for the majority of SME service businesses.
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| Employee Vehicles (Grey Fleet) | km | 0.218 | DEFRA 2024 | Average UK car fleet (petrol+diesel mix). Total annual km across all grey fleet drivers. |
| Rail / Train Travel | km | Country-specific | DEFRA 2024 / national rail operator | UK: 0.036 · France: 0.006 · Germany: 0.023 · Poland: 0.037. Varies by grid mix. |
| Hotel Stays | nights | 28.0 | Cornell/Greenview CHSB 2024 | kgCO₂e per room-night, conservative global estimate — see disclosure below |
VSME OS splits flights into short-haul (under 3,700 km) and long-haul (3,700 km and above). This split matters because:
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| Short-Haul Flights (<3,700 km) | pkm | 0.175 | DEFRA 2025 | Includes Radiative Forcing ×1.9 (IPCC, GHG Protocol recommended). Reduced 31% from 2024 due to post-COVID load factor recovery. |
| Long-Haul Flights (≥3,700 km) | pkm | 0.117 | DEFRA 2025 | Economy class. Includes Radiative Forcing ×1.9. Reduced 40% from 2024 due to post-COVID load factor recovery. |
Radiative Forcing (RF) Multiplier
Aviation emissions at altitude cause additional warming beyond CO₂ alone through contrail formation, cirrus cloud impacts, and NOx effects. The IPCC and GHG Protocol recommend applying a Radiative Forcing Index (RFI) of 1.9× to aviation CO₂ emissions to account for these high-altitude effects. VSME OS applies this multiplier by default, as does DEFRA 2025. This is increasingly required by CSRD auditors and science-based target frameworks. Some legacy calculators omit RF — if comparing VSME OS outputs to another tool that does not include RF, divide VSME OS flight figures by 1.9. Note: DEFRA 2025 significantly revised aviation factors (published June 2025), reducing short-haul by 31% and long-haul by 40%, reflecting post-COVID passenger load factor recovery. VSME OS uses these updated 2025 factors.
pkm = passenger-kilometre. To calculate: number of return trips × route distance × 2 (for return). Route distances can be found using flight distance calculators or IATA published city-pair distances.
Category 7 is the GHG Protocol's category for emissions from employees travelling between their home and their regular workplace. VSME OS covers two sub-categories:
| Activity Source | Unit | Factor (kgCO₂e) | Source | Notes |
|---|---|---|---|---|
| Employee Commuting | km/year (all employees) | 0.141 | DEFRA 2024 / ADEME 2024 | Average mixed-mode commute. Total annual km across all commuting employees. |
| Remote Working Days | WFH days/year (all staff) | 2.840 | DEFRA 2024 / ADEME 2024 | kgCO₂e per WFH day. Covers home heating, cooling, and device energy. |
Remote working note: The 2.840 kgCO₂e/day WFH factor reflects additional home energy consumption attributable to work activity (ADEME 2024, "Empreinte carbone du télétravail"). It is calculated as the marginal energy increase vs a non-working day, applied to the French/EU average residential energy mix. This factor will vary by country in a future update.
Hotel stays — CHSB 2024 disclosure: The 28.0 kgCO₂e/room-night figure is a conservative global estimate derived from the Cornell/Greenview Hotel Carbon Measurement Initiative (CHSB 2024, covering 20,000+ hotels). From CHSB 2024 onwards, Cornell and Greenview no longer publish a single "all hotels" global average, as it can misrepresent results when one segment or geography dominates the dataset. The study now provides segmented benchmarks by asset class, star rating, location type, and climate zone. The 28.0 figure used here is a conservative practitioner estimate for organisations that cannot segment by hotel type. Users with detailed hotel booking data are encouraged to apply geography- and segment-specific CHSB 2024 index values for greater precision. CHSB 2025 (covering 2023 data) is anticipated and this factor will be reviewed upon publication.
VSME OS uses the operational control approach (GHG Protocol, Chapter 3). This means the reporting boundary includes all facilities and vehicles over which the company has operational control — typically the company's own offices, production sites, and owned/leased fleet vehicles. It excludes joint ventures and franchise operations unless specified.
Scope 1 ✓
Scope 2 ✓
Scope 3 ✓
These categories are planned for Phase 3 of the VSME OS roadmap. All currently excluded categories are explicitly listed as boundary exclusions in every generated PDF report (Page 4, Section 5).
Self-Attested (Limited Assurance)
Reports generated by VSME OS are self-attested — they reflect the activity data provided by the supplier and have not been independently verified by a third party. This constitutes "limited assurance" under ISO 14064-3. For many CSRD Scope 3 data collection purposes, self-attested supplier data is acceptable. For highest-tier reporting or where reasonable assurance is required, third-party verification should be engaged.
VSME OS does not independently verify the accuracy of activity data entered by suppliers. The calculation methodology is correct — but the output is only as accurate as the input data. This limitation is disclosed on every generated report.
Future phases will support integration with third-party verification bodies to provide independently assured reports where required.
Emission factors are reviewed and updated annually, following the publication cycles of our primary source databases:
DEFRA UK (2025)
Released June 2025
Used for: UK electricity grid (0.196 combined), flights (major revision), grey fleet, commuting. Next: DEFRA 2026 expected June 2026.
ADEME Base Carbone 2024
Updated July 2025 (v23.6)
Used for: All Scope 1 fuel combustion factors (full lifecycle), French electricity, remote working factor.
IEA / EMBER
Annual, typically Q2
Used for: 40+ country grid factors where no national database is available
IPCC AR5 GWP100
Published 2013, stable
Used for: All refrigerant GWP values
Cornell/Greenview CHSB 2024
Annual
Used for: Hotel night emission factor (conservative global estimate)
When factors are updated, previously generated reports retain the factors that were current at generation time (with version noted in the report). New reports use the latest available factors. The factor version and update date are disclosed in the footer of every generated PDF.
We welcome technical enquiries from ESG auditors, procurement teams, and sustainability consultants.